National Primary Drinking Water Regulations; Disinfectants and Disinfection Byproducts; Proposed Rule

[Federal Register: July 29, 1994]

Part II

Environmental Protection Agency

40 CFR Parts 141 and 142

National Primary Drinking Water Regulations; Disinfectants and
Disinfection Byproducts; Proposed Rule
ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[WH-FRL-4998-2]

Drinking Water; National Primary Drinking Water Regulations:
Disinfectants and Disinfection Byproducts

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: In this document, EPA is proposing maximum residual
disinfectant level goals (MRDLGs) for chlorine, chloramines, and
chlorine dioxide; maximum contaminant level goals (MCLGs) for four
trihalomethanes (chloroform, bromodichloromethane,
dibromochloromethane, and bromoform), two haloacetic acids
(dichloroacetic acid and trichloroacetic acid), chloral hydrate,
bromate, and chlorite; and National Primary Drinking Water Regulations
(NPDWRs) for three disinfectants (chlorine, chloramines, and chlorine
dioxide), two groups of organic disinfection byproducts (total
trihalomethanes (TTHMs)--a sum of the four listed above, and haloacetic
acids (HAA5)--a sum of the two listed above plus monochloroacetic acid
and mono- and dibromoacetic acids), and two inorganic disinfection
byproducts (chlorite and bromate). The NPDWRs consist of maximum
residual disinfectant levels or maximum contaminant levels or treatment
techniques for these disinfectants and their byproducts. The NPDWRs
also include proposed monitoring, reporting, and public notification
requirements for these compounds. This notice proposes the best
available technology (BAT) upon which the MRDLs and MCLs are based and
the BAT for purposes of issuing variances.

DATES: Written comments must be postmarked or hand-delivered by
December 29, 1994. Comments received after this date may not be
considered. Public hearings will be held at the addresses indicated
below under ``ADDRESSES'' on August 29 (and 30, if necessary) in
Denver, CO and on September 12 (and 13, if necessary) in Washington,
DC.

ADDRESSES: Send written comments on the proposed rule to Disinfectant/
Disinfection By-Products Comment Clerk, Drinking Water Docket (MC
4101), Environmental Protection Agency, 401 M Street, S.W., Washington,
D.C. 20460. Commenters are requested to submit three copies of their
comments and at least one copy of any references cited in their written
or oral comments. A copy of the comments and supporting documents are
available for review at the EPA, Drinking Water Docket (4101), 401 M
Street, S.W., Washington, DC 20460. For access to the docket materials,
call (202) 260-3027 between 9:00 a.m. and 3:30 p.m.
The Agency will hold public hearings on the proposal at two
different locations indicated below:

Denver Federal Center, 6th and Kipling Streets, Building 25, Lecture
Halls A and B (3d Street), Denver, CO 80225 on August 29 (and 30, if
necessary), 1994.
EPA Education Center Auditorium, 401 M Street SW., Washington, D.C.
20460, on September 12 (and 13, if necessary), 1994.

The hearings will begin at 9:30 a.m., with registration at 9:00
a.m. The Hearings will end at 4:00 p.m., unless concluded earlier.
Anyone planning to attend the public hearings (especially those who
plan to make statements) may register in advance by writing the D/DBPR
Public Hearing Officer, Office of Ground Water and Drinking Water
(4603), USEPA, 401 M Street, S.W., Washington, D.C. 20460; or by
calling Tina Mazzocchetti, (703) 931-4600. Meeting dates are tentative
and should be confirmed by calling the Safe Drinking Water Hotline
prior to making travel plans. Oral and written comments may be
submitted at the public hearing. Persons who wish to make oral
presentations are encouraged to have written copies (preferably three)
of their complete comments for inclusion in the official record.
Copies of draft health criteria, analytical methods, and regulatory
impact analysis documents are available at some Regional Offices listed
below and for a fee from the National Technical Information Service
(NTIS), U.S. Department of Commerce, 5285 Port Royal Road, Springfield,
Virginia 22161. The toll-free number is (800) 336-4700 or local at
(703) 487-4650.

FOR FURTHER INFORMATION CONTACT: General information may be obtained
from the Safe Drinking Water Hotline, telephone (800) 426-4791; Stig
Regli, Office of Ground Water and Drinking Water (4603), U.S.
Environmental Protection Agency, 401 M Street, SW., Washington, DC
20460, telephone (202) 260-7379; Tom Grubbs, Office of Ground Water and
Drinking Water (4603), U.S. Environmental Protection Agency, 401 M
Street, SW., Washington, DC 20460, telephone (202) 260-7270; or one of
the EPA Regional Office contacts listed below.

SUPPLEMENTARY INFORMATION:

EPA Regional Offices

I. Robert Mendoza, Chief, Water Supply Section, JFK Federal Bldg.,
Room 203, Boston, MA 02203, (617) 565-3610
II. Robert Williams, Chief, Water Supply Section, 26 Federal Plaza,
Room 824, New York, NY 10278, (212) 264-1800
III. Jeffrey Hass, Chief, Drinking Water Section (3WM41), 841
Chestnut Building, Philadelphia, PA 19107, (215) 597-9873
IV. Phillip Vorsatz, Chief, Water Supply Section, 345 Courtland
Street, Atlanta, GA 30365, (404) 347-2913
V. Charlene Denys, Chief, Water Supply Section, 77 W. Jackson Blvd.,
Chicago, IL 60604, (312) 353-2650
VI. F. Warren Norris, Chief, Water Supply Section, 1445 Ross Avenue,
Dallas, TX 75202, (214) 655-7155
VII. Ralph Flournoy, Chief, Water Supply Section, 726 Minnesota
Ave., Kansas City, KS 66101, (913) 234-2815
VIII. Doris Sanders, Chief, Water Supply Section, One Denver Place,
999 18th Street, Suite 500, Denver, CO 80202-2405, (303) 293-1424
IX. Bill Thurston, Chief, Water Supply Section, 75 Hawthorne Street,
San Francisco, CA 94105, (415) 744-1851
X. William Mullen, Chief, Water Supply Section, 1200 Sixth Avenue,
Seattle, WA 98101, (206) 442-1225.
Abbreviations used in this document.

AECL: Alternate enhanced coagulant level
AOC: Assimilable organic carbon
ASDWA: Association of State Drinking Water Administrators
AWWA: American Water Works Association
AWWARF: AWWA Research Foundation
BAC: Biologically active carbon
BAF: Biologically active filtration
BAT: Best Available Technology
BCAA: Bromochloroacetic acid
BDOC: Biodegradable organic carbon
BTGA: Best Technology Generally Available
CI: Confidence interval
CWS: Community Water System
DBP: Disinfection byproducts
D/DBP: Disinfectants and disinfection byproducts
D/DBPR: Disinfectants and disinfection byproducts rule
DBPP: Disinfection byproduct precursors
DBPRAM: DBP Regulatory Assessment model
DPD: N,N-diethyl-p-phenylenediamine
DWEL: Drinking Water Equivalent Level
EBCT: Empty bed contact time
EMSL: EPA Environmental Monitoring and Support Laboratory
(Cincinnati)
EPA: United States Environmental Protection Agency
ESWTR: Enhanced Surface Water Treatment Rule
FY: Fiscal year
GAC: Granular Activated Carbon
GWDR: Ground Water Disinfection Rule
GWSS: Ground Water Supply Survey
HAA5: Haloacetic acids (five)
HOBr: Hypobromous acid
IC: Ion chromotography
ICR: Information Collection Rule
IOC: Inorganic chemical
LOAEL: Lowest observed adverse effect level
LOQ: Limit of Quantitation
MCL: Maximum Contaminant Level (expressed as mg/l, 1,000 micrograms
(<greek-m>g) = 1 milligram (mg))
MCLG: Maximum Contaminant Level Goal
MDL: Method Detection Limit
MF: Modifying factor
mg/dl: Milligrams per deciliter
mg/l: Milligrams per liter
MGD: Million Gallons per Day
MRDL: Maximum Residual Disinfectant Level (as mg/l)
MRL: Minimum reporting level
MRDLG: Maximum Residual Disinfectant Level Goal
NCI: National Cancer Institute
ND: Not detected
NIPDWR: National Interim Primary Drinking Water Regulation
NOAEL: No observed adverse effect level
NOMS: National Organic Monitoring Survey
NORS: National Organics Reconnaissance Survey for Halogenated
Organics
NPDWR: National Primary Drinking Water Regulation
NTNCWS: Nontransient noncommunity water system
OBr: Hypobromite ion
OR: Odds ratio
PE: Performance evaluation
POE: Point-of-Entry Technologies
POU: Point-of-Use Technologies
ppb: Parts per billion
PQL: Practical Quantitation Level
PTA: Packed Tower Aeration
PWS: Public Water System
RIA: Regulatory Impact Analysis
RMCL: Recommended Maximum Contaminant Level
RNDB: Regulations Negotiation Data Base
RSC: Relative Source Contribution
SDWA: Safe Drinking Water Act, or the ``Act,'' as amended in 1986
SM: Standard Method
SMCL: Secondary Maximum Contaminant Level
SMR: Standardized mortality ratios
SOC: Synthetic Organic Chemical
SWTR: Surface Water Treatment Rule
THMFP: Trihalomethane formation potential
TOC: Total organic carbon
TTHM: Total trihalomethanes
TWG: Technologies Working Group
VOC: Volatile Synthetic Organic Chemical
WIDB: Water Industry Data Base
WS: Water Supply

Table of Contents

I. Summary of Today's Action
A. Applicability.
B. Proposed MRDLGs and MRDLs for disinfectants
C. Proposed MCLGs and MCLs for organic byproducts
D. Treatment technique for DBP precursors
E. Proposed Stage 1 MCLGs and MCLs for inorganic byproducts
F. Proposed BAT for disinfectants
G. Proposed BAT for organic byproducts
H. Proposed BAT for inorganic byproducts
I. Proposed Compliance Monitoring Requirements
J. Analytical Methods
K. Laboratory Certification Criteria
L. Variances and Exemptions
M. State Primacy, Recordkeeping, Reporting Requirements
N. System Reporting Requirements
O. D/DBP Stage 2 Rule requirements
P. Guidance
Q. Triennial Regulation Review
II. Statutory Authority
A. MCLGs, MCLs, and BAT
B. Variances and Exemptions
C. Primacy
D. Monitoring, Quality Control, and Records
E. Public Water Systems
F. Public Notification
III. Overview of Existing Interim Standard for TTHMs
IV. Overview of Preproposal Regulatory Development
A. October 1989 Strawman Rule
B. June 1991 Status Report on D/DBP rule development
C. Initiation of Regulatory Negotiation Process
V. Establishing MCLGs
A. Background
B. Proposed MRDLGs and MCLGs

Chlorine, hypochloriteion and hypochlorous acid
Chloramines
Epidemiology Studies of Chlorinated and Chloraminanted Water
Chlorine dioxide, chlorite, and chlorate
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
Dichloroacetic acid
Trichloroacetic acid
Chloral hydrate
Bromate
VI. Occurrence of TTHMs, HAA5, and other DBPs
A. Relationship of TTHMs, HAA5 to disinfection and source water
quality
B. Chlorination Byproducts
C. Other Disinfection Byproducts
Ozonation Byproducts
Chlorine Dioxide Byproducts
Chloramination Byproducts
VII. General Basis for Criteria of Proposed rule
A. Goals of regulatory negotiation
B. Concern for downside microbial risks and unknown risks from
DBPs of different technologies
C. Ecological concerns
D. Watershed protection
E. Narrowing of regulatory options through reg-neg process
VIII. Summary of the Proposed National Primary Drinking Water
Regulation for Disinfectants and Disinfection Byproducts
A. Schedule and coverage
B. Summary of DBP MCLs, BATs, and monitoring and compliance
requirments
C. Summary of disinfectant MRDLs, BATs, and Monitoring and
compliance requirements
D. Enhanced coagulation and enhanced softening requirements
E. Requirement for systems to use qualified operators
F. Basis for analytical method requirements
G. Public Notice Requirements
H. Variances and Exemptions
I. Reporting and Record Keeping requirements for PWSs
J. State Implementation Requirements
IX. Basis for Key Specific Criteria of Proposed Rule
A. 80/60 TTHM/HAA5 MCLs, enhanced coagulation requirements, and
BAT
basis for umbrella concept vs. individual MCLs
basis for level of stringency in MCLs, BAT, and concurrent
enhanced coagulation requirements
basis for enhanced coagulation and softening criteria
basis for GAC definitions
basis for monitoring requirements
B. Bromate MCL and BAT
C. Chlorite MCL and BAT
D. Chlorine MRDL and BAT
E. Chloramine MRDL and BAT
F. Chlorine dioxide MRDL and BAT
G. Basis for analytical method requirements
H. Basis for compliance schedule and applicability to different
groups of systems, timing with other regulations
I. Basis for qualified operator requirements and monitoring
plans
J. Basis for Stage 2 proposed MCLs
X. Laboratory Certification and Approval
A. PE-Sample Acceptance Limits for Laboratory Certification
B. Approval Criteria for Disinfectants and Other Parameters
C. Other Laboratory Performance Criteria
XI. Variances and Exemptions
A. Variances
B. Exemptions
XII. State Implementation
A. Special primacy requirements
B. State recordkeeping
C. State reporting
XIII. System Reporting and Recordkeeping Requirements
XIV. Public Notice Requirements
XV. Economic Analysis
A. Executive Order 12866
B. Predicted cost impacts on public water systems
Compliance treatment cost forecasts
Compliance treatment forecasts
DBP exposure estimates
System level cost estimates
Effect on household costs
Monitoring and State implementation costs, labor burden
estimates
C. Concepts of cost analysis
D. Benefits
XVI. Other Requirements
A. Consultation with State, Local, and Tribal Governments
B. Regulatory Flexibility Act
C. Paperwork Reduction Act
D. National Drinking Water Advisory Council and Science Advisory
Board
XVII. Request for Public Comment
XVIII. References and Public Docket

I. Summary of Today's Action

In 1992 EPA initiated a negotiated rulemaking to develop a
disinfectant/disinfection byproduct rule. The Agency decided to use the
negotiated rulemaking process because it believed that the available
occurrence, treatment, and health effects data were inadequate to
address EPA's concerns about the tradeoff between risks from
disinfectants and disinfection byproducts and microbial pathogen risk,
and wanted all stakeholders to participate in the decision-making on
setting proposed standards. The negotiators included State and local
health and regulatory agency staff and elected officials, consumer
groups, environmental groups, and representatives of public water
systems. The group met from November 1992 through June 1993.
Early in the process, the negotiators agreed that large amounts of
information necessary to understand how to optimize the use of
disinfectants to concurrently minimize microbial and disinfectant/
disinfection byproduct risk were unavailable.
Therefore, the group agreed to propose a disinfectant/disinfection
byproduct rule to extend coverage to all community water systems that
use disinfectants, reduce the current total trihalomethane (TTHM)
maximum contaminant level (MCL), regulate additional disinfection
byproducts, set limits for the use of disinfectants, and reduce the
level of compounds that may react with disinfectants to form
byproducts. These requirements were based on available information. The
group further agreed that revisions to the current Surface Water
Treatment Rule might be required at the same time to ensure that
microbial risk is not increased as byproduct rules go into effect.
Finally, the group agreed that additional information on health risk,
occurrence, treatment technologies, and analytical methods needed to be
developed in order to better understand the risk-risk tradeoff, whether
further control was needed, and how to accomplish this overall risk
reduction.
The outcome of the negotiation was three rules: a Disinfectant/
Disinfection Byproduct rule (this notice), an Enhanced Surface Water
Treatment Rule (also proposed today and appearing separately in today's
Federal Register), and an Information Collection Rule (proposed
February 10, 1994, 59 FR 6332). The Information Collection Rule will
provide information necessary to determine whether the Enhanced Surface
Water Treatment Rule needs to be promulgated and, if so, what
requirements it should set. The Information Collection Rule will also
provide information on the need for, and content of, long-term rules.
The schedule to produce these rules has also been negotiated and is
provided elsewhere in this document. A summary of today's rule follows.
A. Applicability. This action applies to all community water
systems and nontransient noncommunity water systems that add a
disinfectant during any part of the treatment process including
addition of a residual disinfectant. In addition, certain provisions
apply to transient noncommunity water systems that use chlorine
dioxide.
B. Proposed MRDLGs and MRDLs for disinfectants. EPA is proposing
the following maximum disinfectant residual level goals and maximum
residual disinfectant levels.

Disinfectant Residual MRDLG (mg/l) MRDL (mg/l)

(1) Chlorine................ 4 (as Cl<INF>2).......... 4.0 (as Cl<INF>2).
(2) Chloramines............. 4 (as Cl<INF>2).......... 4.0 (as Cl<INF>2).
(3) Chlorine dioxide........ 0.3 (as ClO<INF>2)....... 0.8 (as ClO<INF>2).

C. Proposed MCLGs and MCLs for organic byproducts. EPA is proposing
the following maximum contaminant level goals and maximum contaminant
levels.

MCLG(mg/ MCL(mg/
l) l)

Total trihalomethanes (TTHM)....................... \1\N/A 0.080
Haloacetic acids (five) (HAA5)..................... \2\N/A .060
Chloroform......................................... 0 \1\N/A
Bromodichloromethane............................... 0 \1\N/A
Dibromochloromethane............................... 0.06 \1\N/A
Bromoform.......................................... 0 \1\N/A
Dichloroacetic acid................................ 0 \2\N/A
Trichloroacetic acid............................... 0.3 \2\N/A
Chloral hydrate.................................... 0.04 \3\N/A

\1\Total trihalomethanes are the sum of the concentrations of
bromodichloromethane, dibromochloromethane, bromoform, and chloroform.

\2\Haloacetic acids (five) are the sum of the concentrations of mono-,
di-, and trichloroacetic acids and mono- and dibromoacetic acids.
\3\EPA did not set an MCL for chloral hydrate because the TTHM and HAA5
MCLs and the treatment technique (i.e., enhanced coagulation) for
disinfection byproduct precursor removal will control for chloral

hydrate. (See Section IX.)

D. Treatment Technique for DBP Precursors. EPA is proposing that
water systems that use surface water or ground water under the direct
influence of surface water and use conventional filtration treatment be
required to remove specified amounts of organic materials (measured as
total organic carbon) that may react with disinfectants to form
disinfection byproducts. Removal would be achieved through a treatment
technique (enhanced coagulation or enhanced softening) unless the
system met certain criteria.
E. Proposed Stage 1 MCLGs and MCLs for inorganic by-products. EPA
is proposing the following maximum contaminant level goals and maximum
contaminant levels.

MCLG(mg/
l) MCL(mg/l)

Chlorite.......................................... 0.08 1.0
Bromate........................................... 0 0.010

F. Proposed BAT for disinfectants. EPA is proposing the following
best available technologies for limiting residual disinfectant
concentrations in the distribution system.

Chlorine residual--control of treatment processes to reduce
disinfectant demand and control of disinfection treatment processes to
reduce disinfectant levels
Chloramine residual--control of treatment processes to reduce
disinfectant demand and control of disinfection treatment processes to
reduce disinfectant levels
Chlorine dioxide residual--control of treatment processes to reduce
disinfectant demand and control of disinfection treatment processes to
reduce disinfectant levels.

G. Proposed BAT for organic byproducts. EPA is proposing the
following best available technologies for control of organic
disinfection byproducts in each stage of the rule.

Proposed Stage 1 BAT for organic by-products. Total
trihalomethanes--enhanced coagulation or GAC10, with chlorine as the
primary and residual disinfectant. Total haloacetic acids--enhanced
coagulation or GAC10, with chlorine as the primary and residual
disinfectant.
Proposed Stage 2 BAT for organic byproducts. Total
trihalomethanes--enhanced coagulation and GAC10, or GAC20; with
chlorine as the primary and residual disinfectant. Total haloacetic
acids--enhanced coagulation and GAC10, or GAC20; with chlorine as the
primary and residual disinfectant.
H. Proposed BAT for inorganic by-products. EPA is proposing the
following best available technologies for control of inorganic
disinfection byproducts.

Chlorite--control of treatment processes to reduce disinfectant demand
and control of disinfection treatment processes to reduce disinfectant
levels.
Bromate--control of ozone treatment process to reduce production of
bromate.

I. Proposed Compliance Monitoring Requirements. Compliance
monitoring requirements are explained in Section IX of the preamble and
were developed during the negotiated rulemaking. EPA has developed
routine and reduced monitoring schemes that address the health effects
of each disinfectant or contaminant in an individually appropriate
manner.
J. Analytical Methods. EPA is proposing to withdraw one method for
measurement of chlorine residual and to approve three new methods for
measurement of chlorine residuals. EPA is proposing to approve one new
method for measurement of trihalomethanes; two new methods for
measurement of haloacetic acids; one new method for measurement of
bromate, chlorite, and bromide; and two new methods for measurement of
total organic carbon.
K. Laboratory Certification Criteria. Consistent with other
drinking water regulations, EPA is proposing that only certified
laboratories be allowed to analyze samples for compliance with the
proposed MCLs and treatment technique requirements. For disinfectants
and other specified parameters in today's rule that the Agency believes
can be adequately measured by other than certified laboratories and for
which there is a good reason to allow analysis at other locations
(e.g., for samples which normally deteriorate before reaching a
certified laboratory, especially when taken at remote locations), EPA
is requiring that such analyses be conducted by a party acceptable to
EPA or the State.
L. Variances and Exemptions. Variances and exemptions will be
permitted.
M. State Primacy, Recordkeeping, Reporting Requirements.
Requirements for States to maintain primacy are listed in Section XII
of the preamble. In addition to routine requirements, EPA has included
special primacy requirements.
N. System Reporting Requirements. System reporting requirements
remain consistent with requirements in previous rules.
O. D/DBP Stage 2 Rule requirements. EPA is proposing a total
trihalomethane MCL of 0.040 mg/l and a haloacetic acid (five) MCL of
0.030 mg/l, to apply only to systems using surface water or ground
water under the direct influence of surface water and serving at least
10,000 persons, as part of a plan to develop new standards which
incorporates the results of additional research conducted under the
Information Collection Rule (59 FR 6332).
P. Guidance. EPA is in the process of developing guidance for both
systems and States for implementation of this rule.
Q. Triennial Regulation Review. Under the provisions of the Safe
Drinking Water Act (SDWA or the Act) (Section 1412(b)(9)), the Agency
is required to review national primary drinking water regulations at
least once every three years. As mentioned previously, today's proposed
rule revises, updates, and (when promulgated) supersedes the
regulations for total trihalomethanes, initially published in 1979.
Since that time, there have been significant changes in technology,
treatment techniques, and other regulatory controls that provide for
greater protection for health of persons. As such, in proposing today's
rule, EPA has analyzed innovations and changes in technology and
treatment techniques that have occurred since promulgation of the
initial TTHM regulations. This analysis, contained primarily in the
cost and technology document supporting this proposal, supports
amendment of the TTHM regulation for the greater protection of persons.
EPA believes that the innovations and changes in technology and
treatment techniques will result in amendments to the TTHM regulations
that are feasible within the meaning of SDWA Section 1412(b)(9).

II. Statutory Authority

Section 1412 of the Safe Drinking Water Act, as amended in 1986
(``SDWA'' or ``the Act''), requires EPA to publish Maximum Contaminant
Level Goals (MCLGs) and promulgate National Primary Drinking Water
Regulations (NPDWRs) for contaminants in drinking water which may cause
any adverse effect on the health of persons and which are known or
anticipated to occur in public water systems. Under Section 1401, the
NPDWRs are to include Maximum Contaminant Levels (MCLs) and ``criteria
and procedures to assure a supply of drinking water which dependably
complies'' with such MCLs. Under Section 1412(b)(7)(A), if it is not
economically or technically feasible to ascertain the level of a
contaminant in drinking water, EPA may require the use of a treatment
technique instead of an MCL.
Under Section 1412(b), EPA was to establish MCLGs and promulgate
NPDWRs for 83 contaminants by June 19, 1989. An additional 25
contaminants are to be regulated every 3 years. To meet this latter
requirement, EPA has developed a list of contaminants (National
Drinking Water Priority List; 53 FR 1892) including pesticides, organic
and inorganic elements or compounds, and disinfectants and disinfection
by-products (D/DBP), plus the protozoan Cryptosporidium. From this
list, EPA is to choose at least 25 contaminants for regulation every
three years. Today's regulatory proposal represents part of the first
group of 25 chemicals to be regulated. Both the general contaminants
(organics, inorganics, and pesticides), and the D/DBPs were considered
for regulation. In today's notice, EPA is proposing to regulate certain
disinfectants and disinfection byproducts; Cryptosporidium is proposed
to be regulated in a separate Notice today.
In October of 1990, EPA entered into a consent order with Citizens
Concerned about Bull Run Inc. regarding a timeframe for proposing the
first group of 25. The consent decree stipulated a June 1993 date for
proposal. That decree was subsequently amended to establish a proposal
date of May 30, 1994, for the Disinfectants/Disinfection Byproducts
Rule and a proposal date of February 28, 1995, for the other
contaminants that comprise the required group of 25.

A. MCLGs, MCLs, and BAT

Under Section 1412 of the Act, EPA is to establish MCLGs at the
level at which no known or anticipated adverse effects on the health of
persons occur and which allow an adequate margin of safety. MCLGs are
nonenforceable health goals based only on health effects and exposure
information.
MCLs are enforceable standards which the Act directs EPA to set as
close to the MCLGs as feasible. ``Feasible'' means feasible with the
use of the best technology, treatment techniques, and other means which
the Administrator finds available (taking cost into consideration)
after examination for efficacy under field conditions and not solely
under laboratory conditions (SDWA, section 1412(b)(5)). Also, the SDWA
requires the Agency to identify the best available technology (BAT)
which is feasible for meeting the MCL for each contaminant.
Also, in this proposal, EPA is introducing several new terms--
``maximum residual disinfectant level goals (MRDLGs)'' and ``maximum
residual disinfectant levels (MRDLs)''--to reflect the fact that these
substances have beneficial disinfection properties. As with MCLGs, EPA
has established MRDLGs at the level at which no known or anticipated
adverse effects on the health of persons occur and which allow an
adequate margin of safety. MRDLGs are nonenforceable health goals based
only on health effects and exposure information and do not reflect the
benefit of the addition of the chemical for control of waterborne
microbial contaminants.
MRDLs are enforceable standards, analogous to MCLs, which recognize
the benefits of adding a disinfectant to water on a continuous basis
and in addressing emergency situations such as distribution system pipe
breaks. As with MCLs, EPA has set the MRDLs as close to the MRDLGs as
feasible. The Agency has also identified the best available technology
(BAT) which is feasible for meeting the MRDL for each disinfectant.

B. Variances and Exemptions

Section 1415 authorizes the State to issue variances from NPDWRs
(the term ``State'' is used in this preamble to mean the State agency
with primary enforcement responsibility for the public water supply
system program or EPA if the State does not have primacy). The State
may issue a variance if it determines that a system cannot comply with
an MCL despite application of the best available technology (BAT).
Under Section 1415, EPA must propose and promulgate its finding of the
best available technology, treatment techniques, or other means
available for each contaminant, for purposes of section 1415 variances,
at the same time that it proposes and promulgates a maximum contaminant
level for such contaminant. EPA's finding of BAT, treatment techniques,
or other means for purposes of issuing variances may vary among
systems, depending upon the number of persons served by the system or
for other physical conditions related to engineering feasibility and
costs of complying with MCLs, as considered appropriate by EPA. The
State may not issue a variance to a system until it determines that an
unreasonable risk to health (URTH) does not exist. When a State grants
a variance, it must at the same time prescribe a schedule for (1)
compliance with the NPDWR and (2) implementation of any additional
control measures.
Under Section 1416(a), the State may exempt a public water system
from any MCL or treatment technique requirement if it finds that (1)
due to compelling factors (which may include economic factors), the
system is unable to comply, (2) the system was in operation on the
effective date of the MCL or treatment technique, or, for a newer
system, that no reasonable alternative source of drinking water is
available to that system, and (3) the exemption will not result in an
unreasonable risk to health. Under section 1416(b), at the same time it
grants an exemption, the State is to prescribe a compliance schedule
and a schedule for implementation of any required interim control
measures. The final date for compliance may not exceed three years
after the initial date of issuance unless the public water system
establishes that: (1) the system cannot meet the standard without
capital improvements which cannot be completed within the period of
such exemption; (2) the system has entered into an agreement to obtain
financial assistance for necessary improvements; or (3) the system has
entered into an enforceable agreement to become part of a regional
public water system. For systems which serve 500 or fewer service
connections and which need financial assistance to come into
compliance, the State may renew the exemption for additional two-year
periods if the system is taking all practicable steps to meet the above
requirements.
For exemptions resulting from a NPDWR promulgated after June 19,
1986, the system's final compliance date must be within 12 months of
issuance of the exemption. However, the State may extend the final
compliance date for up to three years if the public water system shows
that capital improvements to meet the MCL or treatment technique
requirement cannot be completed within the exemption period and, if the
system needs financial assistance for the improvements, it has an
agreement to obtain this assistance or the system has an enforceable
agreement to become part of a regional public water system. For systems
that have 500 or fewer service connections that need financial
assistance to comply with the MCLs, the State may renew the exemption
for additional two-year periods if the system is taking all practicable
steps to comply.

C. Primacy

As indicated above, States, territories, and Indian Tribes may
assume primary enforcement responsibility (primacy) for public water
systems under Section 1413 of the SDWA. To date, 55 States and
territories have primacy. To assume or retain primacy, States,
territories, or Indian Tribes need not adopt the MCLGs but must adopt,
among other things, NPDWRs (i.e., MCLs, monitoring, analytical, and
reporting requirements) that are no less stringent than those EPA
promulgates.

D. Monitoring, Quality Control, and Records

Under Section 1401(1)(D) of the Act, NPDWRs are to contain
``criteria and procedures to assure a supply of drinking water which
dependably complies with such maximum contaminant levels; including
quality control and testing procedures to insure compliance with such
levels * * *.''

E. Public Water Systems

Public water systems are defined in section 1401 of the Act as
those systems which provide piped water for human consumption and have
at least 15 connections or regularly serve at least 25 people. By
regulation EPA has divided public water systems into community,
nontransient noncommunity, and (transient) noncommunity water systems.
Community water systems (CWSs) serve at least 15 service connections
used by year-round residents or regularly serve at least 25 year-round
residents (40 CFR 141.2). Nontransient noncommunity water systems
(NTNCWSs) regularly serve at least 25 of the same people over six
months of the year. Schools and factories which serve water to 25 or
more of the same people for six or more months of the year are examples
of NTNCWSs. Transient noncommunity systems, by definition, are all
other public water systems. Transient noncommunity systems may include,
for example, restaurants, gas stations, campgrounds, and churches.
This rule would apply to all CWSs, all NTNCWSs, and any transient
noncommunity water systems that use chlorine dioxide as a disinfectant
or oxidant.

F. Public Notification

Section 1414(c) of the Act requires the owner or operator of a
public water system which does not comply with an applicable maximum
contaminant level or treatment technique, testing procedure, or Section
1445(a) (unregulated contaminant) monitoring requirement to give notice
to the persons served by the system. Notice must also be given if a
variance or exemption is in effect or the system fails to comply with a
compliance schedule resulting from a variance or exemption. EPA's
public notification regulations are codified at 40 CFR Section 141.32.
Those regulations were amended by EPA on October 28, 1987 (52 FR
41534).

III. Overview of Existing Interim Standard for TTHMS

In 1974, researchers in The Netherlands and the United States
clearly demonstrated that total trihalomethanes (TTHMs) are formed as a
result of drinking water chlorination (Rook, 1974; Bellar et al, 1974).
EPA subsequently conducted surveys confirming widespread occurrence of
TTHMs in chlorinated water supplies (Symons, 1975; USEPA, 1978). During
this time toxicological studies became available which supported the
contention that chloroform, one of the four trihalomethanes, is
carcinogenic in at least one strain of rat and one strain of mouse
(National Academy of Sciences, 1977).
EPA then set an interim maximum contaminant level (MCL) for the
TTHMs of 100 <greek-m>g/l as an annual average in November 1979 (USEPA,
1979). This standard was based on the need to balance the requirement
for continued disinfection of water to reduce exposure to pathogenic
microorganisms while simultaneously lowering exposure to animal
carcinogens like chloroform.
The interim TTHM standard only applies to systems serving at least
10,000 people that add a disinfectant (oxidant) to the drinking water
during any part of the treatment process. At their discretion, States
are allowed to extend coverage to smaller size systems. About 80
percent of the smallest systems are served by groundwater systems that
are mostly low in THM precursor content (USEPA, 1979).
The proportion of these small groundwater systems that use chlorine
is less than that of large systems; currently, less than half of these
systems disinfect. Also, the shorter hydraulic detention and chlorine
contact times in the small system distribution systems results in lower
TTHM concentrations. Therefore, drinking water systems serving less
than ten thousand people are less likely to have high concentrations of
TTHMs.
Moreover, these small systems are most likely to have greater risks
of significant microbiological contamination, especially if they reduce
or eliminate chlorination. In 1979, the majority of outbreaks
attributable to inadequate disinfection occurred in small systems.
Further, small systems have limited or no access to the financial
resources and technical expertise needed for TTHM control. Therefore,
EPA concluded that small system resources would best be spent on
maintaining and improving microbiological quality and safety. The
revised drinking water regulations now under consideration will extend
to these small systems as required by the Safe Drinking Water Act
Amendments of 1986 (P.L. 99-339, 1986). EPA will also be considering
disinfection as a treatment technique requirement and maximum
contaminant levels (MCLs) for the residual disinfectants. The impacts
these requirements will have on small systems is an important component
of the regulation development process.

Technology Basis for the Interim TTHM Standard

When an MCL is established for TTHMs or any other contaminant that
can be measured, EPA is not required to specify any particular method
for achieving that standard. Instead, the requirement for the interim
regulations was to set an MCL which could be achieved using technology
generally available in 1974. Three general control alternatives were
available:

(1) use of a disinfectant (oxidant) that does not generate (or produces
less) THMs in water;
(2) treatment to lower precursor concentrations prior to chlorination;
and
(3) treatment to remove THMs after their formation.

There are many possible choices among these broad options and in
some cases a combination of approaches might be necessary. The ultimate
choice was left up to the water supplier based on its individual
circumstances.
EPA's evaluation led to the following conclusions concerning
generally available technologies for setting the TTHM MCL:

(1) alternate oxidants like ozone, chloramines, and chlorine dioxide
are available;
(2) precursor removal strategies like changing the point of
disinfection, off-line raw water storage, and improved coagulation are
available; and,
(3) precursor removal using granular activated carbon (GAC) as a
replacement for existing filter media with a regeneration frequency of
one year is feasible as well as biologically activated carbon (ozone
plus GAC) with a regeneration frequency of every two years.

Three conditions concerning modifications of disinfection processes
were also proposed by EPA:

(1) the total quantity of chlorine dioxide added during the treatment
process should not exceed 1 mg/l;
(2) chloramines should not be utilized as a primary disinfectant; and
(3) monitoring for heterotrophic plate count bacteria (HPC) should be
conducted as determined by the State, but at least every day for a
minimum of one month prior to and six months subsequent to the
modifications.

These recommendations concerning disinfection, although useful,
were deleted from the final regulation to allow States greater
discretion. The basis for the MCL became alternate oxidants and
precursor removal.

Technology Basis for Variances

Later, in 1983, EPA promulgated regulations specifying best
technology generally available for obtaining variances (USEPA, 1983). A
variance is granted by the State when a system has installed the best
technology generally available as specified in the regulation and still
cannot meet the MCL. The best technologies generally available for
variances to the TTHM MCL are:

(1) Use chloramines as an alternate or supplemental disinfectant or
oxidant.
(2) Use chlorine dioxide as an alternate or supplemental disinfectant
or oxidant.
(3) Improve existing clarification for THM precursor reduction.
(4) Move the point of chlorination to reduce TTHM formation and, where
necessary, substituting for the use of chlorine as a pre-oxidant
chloramines, chlorine dioxide, or potassium permanganate.
(5) Use of powdered activated carbon for THM precursor or TTHM
reduction seasonally or intermittently at dosages not to exceed 10 mg/l
on an annual average basis.

EPA also identified Group II technologies, which are not
``generally available,'' but may be available to some systems:

(1) Introduction of off-line water storage for THM precursor reduction.
(2) Aeration for TTHM reduction, where geographically and
environmentally appropriate.
(3) Introduction of clarification where not currently practiced.
(4) Consideration of alternative sources of raw water.
(5) Use of ozone as an alternate or supplemental disinfectant or
oxidant.

Note that GAC and BAC are not mentioned as either Group I or Group
II technologies even though they were discussed as technologies for
standard setting purposes (USEPA, 1979). EPA concluded in its cost and
technologies document for the removal of trihalomethanes from drinking
water that (USEPA, 1981):

(1) GAC in the sand replacement mode of operation is often
inappropriate due to the short performance life and high frequency of
regeneration required to achieve substantial TTHM or THM-formation
potential reduction;
(2) the finding took into consideration costs, but primarily was made
due to the complexities of the modifications to prior unit operations,
i.e., disinfection, and in the logistics of the carbon replacement;
(3) greater operating, maintenance, and monitoring than for other
treatments; and
(4) on-site regeneration had only been demonstrated at one U.S. site.

Thus, EPA decided to defer the decision to include GAC and BAC as
best generally available technology for granting variances under the
Safe Drinking Water Act Amendments of 1974.
EPA also did not list ozonation as being ``generally available''
because:

(1) lack of experience in the U.S.;
(2) mixed results in experimental studies; and
(3) most States require a residual in the distribution system which is
not obtainable with ozone.

Thus, EPA decided to defer the decision to include ozone as best
generally available technology for granting variances under the Safe
Drinking Water Act Amendments of 1974.

Economic Impacts of the Interim Standard

Currently, there are 2,700 community water supply systems serving
at least 10,000 people required to comply with the interim TTHM
regulation. In 1988, a survey of large systems found that, on average,
the MCL of 0.10 mg/l had reduced the concentration of TTHMs by 40 to 50
percent (McGuire and Meadows, 1988). Of these, 33 were in violation of
the standard in FY88 (average=115 <greek-m>g/l, range=108-180
<greek-m>g/l). However, by FY92, only nine systems (a decrease of 73
percent) violated the requirements, for a total of 14 violations. Seven
of the nine violating systems and 12 of the 14 violations occurred in
systems serving 10,000 to 50,000 people. This indicates that even when
systems violate, they are able to return to compliance after one or two
violations of the running annual average.
In 1979, approximately 500 systems were estimated to exceed 100
<greek-m>g/l TTHMs. Most of these were able to come into compliance
with minor modifications of chlorination practices. A smaller portion
used alternate oxidants like chlorine dioxide and chloramines. No
system installed ozone or GAC to meet the interim TTHM regulations.
Compliance with the interim TTHM standard involved estimated capital
expenditures of between $31 million and $102 million and yearly
operating and maintenance costs of between $8 million and $29 million
for systems required to comply with the TTHM MCL (i.e., community water
systems serving a population of at least 10,000 people) (McGuire and
Meadows, 1988).

IV. Overview of Preproposal Regulatory Development

A. October 1989 Strawman Rule

Purpose. EPA was required to develop rules for additional
contaminants under the 1986 Amendments to the Act. In order to solicit
public comment in developing a rule, EPA released a strawman rule
(preproposal draft) in October 1989. A strawman was used because of the
complexity of the problem, the large amount of (occasionally
contradictory) information, and the ability to reorient the rule
approach based on public comment or new data. In this strawman, EPA
included a lead option of setting MCLGs and MCLs for TTHMs, haloacetic
acids, chlorine, chloramines, chlorine dioxide, chlorite, and chlorate.
The Agency also identified potential add-on compounds: chloropicrin,
cyanogen chloride, hydrogen peroxide, bromate, iodate, and
formaldehyde. Some of these compounds could also conceivably be used as
surrogate monitoring compounds for the compounds identified in Table
IV-1 below.

Additional Candidate Byproduct Compounds

Chlorination byproducts Ozonation byproducts

--Individual THMs: chloroform, --Aldehydes: acetaldehyde,
bromodichloromethane, hexanal, heptanal.

dibromochloromethane, bromoform.

--Individual haloacetic acids: mono-, --Organic acids.

di-, and trichloroacetic acids; mono- --Ketones.
and dibromoacetic acids. --Epoxides.
--Individual haloacetonitriles: di- --Peroxides.

and trichloroacetonitrile; --Nitrosamines.

bromochloroacetonitrile,
dibromoacetonitrile.
--Haloketones: 1,1 di- and 1,1,1-
trichloropropanone.

--Chlorophenols: 2-; 2,4-di; and --N-oxy compounds.

2,4,6-trichlorophenol. --Quinones.

--Others: chloral hydrate, N- --Bromine substituted compounds.

organochloroamines.

In addition, the strawman provided that EPA would set treatment
technique requirements or provide guidance for control of the
following: MX, as a surrogate for mutagenicity; total oxidizing
substances, as a surrogate for organic peroxides and epoxides; and
assimilable organic carbon, as a surrogate for microbiological quality
of oxidized waters. Monitoring parameters based on the particular
disinfection process were also identified.
As BAT, EPA included precursor removal (conventional treatment
modifications, GAC of up to 30 minute duration and three months
regeneration), alternate oxidants (ozone plus chloramines, chlorine
dioxide with chlorite removal plus chloramines), and byproduct removal
(aeration, GAC adsorption, reducing agents, AOC removal). Each of the
options had problems. GAC was not universally applicable to all waters
for either precursor removal or DBP removal. Membranes were not
included as BAT because of lack of full-scale experience.
As lead options, EPA included a TTHM MCL of 25 or 50 <greek-m>g/l
and other MCLs based on feasibility analyses similar to those that
would be used to develop the TTHM MCL.
2. Summary of Public Comments. Several commentors expressed a
desire for EPA to look at coordination of requirements with those for
other regulations, including issues such as requirements for
maintenance of distribution system disinfectant residuals and system
optimization for multiple contaminants. Many commentors were concerned
about the lack of health data and the interpretation of existing data.
Many system operators were also concerned about the effects of
modifying their treatment processes to meet DBP MCLs. These concerns
included lowered microbiological protection, creation of conditions
that favored distribution system microbiological growth (e.g., use of
ozone would create biodegradable organics and use of chloramines would
create a nitrogen source), and creation of other environmental problems
when changing treatment (e.g., residual handling with precursor removal
and GAC regeneration). While commentors expressed concern about use of
alternate disinfectants, several offered to provide data and others
recommended epidemiological studies in systems with long histories of
alternative disinfectant use.

B. June 1991 Status Report on D/DBP Rule Development

Purpose and transition from Strawman Rule. EPA published a
status report on the development of D/DBPR in June 1991 that was
designed to indicate the Agency's thinking on rule criteria. The status
report indicated that EPA was considering extending coverage under the
rule to all nontransient systems (instead of just those serving at
least 10,000 people, as under the 1979 TTHM rule) and proposing a
shorter list of compounds for regulation than were included in the 1989
strawman. The 1991 list included disinfectants (chlorine, chloramines,
and chlorine dioxide), THMs, haloacetic acids, chloral hydrate,
bromate, chlorite, and chlorate). For both THMs and haloacetic acids,
three options were included: MCLs for individual compounds, a single
MCL for the total, and a combination of the two. Individual MCLs were
considered because health risks for compounds differed, in some cases
significantly. The total MCL was considered because of the precedent
established in the 1979 TTHM rule and to act as a surrogate to limit
other DBPs for which the Agency lacked adequate health effects and/or
occurrence data.
The list of compounds was shorter than that in the 1989 strawman
for several reasons. Several compounds were deleted because they did
not appear to pose significant health effects at levels present in
drinking water (e.g., haloacetonitriles, chloropicrin). Others were
deleted because the health risks were not expected to be adequately
characterized in time for rule proposal (e.g., certain aldehydes and
organic peroxides), although it was noted that these compounds might be
regulated in the future when more data became available.
Major issues. In the status report, EPA identified several major
issues that needed to be considered as the D/DBP rule was developed.
The first was that of trade-offs with microbial and DBP risks. The goal
was to ensure that the water remained microbiologically safe at the
level that disinfectant and DBP MCLs were set. The discussion raised
questions regarding uncertainties in defining microbial and DBP risks,
levels of risks that would be considered acceptable and at what cost,
and defining practical (implementable) criteria to demonstrate that an
achievable risk had been reached.
The second issue was the use of alternate disinfectants to limit
chlorination byproducts. The Agency recognized that while alternate
disinfection schemes (e.g., ozone and chloramines) could greatly reduce
byproducts typical of chlorination, little was known about the
byproducts of the alternate disinfectants and their associated health
risks. EPA did not want to promulgate a standard that encouraged the
shift to alternate disinfectants unless the associated risks (including
both those from byproducts and differential microbial risks from a
change in disinfectants) were adequately understood.
The third issue was integration with the Surface Water Treatment
Rule. Although the rule only mandated 3-log removal or inactivation of
Giardia and 4-log of viruses, EPA guidance recommended higher levels
for poorer quality source waters. EPA was concerned that systems would
reduce microbial protection to levels nearer to the regulatory
requirements by reducing disinfection and possibly greatly increase
microbial risks in an effort to meet DBP MCLs. The Agency wanted to
ensure adequate microbial protection while reducing risk from DBPs.
The last issue was the best available technology. The BAT defined
would determine the levels at which MCLs were set. For example,
allowing alternate disinfectants as BAT would drive the chlorination
byproduct MCLs down, but could result in increased exposure to (not
well characterized) alternate byproducts. EPA believed that it
therefore might be appropriate to define chlorine and a precursor
removal technology as BAT.
To address these issues, EPA suggested two possible regulatory
strategies. One was to define the MCL(s) based on what was possible to
achieve using the most effective DBP precursor removal strategy as BAT
(e.g., GAC or membrane filtration). While installing such precursor
removal technology might minimize health concerns, the costs would be
substantial (without finding out if other less costly technologies,
such as use of alternative disinfectants, provided similar benefits).
Also, since systems are not required to install BAT to meet MCLs, EPA
believed that many systems would attempt to meet the MCLs by lower-cost
alternative disinfectants (ozone, chloramines, chlorine dioxide). Since
health effects for alternative disinfectant byproducts are not
adequately characterized, risks may not be reduced.
The second strategy was a two-phase regulation, with the first
phase designed to address risks using lower cost options during
concurrent efforts to obtain more data on treatment alternatives and
health effects of compounds not currently adequately characterized.
This strategy would prevent major shifts into use of new treatment
technology until the full consequences of such shifts (both costs and
benefits) are better understood.
Suggested monitoring scenario. In its fact sheet accompanying
the status report, EPA recommended that routine TTHM and haloacetic
acid monitoring for systems serving at least 10,000 people have the
same monitoring requirements as were in the 1979 TTHM rule. Smaller
systems would have less frequent monitoring requirements, but would
have compliance based on worst-case samples. EPA included provisions
for reduced monitoring (compliance based on worst-case samples or
surrogate monitoring), waiver criteria, and requirements for
disinfectant and other DBP monitoring.
Summary of public comments. EPA received comments on the status
report from numerous parties. Many commentors agreed with EPA's
concerns with issues such as alternative disinfectant DBPs and
balancing microbial and DBP risks. Several commentors supported the
two-phase regulatory approach, but expressed concern about timing.
Others recommended that DBP MCLs not be set so low as to force many
systems to install expensive technology or decrease microbial
protection. Several commentors were concerned with the availability of
both analytical methods and certified laboratories for the low levels
that were being considered. One commentor recommended that EPA make it
clear that MCLs set for disinfectants should allow temporary high
levels to address distribution system microbiological problems.
Finally, many commentors supported allowing reduced monitoring wherever
possible.

C. Initiation of the Regulatory Negotiation Process

EPA became interested in pursuing a negotiated rulemaking process
for the development of the D/DBP rule, in large part, because no clear
path for addressing all the major issues identified in the June 1991
Status Report on D/DBP rule was apparent. EPA's most significant
concern was developing regulations for DBPs while also ensuring that
adequate treatment be maintained for controlling microbiological
concerns. A negotiated rule process would help people understand the
complexities of the risk-risk tradeoff issue and, hopefully, reach a
consensus on the most appropriate regulation to address concerns from
both DBPs and microorganisms.
It also appeared to EPA that the criteria for initiating a
negotiated rule under the Negotiated Rulemaking Act of 1990 for
establishing a negotiated rulemaking could be met. These include:
(1) there is a need for a rule,
(2) there are a limited number of identifiable interests that will
be significantly affected by the rule,
(3) there is a reasonable likelihood that a committee can be
convened with a balanced representation of persons who--
(A) can adequately represent the interests identified under
paragraph (2); and
(B) are willing to negotiate in good faith to reach a consensus on
the proposed rule,
(4) there is a reasonable likelihood that a committee will reach a
consensus on the proposed rule within a fixed period of time,
(5) the negotiated rulemaking procedure will not unreasonably delay
the notice of proposed rulemaking and the issuance of a final rule,
(6) the Agency has adequate resources and is willing to commit such
resources, including technical assistance, to the committee, and
(7) the Agency, to the maximum extent possible consistent with the
legal obligations of the Agency, will use the consensus of the
committee with respect to the proposed rule as the basis for the rule
proposed by the Agency for notice and comment.
In 1992 EPA hired a contractor, Resolve, which added a
subcontractor, Endispute, to assess the feasibility and usefulness of
convening a negotiated rulemaking. Resolve and Endispute conducted more
than forty interviews during the summer of 1992 with representatives of
State and local health and regulatory agencies, water suppliers,
manufacturers of equipment and supplies used in drinking water
treatment, and consumer and environmental organizations. These
interviews revealed that:
(1) The entities interested in or affected by the rulemaking were
readily identifiable and relatively few in number.
(2) The rulemaking required resolution of a limited number of
interdependent issues, about which there appeared to be a sufficiently
well-developed factual base to permit meaningful discussion. Further,
there appeared to be several ways to resolve these issues, providing a
potential basis for productive joint problem-solving.
(3) The parties expressed some common goals, along with an
unusually strong degree of good faith interest in resolving the issue
through negotiation.
(4) The Agency had adequate staff and technical resources and was
willing to commit such resources to the negotiated rulemaking.
Resolve and Endispute recommended to EPA that the negotiated
rulemaking proceed. EPA concurred with this recommendation.
However, it was also noted that reaching consensus on the proposed
rule would be a challenge. The interviews revealed that parties
differed in their perceptions about the nature and magnitude of the
risks associated with DBPs, and many expressed strong doubts about the
adequacy of available scientific and technical information. Moreover,
some parties stated that marginal improvements in disinfection
technology were all that should be done until the relative risks are
better understood, while others said that a fundamentally new approach
focusing on precursor reduction should be considered.
EPA published a notice of intent to proceed with a negotiated
rulemaking on September 15, 1992 (57 FRN 42533), proposing 17 parties
to be Negotiating Committee members. In general, comments indicated
very positive support for the negotiated rulemaking.
As part of the convening process, an organizational meeting was
held September 29-30, 1993. Participants discussed Negotiating
Committee composition and organizational protocols. Between comments
expressed at the meeting and submitted in writing, eleven additional
parties--including water suppliers not substantially represented by the
Committee's original proposed membership, and chemical and equipment
suppliers--asked to be added to the Committee. In addition,
participants discussed the need to develop accurate scientific and
technical information.
On November 13, 1992, EPA published a notice of establishment for
the Negotiating Committee (57 FRN 53866), and an 18th member was added
to the Negotiating Committee.
Based on comments received at the organizational meeting, a
Technical Workshop was organized and conducted on November 4-5, 1992.
Composed of presentations and panel discussion by 23 of the Nation's
leading experts on drinking water treatment, the workshop provided
participants with opportunities to familiarize themselves with the
technical elements in this rulemaking and to explore the range of
scientific opinions about: (1) The nature and magnitude of potential
health effects from exposure to DBPs and microbial contaminants in
drinking water, (2) available information on the cost and efficacy of
precursor removal and drinking water disinfection technologies, and (3)
EPA's efforts to model and compare chemical and microbial risks in
drinking water.
Additional presentations were given throughout the rulemaking
process, as new information became available and more questions were
raised by participants.
At the first formal negotiating session, on November 23-24, 1992,
participants formed a technologies working group (TWG) to develop
reliable and consistent information about the cost and efficacy of
drinking water treatment technologies. This approach provided a forum
for participants to arrive at a shared understanding of complex issues
in the rulemaking, setting a cooperative tone for the rest of their
discussions. The working group, which continued to meet throughout the
rulemaking, also provided a formal opportunity for input from the
chemical and equipment suppliers who had not been named to the
Committee.
In addition, three experts were hired through EPA's contract with
Resolve to provide ongoing scientific advice and technical support to
participants in the Committee and on the technologies working group,
principally for members without access to similar resources within
their own organizations.
Based on scientific data presented and discussed through the
November 23-24 meeting, participants agreed that some type of DBP Rule
was warranted.
The Committee developed and reached agreement on criteria for a
``good'' DBP Rule at the September 29-30 and November 23-24 meetings. A
good rule is one which would be flexible and affordable and would
protect public health from chemical and microbial risks. It was noted
that limiting some DBPs could encourage changes in treatment that might
increase the formation of other DBPs, or compromise protections against
microbial contaminants.
Next, Committee members and other participants were invited to
present regulatory options as a starting point for further discussion.
Sixteen options were introduced at the December 17-18 meeting, and
discussed at the meeting on January 13-14, 1993. These were merged into
three consolidated options at the January 13-14 meeting, and discussion
continued at the meeting on February 9-10. At this point, areas of
disagreement included:
(1) Whether to regulate DBPs through Maximum Contaminant Levels
(MCLs) or through a treatment technique (i.e., by exceeding DBP
``action levels,'' systems would trigger additional steps to minimize
chemical and microbial risks).
(2) Whether to minimize formation of the DBPs about which
relatively little is known by establishing a regulatory limit for their
naturally occurring organic precursors (e.g., Total Organic Carbon, or
TOC) in the water prior to the point of disinfection.
(3) Whether to provide greater protection against microbial
contaminants in drinking water, in conjunction with new DBP limits, by
developing an enhanced Surface Water Treatment Rule (ESWTR).
(4) Whether to develop a second round of DBP controls along with
the first (assuring broad improvements in drinking water quality), or
to wait until better scientific information becomes available.
Concurrently, the TWG modelled systems' potential compliance
choices under several regulatory scenarios, and presented revised
household and national compliance cost estimates at several meetings.
Using a ``strawman'' developed from the consolidated options by EPA
staff as the starting point for negotiation, the Committee worked out
an ``agreement in principle'' on the first round of DBP controls at its
February 24-25 meeting. The ``Stage 1'' agreement set MCLs for
trihalomethanes and haloacetic acids--two principal classes of
chlorination by-products--at levels the Committee deemed protective of
public health, based on current information: 80 and 60 micrograms per
liter, respectively. To limit DBP precursors, the Committee agreed to
develop a series of ``enhanced coagulation'' requirements, to vary
according to systems' influent water quality and treatment plant
configurations. Members also agreed to reconvene in several years to
develop a second stage of DBP regulations, when the results of more
health effects research and water quality monitoring are available. In
addition, members agreed that more expeditious changes to the rules may
be necessary if additional information becomes available on short- term
or acute health effects of DBPs. Members also agreed that, if data on
short-term or acute health effects warrant earlier action, a meeting
shall be convened to review the results and to develop recommendations.
A drafting group was named at the February 24-25 meeting. Assisted
by the TWG, these members drafted an ``agreement in principle'' for
presentation and discussion at the March 18-19 meeting. Using ``straw''
provisions from the facilitators, the Committee devised a regulatory
``backstop'' (i.e., Stage 2 MCLs of 0.040 mg/l for TTHMs and 0.030 mg/l
for HAA5 for surface water systems serving at least 10,000 people) at
this meeting to assure participants favoring further DBP controls that
other members would return for the ``Stage 2'' negotiation. The
Committee also agreed to recommend that EPA propose several ESWTR
options for comment, developed a collaborative process to guide the
health effects research program, and agreed to formulate short-term
water quality and technical data collection provisions within an
Information Collection Rule.
Based on the discussion to this point, one member withdrew from the
Committee at the March 18-19 meeting.
The drafting group presented regulatory language for the DBP Rule,
ESWTR, and ICR at each of the Committee's last two meetings, held May
12-13 and June 22-23, 1993. These texts provided a framework for
further discussion and resolution of remaining issues, including:
limits for residual disinfectants and individual by-products; public
notification and affordability provisions; and timing, applicability,
and conditions under which systems might qualify for exceptions from
various requirements. Committee members agreed to reserve their rights
to comment on the draft preambles.
The drafting group continued working through the summer of 1993,
and revisions to each of the rules and their preambles were mailed to
the Committee for comment on July 8, 1993, September 8, 1993, February
8, 1994, and May 12, 1994. Each member had signed the agreement by June
7, 1994.
Unless otherwise noted, EPA has adopted the recommendations of the
Negotiating Committee and its Technologies Working Group and reflects
those recommendations in the following preamble and proposed
regulations.

V. Establishing MCLGs

A. Background

MCLGs and MCLs Must Be Proposed and Promulgated Simultaneously
Congress revised the Safe Drinking Water Act in 1986 to require
that MCLGs and National Primary Drinking Water Regulations (NPDWRs) be
proposed simultaneously and promulgated simultaneously [SDWA section
1412 (a)(3)]. Simultaneous promulgation was intended to streamline the
development of drinking water regulations.
How MCLGs Are Developed
MCLGs are set at concentration levels at which no known or
anticipated adverse health effects occur, allowing for an adequate
margin of safety. Establishment of an MCLG for each specific
contaminant depends on the evidence of carcinogenicity from drinking
water exposure or an assessment for adverse noncarcinogenic health
effects.
a. MCLG Three Category Approach. EPA currently follows a threecategory
approach in developing MCLGs for drinking water contaminants
(Table V-1).

Table V-1.--EPA'S Three-Category Approach for Establishing MCLGs

Evidence of

Category carcinogenicity via MCLG approach

drinking water\1\

I...................... Strong evidence Zero.

considering weight of
evidence,
pharmacokinetics,
potency and exposure.

II..................... Limited evidence RfD approach with

considering weight of added safety margin
evidence, of 1 to 10 or 10-5 to
pharmacokinetics, 10-6 cancer risk
potency and exposure. range.

III.................... Inadequate or no animal RfD approach.

evidence.

\1\Considering oral exposure data such as drinking water, dietary and

gavage studies.

Each chemical is evaluated for evidence of carcinogenicity from
drinking water. For volatile contaminants, inhalation data are also
considered. EPA takes into consideration the overall weight of evidence
for carcinogenicity, pharmacokinetics, potency and exposure.
EPA's policy is to set MCLGs for Category I contaminants at zero.
The MCLG for Category II contaminants is calculated by using the
Reference dose (RfD) approach (described below) with an added margin of
safety to account for possible cancer effects. If adequate data are not
available to calculate an RfD, then the MCLG is based on a cancer risk
level of 10-5 to 10-6. MCLGs for Category III contaminants
are calculated using the RfD approach.
Category I contaminants are those for which EPA has determined that
there is strong evidence of carcinogenicity from drinking water. The
MCLG for Category I contaminants is set at zero because it is assumed,
in the absence of other data, that there is no threshold dose for
carcinogenicity. In the absence of route specific (e.g., oral) data on
the potential cancer risk from drinking water, chemicals classified as
Group A or B carcinogens (see section c below) are generally placed in
Category I.
Category II contaminants include those contaminants for which EPA
has determined that there is limited evidence of carcinogenicity from
drinking water, considering weight of evidence, pharmacokinetics,
potency, and exposure. In the absence of route specific data, chemicals
classified in Group C (see section c below) are generally placed in
Category II.
For Category II contaminants, one of two options have traditionally
been used to set the MCLG. The first option sets the MCLG based upon
noncarcinogenic endpoints of toxicity (the RfD), then applies an
additional safety factor of 1 to 10 to the MCLG to account for possible
carcinogenicity. An MCLG set by the option 1 approach is compared with
the cancer risk, if quantified. The second option is to set the MCLG
based upon a theoretical lifetime excess cancer risk level of 10-5
to 10-6 using a conservative mathematical extrapolation model. EPA
generally uses the first option; however, the second approach is used
when valid noncarcinogenic data are not available to calculate an RfD
and adequate experimental data are available to quantify the cancer
risk.
Category III contaminants include those contaminants for which
there is inadequate or no evidence of carcinogenicity from drinking
water. If there is no additional information to consider, contaminants
classified in Group D or E (see section c below) are generally placed
in Category III. For these contaminants, the MCLG is established using
the RfD approach.
b. Assessment of Noncancer Health Effects. The risk assessment for
noncancer health effects can be characterized by a Reference Dose
(RfD). The oral RfD (expressed in mg/kg/day) is an estimate, with
uncertainty spanning perhaps an order of magnitude, of a daily exposure
to the human population (including sensitive subgroups) that is likely
to be without an appreciable risk of deleterious health effects during
a lifetime. The RfD is derived from a no- or lowest-observed-adverseeffect
level (called a NOAEL or LOAEL, respectively) that has been
identified from a subchronic or chronic study of humans or animals. The
NOAEL or LOAEL is then divided by an uncertainty factor(s) to derive
the RfD. Although the RfD is represented as a point estimate, it is
actually a range since the RfD is a number with an inherent uncertainty
of an order of magnitude.
Uncertainty factors are used to estimate the comparable ``noeffect''
level for a large heterogeneous human population. The use of
uncertainty factors accounts for several data gaps including intra- and
inter-species differences in response to toxicity, the small number of
animals tested compared to the size of the population, sensitive
subpopulations and the possibility of synergistic action between
chemicals (see 52 FR 25690 for further discussion on the use of
uncertainty factors).
EPA has established certain guidelines (shown below) to determine
how to apply uncertainty factors when establishing an RfD (USEPA,
1986).
<bullet> Use a 1- to 10-fold factor when extrapolating from valid
experimental results from studies in average healthy humans. This
factor is intended to account for the variation in sensitivity among
the members of the human population.
<bullet> Use an additional 10-fold factor when extrapolating from
valid results of long-term studies on experimental animals when results
of studies of human exposure are not available or are inadequate. This
factor is intended to account for the uncertainty in extrapolating
animal data to the case of humans.
<bullet> Use an additional 10-fold factor when extrapolating from
less than chronic results on experimental animals when there are no
useful long-term human data. This factor is intended to account for the
uncertainty in extrapolating from less than chronic NOAELs to chronic
NOAELs.
<bullet> Use an additional 10-fold factor when deriving an RfD from
a LOAEL instead of a NOAEL. This factor is intended to account for the
uncertainty in extrapolating from LOAELs to NOAELs.
<bullet> An additional uncertainty factor may be used according to
scientific judgment when justified.
<bullet> Use professional judgment to determine another uncertainty
factor (also called a modifying factor, MF) that is greater than zero
and less than or equal to 10. The magnitude of the MF depends upon the
professional assessment of scientific uncertainties of the study and
data base not explicitly treated above, e.g., the completeness of the
overall data base and the number of species tested. The default value
for the MF is 1.
To determine the MCLG, the RfD is adjusted by the body weight of
the protected (or most sensitive) individual (usually a 70 kg adult),
average volume of water consumed daily over a lifetime (2 L/day for an
adult) and exposure to the contaminant from a drinking water source
(relative source contribution or RSC).
Generally, EPA assumes that the RSC from drinking water is 20
percent of the total exposure, unless other exposure data for the
chemical are available [see 54 FR 22069 and 56 FR 3535]. When adequate
data are available and the data indicate that drinking water exposure
contributes between 20 and 80 percent of total exposure, EPA uses the
actual percentage to determine the MCLG, as is indicated by equation
(3), below. When data indicate that contributions from drinking water
are between zero and 20 percent, or between 80 and 100 percent, EPA
utilizes a 20 percent floor and an 80 percent ceiling, respectively.
The calculations below express the derivation of the MCLG based on
noncancer health effects:

<GRAPHIC><TIFF>TP29JY94.000

c. Assessment of Carcinogenic Health Effects. For chemicals
suspected of being carcinogenic to humans, the assessment for nonthreshold
toxicants consists of the weight of evidence of
carcinogenicity in humans, using bioassays in animals and human
epidemiological studies as well as information that provides indirect
evidence (i.e., mutagenicity and other short-term test results). The
objectives of the assessment are to determine the level or strength of
evidence that the substance is a carcinogen and to provide an
upperbound estimate of the possible risk of human exposure to the
substance in drinking water. A summary of EPA's general carcinogen
classification scheme is (USEPA, 1986):
Group A--Human carcinogen based on sufficient evidence from
epidemiological or other human studies.
Group B--Probable human carcinogen based on limited evidence of
carcinogenicity in humans (Group B1) or based on sufficient evidence in
animals with inadequate or no data in humans (Group B2).
Group C--Possible human carcinogen based on limited evidence of
carcinogenicity in animals in the absence of human data.
Group D--Not classifiable based on lack of data or inadequate
evidence of carcinogenicity from animal data.
Group E--No evidence of carcinogenicity for humans (no evidence for
carcinogenicity in at least two adequate animal tests in different
species or in both epidemiological and animal studies).
d. MRDLGs--appropriateness of a new concept? As stated in section
II.A of this preamble, EPA is proposing a new term, ``maximum residual
disinfectant level goal'' (MRDLG), in lieu of MCLGs for all
disinfectants because disinfectants are intentionally added to drinking
water as a treatment technique to kill disease-causing microorganisms.
The proposal of this concept was agreed to through the negotiated
rulemaking process.
Certain members of the Negotiating Committee were concerned that if
``MCLGs,'' which included the term ``contaminant,'' were set for
disinfectants, water treatment plant operators might be reluctant to
apply disinfectant dosages above the MCLG during short periods of time
to control for microbial risk, even though such exposure to elevated
disinfectant concentration levels would pose little or no risk. For
example, NOAELs for chlorine and chloramines are based upon animal
studies following long term exposure to high levels of the
disinfectants in drinking water. Short-term exposures at elevated
levels would not be a concern (see the following discussion on health
effects for chlorine and chloramines). During emergency situations such
as distribution system pipe breaks or significant fluctuations in
source water quality, systems will on occasion need to apply short term
disinfectant residual concentrations of chlorine or chloramines, well
above the regulatory goal, to protect from waterborne disease.
The MRDLGs are developed in the same way as MCLGs. EPA solicits
comment on the appropriateness of adopting the term ``MRDLG'' in lieu
of MCLGs for disinfectants in the final rule.

B. Proposed MRDLGs and MCLGs

The following includes a summary of the health effects information
available for each disinfectant or by-product. These summaries are
taken from more complete and comprehensive descriptions of the data
given in the cited Health Criteria Documents that have been developed
for each of these chemicals. These documents are available in the water
docket.

Chlorine, hypochlorite ion and hypochlorous acid
The following assessment for both chlorine and chloramines includes
a consideration of available animal data, as well as epidemiology
studies which have been conducted on chlorinated or chloraminated
drinking water. The epidemiology data are discussed in section C of
this preamble.
Chlorine (CAS # 7782-50-5) hydrolyses in water to form hypochlorite
(CAS # as sodium salt 7790-92-3) and hypochlorous acid (CAS # 7681-52-
9). Because of their oxidizing characteristic and solubility, chlorine
and hypochlorites are used in water treatment to disinfect drinking
water, sewage and wastewater, swimming pools, and other types of water
reservoirs. They are also used for general sanitation and control of
bacterial odors in the food industry.
Chlorine is a highly reactive and water soluble species. The fate,
transport, and distribution of chlorine in natural waters is not well
understood. Much of the available information comes from the addition
and oxidation reactions with inorganic and organic compounds known to
occur in aqueous solutions. Factors such as reactant concentrations,
pH, temperature, salinity and sunlight influence these reactions.
Occurrence and Human Exposure. For the purpose of setting an MRDLG,
consideration is given to chlorine levels resulting from disinfection
of drinking water. Chlorine exposures from swimming pools and hot tubs
are not evaluated in determining the MRDLG. Persons who swim frequently
or use a hot tub may have greater dermal and possibly inhalation
exposure to chlorine.
Chlorine is added to drinking water as chlorine gas (Cl<INF>2) or
as calcium or sodium hypochlorite. In drinking water, the chlorine gas
hydrolyses to hypochlorous acid and hypochlorite ion and can be
measured as the free chlorine residual. Maintenance of a chlorine
residual throughout the distribution system is important for minimizing
bacterial growth and for indicating (by the absence of a residual)
water quality problems in the distribution system. Currently, maximum
chlorine dosage is limited by taste and odor constraints and for
systems needing to comply with the total trihalomethane (TTHM) standard
regularly. Additionally, for systems using chlorination, the surface
water treatment rule (SWTR) requires a minimum residual of 0.2 mg/L
prior to the entry point to the distribution system, and the presence
of a detectable residual throughout the distribution system.
Table V-2 presents occurrence information available for chlorine in
drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' USEPA 1992a. The
table lists five surveys conducted by Federal, as well as private
agencies. Median concentrations of chlorine in drinking water appear to
range from <1 to 2 mg/L.

Table V-2.--Summary of Occurrence Data for Chlorine

Occurrence of chlorine in drinking water

Concentration (mg/L)

Survey (year)\1\ Location Sample information (No. of ----------------------------------------------------------------

samples) Range Mean Median Other

EPA, 1992b\2\ (1987-1991). Disinfection By-Products Finished Water:
Field Studies. At the Plant (71).............. 0.1-5.0 1.7 1.4
Distribution System (45)....... 0.0-3.2 0.7 0.5
AWWARF (1987) McGuire & National Survey........... Finished Water From: (Typical doses).
Meadow, 1988. Lakes.......................... 2.2\3\
Flowing Streams................ 2.3\3\
Ground Waters.................. 1.2\3\
Mixed-supplies................. 1.0\3\

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell 0.3-5.2 1.5 1.0 ........................

1989) Krasner et al., Nationwide. Effluent, 4 Quarters (17).
1989b.

WIDB (1989-1990).......... 228 SW Plants............. Residual Chlorine Provided to 0-3.5 0.937 0.8 ........................

215 GW Plants............. the Average Customer (systems 0-5 0.872 0.325
>50,000 people).

AWWA Disinfection Survey 283 Utilities in the U.S.. Finished Water Entering ........... 0.07-5.0 1.1 ........................

(1991). Distribution System.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Typical dosage used by treatment plants.

SW: Surface Water.
GW: Ground Water.
AMWA: Association of Metropolitan Water Agencies.
AWWA: American Water Works Association.
AWWARF: American Water Works Association Research Foundation.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.
WIDB: Water Industry Data Base.

Exposure to chlorine residual varies both between systems and
within systems. Chlorine residual within systems will vary based on
where customers are located within the distribution system and changes
in the system's disinfection needs over time. Using residual
concentrations from the 1989-1991 AWWA Disinfection Survey and WIDB,
exposure to chlorine due to drinking water can be estimated using a
consumption rate of 2 liters per day. Based on the estimated 25th
percentile and 75th percentile chlorine residuals in the 1991 AWWA
Disinfection Survey, exposure was determined to range from 1.5 to 3.8
mg/day and the median would be 2.2 mg/day. Using the WIDB data,
exposures to the average customer from surface and ground water sources
using chlorination, respectively, were determined to be 1.9 mg/day and
1.7 mg/day.
Little information is available concerning the occurrence of
chlorine in food and indoor air in the United States. The Food and Drug
Administration (FDA) does not analyze for chlorine in foods. However,
there are several uses of chlorine in food production, such as the
disinfection of chicken in poultry plants and the superchlorination of
water at soda and beer bottling plants (Borum, 1991). Therefore, the
possibility exists for dietary exposure to chlorine from its use in
food production. However, monitoring data are not available to
characterize adequately the extent of such potential exposures.
Additionally, preliminary discussions with FDA suggest that there are
no approved uses for chlorine in most foods consumed in the typical
diet. Similarly, EPA's Office of Air and Radiation is not currently
conducting any sampling studies for chlorine in indoor air. Data on
levels of chlorine in ambient air are forthcoming.
Considering the limited number of food groups that are believed to
contain chlorine and that no significant levels of chlorine are
expected in ambient or indoor air, it is anticipated that drinking
water is the predominant source of exposure to chlorine. Air and food
are believed to provide only small contributions, although the
magnitude and frequency of these potential exposures are issues
currently under review. EPA, therefore, is considering setting an MRDLG
for chlorine in drinking water using an RSC value of 80%, the current
exposure assessment policy ceiling. EPA requests any additional data on
known concentrations of chlorine in drinking water, food and air.
Health Effects. The health effects information for chlorine is
summarized from the draft Drinking Water Health Criteria Document for
Chlorine, Hypochlorous Acid and Hyperchlorite Ion (USEPA, 1994a). The
studies cited within this section are summarized in the draft criteria
document.
Chlorine and the hypochlorites are very reactive and thus can react
with the constituents of saliva and possibly food and gastric fluid to
yield a variety of reaction by-products (e.g., trihalomethanes). Thus,
the health effects associated with the administration of high levels of
chlorine and/or the hypochlorites in various animal studies may be due
to these reaction by-products and not the disinfectant itself.
Oxidizing species such as chlorine and the hypochlorites are probably
short-lived in biological systems due to both their reactivity and the
large number of organic compounds found in vivo. Scully and White
(1991) noted that reactions of aqueous chlorine with sulfur-containing
amino acids appear to be so fast in saliva that all free available
chlorine is dissipated before the water is swallowed.
Oral studies with radiolabeled (i.e., 36Cl) hypochlorite and
hypochlorous acid indicate that, as measured by the radiolabel, these
compounds may be well absorbed and distributed throughout the body with
the highest levels measured in plasma and bone marrow. However,
considering the reactivity of the hypochlorites, these results may only
reflect the presence of reaction by-products (e.g., chloride). The
major route of excretion appears to be urine and then the feces.
Acute oral LD<INF>50 values for calcium and sodium hypochlorite
have been reported at 850 mg/kg in rats and 880 mg/kg in mice,
respectively. Humans have consumed hyperchlorinated water for short
periods of time at levels as high as 50 mg/L (1.4 mg/kg) with no
apparent adverse effects.
Short-term oral studies in animals have indicated decreases in
blood-glutathione levels, hemolysis and biochemical changes in liver in
rodents following a gavage dose of hypochlorite in water. No adverse
effects on reproduction (Druckery, 1968) or development were observed
in rats administered chlorine in drinking water at concentrations of
100 mg/L or less. However, Meier et al. (1985) observed an increase in
sperm-head abnormalities in mice receiving hypochlorite at 200 mg/L,
but not at 100 mg/L or less.
No systemic effects were observed in rodents following oral
exposure to chlorine as hypochlorite in distilled water at levels up to
275 mg/L over a 2 year period (NTP, 1990).
Chlorinated water has been shown to be mutagenic to bacterial
strains and mammalian cells. Investigations with rodents to determine
the potential carcinogenicity of chlorine, or chlorinated water have
been negative. In the most recent study, no apparent carcinogenic
potential was demonstrated following oral exposure to chlorine in
distilled drinking water as hypochlorite, at levels up to 275 mg/L over
a 2 year period (NTP, 1990). However, NTP observed a marginal increase
in the incidence of mononuclear cell leukemia in mid-dose female F344
rats but not in male rats or male and female mice (NTP, 1990).
Mononuclear cell leukemia has a high spontaneous rate of occurrence in
female F344 rats. The levels reported in the NTP study are within the
historical control range of incidence for the sex and strain of rat.
EPA believes that mononuclear cell leukemia can not be solely
attributed to exposures to chlorine in drinking water but rather may
reflect the high background rate of mononuclear cell leukemia in the
test species.
EPA has classified chlorine in Group D, not classifiable as to
human carcinogenicity (IRIS, 1993). This classification stems from the
findings of the NTP (1990) study indicating equivocal evidence in
female rats (increased mononuclear cell leukemia) and no evidence in
male rats or male and female mice. The International Agency for
Research on Cancer (IARC, 1991) also evaluated chlorinated drinking
water and hypochlorite for potential human carcinogenicity. IARC
determined that there was inadequate evidence for carcinogenicity of
chlorinated drinking water and hypochlorite salts in humans and
animals. (See section C for a description of these studies.) IARC
concluded that chlorinated drinking water and hypochlorite salts were
not classifiable as to their carcinogenicity to humans and thus
assigned these chemicals to IARC Group 3. This category is similar to
EPA cancer classification Group D.
Based on the previous discussion, EPA is proposing that chlorine,
hypochlorite and hypochlorous acid be placed in Category III for the
purpose of setting an MRDLG. The study selected for determining an RfD
is the previously mentioned 2 year rodent study that was conducted by
the National Toxicology Program (NTP, 1990). In this study, male and
female F344 rats and B6C3F1 mice were given chlorine in distilled
drinking water at levels of 0, 70, 140 and 275 mg/L for 2 years. Based
on body weight and water consumption values, these concentrations
correspond to doses of approximately 0, 4, 7 and 14 mg/kg/day for male
rats; 0, 4, 8, and 14 mg/kg/day for female rats; 0, 7, 14, and 24 mg/
kg/day for male mice and 0, 8, 14 and 24 mg/kg/day for female mice.
There was a dose related decrease in water consumption for both rats
and mice, presumably due to taste aversion. No effect on body weight or
survival were observed for any of the treated animals. Using a NOAEL of
14 mg/kg/d identified from female rats in the NTP (1990) study an MRDLG
of 4 mg/L, based on lack of toxicity in a chronic study is derived as
follows.

<GRAPHIC><TIF1>TP29JY94.001

Where 14 mg/kg/d is the NOAEL for female rats in the NTP study, and
100 is the uncertainty factor applied to account for inter and intraspecies
differences in accordance with EPA guidelines when a NOAEL from
a chronic animal study is the basis for the RfD. The MRDLG is based on
a 70 kg adult consuming an average of 2 liters water per day over their
lifetime. In addition, an 80% RSC is assumed in the absence of data to
the contrary.
Public comments are requested on the following issues: 1) placing
chlorine in Category III for developing an MRDLG, 2) selection of the
study and NOAEL as the basis for the MRDLG, 3) the 80% RSC, 4) the
appropriateness of the UF of 100, 6) the cancer classification for
chlorine.
2. Chloramines
Inorganic chloramines (CAS Nos. 10599-90-3 and 10025-85-1 for monoand
trichloramine, respectively) are formed in waters undergoing
chlorination which contain ammonia. Monochloramines, dichloramines and
trichloramines may be formed. Monochloramine is the principal
chloramine formed in chlorinated natural and wastewater at a neutral pH
and is much more persistent in the environment.
Chloramine is used as a disinfectant in drinking water to control
taste and odor problems, limit the formation of chlorinated
disinfection by-products, and maintain a residual in the distribution
system for controlling biofilm growth. At typical pHs of most drinking
waters, the predominant chloramine specie is monochloramine. For
purposes of this regulation, only monochloramine will be considered
since the other chloramines occur at much lower concentrations in
almost all drinking waters. Monochloramine has also been much more
extensively studied.
Monochloramine, the principal chloramine formed in chlorinated
natural and wastewaters at neutral pH, is relatively stable when
discharged to the environment. First-order decay rate constants of 0.03
to 0.075 hr-1 for monochloramine in the laboratory, and higher
rate constants of 0.28 to 0.31 hr-1 outdoors using chlorinated
effluents, have been reported. If discharged into receiving waters
containing bromide, monochloramine will decompose faster, probably
through the formation of NHBrCl and decomposition of the dihalamine.
The rate of monochloramine disappearance is primarily a function of pH
and salinity. For example, at pH 7 and 25 deg.C, the half-life of
monochloramine is 6 hr at 5 parts per thousand (ppt) salinity and 0.75
hr at 35 ppt salinity; at pH 8.5 and 25 deg.C, the half-life is 188 hr
at 5 ppt salinity and 25 hr at 35 ppt salinity. Monochloramine is
expected to decompose in wastewater discharges receiving waters via
chlorine transfer to organic nitrogen-containing compounds.
Occurrence and Human Exposure. Chloramine occurs in drinking water
both as a by-product and intentionally for disinfection. Chloramine is
formed during chlorination when source waters contain ammonia. It is
also used as a primary or secondary disinfectant, usually with
chloramine being generated on site by the addition of ammonia to water
following treatment by chlorination. The use of chloramines has been
shown to reduce the formation of certain by-products, notably
trihalomethanes, relative to the by-products formed with chlorination
alone. Chlorination by-product formation can be minimized when the
ammonia is added prior to or in combination with chlorine by reducing
the chlorine residual of the water being treated. In most plants,
however, ammonia is added some time after the addition of chlorine, to
allow for more effective disinfection since chlorine is a much stronger
disinfectant than chloramines.
Table V-3 presents occurrence information available for chloramine
in drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' USEPA, 1992a.
Typical dosages of chloramine used as a disinfectant in drinking water
treatment facilities range from 1.5 to 2.7 mg/L. Median concentrations
of chloramine in drinking water were found to range from 1.1 to 1.8 mg/
L.

Table V-3.--Summary of Occurrence Data for Chloramines

Occurrence of chloramine in drinking water

Concentration (mg/L)

Survey (year)\1\ Location Sample information (No. of ----------------------------------------------------------------

samples) Range Mean Median Other

AWWARF (1987) McGuire & National Survey........... Finished Water From: ........... ........... ........... Typical dosages:

Meadow, 1988. Lakes.......................... 1.5 mg/L
Flowing Streams................ 2.7 mg/L

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell 0.9-5.5 2.3 1.8 ........................

1989) Krasner et al., Nationwide. Effluent, 4 Quarters (13).
1989b.

EPA, 1992b\2\ (1987-1991). Disinfection By-Products At the Plant (11).............. 1.2-3.6 2.1 1.5 ........................

Field Studies. Distribution System (8)........ 0.1-3.3 1.4 1.1

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.

AMWA: Association of Metropolitan Water Agencies.
AWWARF: American Water Works Association Research Foundation.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.

Based on the residual concentrations given above, a high and low
estimate for exposure to chloramine from drinking water can be
calculated using an assumed consumption of 2 liters per day. Using the
target range of 1.5 to 2 mg/L, the exposure may range from 3 to 4 mg/
day. Some systems may deviate significantly from this range.
No information is available on the occurrence of chloramine in food
or air. Currently, the Food and Drug Administration (FDA) does not
measure for chloramine in foods since the analytical methods have not
been developed. Preliminary discussions with FDA suggest that there are
not approved uses for chloramine in foods consumed in the typical diet.
Similarly, EPA's Office of Air and Radiation is not sampling
chloramines in air (Borum, 1991).
Based on the previous discussion, EPA assumes that drinking water
is the predominant source of exposure to chloramine. Air and food
intakes are believed to provide only small contributions, although the
magnitude and frequency of these potential exposures are issues
currently under review. EPA, therefore, is proposing to establish an
MRDLG for chloramine in drinking water with an RSC value of 80%, the
current exposure assessment policy ceiling. EPA requests any additional
data on known concentrations of chloramine in drinking water, food and
air.
Health Effects. The health effects information in this section is
summarized from the draft Drinking Water Health Criteria Document for
Chloramines (USEPA, 1994b). Studies mentioned in this section are
summarized in the Criteria Document.
Short-term inhalation exposures to high levels (500 ml of 5%
household ammonia mixed with 5% hypochlorite bleach) of chloramines in
humans result in burning in the eyes and throat, dyspnea, coughing,
nausea and vomiting. Inhalation of the chloramine fumes resulted in
pneumonitis but did not result in permanent pulmonary damage.
Short-term exposures to chloramines in drinking water, in which
human subjects were administered single concentrations ranging between
1 and 24 mg/L (1, 8, 18 or 24 mg/L), have not resulted in any adverse
effects in human subjects. Following human exposure, the subject's
physical condition, urinalysis, hematology, and clinical chemistry were
evaluated. No adverse clinical effects were noted in any of the
studies.
In another study, acute hemolytic anemia, characterized by
oxidation of hemoglobin to methemoglobin and denaturation of
hemoglobin, was reported in hemodialysis patients when tap water
disinfected with chloramines was used for dialysis baths. Chloramines
were reported to produce oxidant damage to red blood cells and inhibit
the metabolic pathway used by red blood cells to prevent and repair
such damage. Many dialysis centers have installed reverse osmosis units
coupled with charcoal filtration or the addition of ascorbic acid to
prevent hemolytic anemia.
Animal studies indicate varying sensitivity and conflicting results
among different animal species. Toxic effects noted among rats are
changes in blood glutathione and methemoglobin. Both monkeys and mice
were unaffected during short-term assays with doses up to 200 mg/L
chloramines. Based on studies up to 6 weeks in length, rats appear to
be more sensitive to monochloramine than mice and monkeys.
Toxicokinetic studies of chloramines indicate that the absorption
of chloramines is rapid, peaking within 8 hours of administration. In
the rat, chloramines are metabolized to chloride ion and excreted
mostly through the urine with a small portion excreted through the
feces.
Longer-term oral studies (90 days or longer) showed decreased body
and organ weights in rodents. Some effects to the liver (weight
changes, hypertrophy, and chromatid pattern changes) appear to be
related to overall body weight changes caused by decreased water
consumption due to the unpalatibility of chloramines to the test
animals.
In addition, chloramine may induce immunotoxicity in rats in the
form of increased prostaglandin E<INF>2 synthesis, reduced antibody
synthesis, and spleen weight at levels as low as 9 to 19 mg/L
chloramines for 90 days. The significance of these findings for risk
use in risk assessment is compromised by the design flaws of the study
(i.e., animals were exposed to two antigens) and the lack of
corroboration of these findings by a follow-up study.
Two lifetime rodent studies involving oral exposures to rats and
mice via drinking water have been considered by EPA for the derivation
of the MRDLG for monochloramine. Both studies were performed by the
National Toxicology Program (NTP, 1990) and involved 70 animals/sex/
dose exposed to distilled drinking water containing 0, 50, 100 or 200
ppm chloramines.
The first NTP (1990) study was a 2-year study in mice to determine
the potential chronic toxicity or carcinogenic activity of
chloraminated drinking water. B6C3F<INF>1 mice were administered
chloramine at doses of 0, 50, 100 and 200 ppm in distilled drinking
water. These doses were calculated based on a time-weighted average to
be 0, 5.0, 8.9 and 15.9 mg/kg/day for male mice and 0, 4.9, 9.0 and
17.2 mg/kg/day for female mice. There was a dose-related decrease in
the amount of water consumed by both sexes; this decrease was noted
during the first week and continued throughout the study. Dosed male
and female mice had similar food consumption as controls except for
females in the 200 ppm dose group that exhibited slightly lower
consumption than controls.
Study results indicated that there was a dose-related decrease in
mean body weights of dosed male and female mice throughout the study.
Mean body weights of high-dose male mice were 10-22% lower than their
control group after week 37 and the body weights of high-dose female
mice were 10-35% lower after week 8. However, the survival of mice
receiving monochloramine in drinking water was not significantly
different than controls. Clinical findings observed were not attributed
to the consumption of chloraminated drinking water. Body weight loss
and systemic toxicity were not considered related to the toxicity of
chloramine, but rather due to decreased water consumption resulting
from the unpalatability of chloramines in drinking water to the test
animals. Therefore, the highest dose tested, 17.2 mg/kg/day, is
considered a NOAEL in mice.
In the second study F344/N rats were administered monochloramine
for 2 years at doses of 0, 50, 100 and 200 ppm in distilled drinking
water. These doses were calculated on the basis of a time-weighted
average to be 0, 2.1, 4.8 and 8.7 mg/kg/day for male rats and 0, 2.8,
5.3 and 9.5 mg/kg/day for female rats. There was a dose-related
decrease in the amount of water consumed by both sexes; this decrease
was noted during the first week and continued throughout the study.
Food consumption of treated rats was the same as the controls with
males consuming more. In addition, mean body weights of 200 ppm dosed
rats (both sexes) were lower than their control groups. However, mean
body weights of rats receiving monochloramine in drinking water (at all
levels) were within 10% of controls until week 97 for females and week
101 for males. Though several clinical changes were noted, no clinical
changes were attributable to chloraminated drinking water. The survival
of rats receiving chloraminated drinking water was not significantly
different than controls except that, for the 50 ppm dose groups,
survival was greater than that of controls. Therefore, EPA considers
the highest dose tested, 9.5 mg/kg/day, as the NOAEL.
Based on two bacterial assays, monochloramine appears to be weakly
mutagenic. One study examining the reproductive effects and another
which examined developmental effects of chloramines concluded that
there are no chemical-related effects due to chloramines.
The NTP evaluation, using the results of the two lifetime NTP
bioassays, concluded that chloramines exhibited equivocal evidence of
carcinogenic activity of chloraminated drinking water in female F344/N
rats. This conclusion results from an increase in mononuclear cell
leukemia. There was no evidence of carcinogenic activity in male rats
or mice of either sex. The findings do not establish a link between
chloramine exposure and carcinogenicity because of the high historical
background occurrence of this type of cancer in test animals. The
incidence of mononuclear cell leukemia in the female control groups
(16%) was substantially less than the incidence reported in untreated
historical controls (25%). Incidence of mononuclear cell leukemia in
test animals reached a high of 32% in the high dose female rats. This
study also discovered incidence of renal tubular cell neoplasms in two
high-dose male mice receiving chloraminated water. Since this type of
tumor is rarely seen in historical controls, there is some concern that
these may be treatment related. However, the overall evidence regarding
the potential carcinogenicity of chloramines in drinking water can be
described as inconclusive since no long-term study has linked any tumor
development to actual chloramination exposure. On this basis, as well
as consideration of those studies described in section C, EPA placed
chloramine in Group D: not classifiable based on inadequate evidence of
carcinogenicity.
EPA selected the lifetime study in rats (NTP, 1990) as the basis
for calculating the MRDLG for chloramines. The NOAEL for the rat (9.5
mg/kg/d) is proposed because the rat was not tested at the higher doses
where mice were tested (17.2 mg/kg/d). Rats appear to be more sensitive
considering observed changes in biochemistry. Following a Category III
approach and using the rat NOAEL of 9.5 mg/L from the NTP study, an
MRDLG of 4 mg/L (measured as total chlorine), based on lack of toxic
effects in a chronic study can be derived for the 70-kg adult consuming
2 liters of water per day applying an uncertainty factor of 100, which
is appropriate for use of a NOAEL derived from an animal study and
assuming an RSC drinking water contribution of 80 percent.

*Since chloramines, on a practical basis, will be measured as
total chlorine, it is necessary to present the MRDLG in terms of a
chlorine equivalent concentration. Three mg/L chloramine is
equivalent to 4 mg Cl<INF>2/liter, based on the molecular weights of
Cl<INF>2 and NH<INF>2Cl.

<GRAPHIC><TIF2>TP29JY94.002

EPA requests comments on the proposed MRDLG for chloramines and the
RSC of 80%, the significance of the findings of immunotoxicity for
setting the RfD instead of the NTP study, the significance of the
finding of mononuclear cell leukemia in female F344 rats, the
significance of the finding of tubular cell neoplasms in high-dose
exposed mice, and whether the adjusted MRDLG, which takes into account
the measurement of monochloramine as total chlorine, is appropriate.

<GRAPHIC><TIF3>TP29JY94.003

3. Epidemiology Studies of Chlorinated and Chloraminated Water
Several studies have been conducted to evaluate the association of
chlorination or chloramination with the risk of cancer, cardiovascular
disease or adverse reproductive effects in humans. A summary of some of
these studies is given below. This discussion reflects EPA's assessment
of these data and is summarized from the draft Drinking Water Criteria
Documents for Chlorine (USEPA, 1994a) and Chloramines (USEPA, 1994b),
respectively.
Introduction to Epidemiology Studies. Two distinct types of
epidemiology studies have been conducted: ecologic and analytical.
These types of studies differ markedly in what they reveal about the
association between water quality and disease. In an ecological
epidemiology study, information is available on exposure and disease
for groups of people rather than for individuals, and therefore, the
results are difficult to interpret. What is considered to be an
important or relevant group variable may not be important for or may
not pertain to individuals within that group. Theoretical and empirical
analyses have offered no consistent guidelines for the interpretation
of ecological associations, and results from these studies are
appropriate only to suggest hypotheses for further study by analytical
epidemiological methods (Piantiadosi et al., 1988; Connor and Gillings,
1974).
Analytical epidemiology studies provide an estimate of the
magnitude of risk and information which can be used to evaluate
causality. For each individual in the study, information is obtained
about disease status and exposure to various contaminants and other
characteristics. In several of the studies reported here, individual
exposures to disinfected water or specific disinfection by-products
were estimated using group exposure information. All reported
epidemiological associations from analytical studies require an
evaluation of random error (statistical significance) and potential
sources of systematic bias (misclassification, selection, observation,
and confounding biases) so that results can be interpreted properly. It
must be noted that random error or chance can never be completely ruled
out as the explanation for an observed association and that statistical
significance does not necessarily imply biological significance.
Regardless of statistical significance, it is important to consider
potential biological mechanisms. Random error does not address the
possibility of systematic error or bias. Misclassification of exposure
and disease, selection bias, and observation bias must be avoided;
confounding bias, on the other hand, can be prevented both in study
design and during analysis if information is obtained about possible
confounders. It is important to determine for each specific
epidemiology study the validity of the association observed between
exposure and disease before considering possible causality between
exposure and disease or inferring that the results apply to a larger or
target population. Systematic bias can lead to spurious associations;
in some but not all instances, the direction of the bias can be
determined. For example, a random misclassification of exposure usually
biases a study toward not observing an effect or observing a smaller
risk than may actually be present, but nonrandom misclassification can
result in either higher or lower estimates of risk depending upon the
distribution of misclassification.
In addition, because of the observational nature of epidemiology,
the interpretation of epidemiology studies requires a sufficient number
of well designed and well conducted epidemiology studies, and must
include appropriate toxicological and biological information. Judging
causality from epidemiology studies is based largely on guidelines
developed over the years, including sequence of events, strength of
association (relative risk or odds ratio), consistency of results under
different conditions of study, biological plausibility, dose or
exposure response relationship, and specificity of effect. The relative
risk represents a basic measure of an association between exposure and
disease. It is defined as the rate of disease in the exposed population
divided by the rate of disease in an unexposed population.
a. Cancer Studies. Since the early 1970's, numerous epidemiologic
studies have attempted to assess the association between cancer and the
long term consumption of water from various sources with and without
disinfection and of various chemical quality, especially chlorinated
surface waters which supply the majority of the U.S. population.
Ecological, case control, and cohort studies have been conducted. Case
control studies have included incident and decedent cases; in some
studies information about various risk factors has been collected
through interviews, but in others information was obtained primarily
from death certificates.
i. Ecological Studies. The earliest studies were analyses of group
or aggregate data available on drinking water exposures and cancer.
Usually the variables selected for analyses were readily available in
published census, vital statistics, or public records and easily
abstracted and assembled. These analyses, referred to as ecological but
also called aggregate, geographical, or correlational, were designed to
investigate cancer mortality rates, usually on a county or State level.
Areas of different water quality, source, and chlorination status were
compared to identify possible statistical associations for further
study. Drinking water exposures were most often characterized as simple
dichotomous variables which served as indicators of exposure to
differing source water quality, e.g., the drinking water source for the
county or geographic area was categorized as a surface or groundwater
source. In some instances exposure variables included estimates of the
proportion of the area's or county's population that received surface
or groundwater and whether it was chlorinated. Surface water was
assumed to be more contaminated with synthetic organics than
groundwater, but no attempt was made to estimate levels of
contaminants.
In 1974 it was discovered that when surface waters were disinfected
with chlorine, the chlorine reacted with pre-existing organic materials
in the water to create a great number of chemical by-products (Craun,
1988). The major group of disinfection by-products (by weight) was the
trihalomethanes (THMs) which included an animal carcinogen, chloroform.
Chlorinated surface water was evaluated as an exposure variable in
several of the ecological studies, and since almost all surface waters
are chlorinated, the analyses usually compared cancer mortality among
populations receiving chlorinated surface water with those receiving
unchlorinated groundwater. Chlorinated water was assumed to contain
disinfection by-products, and at higher levels than chlorinated
groundwaters. However, the quality of surface and groundwater may also
differ for other contaminants, and this was not considered. Any
observed association might be due to other water quality differences
among surface and groundwaters (e.g., organic contaminants from
nonpoint and point source discharges to surface waters from industrial,
urban, and agricultural sources before pollution control regulations).
In some ecological analyses, the investigators attempted to study
the association between cancer mortality and an estimate of group
exposure to levels of chlorinated by-products based on THM or
chloroform levels was determined from a limited number of water
samples. The exposure information used in ecological studies was
available in only broad geographic units such as census tracts or
counties (Crump and Guess, 1982; Shy, 1985). Although these exposure
variables were statistically associated with mortality rates for all
cancers combined and several site-specific cancers, the interpretation
must necessarily be cautious due to limitations of ecological studies.
In several of these studies, aggregate or group information on several
covariates, e.g., occupation, income, or population density, also was
included in the statistical analysis in an attempt to adjust for
potential confounding factors. In one study the statistical
significance of the observed associations between stomach and rectal
cancer mortality and group exposures to current THM levels disappeared
when migration patterns and ethnic data were included in the regression
model (Tuthill and Moore, 1980). A wide range of cancer sites was found
to be statistically associated with estimates of population group
exposures based on current levels of THM or chloroform including gall
bladder, esophagus, kidney, breast, liver, pancreas, prostate, stomach,
bladder, colon, and rectum. The most frequent associations observed
were for the last four sites; however, these associations were not
consistent when viewed by gender, race, and geographic region.
The ecologic design coupled with the lack of specific exposure
indicators in these studies precludes the inference of a causal
relationship (Morgenstern, 1982). A subcommittee of the National
Academy of Sciences (NAS, 1980) reviewed 12 of the ecological studies
and noted ``Results of these studies demonstrate the problems of
establishing relationships between health statistics and environmental
variables, and lend emphasis to the caution with which they should be
interpreted.'' The NAS further commented that the ecological studies in
which the current THM exposures were estimated were deemed to be more
informative than others and ``suggest that higher concentrations of THM
in drinking water may be associated with an increased frequency of
cancer of the bladder. The results do not establish causality, and the
quantitative estimates of increased or decreased risk are extremely
crude. The effects of certain potentially important confounding
factors, such as cigarette smoking, have not been determined.'' The
studies are useful, however, as an initial step for identification of
potential hazards and they indicated the need for further epidemiologic
studies or analytic studies of individuals with a specific etiologic
hypothesis.
ii. Cohort Studies. A cohort study (or follow-up) study (the study
can be called either retrospective or prospective) is one in which two
or more groups (referred to as `cohorts') of people that differ
according to the extent of exposure to a potential cause of disease are
compared with respect to incidence of the disease of interest in each
of the groups. The essential element of this study type is that
incidence rates are calculable directly for each study group (Rothman,
1986). One advantage of this study type is the ability to study
multiple disease endpoints. One disadvantage of this study type is that
a large study population is needed to detect a relatively small risk.
In addition, because of the latency period for carcinogenicity, a long
follow-up time may be required for the study.
There exists one cancer drinking water cohort study where
individual data were available for a well-defined, fairly homogeneous
area that allowed disease rates to be computed by presumed degree of
exposure to by-products of chlorination, although the population was
relatively small. Wilkins and Comstock (1981) studied the residents of
Washington County, Maryland and ascertained the source of drinking
water at home for each county resident in a private census conducted in
1963. In addition to water source, information was collected on age,
marital status, education, smoking history, number of years lived in
the household, and frequency of church attendance. Death certificates
and cancer registry information was sought for county residents whose
date of death or diagnosis occurred in the 12 year period following the
census. Sex and site-specific cancer rates were constructed for
malignant neoplasms of biliary passages and liver, kidney, and bladder.
Several additional causes of death were analyzed as well for comparison
purposes. The population was stratified into three separate exposure
subgroups: chlorinated surface water, unchlorinated deep wells, and
small municipal systems with a mixture of chlorinated and unchlorinated
water, each reflecting a different history of exposure to by-products
of chlorination. The study group which included individuals who
obtained drinking water from small municipal systems were not included
as a comparison with the other drinking water cohorts because of their
exposure to both chlorinated and unchlorinated water.
Both crude and adjusted incidence rates for liver cancer in males
and females and for cancer of the liver among males were essentially
the same for persons supplied with chlorinated surface water at home
(high THM exposure) and for persons with deep wells (low THM exposure).
The adjusted rates for bladder cancer (RR=1.6; 95% CI=0.54,6.32) and
cancer of the liver (RR=1.8; 95% CI=0.64,6.79) among females were
highest among persons using chlorinated surface water. Given the low
relative risk and broad confidence intervals, the authors indicated
that this finding could be attributed to chance (Wilkins and Comstock,
1981). Confounding bias may also influence the interpretation of a
small relative risk. EPA considers that the results of this study are
inconclusive because the results are based on small numbers of cases,
hence, the reported rates are statistically unstable and subject to
random variation.
iii. Case Control Studies. In a case control study, persons with a
given disease (the cases) and persons without the given disease (the
controls) are selected for study. The proportions of cases and controls
who have certain background characteristics or who have been exposed to
possible risk factors are then determined and compared. Exposure odds
ratios (ORs) are determined. The odds of exposure among cases is
compared with that of controls. For rare diseases, the ORs are
considered good estimates of relative risk. These studies are sometimes
called case-referent or retrospective studies. Because there are many
variations of this study design (e.g., how cases and controls are
selected, how information on exposures, risk factors, and confounding
factors are obtained, and who is interviewed), each case control study
should be evaluated individually to determine if the specific study
design parameters introduce systematic bias (Kelsy et al., 1986). As
previously noted, all epidemiology studies require careful evaluation
of systematic bias. For those studies with major bias, the results are
generally considered inconclusive. Those studies with minor bias may
still provide useful information.
Two types of studies were conducted: (1) Decedent cases without
interviewing survivors for information about residential histories and
risk factors and (2) incident cases with interviews.
Decedent Case-Control Studies. Several case-control studies were
conducted to continue to investigate the possibility that there was a
causal relationship between chlorinated drinking water, including
byproducts such as THMs, and gastrointestinal or urinary tract cancers.
Most of these case-control studies used deceased cases of the specific
cancers of interest, although some continued their investigations in a
relatively nonspecific way by using both total cancer mortality as well
as several of the site- specific cancers studied in the ecologic
studies (Crump and Guess, 1982; Shy, 1985). Controls were noncancer
deaths from the same geographic area and in all but one study matched
for several potentially confounding variables including age, race, sex,
and year of death. As in all studies of this design (i.e., death
certificate studies with no available interviews), control of
confounding factors was restricted to information that is routinely
recorded on death certificates and no information was obtained from
next-of-kin interviews. The exposure variables of interest at this time
included a comparison of surface v ground water sources, or chlorinated
v nonchlorinated ground water sources. The place of residence listed on
the death certificate was linked to public records of water source and
treatment practices in order to classify the drinking water exposure
variable for a particular case or control (Shy, 1985).
Similar to the earlier ecologic studies, the Agency considers the
results from these studies to be inconsistent in their findings. The
calculated ORs, varied by cancer site and sex, as well as in their
magnitude and statistical significance. This variability was found for
all the cancer endpoints studied including those of specific interest,
i.e., bladder, colo-rectal, and/or colon. These endpoints were found to
vary by geographic region. For example, a statistically significant
increased bladder cancer risk was observed in North Carolina for males
and females combined (OR=1.54) and New York for males (OR=2.02), but
not for females; no statistically significant risk was seen in
Louisiana, Wisconsin or Illinois. Increased colon cancer risk was
observed in Wisconsin (OR=1.35) and North Carolina (OR=1.30) for males,
but not females; no increased risk was seen in Louisiana or Illinois.
Increased rectal cancer risk was observed in North Carolina (OR=1.54)
and Louisiana (OR=1.68) for males and females combined, in Illinois for
females (OR=1.35) but not males, and in New York for males (OR=2.33)
but not females; no increased risk was seen in Wisconsin. Although
increased risk was observed for cancer of the liver and kidney
(OR=2.76), esophagus (OR=2.39), and pancreas (OR=2.23) among males in
New York, no increased risk for these cancers was seen among females in
New York, Illinois, Wisconsin or Louisiana.
Although many of the ORs were statistically significant, these
decedent case control studies with extremely limited information on
confounding factors and potential exposures to chlorinated water are of
limited usefulness in assessing whether cancer is associated with
chlorinated drinking water, or judging the causality of such as
association. Although some of the ORs were large enough to cause
concern about an exposure association, the magnitude of the OR was such
that the association could be attributed to incomplete control of
confounding factors and the ORs might represent spurious elevations
(Crump and Guess, 1982).
Although not subject to all the same limitations as ecologic
studies, decedent case-control studies are considered more limited by
some epidemiologists than others as a tool for causal inference because
of a high probability of systematic bias associated with the use of
information obtained only from the death certificate (e.g., inadequate
or no information on residential history, water exposures, and major
potential confounders). The variability seen in these five studies is
likely a combination of several factors, including available sample
size, choice of causes of death included as controls, regional
variability in true composition of the raw and treated drinking waters,
definition of exposure variables, a high probability of exposure
misclassification from imputing a lifetime exposure to a certain water
source or treatment from residence listed on the death certificate, and
uncontrolled confounding (e.g., diet and smoking).
Given the limitations of decedent case control studies without
interviews, the evidence from these studies are considered insufficient
to determine a causal association between any or all the components
which exist in the complex mixture created during the chlorination of
surface waters and any site-specific cancer. The findings provided a
stimulus for a further refined epidemiologic study using incident cases
of bladder and colon cancer and appropriate controls who could be
interviewed for residential history and numerous other covariates.
Case-Control Studies with Interviews. At the time when these more
recent studies were planned, it was still believed that THMs were the
major by-products of chlorinated drinking water that should be
investigated and studies were designed and conducted in areas where a
THM difference might be expected and somehow measurable. Exposure
assessment for individuals remained problematic in the study design.
The best available means of exposure measurement, however, was at best
a surrogate for the true exposure of interest which is the actual level
of THMs or other by-products ingested over a person's lifetime through
consumption of surface water disinfected with chlorine. Only two
studies attempted to estimate long-term exposure to THMs. Most studies
used residence at a location served by chlorinated drinking water. In
all except one of the studies, comparisons of exposure were between
chlorinated surface water and unchlorinated groundwater. As previously
discussed in the section on ecological studies, the water quality for
surface and ground water differ for many other consituents.
Because it was known that disinfection of surface water using
chloramine produced very low levels of THMs and other by-products
compared to the same water disinfected with chlorine, a study was
conducted in Massachusetts to compare the patterns of mortality in
communities which used these different disinfectants (Zierler et al.,
1986). Statewide mortality records for 1969-1983 were analyzed using
standardized mortality ratios (SMRs) and showed little variation by
community. However, mortality odds ratios (MORs) comparing bladder
cancer deaths to all other deaths were considered by the authors to
indicate a slight elevation for last residence in a chlorinated
community compared to a chloraminated community (MOR=1.7; 95% CI=1.3,
2.2). The authors noted that the results were preliminary and ``crude
descriptions of the relationship under study'' (Zierler et al., 1986).
The authors further indicated that the results may have been caused by
unidentified or uncontrolled confounding factors.
Bladder cancer deaths were investigated further using a casecontrol
design with proxy interviews to determine residential and
smoking histories (Zierler et al., 1988). The association of bladder
cancer was assessed for individuals with lifetime and usual exposure to
chlorinated and chloraminated water depending on the number of years of
residence at a particular water source. Residence in a community using
chlorinated drinking water was used as an index for exposure to
chlorinated by-products, while residence in a community using
chloramine for disinfection was considered an index for no exposure to
chlorinated by-products. An association was observed between bladder
cancer and both lifetime (MOR=1.6; 95% CI=1.2-2.1) and usual (MOR=1.4;
95% CI=1.1-1.8) exposure to chlorinated water. A subgroup of study
participants was noted to have lived their entire lives in an area
served with water supplied by the Massachusetts Water Resources
Authority, disinfected with either chlorine or chloramine (same water
source, different disinfectant, lifetime exposure). Within this group
the bladder cancer mortality risk was 1.6 times higher (MOR=1.6; 95%
CI=1.1, 2.4) when the water had been disinfected with chlorine compared
to chloramine (Zierler et al., 1988).
In addition to analyses using a control group which consisted of
deaths from cardiovascular disease, cerebrovascular disease, chronic
obstructive lung disease, lung cancer, and lymphatic cancer, a separate
analysis was done using only the lymphatic cancer controls. This was
considered necessary by the authors because of the possibility that
some of the other deaths among controls may also be related to the
exposure of interest. If true, then the MOR estimate would be biased
toward the hypothesis of no increased risk. When the analysis
considered only lymphatic cancer controls, the magnitude of the
association with chlorinated water increased for lifetime exposure
(MOR=2.7; 95% CI=1.7-4.3), usual exposure (MOR=2.0; 95% CI=1.4-3.0),
and lifetime exposure in the previously mentioned subgroup (MOR=3.5;
95% CI=1.8-6.7). Sources of misclassification bias that may have been
present were considered to be randomly distributed among the cases and
controls which implies that the observed MOR would be an underestimate
of risk (Zierler et al., 1988). It is also possible that
nondifferential misclassification of the variables used to control
confounding, leading to residual confounding of the summary estimates,
could have caused a systematic spurious elevation in the MORs.
The largest study to date investigating the relationship of
chlorinated water and bladder cancer incidence involved an ancillary
study to the National Cancer Institute's (NCI) 10 area study of bladder
cancer and artificial sweeteners (Cantor et al., 1985, 1987, 1990). The
original study conducted interviews with 2,982 newly diagnosed bladder
cancer cases and 5,782 population controls; lifetime information on
source and treatment of drinking water was collected and analyzed for
only a subset of the original study population (1,244 cases and 2,550
controls). Subgroup analyses of nonsmokers among participants and those
reporting beverage intake necessarily involved even smaller numbers.
Duration of exposure, measured by years of residence at a chlorinated
surface or nonchlorinated ground water source was presumed to be a
surrogate for dose of disinfectant by-products. Overall, there was no
association of duration of exposure with bladder cancer risk (Cantor et
al., 1985, 1987). In nonsmokers who never smoked, a 2-fold increased
risk was reported for those exposed for 60 or more years to chlorinated
surface water (n=46 cases, 77 controls) compared to unchlorinated
ground water (n=61 cases, 268 controls) users (OR=2.3; 95% CI=1.3,
4.2). These data were further analyzed according to beverage intake
level, type of water source and treatment (Cantor et al., 1987, 1990).
It was observed that people who reported drinking the most tap waterbased
beverages from any source (>1.96 liters/day) had a bladder cancer
risk about 40% higher (OR=1.43; 95% CI=1.23-1.67, males and females
combined) than people who drank the least. The association between
water ingestion and bladder cancer risk for males was an OR=1.47; 95%
CI=1.2-1.8, and for females an OR=1.29; 95% CI=0.9-1.8.
Evaluation of bladder cancer risk by both duration of exposure and
amount of water consumed showed that the risk increased with higher
water consumption only among those who drank chlorinated surface water
for 40 or more years. Evaluation of risk by smoking status revealed
that most of the duration effect was observed in nonsmokers. Among
nonsmokers who consumed tap water in amounts above the population
median (>1.4 L/day), a risk gradient was apparent only for males.
However, a higher risk was also seen for nonsmoking females who
consumed less than the median level. The increasingly smaller numbers
of cases and controls available for these subgroup analyses produce
statistically unstable OR estimates making it difficult to evaluate the
trend results.
This is the first study of incident bladder cancer cases that
obtained and analyzed fluid consumption patterns in this way. The noted
inconsistencies in the reported data must be more thoroughly explored
and indicate a need for replication before any causal relationship can
be assumed (Devesa et al., 1990). An additional consideration is a more
refined exposure measurement; many of the disinfection by-products are
volatile. Thus exposure may occur through inhalation as well as
ingestion.
Two conflicting studies of colon cancer and presumed THM exposure
have been reported. The first one (Cragle et al., 1985) was a hospital
based case control study that included 200 incident colon cancer cases
from seven hospitals and 407 hospital controls with no history of
cancer who were diagnosed with diseases unrelated to colon cancer. It
should be noted that both colon and rectal cancer cases were included
as cases in the study. Controls were matched to cases on hospital and
admission date, as well as age, race, sex and vital status. Residential
histories were linked with water source and disinfectant information
for the 25 years prior to diagnosis. Logistic regression analysis using
qualitative data groupings for the variables of interest showed a
strong interaction of age and chlorination status (Table V-4). THM
levels were not estimated. Odds ratios computed from the regression
coefficients increased with age, and within age groups. The ORs are
higher for a longer duration of exposure.

Table V-4.--Comparison of OR's By Exposure Duration and Age

OR (95% CI) 1-15 OR (95% CI) > 15

Age (years) years exposure years exposure

20-29............................. 0.23
(0.11, 0.49) 0.48
(0.23, 1.01)
30-39............................. 0.36
(0.2, 0.66) 0.6
(0.33, 1.09)
40-49............................. 0.57
(0.36, 0.88) 0.75
(0.48, 1.18)
50-59............................. 0.89
(0.83, 1.12) 0.94
(0.69, 1.29)
60-69............................. 1.18
(0.94, 1.47) 1.38
(1.1, 1.72)
70-79............................. 1.47
(1.16, 1.84) 2.15
(1.7, 2.69)
80-89............................. 1.83
(1.32, 2.53) 3.36
(2.41, 4.61)

From these data, it appears that risk is increased only in those
persons 60 years old and older with greater than 15 years of exposure
to chlorinated water and in those greater than 70 years of age,
regardless of exposure duration.
A second colon cancer study (Young et al., 1987) conducted in
Wisconsin involved 366 incident colon cancer cases, 785 controls
diagnosed with other cancers, and 654 population controls. Extensive
interviews were conducted with all participants to obtain information
on past drinking water sources, drinking water habits and a number of
potentially confounding covariates. This information was combined with
data provided by water companies to construct models to predict
historical levels of THMs to be used as both cross-sectional and
cumulative exposure variables. Simpler methods of defining exposure
were also used, (e.g., surface vs. ground, chlorinated v.
nonchlorinated), and all methods looked at the data by period specific
exposure levels. The results did not indicate any association between
THMs in Wisconsin drinking water and colon cancer risk. Odds ratios for
all exposure variables were uniformly close to 1.0 with few exceptions.
It should be noted, however, that in this study the majority of the
water supplies contained less than 20 <greek-m>g/l of THMs. No excess
risk was observed at these levels, given the limitations of this study
design in detecting a small risk.
The association of THM and colo-rectal cancer was studied in New
York where the THM levels were higher than those in the above Wisconsin
study (Lawrence et al., 1984). A total of 395 colon and rectal cancer
deaths among white female teachers in New York State (excluding New
York City) was compared with an equal number of deaths of teachers from
causes of death other than cancer. All deaths were ascertained using
the defined cohort of the New York State Teachers Retirement System.
Cumulative chloroform exposure was estimated by the application of a
statistical model to operational records from water systems that served
the home and work addresses of the study participants during the 20
years prior to death. The distribution of chloroform exposure was not
significantly different between cases and controls. No effect of
cumulative chloroform exposure was observed in a logistic analysis
controlling for type, population density, marital status, age, and year
of death. No excess risk was associated with exposure to a surface
water source containing THMs (OR=1.07; 90% CI=0.79, 1.43). Although the
data were not presented in the article, the authors reported that no
appreciable differences were seen when the colon and rectal cases were
analyzed separately, compared to the combined analyses reported above.
Although most all the studies reviewed here have looked at colon,
colo-rectal or bladder cancer risk, one recently published work
investigated the risk of pancreatic cancer in relation to presumed
exposure to chlorinated drinking water. Ijsselmuiden et al. (1992)
conducted a population-based case-control study in Washington County,
Maryland, using the same population data that were originally
ascertained during a private population census for an earlier cohort
study (Wilkins and Comstock, 1981). The original cohort study did not
find any association between pancreatic cancer and chlorinated drinking
water (OR=0.80, 95% CI=0.44-1.52).
This case-control study was conducted to reexamine chlorinated
drinking water as a possible independent risk factor for pancreatic
cancer in this population. It is not reported of any of the other
endpoints from the original study also were reexamined, e.g., bladder,
kidney, or liver cancer. Cases were those residents who were reported
to the County cancer registry with a first time pancreatic cancer
diagnosis during the period July, 1975 through December 1989, and who
had been included in the 1975 census (n=101). Controls were randomly
selected by computer from the 1975 census population (n=206). Drinking
water source, as obtained during the 1975 census, was the exposure
variable used. In univariate analyses, municipal water as a source of
drinking water, increasing age, and unemployment were significantly
associated with increased risk of pancreatic cancer. Multivariable
analyses that controlled for confounding variables indicated that the
use of municipal chlorinated water at home was associated with a
significant OR of 2.23 (95% CI=1.24-4.10). The OR adjusted is 2.18 (95%
CI=1.20-3.95); only age and smoking were assessed as potential
confounders.
Interpretation of these findings is hampered by several problems
regarding the assessment of exposure, including the fact that
information obtained in 1975 on type of water and other variables is an
exposure collected at one point in time and may not reflect actual
exposure patterns prior to 1975. In addition, there is no information
on the actual amounts of water consumed. Additionally, different
residential criteria were used for the cases and controls. The cases
had to still be residing in the County at the time of their cancer
diagnosis to be included in the study, but the controls may not have
been current residents. If controls emigrated out of the county
differentially on the basis of exposure, the ORs may be an over- or
underestimate of the risk depending on emigration patterns. Finally, it
can not be ruled out that the exposure variable used for this and other
studies--residence served by a particular water source--is simply a
surrogate for some other unidentified factor associated with nonrural
living. The nonspecific relationship of several different causes of
death and water source at home observed in the earlier cohort study
(Wilkins and Comstock, 1981) lends some support to this possibility.
More valid individual exposure information over a long period of time
for both specific contaminants and the use of chlorinated/unchlorinated
water are needed to assess the results of this and other analytical
epidemiology studies.
Morris et al. (1992) conducted a meta-analysis, evaluating 12
studies and pooling the relative risks from 10 epidemiological studies
of cancer and a presumed exposure to chlorinated water and its
byproducts. Meta-analysis refers to the application of quantitative
methods to combine the published results of a related body of
literature (Dickerson and Berlin, 1992). Morris et al. (1992) reported
a pooled relative risk estimate of 1.21 (95% CI, 1.09-1.34) for bladder
cancer and 1.38 (95% CI, 1.01-1.87) for rectal cancer (i.e., 9% of
bladder cancer cases and 15% of the rectal cancer cases in the U.S. or
approximately 10,000 additional cases of cancer per year could be
attributed to chlorinated water and its by-products). Pooled relative
risk estimates for ten other site specific cancers including colon,
colo-rectal and pancreas were not felt to be significantly elevated nor
were they statistically significant.
If the indications from this analysis are true such that water
chlorination could result in as many as 10,000 cases of cancer a year,
then chlorination could represent a significant cause of rectal and
bladder cancer in the U.S. However, there was disagreement among the
negotiating parties over the appropriateness of this meta-analysis.
Some believed that the use of the meta-analysis may not be appropriate
for these data. Others disagreed, expressing their view that the
analysis was statistically probative and otherwise valuable. Metaanalysis
has been used successfully to combine the results of small
clinical trials and of some epidemiology studies that have similar
experimental design and exposure conditions. Application of metaanalysis
to the water chlorination data requires careful consideration
of exposure variables and systematic bias in each of the studies.
Chlorinated drinking water is a complex mixture of many substances that
vary geographically and seasonally. There is even variability within a
geographic region. In addition, the information on exposure and
potential confounding is much more limited for the four decedent case
control studies used in the meta-analysis. Their study design is
dissimilar to the other studies included, resulting in concerns about
their inclusion in the meta-analysis. Study-specific methodological
problems, systematic bias, and problems of exposure definition and
assessment could not be corrected by this analysis (Murphy, 1993).
Thus, the overall results of the Morris et al. analysis may over- or
underestimate the risk. However, the estimate of risk in regard to
rectal cancer might be particularly affected by the inclusion of these
case control studies. It should also be noted that the results of the
Morris et al. analysis does not provide additional information to
establish causality.
The chlorinated drinking water epidemiology studies have been
reviewed extensively by EPA, the National Academy of Sciences, the
International Agency for Research on Cancer (IARC), and the
International Society for Environmental Epidemiology (ISEE). In 1987,
the National Academy of Sciences Subcommittee on Disinfectants and
Disinfectant By-Products concluded that there was a major health
concern with the chronic ingestion of low levels of disinfection
byproducts (NRC, 1987). The Subcommittee commented that some of the
epidemiology studies reported ``increased rates of bladder cancer
associated with trends of levels of certain contaminants in water
supplies. Interpretation of these studies is hampered by a lack of
control for confounding variables (e.g., age, sex, individual health,
smoking history, other exposures).'' The Subcommittee recommended that
epidemiologists continue to improve protocols and conduct studies on
drinking water and bladder cancer where exposure data can be obtained
from individuals, rather than through estimation from exposure models.
EPA and IARC, along with other individual scientists, have
interpreted the epidemiologic evidence as inadequate. IARC concluded
that ``there is inadequate evidence for carcinogenicity of chlorinated
drinking water in humans.''
The ISEE presented a full spectrum of opinion regarding the
epidemiology data (Neutra and Ostro, 1992). The ISEE reported a
``general consensus that the results of the recent EPA-sponsored
studies of cancer endpoints have strengthened the evidence for linking
bladder cancer with long term exposure to chlorinated drinking water.
The evidence for links with colon cancer are not convincing. * * * Any
risks, if real, are low when compared to the risk of infection from not
disinfecting water.''
In 1992, the International Life Sciences Institute sponsored a
conference with the Pan American Health Organization, EPA, Food and
Drug Administration, World Health Organization, and the American Water
Works Association on the safety of water disinfection. Although they do
not necessarily reflect the views of the sponsoring organizations,
conclusions prepared by the conference's editor and editorial board
(Craun et al., 1993) noted that ``Adverse human health effects may be
associated with the chemical disinfection of drinking water. However,
current scientific evidence is inadequate to conclude that water
chlorination poses a significant risk to humans. Uncertainties about
the available toxicologic evidence limit assessment of human health
risks associated with chlorine, chloramine, chlorine dioxide, and ozone
disinfection. The epidemiologic evidence for increased cancer risks of
chlorinated drinking water is equivocal.''
Some members of the reg-neg committee felt that the epidemiology
data, taken in conjunction with the results from toxicological studies,
provide an ample and sufficient basis to conclude that the usual
exposure to disinfection by-products in drinking water could result in
an increased cancer risk at levels encountered in some public water
supplies.
Because of the spectrum of conclusions concerning these data, the
Agency is pursuing additional research to reduce the uncertainties
associated with these data and better characterize the potential of
cancer risks associated with the consumption of chlorinated drinking
water.
b. Serum Lipids/Cardiovascular Disease. Laboratory studies on
animals, conducted in the early 1980's indicated a possible link
between consumption of chlorinated drinking water and elevated serum
lipid profiles which are indicators of cardiovascular disease (USEPA
1994a). The animal work was followed by a cross-sectional study in
humans (Zeighami et al., 1990) that included 1,520 adult residents,
aged 40 to 70 years, in 46 Wisconsin communities supplied with either
chlorinated or unchlorinated drinking water of varying hardness. The
study was designed to determine whether differences in calcium or
magnesium intake from water and food and chlorination of drinking water
affect serum lipids.
The communities selected for study had the following
characteristics: (1) They were small in population size (300-4,000) and
not suburbs of larger communities; (2) they had not undergone more than
20% change in population between 1970 and 1980; (3) they had been in
existence for at least 50 years; and (4) all obtained water from
groundwater sources with no major changes in water supply
characteristics since 1980 and did not artificially soften water. The
water for the communities contained total hardness of either
<ls-thn-eq> 80 mg/l CaCO<INF>3 (soft water) or <gr-thn-eq> 200 mg/l
CaCO3 (hard water); 24 communities used chlorine for disinfection and
22 communities did not disinfect. Eligible residents were identified
through state driver's license tapes and contacted by telephone; an
age-sex stratified sampling technique was used to choose a single
participant from each eligible household. Only persons residing in the
community for at least the previous 10 years were included. A
questionnaire was administered to each participant to obtain data on
occupation, health history, medications, dietary history water use,
water supply and other basic demographic information. Water samples
were collected from a selected subset of homes and analyzed for
chlorine residual, pH, calcium, magnesium, lead, cadmium, and sodium.
Fasting blood specimens were collected from each participant and
analyzed for total cholesterol, triglycerides and high- and low-density
lipoprotein (HDL and LDL, respectively) subfractions.
Among females, adjusted mean total serum cholesterol levels were
statistically significantly higher in the chlorinated communities
compared to the nonchlorinated communities (249 mg/dl and 238 mg/dl,
respectively). These changes are not considered biologically
significant as they reflect background variation. Total serum
cholesterol levels were also higher for males in chlorinated
communities, on the average, but the difference was smaller and not
statistically significant (236 mg/dl vs. 232 mg/dl). LDL mean values
followed a similar pattern to that for total cholesterol, higher in
chlorinated communities for females, but not different for males.
However, for both sexes, HDL cholesterol levels are nearly identical in
chlorinated and nonchlorinated communities and there were no
significant differences found in the HDL/LDL ratios. The implications
of these findings for cardiovascular disease risk are unclear at this
time given the inconsistencies in the data. The possibility exists that
the observed association in females may have resulted from some unknown
or undetermined variable in the chlorinated communities.
The results from a second study, designed to further explore the
findings among female participants in the Wisconsin study (Zieghami et
al., 1990), were presented in 1992 (Riley et al., 1992, manuscript
submitted for publication). Participants were 2,070 white females, aged
65 to 93 years who were enrolled in the Study of Osteoporotic Fractures
(University of Pittsburgh Center) and had completed baseline
questionnaires on various demographic and lifestyle factors. Total
serum cholesterol was determined for all participants. Full lipid
profiles (total cholesterol, triglycerides, LDL, total HDL, HDL-2, HDL-
3, Apo-A-I, and Apo-B) were available from fasting blood samples for a
subset of 821 women. Interviews conducted in 1990 ascertained
residential histories and type of water source used back to 1950 and
all reported public water sources were contacted for verification of
disinfectant practices. Private water sources were presumed to be
nonchlorinated. A total of 1,896 women reported current use of public,
chlorinated water, 201 reported current use of nonchlorinated springs,
cisterns, or wells and 35 reported having mixed sources of water. Most
of the women had been living in the same home with the same water
service for at least 30 years.
Overall, there were no meaningful differences detected in any of
the measured serum lipid levels between women currently exposed to
nonchlorinated water and those exposed to chlorinated water (246 mg/dl
vs. 247 mg/dl, respectively, for total cholesterol). The data were also
stratified by age and person-years of exposure to chlorinated water at
home. There was some suggestion that women with no exposure to chlorine
had lower total cholesterol levels but this finding was inconsistent
and may represent random fluctuation since there was no trend noted
with LDL cholesterol or Apo-B, both of which are known to correlate
with total cholesterol. There was also no association between
increasing duration of exposure to chlorine and HDL cholesterol, Apo-AI,
or triglycerides.
The only notable differences were that women with chlorinated water
reported significantly more cigarette and alcohol consumption than the
women with nonchlorinated drinking water (Riley et al., 1992). This was
evident in all age groups and across strata of duration of exposure.
This finding lends support to the possibility that the previously
reported association of chlorinated drinking water and elevated total
serum cholesterol (Zeighami et al., 1990) may have arisen due to
incomplete control of lifestyle factors which were differentially
distributed across chlorination exposure groups.
c. Reproductive/Developmental Outcomes. Several recently conducted
epidemiologic studies have examined the relationship between different
reproductive or developmental endpoints and various components of
drinking water. Kramer et al. (1992) conducted a population-based casecontrol
study to determine whether water supplies containing relatively
high levels of chloroform and other THMs within the state of Iowa are
associated with low birthweight, prematurity, or intrauterine growth
retardation (IUGR). Iowa birth certificate data from January, 1989
through June, 1990 served as the source of both cases and controls.
Definitions for cases and controls were as follows: the low birthweight
group included 159 live singleton infants weighing <2,500 grams and 795
randomly selected control infants weighing <gr-thn-eq>2,500 grams from
the same population; the prematurity group included 342 live singleton
infants with gestational ages of <37 weeks as determined from the
mother's reported last menstrual period, and 1,710 randomly selected
control infants with gestational ages <gr-thn-eq>37 weeks; IUGR
analyses included 187 IUGR infants (defined as weighing less than the
5th percentile for a particular gestational age based on California
standards for non-Hispanic whites) and 935 randomly selected controls.
Exposure status was assigned to infants according to reported maternal
residence in a given municipality at the time of birth. The assigned
THM levels came from a water survey conducted in 1987 in the state of
Iowa so the exposure information came from aggregate data. Odds ratios
were computed using multiple logistic regression to control for
measured confounders (including smoking, but not alcohol consumption).
The authors reported an increased risk for IUGR associated with
residence in communities where chloroform levels exceeded 10 ug/l
(OR=1.8; 95% CI=1.1-2.9). Prematurity was not associated with
chloroform exposure and the risk for low birthweight was only slightly
increased (OR=1.3; 95% CI=0.8-2.2).
The authors considered the results of this study to be preliminary.
Accordingly, they should be interpreted with caution. They considered
the major limitations of the study to involve assessment and
classification of individual exposure, the potential misclassification
due to residential mobility and the fluctuation of THM levels.
Aschengrau et al. (1993) conducted a case-control study in
Massachusetts to determine the relationship between community drinking
water quality and a wide range of adverse pregnancy outcomes, including
congenital anomalies, stillbirths, and neonatal deaths. The data were
obtained during a previous study of 14,130 pregnant women who delivered
infants at Brigham and Women's Hospital in Boston between 1977 and
1980. Drinking water quality information came from routine analyses of
the metal and chemical content of Massachusetts public water. An
attempt was made to link each woman in the study to the result of the
water analyses conducted in her town at the time of her pregnancy.
Information was also obtained on drinking water source and chlorination
of surface water. Drinking water samples from 155 towns were linked to
2,348 pregnant women to estimate exposure for the case-control study.
A large number of exploratory analyses were conducted with this
data set, which demonstrated both increases and decreases in risk
associated with various water quality parameters. A higher frequency of
stillbirths was correlated with chlorination and detectable lead
levels, cardiovascular defects were associated with lead levels, CNS
defects with potassium levels, and face, ear, and neck anomalies with
detectable silver levels. A decrease in neonatal deaths was associated
with detectable fluoride levels.
The authors indicated that the findings from this study, being nonspecific,
must be considered as preliminary given the problems and
limitations of the exposure assessment and the lack of an a priori
study hypothesis. They indicated a need for further research
(Aschengrau et. al. 1993).
The New Jersey Department of Health recently reported the results
of a cross-sectional study and a case-control study evaluating the
association of drinking water contaminants with birth weight and
selected birth defects (Bove et al. 1992a and b). Four counties
selected for the study were included because they had the highest
levels of monitored drinking water and they were served by well defined
public water systems which used ground and surface water, or a mixture
of these sources. The exposures evaluated total volatile organic
contaminants (VOCs) as well as individual VOCs such as
trichloroethylene, tetrachloroethylene, carbon tetrachloride, benzene
and THMs. The cross sectional study base included 81,055 live single
births and 599 single fetal deaths between January, 1985 and December,
1988; 593 mothers were interviewed in the case control study. Exposure
scenarios to THMs were stratified as follows: >20-40 <greek-m>g/L, >40-
60 <greek-m>g/L, >60-80 <greek-m>g/L, and >80 <greek-m>g/L.
In the cross sectional study, ORs with exposure to THMs >80
<greek-m>g/L were elevated for low term birth weight (OR=1.34; 95%
CI=1.13-1.6; adjusted OR=1.29; 95% CI=1.08-1.5), small for gestational
age (OR=1.22; 95% CI=1.12-1.3; adjusted OR=1.14; 95% CI=1.04-1.3), and
prematurity (OR=1.09; 95% CI=0.99-1.2; adjusted OR=1.04; 95% CI=0.94-
1.1). Among birth defects, the ORs were elevated for all surveillance
malformations: OR=1.53; 95% CI=1.14-2.1; central nervous system defects
OR=2.6; 95% CI=1.48-4.6; neural tube defects: OR=2.98; 95% CI=1.25-7.1;
and cardiac defects: OR= 1.44; 95% CI=0.97-2.1. In the case control
study, associations were found between THMs >80 <greek-m>g/L and neural
tube defects (OR=4.25; 95% CI=1.02-17.7) and between THM levels >15
<greek-m>g/L and cardiac defects (OR=2.0; 95% CI= 0.94-4.5). The
authors note their findings should be interpreted with caution because
of possible exposure misclassification, unmeasured confounding, and
associations which could be due to chance occurrences. Although the
case control study included interviews of mothers for information about
residence and various risk factors, the authors reported a number of
limitations in the interpretation of the results from the case control
study, especially as a result of selection bias. Evaluation of
selection bias indicated that the bias led to an overestimate of the
associations with THM levels.
Some members of the Reg Neg committee viewed that these studies
indicate the possibility of a reproductive risk related to exposure to
disinfectant by-products. As a result of this concern, EPA convened a
panel of experts to review the epidemiology studies described above
(USEPA, 1993a). The panel concluded that the studies by Bove et al.
(1992a and b) were useful for hypothesis generation and identification
of a number of areas for further research. The panel further concluded
that the findings were limited by a number of issues surrounding study
design and data analysis. Some of the limitations included untested
assumptions of maternal exposure to chlorinated water, limitations in
the exposure assessment for THMs and other disinfection by-products,
possibility for exposure misclassification, confounding risk factors
and that some of these findings may have been due to chance.
d. Request for Public Comments. EPA requests comments on the
significance of the epidemiological studies with chlorine and
chloramines as indicators of risk. EPA recognizes that there are
different interpretations of these epidemiological studies and
specifically solicits comment on the rationale for EPA's
interpretations. EPA further requests comments on the studies
suggesting a reproductive risk related to disinfectant by-product
exposure.
4. Chlorine Dioxide, Chlorite and Chlorate
Chlorine dioxide is used as a disinfectant in drinking water
treatment as well as an additive with chlorine to control tastes and
odors in water treatment. It has also been used for bleaching pulp and
paper, flour and oils and for cleaning and tanning of leather. Chlorine
dioxide is a strong oxidizer that does not react with organics in the
water, as does chlorine, to produce by-products such as the
trihalomethanes. Chlorine dioxide is fairly unstable and rapidly
dissociates into chlorite, and chloride in water. Chlorate may also be
formed as a result of inefficient generation or generation of chlorine
dioxide under very high or low pH conditions. The dissociation of
chlorine dioxide into chlorite and chloride may be reversible with some
chlorite converting back to chlorine dioxide if free chlorine is
available. Chlorite ion is generally the primary product of chlorine
dioxide reduction. The distribution of chlorite, chloride and chlorate
is influenced by pH and sunlight. Chlorite, (as the sodium salt), is
used in the onsite production of chlorine dioxide and as a bleaching
agent by itself, for pulp and paper, textiles and straw. Chlorite is
also used to manufacture waxes, shellacs and varnishes. Chlorate, as
the sodium salt, was once a registered herbicide to defoliate cotton
plants during harvest, to tan leather and in the manufacture of dyes,
matches, explosives as well as chlorite.
Occurrence and Human Exposure. Based on information from the Water
Industry Data Base (WIDB), it has been estimated that for large systems
(serving greater than 10,000 people), approximately 10% of community
surface water systems serving 12.4 million people and 1% of community
ground water systems, serving 0.2 million people currently use chlorine
dioxide for disinfection in the United States. It was assumed that none
of the smaller community systems (fewer than 10,000 people) use
chlorine dioxide (WIDB, 1990).
Table V-5 presents occurrence information available for chlorine
dioxide, chlorate, and chlorite in drinking water. Descriptions of
these surveys and other data are detailed in ``Occurrence Assessment
for Disinfectants and Disinfection By- Products (Phase 6a) in Public
Drinking Water,'' (USEPA, 1992a). Typical dosages of chlorine dioxide
used as a disinfectant in drinking water treatment facilities appear to
range from 0.6 to 1.0 mg/L. For plants using chlorine dioxide, median
concentrations of chlorite and chlorate were found to be 240 and 200
<greek-m>g/L, respectively. However, the data base upon which these
numbers are based is very limited. A more extensive discussion of
chlorine dioxide and chlorite occurrence is described in section VI. of
this preamble.

Table V-5:--Summary of Occurrence Data For Chlorine Dioxide and Chlorite
Occurrence of Chlorine Dioxide, Chlorate, and Chlorite in Drinking Water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information -----------------------------------------------------

(No. of samples) Range Mean Median Other

AWWARF (1987) Finished Water From:
McGuire &
Meadow, 1988.
Lakes................ 1.0 mg/L\3\
Flowing Streams...... 0.6 mg/L\3\
Plants Using CIO<INF>2: Positive
Detections
Chlorite at the Plant 15-740 240 110 100%
(4).

EPA, 1992b\2\ Disinfection By- Chlorate at the Plant 21-330 200 220 100%

(1987-1991). Products Field (4).
Studies
Plants Not Using
CIO<INF>2:
Chlorate at the Plant <10-660 87 16 60%
(30).
Chlorate, Distr. <10-47 18 13 75%
System (4).

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Typical dosage used by treatment plants.
AWWARF American Water Works Association Research Foundation.
EPA Environmental Protection Agency.

No information is available on the occurrence of chlorine dioxide,
chlorate, and chlorite in food or ambient air. Currently, the Food and
Drug Administration (FDA) does not analyze for these compounds in
foods. Preliminary discussions with FDA suggest that there are not
approved uses for chlorine dioxide in foods consumed in the typical
diet. In addition, the EPA Office of Air and Radiation does not require
monitoring for these compounds in air. However, chlorine dioxide is
used as a sanitizer for air ducts (Borum, 1991).
EPA believes that drinking water is the predominant source of
exposure for these compounds. Air and food exposures are considered to
provide only small contributions to the total chlorine dioxide,
chlorate, and chlorite exposures, although the magnitude and frequency
of these potential exposures are issues currently under review.
Therefore, EPA is considering proposing to regulate these compounds in
drinking water with an RSC value of 80 percent, the current exposure
assessment policy ceiling. EPA requests any additional data on known
concentrations of chlorine dioxide, chlorate and chlorite in drinking
water, food and air.
Health Effects. The following health effects information is
summarized from the draft Drinking Water Health Criteria Document for
Chlorine Dioxide, Chlorite and Chlorate (USEPA, 1994c). Studies cited
in this section are summarized in the draft criteria document.
As noted above, chlorine dioxide is fairly unstable and rapidly
dissociates predominantly into chlorite and chloride, and to a lesser
extent, chlorate. There is a ready interconversion among chemical
species in water (before administration to animals) and in the gut
(after ingestion). Therefore, what exists in water or the stomach is a
mixture of these chemical species and possibly their reaction products
with the gastrointestinal contents. Thus, the toxicity information on
chlorite, the predominant degradation product of chlorine dioxide, may
also be relevant to characterizing chlorine dioxide toxicity. In
addition, studies conducted with chlorine dioxide may be relevant to
characterizing the toxicity of chlorite. As a result, the toxicity data
for one compound are considered applicable for addressing toxicity data
gaps for the other.
The main health effects associated with chlorine dioxide and its
anionic by-products include oxidative damage to red blood cells,
delayed neurodevelopment and decreased thyroxine hormone levels.
Chlorine dioxide, chlorite and chlorate are well absorbed by the
gastrointestinal tract and excreted primarily in urine. Once absorbed,
36Cl-radiolabeled chlorine dioxide, chlorite and chlorate are
distributed throughout the body. Lethality data for ingested chlorine
dioxide have not been located in the available literature. A lethal
concentration for guinea pigs by inhalation was reported at 150 ppm.
Oral LD<INF>50 values for chlorite have been reported at 100 to 140 mg/
kg in rats. A more recent study indicates that the oral LD<INF>50 may
be closer to 200 mg/L. Limited data suggest an oral LD<INF>50 value
between 500 to 1500 mg/kg for chlorate in dogs.
In subchronic and chronic studies, animals given chlorine dioxide
treated water exhibited osmotic fragility of red blood cells (1 mg/kg/
d), decreased thyroxine hormone levels (14 mg/kg/d), possibly due to
altered iodine metabolism and hyperplasia of goblet cells and
inflammation of nasal tissues. The nasal lesions are not considered
related to ingested chlorine dioxide. However, it is not clear if the
nasal effects are due to off-gassing of chlorine dioxide from the
sipper tube of the animal water bottles, or from dermal contact while
the animal drinks from the sipper tube. In addition, the chlorine
dioxide treated group drank water at a pH of 4.7 which may also have
contributed to the nasal tissue inflammation. The concentration
associated with this effect (25 mg/L) is considerably greater than what
would be found in drinking water.
Studies evaluating developmental or reproductive effects have
described decreases in the number of implants and live fetuses per dam
in female rats given chlorine dioxide in drinking water before mating
and during pregnancy. Delayed neurodevelopment has been reported in rat
pups exposed perinatally to chlorine dioxide (14 mg/kg/d) or chlorite
(3 mg/kg/d) treated water. Delayed neurodevelopment was assessed by
decreased locomotor activity and decreased brain development.
Subchronic studies with chlorite administered to rats via drinking
water resulted in transient anemia, decreased red blood cell
glutathione levels and increased hydrogen peroxide formation at doses
greater than 5 mg/kg/d. Chlorite administration orally to cats at a
dose of 7 mg/kg/d produced 10 to 40 percent methemoglobin formation
within a couple of hours following dosing. Exposure to chlorite in
drinking water resulted in an increased turnover of red blood cells in
cats rather than oxidation of hemoglobin.
Oral studies with chlorate also demonstrate effects on
hematological parameters and formation of methemoglobin, but at much
higher doses than chlorite (157-256 mg/kg/d).
No clear tumorigenic activity has been observed in animals given
oral doses of chlorine dioxide, chlorite or chlorate. Chlorine dioxide
concentrates did not increase the incidence of lung tumors in mice nor
was any initiating activity observed in mouse skin or rat liver
bioassays. Lung and liver tumors were increased in mice given sodium
chlorite; however, the incidence was within the historical range for
these tumor types. Carcinogenic studies on chlorate were not located in
the available literature. Chlorate has been reported to be mutagenic in
bacterial and Drosophila tests. EPA has classified chlorine dioxide and
chlorite in Group D: not classifiable as to human carcinogenicity. This
classification is for chemicals with inadequate evidence or no data
concerning carcinogenicity in animals in the absence of human data. EPA
has not classified chlorate with respect to carcinogenicity.
There are a number of cases of poisoning in humans who used
chlorate as an herbicide. Effects observed following exposures to 11 to
3,400 mg/kg include cyanosis, renal failure, convulsions and death. The
lowest lethal dose reported in adults is approximately 200 mg/kg. It is
not clear if this is the actual dose received or if other components in
the formulation were contributors to the toxicity. In an epidemiology
study of a community where chlorine dioxide was used as the primary
drinking water disinfectant for 12 weeks, no consistent changes were
observed in the clinical parameters measured.
Three studies have been selected as the basis for the RfD and MRDLG
for chlorine dioxide. These studies identify a NOAEL of 3 mg/kg/d and a
LOAEL of approximately 10 mg/kg/d. A NOAEL of 3 mg/kg/d has been
identified in an 8 week rat study by Orme et al. (1985). In this study,
chlorine dioxide was administered to female rats via drinking water at
concentrations of 0, 2, 20 and 100 mg/L before mating, during gestation
and lactation until the pups were 21 days old. Based on body weight and
water consumption data, these concentrations correspond to doses of 1,
3 and 14 mg/kg/d. No effects were noted in dams. Pups in the high dose
group (14 mg/kg/d) exhibited decreased exploratory and locomotor
activity and a significant depression of thyroxine. These effects were
not observed at the 3 mg/kg/d dose level. In a second experiment, pups
were given 14 mg/kg/d chlorine dioxide directly by gavage during
postnatal days 5 through 20. A greater and more consistent delay in
neurobehavioral activity was observed along with a greater depression
in thyroxine. Analysis of the DNA content of cells in the cerebellum
from animals in the high dose drinking water group (14 mg/kg/day) at
postnatal day 21 and the gavage group at day 11 indicated a significant
depression (Taylor and Pfohl, 1985). Another study confirmed 14 mg/kg/d
as a LOAEL based on decreased brain cell proliferation in rats exposed
postnatally by gavage (Toth et al., 1990).
The no-effect level of 3 mg/kg/day is also supported by a monkey
study (Bercz et al., 1982), where animals were given chlorine dioxide
at concentrations of 0, 30, 100 or 200 mg/L in drinking water following
a rising dose protocol. These concentrations correspond to doses of 0,
3.5, 9.5 and 11 mg/kg/d based on animal body weight and water
consumption. Animals showed signs of dehydration at the high dose;
exposure was discontinued at that dose (11 mg/kg/d). A slight
depression of thyroxine was observed following exposure to 9.5 mg/kg/d.
No effects were seen with 3.5 mg/kg/d, which is considered the NOAEL.
MRDLG for Chlorine Dioxide. EPA is proposing an MRDLG for chlorine
dioxide based on developmental neurotoxicity following a Category III
approach. Using a NOAEL of 3 mg/kg/d and an uncertainty factor of 300,
an RfD of 0.01 mg/kg/d for chlorine dioxide is calculated. An
uncertainty factor of 300 is used to account for differences in
response to toxicity within the human population and between humans and
animals. This factor also accounts for lack of a two-generation
reproductive study. Availability of an acceptable two-generation
reproduction study would likely reduce the total uncertainty factor to
100. The Chlorine Dioxide panel of the Chemical Manufacturers
Association is conducting a two-generation reproductive study with
chlorite to address this data gap. EPA will review the results of this
study and determine if any changes to the RfD for chlorine dioxide are
warranted.
After adjusting for an adult consuming 2 L water per day, an RSC of
80 percent is applied to calculate an MRDLG of 0.3 mg/L. An RSC of 80%
is used since most chlorine dioxide exposure is likely to come from a
drinking water source.

<GRAPHIC><TIF4>TP29JY94.004

The Drinking Water Committee of the Science Advisory Board (SAB)
agreed with the use of the Orme et al. (1985) study as the basis for
the MRDLG and suggested that an uncertainty factor of 100 be applied
(USEPA, 1992c). They also suggested that a child's body weight of 10 kg
and water consumption of 1 L/d may be more appropriate for setting the
MRDLG than the adult parameters, given the acute nature of the toxic
effect. EPA requests comments on the SAB's suggestion.
EPA also requests comment on the appropriateness of the 300-fold
uncertainty factor, the studies selected as the basis for the RfD, and
the 80% relative source contribution.
MCLG for Chlorite. The developmental rat study by Mobley et al.
(1990) has been selected to serve as the basis for the RfD and MCLG for
chlorite. Other studies reported effects at doses higher than the
Mobley et al. study. In this study, female Sprague-Dawley rats (12/
group) were given drinking water containing 0, 20, or 40 mg/L chlorite
(0, 3, or 6 mg chlorite ion/kg/day) as the sodium salt beginning 10
days prior to breeding with untreated males until the pups were
sacrificed at 35 to 42 days postconception (a total exposure of 9
weeks). Exploratory activity was depressed in the pups treated with 3
mg/kg/day chlorite on postconception days 36-37 but not on days 38-40.
Pups from the high exposure group also exhibited depressed exploratory
behavior during days 36-39 postconception (p<0.05). Exploratory
activity was comparable among the treated and control groups on
postconception days 39-41. No significant differences in serum total
thyroxine or triiodothyronine were observed between treated and control
pups. Free thyroxine was significantly elevated in the 6 mg/kg/day
pups. A LOAEL of 3 mg/kg/day was determined in this study based on the
neurobehavioral effect (depressed exploratory behavior) in rats. This
endpoint is similar to that reported for chlorine dioxide.
EPA had considered using a study by Heffernan et al. (1979) which
described dose-related decreases in red blood cell glutathione levels
from rats orally exposed to chlorite in drinking water for up to 90
days. The decreases in glutathione were accompanied by decreases in red
blood cell concentration, hemaglobin concentration and packed red cell
volume. Taken together, these effects were considered reflective of
oxidative stress resulting from the ingested chlorite. In this study, a
NOAEL of 1 mg/kg/d and LOAEL og 5 mg/kg/d were identified.
The EPA Science Advisory Board had cautiously agreed with the
selection of the Heffernan et al. (1979) study as the basis for the
RfD, but noted that the endpoint would likely be controversial since
normal fluctuations occur with glutatione levels. Thus this effect,
alone, may not necessarily be the result of chlorite exposure. The EPA
RfD workgroup was unable to reach consensus on decreased glutathione
levels as an appropriate endpoint to base an RfD. They agreed with the
selection of the Mobley et al. (1990) study since the endpoint,
developmental neurotoxicity, represented the next critical effect and
was consistent with the toxicity observed with chlorine dioxide.
Following a Category III approach, EPA is proposing an MCLG of 0.08
for chlorite. The MCLG is based on an RfD of 0.003 determined from the
LOAEL of 3 mg/kg/day from the Mobley et al. study. This endpoint was
selected since it is similar to that reported for chlorine dioxide. An
uncertainty factor of 1,000 is used in the derivation of the RfD and
MCLG to account for use of a LOAEL from an animal study.
After adjusting for an adult consuming 2 L water per day, an RSC of
80% is applied to calculate an MCLG of 0.08 mg/L. An RSC of 80% was
used since most exposure to chlorite is likely to come from drinking
water.

<GRAPHIC><TIF5>TP29JY94.005

The Drinking Water Committee of the EPA Science Advisory Board
suggested that EPA consider basing the MCLG on the child body weight of
10 kg and water consumption of 1 L/day instead of the adult default
values. EPA requests comments on the SAB's suggestion along with the
study selected as the basis for the MCLG, the uncertainty factor and
the RSC of 80%.
MCLG for Chlorate. Data are considered inadequate to develop an
MCLG for chlorate at this time. A NOAEL of 0.036 mg/kg/d (the only dose
tested) was identified in the Lubbers et al. (1982) human clinical
study following a 12-week exposure to chlorate in drinking water.
NOAELs identified from animal studies are considerably higher
(approximately 78 mg/kg/d). However, doses that are lethal to humans
(200 mg/kg/d) are only 2-fold greater than this animal no-effect level.
No information is available to characterize the potential human
toxicity between the doses of 0.036, the only human NOAEL and 200 mg/
kg/d, the apparent human lethal dose. Thus, EPA considers the data base
too weak to derive a separate MCLG for chlorate at this time. The
Agency will continue to evaluate the animal data and any new
information that become available for future consideration of an MCLG
for chlorate.
EPA requests comments on the decision not to propose an MCLG for
chlorate at this time.
5. Chloroform
Chloroform [trichloromethane, CAS No. 67-66-3] is a nonflammable,
colorless liquid with a sweet odor and high vapor pressure (200 mm Hg
at 25 deg.C). It is moderately soluble in water (8 gm/L at 20 deg.C)
and soluble in organic solvents (log octanol/water partition
coefficient of 1.97). Chloroform is used primarily to manufacture
fluorocarbon-22 (chlorodifluoromethane) which in turn is used for
refrigerants and fluoropolymer synthesis. A small percentage of the
manufactured chloroform is used as an extraction solvent for various
products (e.g. resins, gums). In the past, chloroform was used in
anesthesia and medicinal preparations and as a grain fumigant
ingredient. Chloroform can be released to the environment from direct
(manufacturing) and indirect (processing/use) sources and chloroform is
a prevalent chlorination disinfection by-product. Volatilization is the
principle mechanism for removal of chloroform from lakes and rivers.
Chloroform bioconcentrates slightly in aquatic organisms and adsorbs
poorly to sediments and soil. Chloroform can be biodegraded in water
and soil (half-life of weeks to months) and ground water (half-life of
months to years), and photo-oxidized in air (half-life of months).
Occurrence and Human Exposure. The principle source of chloroform
in drinking water is the chemical interaction of chlorine with commonly
present natural humic and fulvic substances and other precursors
produced by either normal organic decomposition or by the metabolism of
aquatic biota. Because humic and fulvic material are generally found at
much higher concentrations in surface water sources than in ground
water sources, surface water systems have higher frequencies of
occurrence and higher concentrations of chloroform than ground water
systems. Several water quality factors affect the formation of
chloroform including Total Organic Carbon (TOC), pH, and temperature.
Different treatment practices can reduce the formation of chloroform.
These include the use of precursor removal technologies such as
coagulation/filtration, granular activated carbon (GAC), and membrane
filtration and the use of chlorine dioxide, chloramination, and
ozonation.
Table V-6 presents occurrence information available for chloroform
in drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' (USEPA, 1992a). The
table lists six surveys conducted by Federal and private agencies.
Median concentrations of chloroform in drinking water appear to range
from 14 to 57 <greek-m>g/L for surface water supplies and
<ls-thn-eq>0.5 <greek-m>g/L for ground-water supplies (many of which do
not disinfect). The lower bound median concentration for chloroform in
surface water supplies is biased to the low side because concentrations
in this survey were measured in the plant effluent; the formation of
chloroform would be expected to increase in the distribution in systems
using chlorine as their residual disinfectant.

Table V6.--Summary of Occurrence Data For Chloroform
[Occurrence of Chloroform in Drinking Water]

Concentration (<greek-m>g/L

Survey (year) Location Sample information -----------------------------------------------------

(No. of samples) Rage Mean Median Other

CWSS (1978) Brass 450 Water Supply Finished Water ........... ........... ........... Positive

et al., 1981. Systems (1,100):. Detections:

................ Surface Water........ ........... \3\60 ........... \4\97%
................ Ground Water......... ........... \3\<0.5 ........... \4\34%
RWS (1978-1980) >600 Rural Drinking Water from:. ........... ........... ........... Postive

Brass, 1981. Systems (>2,000 Detection:
Households)

................ Surface Water........ ........... \3\84 57 \4\82%
................ Ground Water......... ........... \3\8.9 <0.5 \4\17%
GWSS (1980-1981) 945 GW Systems: ..................... ........... ........... ........... 90th

Westrick et al. percentile:
1983.

(466 Random and Serving >10,000 (327) Max. 300 ........... 0.5 17
479 Nonrandom) Serving <10,000 (618) Max. 430 ........... 0 7.8
EPA, 1991a\2\ Unregulated Sampled at the Plant ........... 17 5 .............

(1984-1991). Contaminant (5,806).
Data Base--
Treatment
Facilities from
19 States

EPA, 1992b\2\ Disinfection By- Finished Water:...... ........... ........... ........... Positive

(1987-1991). Products Field Detections:
Studies

................ At the Plant (73).... <0.2-240 36 28 96%
................ Distribution System <0.2-340 57 42 98%

(56).

EPA/AMWA/CDHS\2\ 35 Water Samples from Max. 130 ........... \5\9.6-15 75% of Data

(1988-1989). Utilities Clearwell. was Below 33
Nationwide <greek-m>gL.

Krasner et al., ................ Effluent for 4 ........... ........... 14 .............

1989b. Quarters.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Mean of the positives.
\4\Of systems sampled.
\5\Range of medians for individual quarters.
AMWA Association of Metropolitan Agencies.
CDHS California Department of Health Services.
CWSS Community Water Supply Survey.
GWSS Ground Water Supply Survey.
RWS Rural Water Survey.
EPA Environmental Protection Agency.

Several studies have assessed inhalation exposure to chloroform.
The major source of these data is from the USEPA's Total Exposure
Assessment Methodology (TEAM) studies, which measured chloroform
exposure to approximately 750 persons in eight geographic areas from
1980 to 1987. Personal exposure to chloroform from air was measured
over a 12-hour period (excluding showers) for individuals in three
areas. The average exposures were reported to range from 4 to 9
<greek-m>g/m3 in New Jersey and Baltimore, and about 0.5 to 4
<greek-m>g/m3 in California cities (Wallace, 1992). In the 1987
Los Angeles TEAM study, chloroform in indoor air was measured in the
living room and kitchen of private residences. Observed mean indoor
concentrations ranged from 0.9 to 1.5 <greek-m>g/m3 (Pellizzari et
al., 1989 and Wallace et al., 1990 in Wallace, 1992). For outdoor
levels, the 12-hour average outdoor concentrations measured in the
California and New Jersey TEAM studies ranged from 0.2 to 0.6
<greek-m>g/m3 and 0.1 to 1.5 <greek-m>g/m3, respectively
(Pellizzari et al., 1989, Wallace et al., 1990 and PEI et al., 1989 in
Wallace, 1992).
Given the limited exposure data in air, inhalation exposure can be
estimated using an inhalation rate of 20 m3/day. Resulting
estimates for average ambient air exposures range from 2 to 30
<greek-m>g/d and 18-30 <greek-m>g/d for average indoor air exposures.
However, based on the personal air monitoring data, a potentially
higher average inhalation exposure is indicated with a range of 10 to
180 <greek-m>g/d.
Two studies analyzed some foods for chloroform. In a pilot market
basket survey of four food groups at five sites, measured chloroform
levels were as follows: dairy composite, 17 ppb (1 of 5 sites); meat
composite, not detected; oil and fat composite, trace amounts (1 of 5
sites); beverage composite, 6 to 32 ppb (4 of 5 sites) (Entz et al.,
1982). In a study of 15 table-ready food items, chloroform was detected
in 53% of the foods tested: butter, 670 ppb; cheddar cheese, 80 ppb;
plain granola, 57 ppb; peanut butter, 29 ppb; chocolate chip cookies,
22 ppb; frozen fried chicken dinner, 29 ppb; and high meat dinner, 17
ppb (Heikes, 1987).
Limited data are available to characterize dietary exposure to
chloroform. Although some uses of chlorine have been identified in the
food production/food processing area, monitoring data are not adequate
to characterize the magnitude or frequency of exposure to chloroform.
Based on the limited number of food groups that are believed to contain
chloroform and low levels expected in ambient and indoor air, EPA
assumes that drinking water is the predominant source of chloroform
intake. The characterization of potential food and air exposures are
issues currently under review. EPA requests any additional data on
known concentrations of chloroform in drinking water, food, and air.
Health Effects. The health effects information is summarized from
the draft Drinking Water Criteria Document for Trihalomethanes (USEPA,
1994d). Studies cited in this section are summarized in the criteria
document.
Chloroform has been shown to be rapidly absorbed upon oral,
inhalation and peritoneal administration and subsequently metabolized.
The reported mean human lethal dose, from clinical observations of
overdoses, was around 630 mg/kg. The LD<INF>50 values in mice and rats
have been reported in the range of 908-1,400 mg/kg. Several reactive
metabolic intermediates (e.g. phosgene, carbene, dichloromethyl
radicals) can be produced via oxidation (major pathway) or reduction
(minor pathway) by microsomal preparations. Experimental studies
suggested that these active metabolic intermediates are responsible for
the hepatic and renal toxicity and possibly, carcinogenicity, of the
parent compound. Animal studies suggest that the extent of chloroform
metabolism varies with species and sex. The retention of chloroform in
organs after dosing was small. Due to the lipophilic nature of the
compound, the residual concentration is in tissues with higher fatty
content. In humans, the majority of the tested oral intake doses (0.1
to 1 gm) were excreted through the lungs in the form of a metabolite
CO<INF>2 or as the unchanged compound. Urinary excretion levels were
below 1%.
Mammalian bioeffects following exposure to chloroform include
effects on the central nervous system (CNS), hepatotoxicity,
nephrotoxicity, reproductive toxicity and carcinogenicity. Chloroform
caused CNS depression and affected liver and kidney function in humans
in both accidental and long term occupational exposure situations. In
experimental animals, chloroform caused changes in kidney, thyroid,
liver, and serum enzyme levels. These responses are discernible in
mammals from exposure to levels of chloroform ranging from 15 to 290
mg/kg; the intensity of response was dependent upon the dose and the
duration of the exposure. Ataxia and sedation were noted in mice
receiving a single dose of 500 mg/kg chloroform. Short-term exposure to
the low levels of chloroform typically found in air, food, and water
are not known to manifest acute toxic effects. The potential for human
effects from chronic lifetime exposure is the basis for this
regulation.
Developmental toxicity and reproductive toxicity have been
investigated in animals. One developmental study reported maternal
toxicity in rabbits administered chloroform by the oral route.
Decreased weight gain and mild fatty changes in liver were observed in
dams receiving 50 mg/kg/day (LOAEL); the maternal NOAEL was noted to be
35 mg/kg/day. There was no evidence of developmental effects.
The data from a 7.5-year oral study in dogs conducted by Heywood et
al. (1979) were used to calculate the RfD. EPA considers this study
suitable for the RfD derivation since it is a chronic study and
sensitive indices of hepatotoxicity (serum enzyme levels, liver
histology) of sufficient numbers of experimental animals were
monitored. In this study, chloroform was administered to beagle dogs
(16 per dose group) in toothpaste base gelatin capsules at dose levels
of 15 or 30 mg/kg/day 6 days/week for 7.5 years. A LOAEL of 15 mg/kg/
day was established based on the observation of hepatic fatty cysts in
treated animals at both doses. An RfD of 0.01 mg/kg/day has been
derived from this LOAEL by the application of an uncertainty factor of
1,000, in accordance with EPA guidelines.
The results of a number of assays to determine the mutagenicity
potential of chloroform are inconclusive. Studies on the in vitro
genotoxicity of chloroform reported negative results in bacteria (Ames
assays), negative results for gene mutations and chromosomal
aberrations in mammalian cells, and mixed results in yeasts. In vivo
and in vitro DNA damage tests indicate that chloroform will bind to
DNA. Gene mutation tests in Drosophila were marginal, whereas tests for
chromosomal aberrations and sperm abnormalities were mixed.
Several chronic animal studies confirmed the carcinogenicity of
chloroform. Chloroform induced hepatocellular carcinomas in mice when
administered by gavage in corn oil (NCI, 1976). Chloroform also induced
renal adenomas and adenocarcinomas in male rats regardless of the
carrier vehicle (oil or drinking water) employed (NCI, 1976; Roe et
al., 1979; Jorgenson et al., 1985).
In the study by Jorgenson et al. (1985), chloroform was
administered in drinking water to male Osborne-Mendel rats and female
B6C3F<INF>1 mice at doses of 0, 200, 400, 900 or 1,800 ppm (0, 19, 38,
81 or 160 mg/kg/day in rats and 0, 34, 65, 130 or 263 mg/kg/day in
mice) for 2 years. Chloroform increased the incidence of kidney tumors
in male rats in a dose-related manner. The combined incidence of renal
tubular cell adenomas, renal tubular cell adenocarcinomas, and
nephroblastomas in control, 200, 400, 900 and 1,800 ppm groups were 5/
301, 6/313, 7/148, 3/48, and 7/50, respectively. Jorgenson's study
reported no statistically significant increase in the incidence of
hepatocellular carcinomas in the female mice exposed to similar doses
of chloroform as reported in the 1976 NCI study.
Since hepatic changes appeared to be related to the corn oil
vehicle, the interaction of corn oil and chloroform could account for
the enhanced hepatic toxicity and thus for the difference in the NCI
and Jorgenson studies. Because the drinking water study did not
replicate hepatic tumors in female mice and the potential role of corn
oil in enhancing toxicity, the National Academy of Science Subcommittee
on the Health Effects of Disinfectants and Disinfection By-Products
(NAS, 1987) recommended that male rat kidney tumor data obtained from
Jorgenson's study be used to estimate the carcinogenic potency of
chloroform. EPA agreed with the NAS Subcommittee recommendation for
estimating risks of chloroform from drinking water exposures.
Based on all kidney tumor data in male Osborne-Mendel rats reported
by Jorgenson et al. (1985), EPA used a linearized multistage model and
derived a carcinogenic potency factor for chloroform of 6.1 x
10-3 (mg/kg/day)-1. Assuming a daily consumption of two
liters of drinking water and an average human body weight of 70 kg, the
95% upper bound limit lifetime cancer risk levels of 10-6,
10-5, and 10-4 are associated with concentrations of
chloroform in drinking water of 6, 60 and 600 <greek-m>g/L,
respectively.
In 1987 the Commission on Life Sciences of the National Research
Council published Drinking Water and Health (NAS, 1987). Volume 7,
Disinfectants and Disinfectant By-Products, prepared by the Subcomittee
on Disinfectants and Disinfection By-Products, discussed the available
data on chloroform, which are the same data summarized above. The
Subcommittee concluded that ``[n]oting that chloroform is the principal
THM produced by chlorination, the subcommittee found [the 100 THM]
level to be unsupportable on the basis of the risk values for
chloroform developed in this review,'' and that the level should be
reduced.
EPA has classified chloroform in Group B2, probable human
carcinogen, based on sufficient evidence of carcinogenicity in animals
and inadequate evidence in humans (IRIS, 1985). The International
Agency for Research on Cancer (IARC) has classified chloroform as a
Group 2B carcinogen, agent possibly carcinogenic to humans. (IARC,
1982).
According to EPA's three-category approach for establishing MCLGs,
chloroform is placed in Category I since there is sufficient evidence
of carcinogenicity via ingestion considering weight of evidence,
potency, pharmacokinetics, and exposure. Thus, EPA is proposing an MCLG
of zero for this contaminant. EPA requests comment on the basis for the
proposed MCLG for chloroform.
6. Bromodichloromethane
Bromodichloromethane (BDCM; CAS No. 75-27-4) is a nonflammable,
colorless liquid with a relatively high vapor pressure (50 mmHg at
20 deg.C). BDCM is moderately soluble in water (3.3 gm/L at 30 deg.C)
and soluble in organic solvents (log octanol/water partition
coefficient of 1.88). Only a small amount of BDCM is currently produced
commercially in the United States. The chemical is used as an
intermediate for organic synthesis and as a laboratory reagent. The
principle source of BDCM in drinking water is the chemical interaction
of chlorine with the commonly present organic matter and bromide ions.
Degradation of BDCM is not well studied, but probably involves
photooxidation. The estimated atmospheric half-life of BDCM is two to
three months. Volatilization is the principal mechanism for removal of
BDCM from rivers and streams (half-life of hours to weeks). Limited
studies reported that BDCM adsorbed poorly to sediments and soils. No
study of bioaccumulation of BDCM was located. Based on the data of a
few structurally similar chemicals such as chloroform, the
bioconcentration potential of BDCM in aquatic organisms is low.
Biodegradation of BDCM is limited under aerobic conditions and
extensive (completion within days) under anaerobic conditions.
Occurrence and Human Exposure. BDCM, occurs in public water systems
that chlorinate water containing humic and fulvic acids and bromine
that can enter source waters through natural and anthropogenic means.
Several water quality factors affect the formation of BDCM including
Total Organic Carbon (TOC), pH, bromide, and temperature. Different
treatment practices can reduce the formation of BDCM. These include the
use of chlorine dioxide, chloramination, and ozonation prior to
chloramination, as well as the use of precursor removal technologies
such as coagulation/filtration, granular activated carbon (GAC), and
membrane filtration.
Table V-7 presents occurrence information available for BDCM in
drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' (USEPA, 1992a). The
table lists six surveys conducted by Federal and private agencies.
Median concentrations of BDCM in drinking water appear to range from
6.6 to 15 <greek-m>g/L for surface water supplies and <0.5 <greek-m>g/L
for ground-water supplies. The lower bound median concentration for
BDCM in surface water supplies is biased to the low side because
concentrations in this survey were measured in the plant effluent; the
formation of BDCM would be expected to increase in the distribution
system when chlorine is used as the residual disinfectant.

Table V-7: Summary of Occurrence Data for Bromodichloromethane

Occurrence of Bromodichloromethane

Concentration (<greek-m>g/L)

Survey (Year)\1\ Location Sample Information(No. of ----------------------------------------------------------------------

Samples) Range Mean Median Other

CWSS (1978, Brass et 450 Systems............. Finished Water (1,100): Positive Detections:
al., 1981. Surface Water................ \3\12 6.8 94%\4\
Ground Water................. \3\5.8 <0.5 33%\4\
RWS (1978-1980) Brass, >600 Rural Systems Drinking Water from: Positive Detections:
1981. (>2,000 households). Surface Water................ ............. ........... 11 76%\4\
Ground water................. ............. ........... <0.5 13%\4\
GWSS (1980-1981) 945 GW Systems: ............. 90Percentile
Westrick et al. 1983. (466 Random and 479 Serving >10,000 (327)........ Max. 110..... ........... 0.4 9.2
Nonrandom).. Serving <10,000 (618)........ Max. 79...... ........... 0 6.1
EPA, 1991a\2\ (1984- Unregulated Contaminant Finished Water at Treatment ............. 5.6 3
1991). Data Base--Treatment Plants (4,439).
Facilities from 19
States.
EPA, 1992b\2\ (1987- Disinfection By-Products Finished Water: Positive Detections:
1989). Field Studies. At the Plant (73)............ <0.2-90...... 13 11 96%
Distribution System (56)..... <0.2-100..... 17 15 98%

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell Max. 82...... 4.1-10\5\ 6.6 75% of Data was Below 14

1989) Krasner et al., Nationwide. Effluent for 4 Quarters. <greek-m>g/L.
1989b.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Mean of the positives.
\4\Of systems sampled.
\5\Range of medians for individual quarters.

AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
CWSS: Community Water Supply Survey.
GWSS: Ground Water Supply Survey.
RWS: Rural Water Survey.
EPA: Environmental Protection Agency.

BDCM is usually found in air at low concentrations. Based on
information obtained through a literature review, Howard (1990)
estimated the average daily intake of BDCM from air using an inhalation
rate of 20 m\3\/day. Assuming a range of 6.7 to 670 ng/m\3\, the
average exposure may be as low as 0.134 <greek-m>g/day or as high as
13.4 <greek-m>g/day.
BDCM is not a common contaminant in food. In one market study of 39
different food items, BDCM was detected in one dairy composite (1.2
ppb), butter (7 ppb), and two beverages (0.3 and 0.6 ppb). Analysis of
cola soft drinks found BDCM in three samples with reported
concentrations of 2.3 ppb, 3.4 ppb, and 3.8 ppb (Entz et al., 1982 in
Howard, 1990).
Limited data are available to characterize food and air exposures
to BDCM. Although some uses of chlorine have been identified in the
food production/food processing area, monitoring data are inadequate to
characterize the magnitude and frequency of potential BDCM exposures.
Based on the limited number of food groups that are believed to contain
BDCM and that there are not significant levels expected in ambient or
indoor air, EPA assumes that drinking water is the predominant source
of BDCM intake. EPA requests any additional data on known
concentrations of BDCM in drinking water, food, and air.
Health Effects. The health effects information in this section is
summarized from the draft Drinking Water Criteria Document for
Trihalomethanes (USEPA, 1994d). Studies mentioned below are summarized
in the criteria document.
Studies indicated that gastrointestinal absorption of BDCM is high
in animals. No studies were located regarding BDCM in humans or animals
following inhalation or dermal exposure. By analogy with the
experimental data of a structurally-related halomethane chloroform,
inhalation and dermal absorption may be high for BDCM. The reported
LD<INF>50 values in mice and rats ranged from 450 to 969 mg/kg. Under
both in vivo and in vitro conditions, several active metabolic
intermediates (e.g. dichlorocarbonyl, dichloromethyl radicals) were
produced via oxidation or reduction by microsomal preparations.
Experimental studies suggested that these active metabolic
intermediates may be responsible for hepatic and renal toxicity and
possibly, carcinogenicity of the parent compound. Animal studies
suggest that the extent of BDCM metabolism varies with species and sex.
The retention of BDCM in organs after dosing was small, even after
repeated doses. Urinary excretion levels were below 3 percent.
Mammalian bioeffects following exposure to BDCM include effects on
the central nervous system (decreased operant response),
hepatotoxicity, nephrotoxicity, reproductive toxicity, and
carcinogenicity. In experimental mice and rats, BDCM caused changes in
kidney, liver, serum enzyme levels, and decreased body weight. These
responses were discernible in rodents from exposure to levels of BDCM
that ranged from 6 to 300 mg/kg; the intensity of response was
dependent upon the dose and the duration of the exposure. Ataxia and
sedation were observed in mice receiving a single dose of 500 mg/kg
BDCM.
One study investigated developmental and reproductive toxicity of
BDCM in rodents. Ruddick et al. (1983) administered BDCM in corn oil to
groups of pregnant rats by gavage at doses of 0, 50, 100 or 200 mg/kg/
day on days 6 to 15 of gestation. At 200 mg/kg/day, BDCM significantly
(p <0.05) decreased maternal weight (25%) and increased relative kidney
weights. There were no increases in the incidence of fetotoxicity or
external/visceral malformations, but sternebral anomalies were more
prevalent at 100 and 200 mg/kg than at 50 mg/kg. The sternebral
anomalies were not considered by the authors to be evidence of a
teratogenic effect, but rather evidence of maternal toxicity.
Data from a National Toxicology Program (NTP) chronic oral study in
B6C3F<INF>1 mice (NTP, 1987) was used to calculate the RfD. BDCM in
corn oil was given to mice by gavage 5 days/week for 102 weeks. Male
mice (50/dose) were administered doses of 0, 25 or 50 mg/kg/day while
female mice (50/dose) received doses of 0, 75 or 150 mg/kg/day.
Following treatment, mortality, body weight and histopathology were
observed. Renal cytomegaly and fatty metamorphosis of the liver was
observed in male mice <gr-thn-eq>25 mg/kg/day). Compound-related
follicular cell hyperplasia of the thyroid gland was observed in both
males and females. The survival rate decreased in females and decreases
in mean body weights were observed in both males and females at high
doses. Based on the observed renal, liver and thyroid effects in male
mice, a LOAEL of 25 mg/kg/day was identified. A RfD of 0.02 mg/kg/day
has been derived from the LOAEL of 25 mg/kg/day in mice by the
application of an uncertainty factor of 1,000, in accordance with EPA
guidelines for use of a LOAEL derived from a chronic animal study.
In vitro genotoxicity studies reported mixed results in bacterial
Salmonella strains and yeasts. BDCM was not mutagenic in mouse lymphoma
cells without metabolic activation, but induced mutation with
activation. An increase in frequency of sister chromatid exchange was
reported in cultured human lymphocytes, rat liver cells, and mouse bone
marrow cells (in vivo), but not in Chinese hamster ovary cells.
Overall, more studies yielded positive results and evidence of
mutagenicity for BDCM is considered adequate.
Evidence of the carcinogenicity of BDCM has been confirmed by a NTP
(1987) chronic animal study. In this study BDCM in corn oil was
administered via gavage to groups of 50 rats (Fischer 344/N) of each
sex at doses of 0, 50 or 100 mg/kg, 5 days/week, for 102 weeks (NTP,
1987). Male B6C3F<INF>1 mice (50/dose) were administered 0, 25 or 50
mg/kg by the same route while females received 0, 75 or 150 mg/kg/day.
BDCM caused statistically significant increases in kidney tumors in
male mice, the liver in female mice, and the kidney and large intestine
in male and female rats. In male mice, the combined incidence of
tubular cell adenomas or adenocarcinomas of the kidneys increased
significantly in the high-dose group (vehicle control, 1/46; low-dose,
2/49; high-dose 9/50). The combined incidences of hepatocellular
adenomas or carcinomas in vehicle control, low-dose and high-dose
female mice groups were 3/50, 18/48 and 29/50, respectively.
In rats from the NTP study, the combined incidences of tubular cell
adenomas or adenocarcinomas in vehicle control, low-dose and high-dose
groups were 0/50, 1/49 and 13/50 for males and 0/50, 1/50 and 15/50 for
females, respectively. Tumors of large intestines were significantly
increased in a dose-dependent manner in male rats, and only observed in
high-dose female rats. The combined incidences of adenocarcinomas or
adenomatous polyps were 0/50, 13/49, 45/50 for males and 0/46, 0/50,
12/47 for females, respectively. The combined tumor incidences of large
intestine and kidney were 0/50, 13/49, 46/50 for male rats and 0/46, 1/
50, 24/48 for female rats, respectively.
Using the linearized multistage model, several cancer potency
factors for BDCM were derived based on the observed cancer incidence of
various tumor types (large intestine, kidney, or combined) in mice or
rats reported in the NTP bioassay. The resulting cancer potency factors
are in the range of 4.9 x 10-3 to 6.2 x 10-2 (mg/kg/
day)-1. A potency factor of 1.3 x 10-1 (mg/kg/day)-1 was
derived from the incidence of hepatic tumors in female mice (IRIS,
1990). However, hepatic tumor data should be interpreted with caution
because studies of an analog chloroform indicated a possible role of
the corn oil vehicle in induction of these tumors. Until future studies
can provide a better understanding of the corn oil effect on hepatic
carcinogenicity, EPA considers carcinogenic risk quantification for
BDCM based on kidney or large intestine tumor data to be more
appropriate. EPA is presently conducting a cancer bioassay with BDCM in
drinking water for comparison with the NTP study. EPA will evaluate the
results of this study when available to determine if changes to the
risk assessment are warranted.
Following the Agency's Cancer Risk Assessment Guidelines (USEPA,
1986), when two or more significantly elevated tumor sites or types are
observed in the same study, the slope factor of the greatest
sensitivity preferably should be used for carcinogenic risk estimation.
Based on the potency factor of 6.2 x 10-2 (mg/kg/day)-1
derived from the kidney tumor incidence in male mice, the estimated
concentrations of BDCM in drinking water associated with excess cancer
risks of 10-4, 10-5 and 10-6 are 60, 6 and 0.6
<greek-m>g/L, respectively.
EPA has classified BDCM in Group B2, probable human carcinogen,
based on sufficient evidence of carcinogenicity in animals and
inadequate evidence in humans. The International Agency for Research on
Cancer (IARC) has recently classified BDCM as a Group 2B carcinogen,
agent probably carcinogenic to humans (IARC, 1991).
Following EPA's three-category approach for establishing MCLGs,
BDCM is placed in Category I since there is sufficient evidence for
carcinogenicity via ingestion considering weight of evidence, potency,
pharmacokinetics, and exposure. Thus, EPA is proposing an MCLG of zero
for this contaminant. EPA requests comments on the basis of the
proposed MCLG for BDCM and the use of tumor data of large intestine and
kidney, but not liver, in quantitative estimation of carcinogenic risk
of BDCM from oral exposure.
7. Dibromochloromethane
Dibromochloromethane (DBCM; CAS No. 124-48-1) is a nonflammable,
colorless liquid with a relatively high vapor pressure (76 mmHg at 20
deg.C). DBCM is moderately soluble in water (4 gm/l at 20 deg.C) and
soluble in organic solvents (log octanol/water partition coefficient of
2.09). Currently DBCM is not produced commercially in the United
States. The chemical has only limited uses as a laboratory agent. The
principal source of DBCM in drinking water is the chemical interaction
of chlorine with commonly present organic matter and bromide ions.
Degradation of DBCM has not been well studied, but probably involves
photooxidation. The estimated atmospheric half-life of DBCM is one to
two months. Volatilization is the principle mechanism for removal of
DBCM from rivers and streams (half-life of hours to weeks). Several
studies reported that DBCM adsorbs poorly to soil and sediments. No
experimental study was found regarding the bioconcentration of DBCM.
Based on the data of a few structurally similar chemicals, the
bioconcentration potential of DBCM in aquatic organisms is assumed to
be low. Biodegradation of DBCM is limited under aerobic conditions and
more extensive under anaerobic conditions.
Occurrence and Human Exposure. DBCM occurs in public water systems
that chlorinate water containing humic and fulvic acids and bromine
that can enter source waters through natural and anthropogenic means.
Several water quality factors can affect the formation of DBCM,
including Total Organic Carbon (TOC), pH, bromide, and temperature.
Different treatment practices can reduce the formation of DBCM in
drinking water. These include the use of precursor removal technologies
such as coagulation/filtration, granular activated carbon (GAC),
membrane filtration, and the use of chlorine dioxide, chloramination,
and ozonation.
Table V-8 presents occurrence information available for DBCM in
drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' (USEPA, 1992a). The
table lists six surveys conducted by Federal and private agencies.
Median concentrations of DBCM in drinking water appear to range from
0.6 to 3.6 <greek-m>g/L for surface water supplies and <0.5 <greek-m>g/
L for ground-water supplies. The lower bound median concentration for
DBCM in surface water supplies is biased to the low side because
concentrations in this survey were measured in the plant effluent; the
formation of DBCM would be expected to increase in the distribution in
systems using chlorine as their residual disinfectant.

Table V-8.--Summary of Occurrence Data for Dibromochloromethane

Occurrence of dibromochloromethane in drinking water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information(No. of --------------------------------------------------------------------------

samples) Range Mean Median Other

CWSS (1978) Brass et al., 450 Systems.......... Finished Water (1,100): Positive Detections:
1981. Surface Water............. ............. \3\5.0 1.5 67%\4\
Ground Water.............. ............. \3\6.6 <0.5 34%\4\
RWS (1978-1980) Brass, >600 Rural Systems Drinking Water from: Positive Detections:
1981. (>2,000 households). Surface Water............. ............. \3\8.5 0.8 \4\56%
Ground Water.............. ............. \3\9.9 <0.5 \4\13%
GWSS (1980-1981) Westrick 945 GW Systems: (466 90th Percentile:
et al. 1983. Random and 479 Serving >10,000 (327)..... Max. 59...... ........... 0.7 9.2
Nonran. Serving <10,000 (618)..... Max. 63...... ........... 0 5.6
dom).................

EPA, 1991a2 (1984-1991)... Unregulated Sampled at the Plant ............. 3.0 1.7 ..............................

Contaminant Data (4,439).
Base--Treatment
Facilities from 19
States.
EPA, 1992<INF>b2 (1987-1989)... Disinfection By- Finished Water: Positive Detections:
Products Field At the Plant (73)......... <0.2-41...... 4.9 2.0 92%
Studies. In Distribution System <0.2-41...... 6.6 3.4 93%
(56).

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell Max. 63...... ........... 3.6 75% of Data was Below 9.1

1989) Krasner et al., Nationwide. Effluent for 4 Quarters. 2.6-4.5\5\ <greek-m>g/L
1989b.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Mean of the positives.
\4\Of systems sampled.
\5\Range of medians for individual quarters.

No information is available concerning the occurrence of DBCM in
food in the United States. The Food and Drug Administration (FDA) does
not analyze for DBCM in foods. However, there are several uses of
chlorine in food production, such as disinfection of chicken in poultry
plants and the superchlorination of water at soda and beer bottling
plants (Borum, 1991). Therefore, the possibility exists for dietary
exposure from the by-products of chlorination in food products.
Based on information obtained through a literature review, Howard
(1990) estimated the average daily intake of DBCM from air using an
inhalation rate of 20m\3\/day. Assuming a range of 8.25 to 425 ng/m\3\
the exposure may be as low as 0.17 <greek-m>g/day or as high as
8.5<greek-m>g/day.
Although some uses of chlorine have been identified in the food
production/food processing area, monitoring data are not available to
adequately characterize the magnitude or frequency of potential
exposure to DBCM. Additionally, preliminary discussions with FDA
suggest that there are not approved uses for chlorine in most foods
consumed in the typical diet. Based on the limited number of food
groups that are believed to contain chlorinated chemicals and that
there are not significant levels expected in ambient or indoor air, EPA
assumes that drinking water is the predominant source of DBCM intake.
Characterization of food and air exposure are issues currently under
review. EPA, therefore, is proposing to regulate DBCM in drinking water
with an RSC value at the ceiling level of 80 percent. EPA requests any
additional data on known concentration of DBCM in drinking water, food,
and air.
Health Effects. The health effects information in this section is
summarized from the Drinking Water Health Criteria Document for
Trihalomethanes (USEPA, 1994d). Studies mentioned in this section are
summarized in the criteria document.
Studies indicated that gastrointestinal absorption of DBCM is high
in animals. No studies were located regarding DBCM in humans or animals
following inhalation or dermal exposure. Based on the physical-chemical
properties of DBCM, and by analogy with the structurally-related
halomethanes such as chloroform, it is expected that the inhalation and
dermal absorption could be significant for DBCM.
The LD<INF>50 values in mice and rats range from 800 to 1,200 mg/
kg. Under both in vivo and in vitro conditions, several active
metabolic intermediates (e.g. dihalocarbonyl, bromochloromethyl
radicals) can be produced via oxidation or reduction by microsomal
preparations. Environmental studies suggest that these active metabolic
intermediates are responsible for the hepatic and renal toxicity, and
possibly carcinogenicity, of the parent compound. Animal studies
suggest that the extent of DBCM metabolism varies with species and sex.
The retention of DBCM in organs after dosing was small and relatively
higher concentrations were found in stomach, liver and kidneys. Urinary
excretion levels were below 2 percent.
Mammalian bioeffects following oral exposure to DBCM include
effects on the central nervous system (decreased operant response),
hepatotoxicity, nephrotoxicity, reproductive toxicity and possible
carcinogenicity. In experimental mice and rats, DBCM caused changes in
kidney, liver, and serum enzyme levels, and decreased body weight.
These responses are discernible in mammals from exposure to levels of
DBCM ranging from 39 to 250 mg/kg; the intensity of response was
dependent upon the dose and the duration of the exposure. Ataxia and
sedation were observed in mice receiving a single dose of 500 mg/kg
DBCM.
Developmental and reproductive toxicity of DBCM was investigated in
rodents. A multi-generation reproductive study of mice treated with )in
drinking water showed maternal toxicity (weight loss, liver
pathological changes) and fetal toxicity (decreased pup weight &
viability). The study identified a NOAEL of 17 mg/kg/day and a LOAEL of
171 mg/kg/day.
The National Toxicology Program (NTP, 1985) evaluated the
subchronic and chronic toxicity of DBCM in F344/N rats and B6C3F<INF>1
mice. In this study corn oil is used as the gavage vehicle. The chronic
data indicated that doses of 40 and 50 mg/kg/day produced
histopathological lesions in the liver of rats and mice, respectively.
However, the chronic studies did not identify a reliable NOAEL. The
subchronic study identified both a LOAEL and a NOAEL for
hepatotoxicity, and was used to calculate the RfD of 0.02 mg/kg/d.
In the NTP subchronic study, DBCM in corn oil was administered to
Fischer 344/N rats and B6C3F<INF>1 mice via gavage at dose levels of 0,
15, 30, 60, 125 or 250 mg/kg/day, 5 days a week for 13 weeks. Following
treatment, survival, body weight, clinical signs, histopathology and
gross pathology were evaluated. Final body weights of rats that
received 250 mg/kg/day were depressed 47% for males and 25% for
females. Kidney and liver toxicity was observed in male and female rats
and male mice at 250 mg/kg/day. A dose-dependent increase in hepatic
vacuolation was observed in male rats. Based on this hepatic effect,
the NOAEL and LOAEL in rats were 30 and 60 mg/kg/day, respectively.
Several studies on the mutagenicity potential of DBCM have reported
inconclusive results. Studies on the in vitro genotoxicity of DBCM
reported mixed results in bacteria Salmonella typhimurium strains and
yeasts. DBCM produced sister chromatid exchange uncultured human
lymphocytes and Chinese hamster ovary cells (without activation). An
increased frequency of sister chromatid exchange was observed in mouse
bone marrow cells from mice dosed orally, but not via the
intraperitoneal route.
The carcinogenicity of DBCM was reported in a NTP (1985) chronic
animal study. In this study DBCM in corn oil was administered via
gavage to groups of male and female F344/N rats at doses of 0, 40 or 80
mg/kg/day, 5 days/week for 104 weeks; and groups of male and female
mice at 0, 50 or 100 mg/kg/day, 5 days/week for 105 weeks.
Administration of DBCM showed a significant increase in the incidence
of hepatocellular adenomas in high-dose female mice (vehicle control,
2/50; low dose, 4/49; high dose, 11/50) and combined incidence of
hepatocellular adenomas or carcinomas (6/50, 10/49, 19/50). In highdose
male mice, administration of DBCM showed a significant increase in
the incidence of hepatocellular carcinomas (10/50, -, 19/50); however,
the combined incidence of hepatocellular adenomas or carcinomas was
only marginally increased (23/50, -, 27/50). Administration of DBCM did
not result in increased incidence of tumors in treated rats.
Using the linearized multistage model, EPA derived a cancer potency
factor of 8.4 x 10-2 (mg/kg/day)-1 (IRIS, 1990). The
derivation was based on the tumor incidence of the hepatocellular
adenomas or carcinomas in the female mice reported in the 1985 NTP
study. Due to the possible role of the corn oil vehicle in induction of
hepatic tumors as reported in studies on chloroform, some uncertainty
exists regarding the relevance of this derived cancer potency factor to
exposure via drinking water. However, the only tumor data currently
available on DBCM are for liver tumors in mice. Until future studies
can provide additional data, EPA considers this cancer potency factor
valid for potential carcinogenic risk quantification for DBCM.
EPA has classified DBCM in Group C, possible human carcinogen,
based on the limited evidence of carcinogenicity in animals (only in
one species) and inadequate evidence of carcinogenicity in humans. The
International Agency for Research on Cancer (IARC) has classified DBCM
as a Group 3 carcinogen: agent not classifiable as to its
carcinogenicity to humans.
Using EPA's three-category approach for establishing MCLG, DBCM is
placed in Category II since there is limited evidence for
carcinogenicity via drinking water considering weight of evidence,
potency, pharmacokinetics, and exposure. As a Category II chemical, EPA
proposes to follow the first option and set the MCLG for DBCM on
noncarcinogenic endpoints (the RfD) with the application of an
additional safety factor to account for possible carcinogenicity. An
RfD of 0.02 mg/kg/day has been derived from the NOAEL of 30 mg/kg/d,
adjusted for dosing 5 days per week and divided by an uncertainty
factor of 1,000. This factor is appropriate for use of a NOAEL derived
from a subchronic animal study. EPA is proposing an MCLG of 0.06 mg/L
for DBCM based on liver toxicity and possible carcinogenicity. An
additional safety factor of 10 for possible carcinogenicity is used to
calculate the MCLG along with an assumed drinking water contribution of
80 percent of total exposure.

<GRAPHIC><TIF6>TP29JY94.006

EPA requests comments on the basis for the proposed MCLG for DBCM,
the RSC of 80%, and the cancer classification for DBCM.
8. Bromoform
Bromoform (tribromomethane, CAS No. 75-25-2) is a nonflammable,
colorless liquid with a sweet odor and a relatively high vapor pressure
(5.6 mmHg at 25 deg.C). Bromoform is moderately soluble in water (3.2
gm/L at 30 deg.C) and soluble in organic solvents (log octanol/water
partition coefficient of 2.38). Bromoform is not currently produced
commercially in the United States. The chemical has only limited uses
as a laboratory agent and as a fluid for mineral ore separation. The
principle source of bromoform in drinking water is the chemical
interaction of chlorine with commonly present organic matter and
bromide ion. Degradation of bromoform is not well studied, but probably
involves photooxidation. The estimated atmospheric half-life of
bromoform is one to two months. Volatilization is the principle
mechanism for removal of bromoform from rivers and streams (half-life
of hours to weeks). Studies reported that bromoform adsorbs poorly to
sediments and soils. No experimental studies were located regarding the
bioconcentration of bromoform. Based on the data from a few
structurally similar chemicals, the potential for bromoform to be
bioconcentrated by aquatic organisms is low. Biodegradation of
bromoform is limited under aerobic conditions but more extensive under
anaerobic conditions.
Occurrence and Human Exposure. Bromoform occurs in public water
systems that chlorinate water containing humic and fulvic acids and
bromine that can enter source waters through natural and anthropogenic
means. Several water quality factors affect the formation of bromoform
including Total Organic Carbon (TOC), pH, and temperature. Different
treatment practices can reduce the level of bromoform. These include
the use of chloride dioxide, chloramination, and ozonation prior to
chloramination.
Table V-9 presents occurrence information available for bromoform
in drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' (USEPA, 1992a). The
table lists six surveys conducted by Federal and private agencies.
Median concentrations of bromoform in drinking water appear to range
from <0.2 to 0.57 <greek-m>g/L for surface water supplies and <0.5
<greek-m>g/L for ground- water supplies. The lower bound median
concentration for bromoform in surface water supplies is biased to the
low side because concentrations in this survey were measured in the
plant effluent; the formation of bromoform would be expected to
increase in the distribution in systems using chlorine as their
residual disinfectant.

Table V-9.--Summary of Occurrence Data for Bromoform

Occurrence of bromoform in drinking water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information (No. of --------------------------------------------------------------------------

samples) Range Mean Median Other

CWSS (1978) Brass et al., 450 Systems.......... Finished Water (1,100): ............. Positive Detections:
1981. Surface Water............. \3\2.1 <1.0 13%\4\
Ground Water.............. \3\11 <0.5 26%\4\
RWS (1978-1980) Brass, >600 Rural Systems Drinking Water from: ............. Positive Detections:
1981. (>2,000 Households). Surface Water............. \3\8.7 <0.5 18%\4\
Ground Water.............. \3\12 <0.5 12%\4\

GWSS (1980-1981) Westrick 945 GW Systems: (466 .......................... ............. ........... ............. 90th Percentile:

et al. 1983. Random and 479 Serving >10,000 (327)..... Max. 68...... 0 8.3
Nonran-dom). Serving <10,000 (618)..... Max. 110..... 0 4.1

EPA, 1991a\2\ (1984-1991). Unregulated Sampled at the Plants ............. 2.5 1 ..............................

Contaminant Data (1,409).
Base--Treatment
Facilities from 19
States.
EPA, 1992b\2\ (1987-1989). Disinfection By- Finished Water: Positive Detections:
Products Field At the Plant (73)......... <0.2-6.7..... 0.7 <0.2 45%
Studies. In Distr. System (56)..... <0.2-10...... 1.0 <0.2 48%

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell Max. 72...... ........... ............. 75% of Data was Below 2.8

1989) Krasner et. al., Nationwide. Effluent for 4 Quarters. 0.33-0.88\5\
1989b. 0.57

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Mean of the positives.
\4\Of systems sampled.
\5\Range of medians for individual quarters.

No information is available concerning the occurrence of bromoform
in food in the United States. The Food and Drug Administration (FDA)
does not analyze for bromoform in foods. However, there are several
uses of chlorine in food production, such as disinfection of chicken in
poultry plants and the superchlorination of water at soda and beer
bottling plants (Borum, 1991). Therefore, the possibility exists for
dietary exposure from the by-products of chlorination in food products.
Bromoform is usually found in ambient air at low concentrations.
One study reported ambient air concentrations from several urban
locations across the U.S. The overall mean concentration of positive
samples was found to be 4.15 ng/m\3\ and the maximum level was 71 ng/
m\3\ (Brodzinsky and Singh, 1983 in USEPA, 1991b). Although the data
are limited for bromoform, an inhalation intake could be estimated
using the mean and maximum values from the Brodzinsky and Singh (1983)
study, indicating a possible range of 0.08 to 1.4 <greek-m>g/d.
Based on the limited number of food groups that are believed to
contain bromoform and that significant levels are not expected in
ambient or indoor air, EPA is assuming that drinking water is the
predominant source of bromoform intake. Characterization of food and
air exposures are issues currently under review. The EPA requests any
additional data on known concentrations of bromoform in drinking water,
food, and air.
Health Effects. The health effects information in this section is
summarized from the draft Drinking Water Health Criteria Document for
Trihalomethanes (USEPA, 1994d) and the draft Drinking Water Health
Advisory for Brominated Trihalomethanes (USEPA, 1991b). Studies
mentioned in this section are summarized in the criteria document or
health advisory.
Studies have indicated that gastrointestinal absorption of
bromoform is high in humans and animals. No studies were located
regarding bromoform in humans or animals following inhalation or dermal
exposure. Based on the physical-chemical properties of bromoform, and
by analogy with the structurally-related halomethanes such as
chloroform, it is expected that both inhalation and dermal absorption
could be significant for bromoform.
Bromoform was used as a sedative for children with whooping cough.
Based on clinical observations of accidental overdose cases, the
estimated lethal dose for a 10- to 20-kg child is about 300 mg/kg. The
clinical signs in fatal cases were central nervous system (CNS)
depression followed by respiratory failure.
The LD<INF>50 values in mice and rats have been reported in the
range of 1,147-1550 mg/kg. Under both in vivo and in vitro conditions,
several active metabolic intermediates (e.g., dibromocarbonyl,
dibromomethyl radicals) are produced via oxidation or reduction by
microsomal preparations. Experimental studies suggested that these
active metabolic intermediates are responsible for hepatic and renal
toxicity and possibly, carcinogenicity, of the parent compound. Animal
studies suggest that the extent of bromoform metabolism varies with
species and sex. The retention of bromoform in organs after dosing was
small; relatively higher concentrations were found in tissues with
higher lipophilic content. Urinary excretion levels were below 5
percent.
Mammalian bioeffects following exposure to bromoform include
effects on the central nervous system (CNS), hepatotoxicity,
nephrotoxicity, and carcinogenicity. Bromoform causes CNS depression in
humans. The reported LOAEL which results in mild sedation in humans is
54 mg/kg. In experimental mice and rats, bromoform caused changes in
kidney, liver, serum enzyme levels, decrease of body weight, and
decreased operant response. These responses are discernible in mammals
from exposure to levels of bromoform ranging from 50 to 250 mg/kg; the
intensity of response was dependent upon the dose and the duration of
the exposure. Ataxia and sedation were noted in mice receiving a single
dose of 1,000 mg/kg bromoform or 600 mg/kg for 14 days.
Few studies have investigated developmental and reproductive
toxicity of bromoform in rodents. A developmental study in rats showed
no fetal variations in a group fed with 50 mg/kg/day. An increased
incidence of minor anomalies was noted at doses of 100 and 200 mg/kg/
day. No maternal toxicity in rats was observed. One detailed
reproductive toxicity study reported no apparent effects on fertility
and reproduction when male and female rats were administered bromoform
via gavage in corn oil at doses up to 200 mg/kg/day.
EPA used subchronic data from an oral study (NTP, 1989) to
calculate the RfD. In this study, bromoform was administered to rats in
corn oil via gavage at dose levels of 0, 12, 25, 50, 100 or 200 mg/kg/
day 5 days a week for 13 weeks. Based on the observation of
hepatocellular vacuolization in treated male rats, a NOAEL of 25 mg/kg/
day was established. An RfD of 0.02 mg/kg/day has been derived from
this NOAEL by the application of an uncertainty factor of 1,000, in
accordance with EPA guidelines for use of a NOAEL from a subchronic
study.
A number of studies investigated the mutagenicity potential of
bromoform. Studies on the in vitro genotoxicity of bromoform reported
mixed results in bacterial Salmonella typhimurium strains. Bromoform
produced mutations in cultured mouse lymphoma cells and sister
chromatid exchange in human lymphocytes. Under in vivo condition
bromoform induced sister chromatid exchange, and chromosomal aberration
and micronucleus in mouse bone marrow cells. Overall, most studies
yielded positive results and evidence of mutagenicity for bromoform is
considered adequate.
The National Toxicology Program (NTP, 1989) conducted a chronic
animal study to investigate the carcinogenicity of bromoform. In this
study bromoform was administered in corn oil via gavage to F344/N rats
(50/sex/group) at doses of 0, 100 or 200 mg/kg/day, 5 days/week for 105
weeks. An evaluation of the study results showed that adenomatous
polyps or adenocarcinoma (combined) of the large intestine (colon or
rectum) were induced in three male rats (vehicle control, 0/50; low
dose, 0/50; high dose, 3/50) and in nine female rats (0/50, 1/50, 8/
50). The increase was considered to be significant since these tumors
are rare in control animals. Neoplastic lesions in the large intestine
in female rats reported in the NTP study were used to estimate the
carcinogenic potency of bromoform. EPA derived a cancer potency factor
of 7.9 x 10-3 (mg/kg/day)-1 using the linearized multistage
model (IRIS, 1990). Assuming a daily consumption of two liters of
drinking water and an average human body weight of 70 kg, the 95% upper
bound limit lifetime cancer risks of 10-6, 10-5 and 10-4
are associated with concentrations of bromoform in drinking water of 4,
40 and 400 <greek-m>g/L, respectively.
EPA classified bromoform in Group B2, probable human carcinogen,
based on the sufficient evidence of carcinogenicity in animals and
inadequate evidence of carcinogenicity in humans. The International
Agency for Research on Cancer (IARC) has recently classified bromoform
in Group 3: agent not classifiable as to its carcinogenicity to humans
(IARC, 1991). IARC determined that there was limited evidence of
carcinogenicity in animals, in contrast to EPA's judgment that there is
sufficient evidence in laboratory animals. EPA requests comments on the
different viewpoints between IARC and EPA regarding bromoform's
carcinogenic potential.
Using EPA's three-category approach for establishing MCLG,
bromoform is placed in Category I since there is sufficient evidence
for carcinogenicity from drinking water considering weight of evidence,
potency, pharmacokinetics, and exposure. Thus, EPA is proposing an MCLG
of zero for this contaminant. EPA requests comments on the basis for
the proposed MCLG for bromoform.
9. Dichloroacetic Acid
Chlorination of water containing organic material (humic, fulvic
acids) results in the generation of many organic compounds, including
dichloroacetic acid (DCA) (CAS. No. 79-43-6), a nonvolatile compound.
Though DCA is generally a concern due to its occurrence in
chlorinated drinking water, it is also used as a chemical intermediate,
and an ingredient in pharmaceuticals and medicine. Previously, DCA was
used experimentally to treat diabetes and hypercholesterolemia in human
patients. In addition, DCA was used as an agricultural fungicide and
topical astringent. It has also been extensively investigated for
potential therapeutic use as a hypoglycemic, hypolactemic and
hypolipidemic agent.
Occurrence and Human Exposure. DCA has been found to occur as a
disinfection by-product in public water systems that chlorinate water
containing humic and fulvic acids.
Table V-10 presents occurrence information available for DCA in
drinking water. Descriptions of these surveys and other data are
detailed in ``Occurrence Assessment for Disinfectants and Disinfection
By-Products (Phase 6a) in Public Drinking Water,'' (USEPA, 1992a).
Median concentrations of DCA in drinking water were found to range from
6.4 to 17 <greek-m>g/L. The lower bound median concentration for DCA in
surface water supplies is biased to the low side because concentrations
in this survey were measured in the plant effluent; the formation of
DCA would be expected to increase in the distribution system in systems
using chlorine as their residual disinfectant.

Table V-10.--Summary of Occurrence Data for Dichloroacetic Acid

Occurence of dichloroacetic acid in drinking water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information (No. of -------------------------------------------------------------------

samples) Range Mean Median Other

EPA, 1992b\2\ (1987-1989) Disinfection By-Products Finished Water: ............. 18 16 Positive Detections:

Field Studies. At the Plant (72) <0.4-61 21 17 93%
In the Distr. System (56) <0.4-75 96%

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell <0.6-46 ........... \3\5.0-7.3 75% of Data was Below 12

1989) Krasner et al., Nationwide. Effluent for 4 Quarters. 6.4 <greek-m>g/L DL = 0.6
1989b. <greek-m>g/L

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Range of medians for individual quarters.

AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.

Based on the above data, a range of exposure to DCA from drinking
water can be calculated using a consumption rate of 2 liters per day.
The expected median exposure from drinking water would range from 13 to
34 <greek-m>g/day, using these data sets.
No information is available concerning the occurrence of DCA in
food and ambient or indoor air in the United States. The Food and Drug
Administration (FDA) does not analyze for DCA in foods. However, there
are several uses of chlorine in food production, such as the
disinfection of chicken in poultry plants and the superchlorination of
water at soda and beer bottling plants. Therefore, the possibility
exists for dietary exposure from the by-products of chlorination in
food products. However, monitoring data are not available to
characterize adequately the magnitude or frequency of potential DCA
exposure from diet. Additionally, preliminary discussions with FDA
suggest that there are not approved uses for chlorine in most foods
consumed in the typical diet. Similarly, EPA's Office of Air and
Radiation is not currently sampling for DCA in air (Borum, 1991).
Little exposure to DCA from air is expected since DCA is nonvolatile.
Since only a limited number of food groups are expected to contain
chlorinated chemicals and no significant DCA levels are expected in
ambient or indoor air, EPA believes that drinking water is the
predominant source of DCA intake. Characterization of the potential
exposures from food and air are issues currently under review. EPA
requests any additional data on known concentrations of DCA in drinking
water, food, and air.
Health Effects. The health effects information in this section is
summarized from the draft Drinking Water Health Criteria Document for
Chlorinated Acetic Acids, Alcohols, Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this section are summarized in the
criteria document.
Humans treated with DCA for 6 to 7 days at 43 to 57 mg/kg/day have
experienced mild sedation, reduced blood glucose, reduced plasma
lactate, reduced plasma cholesterol levels, and reduced triglyceride
levels. At the same time, the DCA treatment depressed uric acid
excretion, resulting in elevated serum uric acid levels.
A longer term study in two young men receiving 50 mg/kg for 5 weeks
up to 16 weeks, indicated that DCA significantly reduces serum
cholesterol levels and blood glucose, and causes peripheral neuropathy
in the facial, finger, leg and foot muscles.
Estimates of acute oral LD<INF>50 values range from 2,800 to 4,500
mg/kg in rats and up to 5,500 mg/kg in mice. Short-term studies in dogs
and rats indicate an effect on intermediary metabolism, as demonstrated
by decreases in blood lactate and pyruvate. Exposures to DCA up to 3
months in dogs and rats result in a variety of adverse effects
including effects to the neurological and reproductive systems. These
effects are seen above 100 mg/kg/day in dogs and rats.
Studies on the toxicokinetics of DCA indicate that absorption is
rapid and that DCA is quickly distributed to the liver and muscles in
the rat. DCA is metabolized to glyoxylate which in turn is metabolized
to oxalate. Although there are few studies regarding the excretion of
DCA, studies in which rats, dogs and humans received intravenous
injections of DCA indicated that the half-life of DCA in human blood
plasma is much shorter than in rats or dogs. Urinary excretion of DCA
was negligible after 8 hours. Total excretion of DCA was less than 1%
of total dose.
A drinking water study by Bull et al. (1990) reported a doserelated
increase in hepatic effects in mice that received DCA at 270
mg/kg/day for 37 weeks and at 300 mg/kg/day for 52 weeks. Adverse
effects included enlarged livers, marked cytomegaly with massive
accumulation of glycogen in hepatocyte and focal necrosis. The NOAEL
for this study was 137 mg/kg/day for 52 weeks.
DeAngelo et al. (1991) conducted a drinking water study in which
mice received DCA at levels of 7.6, 77, 410, and 486 mg/kg/day for 60
or 75 weeks. While this study was intended as an assessment of
carcinogenicity, other systemic effects were measured. This study
concluded that levels at 77 mg/kg/day and above caused an extreme
increase of relative liver weights and a significant increase in
neoplasia at levels of 410 mg/kg/day and above. This study indicates a
NOAEL of 7.6 mg/kg/day for noncancer liver effects.
Based on the available data, DCA does not appear to be a potent
mutagen. Studies in bacteria have indicated that DCA did not induce
mutation or activate repair activity. Two studies have shown some
potential for mutagenicity but these results have not been
reproducible.
DCA appears to induce both reproductive and developmental toxicity.
Damage and atrophy to sexual organs has been reported in male rats and
dogs exposed to levels from 50 mg/kg/day to 2000 mg/kg/day for up 3
months. Malformation of the cardiovascular system has been observed in
rats exposed to 140 mg/kg/day DCA from day 6 to 16 of pregnancy.
A 90-day dog study was selected to determine the RfD for DCA
(Cicmanec et al., 1991). In this study, four month old beagle dogs (5/
sex/group) were administered gelatin capsules containing 0, 12.5, 39.5,
or 72 mg/kg DCA/day for 90 days. Dogs were observed for clinical signs
of toxicity; blood samples were collected for hematology and serum
chemistry analysis. Clinical signs included diarrhea and dyspnea in the
mid and high dose groups. Dyspnea was evident at 45 days and became
more severe with continued exposure leading to general depression and
decreased activity by day 90. Hindlimb paralysis was observed in 3 dogs
in the high dose group. Other effects included conjunctivitis, weight
loss, reduced food and water consumption, pneumonia, decreased liver
weights, and elevated kidney weights in the dosed animals.
Histopathology revealed toxic effects in liver, testis, and brain of
the treated dogs. A NOAEL was not identified in this study. The lowest
dose tested, 12.5 mg/kg/d, was considered a LOAEL. An uncertainty
factor of 3,000 was applied in accordance with EPA guidelines to
account for use of a LOAEL from a less-than-lifetime animal study in
which frank effects were noted as the critical effect. The resulting
RfD is 0.004 mg/kg/d.
Several studies indicate that DCA is a carcinogen in both mice and
rats exposed via drinking water lifetime studies. These studies
indicate that DCA induces liver tumors. In one study with male
B6F3F<INF>1 mice, exposure to DCA at 0.5 g/L and 3.5 g/L for 104 weeks
resulted in tumor formation in exposed animals at 75% (18/24) and 100%
(24/24) respectively. In female mice exposed for 104 weeks to DCA at
the same levels, tumor prevalence was 20% and 100%, respectively. In
male rats exposed to 0.05, 0.5 or 5 g/L DCA for 104 weeks, tumor
prevalence increased to 22% in the highest dose. No tumors were seen at
the lower doses. However, at 0.5 g/L, there was an increase in the
prevalence of proliferation of liver lesions. Some of these lesions are
likely to progress into malignant tumors.
EPA has classified DCA in Group B2: probable human carcinogen,
based on positive carcinogenic findings in two animal species exposed
to DCA in drinking water. A quantitative risk estimate has not yet been
determined for DCA.
Following a Category I approach, EPA is proposing an MCLG for DCA
of zero based on the strong evidence of carcinogenicity via drinking
water. EPA requests comments on the basis for the proposed MCLG for DCA
in drinking water and the cancer classification of Group B2.
10. Trichloroacetic Acid.
Trichloroacetic acid (TCA; CAS No. 76-03-9) is also a major byproduct
of chlorinated drinking water. Chlorination of source waters
containing organic materials (humic, fulvic acids) results in the
generation of organic compounds such as TCA.
TCA is also sold as a pre-emergence herbicide. It is used in the
laboratory to precipitate proteins and as a reagent for synthetic
medicinal products. It is applied medically as a peeling agent for
damaged skin, cervical dysplasia and removal of tatoos.
Occurrence and Human Exposure. TCA occurs in public water systems
that chlorinate water containing humic and fulvic acids.
Table V-11 presents the most recent and comprehensive occurrence
information available for TCA in drinking water. Descriptions of these
surveys and other data are detailed in ``Occurrence Assessment for
Disinfectants and Disinfection By-Products (Phase 6a) in Public
Drinking Water,'' (USEPA, 1992a). Median concentrations of TCA acid in
drinking water were found to range from 5.5 to 15 <greek-m>g/L. The
lower bound median concentration for TCA in surface water supplies is
biased to the low side because concentrations in this survey were
measured in the plant effluent; the formation of TCA would be expected
to increase in the distribution system in systems using chlorine as
their residual disinfectant. Based on the available data sets, and
assuming a drinking water consumption rate of 2 L/day, median exposures
from drinking water would range from 11 to 30 <greek-m>g/day.

Table V-11.--Summary of Occurrence Data for Trichloroacetic Acid

Occurrence of trichloroacetic acid in drinking water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information (No. ------------------------------------------------------------------------

of samples) Range Mean Median Other

EPA, 1992b\2\ (1987-1989) Disinfection By-Products Finished Water: ............. ........... ........... Positive Detections:

Field Studies. At the Plant (72) <0.4-54 13 11 90%
Distribution System <0.4-77 15 15 91%
(56).....................

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell ............. ........... 4.0-5.8 75% of Data was Below 15.3

1989) Krasner et al., Nationwide. Effluent for 4 Quarters. 5.5 <greek-m>g/L DL = 0.6
1989b.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Range of medians for individual quarters.

AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.

No information is available concerning the occurrence of TCA in
food and ambient or indoor air in the United States. The Food and Drug
Administration (FDA) does not analyze for TCA in foods. However, there
are several uses of chlorine in food production, such as the
disinfection of chicken in poultry plants and the superchlorination of
water at soda and beer bottling plants. Therefore, the possibility
exists for dietary exposure from the by-products of chlorination in
food products. Also, TCA has limited use as a herbicide. However,
monitoring data are not available to characterize adequately the
magnitude or frequency of potential TCA exposure from diet. Similarly,
EPA's Office of Air and Radiation is not currently measuring for TCA in
air (Borum, 1991). The exposure from air for TCA is probably not a
large source since TCA is nonvolatile.
Since only a limited number of food groups are expected to contain
chlorinated chemicals and no significant TCA levels are expected in
ambient or indoor air, EPA assumes that drinking water is the
predominant source of TCA intake. Characterization of potential
exposures from food and air are issues currently under review. EPA is,
therefore, proposing to regulate TCA in drinking water with a relative
source contribution (RSC) value at the ceiling level of 80 percent. EPA
requests any additional data on known concentrations of TCA in drinking
water, food, and air.
Health Effects. The health effects information in this section is
summarized from the Drinking Water Health Criteria Document for
Chlorinated Acetic Acids, Alcohols, Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this section are summarized in the
criteria document.
Estimates of acute and LD<INF>50 values for TCA range from 3.3 to 5
g/kg in rats to 4.97 g/kg in mice. Short-term studies, up to 30 days,
in rats demonstrate few effects other than decreased weight gain after
administration of 240-312 mg/kg/day.
Few studies on toxicokinetics of TCA were located; however, a human
study and a dog study show TCA to respond pharmacokinetically similarly
to DCA. The response indicates a rapid absorption, distribution to the
liver and excretion primarily through the urine. The two studies
indicate that TCA is readily absorbed from all sections of the
intestine and that the urinary bladder may be significant in the
absorption of TCA. TCA is also a major metabolite of trichloroethylene.
Longer-term studies in animals indicate that TCA affects the liver,
kidney and spleen by altering weights, focal hepatocellular
enlargement, intracellular swelling, glycogen accumulation, focal
necrosis, an accumulation of lipofuscin, and ultimately tumor
generation in mice.
In a study by Mather et al. (1990), male rats received TCA in their
drinking water at 0, 4.1, 36.5 or 355 mg/kg/day. The high dose resulted
in spleen weight reduction and increased relative liver and kidney
weights. Hepatic peroxisomal <greek-B>-oxidation activity was
increased. Liver effects at the high dose included focal hepatocellular
enlargement, intracellular swelling and glycogen accumulation. The
NOAEL for this study was 36.5 mg/kg/day.
Parnell et al. (1988) exposed male rats to TCA in their drinking
water at 2.89, 29.6 or 277 mg/kg/day for up to one year. No significant
changes were detected in body weight, organ weight or histopathology
over the study duration. This study identified a NOAEL as the highest
dose tested, 277 mg/kg/day.
Bull et al. (1990) investigated the effects of TCA on liver lesions
and tumor induction in male and female B6C3F<INF>1 mice. Mice received
TCA in their drinking water at 0, 1 or 2 g/L (164 or 329 mg/kg/day) for
37 or 52 weeks. Dose-related increases in relative and absolute liver
weights were seen in females and males exposed to 1 and 2 g/L for 52
weeks. Small increases in liver cell size, accumulation of lipofuscin
and focal necrosis were also seen. A LOAEL of 164 mg/kg/day (1 g/L) was
identified.
Several studies show that TCA can produce developmental
malformations in fetal Long Evans rats, particularly in the
cardiovascular system. Teratogenic effects were observed at the lowest
dose tested, 330 mg/kg/day.
With regard to mutagenicity tests, TCA was negative in Ames
mutagenicity tests using Salmonella strain TA100, but was positive for
bone marrow chromosomal aberrations and sperm abnormalities in mice. It
also induced single-strand DNA breaks in rats and mice exposed by
gavage.
TCA has induced hepatocellular carcinomas in two tests with
B6C3F<INF>1 mice, one of 52 weeks and another of 104 weeks. In the Bull
et al. (1990) study, a dose-related increase in the incidence of
hepatoproliferative lesions was observed in male B6C3F<INF>1 mice
exposed to 1 or 2 g/L for 52 weeks. An increase in hepatocellular
carcinomas was observed in males at both dose levels. Carcinomas were
not found in females.
DeAngelo et al. (1991) administered mice and rats with TCA over
their lifetime. Male and female B6C3F<INF>1 mice were exposed to 4.5 g/
L TCA for 104 weeks. Male mice at 4.5 g/L TCA had a tumor prevalence of
86.7%. Female mice appeared to be less sensitive to TCA than males: 60%
prevalence over a 104-week exposure to 4.5 g/L. At 104 weeks, 0.5 g/L
TCA did not result in a significant increase in tumors. In a
preliminary study of 60 weeks exposure to 0.05, 0.5 and 5 g/L, no
significant additional increase in tumors was seen at 0.05 g/L, but
tumor prevalence was 37.9% and 55.2% at 0.5 and 5 g/L, respectively.
F344 male rats administered TCA over a lifetime at 0.05 to 5 g/L
did not produce a significant increase in carcinogenicity.
EPA has placed TCA in Group C: possible human carcinogen. Group C
is for those chemicals which show limited evidence of carcinogenicity
in animals in the absence of human data.
EPA is following a Category II approach for setting an MCLG for
TCA. The developmental toxicity study by Smith et al. (1989) has been
selected to serve as the basis for the RfD and MCLG. In this
developmental study, pregnant Long-Evans rats (20/dose) were
administered TCA at doses of 0, 330, 800, 1,200, or 1,800 mg/kg/d by
gavage during gestation days 6-15. Maternal body weight was
significantly reduced at doses of 800 mg/kg/d and above. Maternal
spleen and kidney weights were increased significantly in a dosedependent
manner. Postimplantation loss was noted in the three highest
dose groups with a significant decrease in the number of live fetuses
per litter observed in the two highest dose groups. Other fetal effects
included decreased fetal weight and crown-rump length, and
malformations of the cardiovascular system, particularly the heart. The
lowest dose tested, 330 mg/kg/d, was identified as a LOAEL. A NOAEL was
not identified from this study.
An RfD of 0.1 mg/kg/day was derived using the LOAEL of 330 mg/kg/d
and an uncertainty factor of 3,000 to account for use of a LOAEL and
lack of a 2 generation reproductive study. Adjusting the RfD for a 70
kg adult drinking 2 L water per day, possible carcinogenicity and an
RSC of 80%, an MCLG of 0.3 mg/L can be determined.

<GRAPHIC><TIF7>TP29JY94.007

EPA requests comments on the basis for the MCLG and the cancer
classification for TCA.
11. Chloral Hydrate
Chlorination of water containing organic materials (humic, fulvic
acids) results in the generation of organic compounds such as
trichloroacetaldehyde monohydrate or chloral hydrate (CH) (CAS No. 302-
17-0).
CH is used as a hypnotic or sedative drug (i.e., knockout drops) in
humans, including neonates. CH is also used in the manufacture of DDT.
Occurrence and Human Exposure. CH has been found to occur as a
disinfection by-product in public water systems that chlorinate water
containing humic and fulvic acids.
Table V-12 presents occurrence information available for chloral
hydrate in drinking water. Descriptions of these surveys and other data
are detailed in ``Occurrence Assessment for Disinfectants and
Disinfection By-Products (Phase 6a) in Public Drinking Water,'' (USEPA,
1992a). Median concentrations of chloral hydrate in drinking water were
found to range from 2.1 to 4.4 <greek-m>g/L.

TABLE V-12.--Summary of Occurrence Data for Chloral Hydrate

Occurrence of chloral hydrate in drinking water

Concentration (<greek-m>g/L)

Survey (Year)\1\ Location Sample information (No. ------------------------------------------------------------------------

of samples) Range Mean Median Other

EPA, 1992b\2\ (1987-1989) Disinfection By-Products Finished Water:.......... <0.2-25 5.0 2.5 Positive Detections:

Field Studies. At the Plant (67)........ <0.2-30 7.8 4.4 90%
Distribution System...... 91%
(53).....................

EPA/AMWA/CDHS\2\ (1988- 35 Water Utilities Samples from Clearwell Max. 22 ........... \3\1.7-3.0 75% of Data was below 4.1

1989) Krasner et al., Nationwide. Effluent for 4 Quarters. 2.1 <greek-m>g/L\4\
1989b.

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.
\3\Range of medians for individual quarters.
\4\Detection limit was 0.02 <greek-m>g/L in the first quarter and 0.1 <greek-m>g/L thereafter.

AMWA: Association of Metropolitan Water Agencies.
CDHS: California Department of Health Services.
EPA: Environmental Protection Agency.

Based on the available data sets, median exposures from CH due to
drinking water would range from 3.4 to 8.8 <greek-m>g/day, based on the
consumption of 2 liters per day.
No information is available concerning the occurrence of CH in food
and ambient or indoor air in the United States. The Food and Drug
Administration (FDA) does not analyze for CH in foods since the
analytical methods for such an evaluation have not been developed
(Borum, 1991).
CH has been used as a sedative of hypnotic drug (see Health Effects
Section). There are several uses of chlorine in food production, such
as the disinfection of chicken in poultry plants and the
superchlorination of water at soda and beer bottling plants. Therefore,
the possibility exists for dietary exposure from the by-products of
chlorination in food products. However, monitoring data are not
available to adequately characterize the magnitude or frequency of
potential CH exposure from the diet. Similarly, EPA's Office of Air and
Radiation is not currently measuring for CH in air (Borum, 1991).
However, CH from indoor air may contribute to exposure due to the
volatilization from tap water.
Since only a limited number of food groups are expected to contain
chlorinated chemicals and no significant levels are expected in ambient
or indoor air, EPA believes that drinking water is the predominant
source of CH intake. Characterization of potential food and air
exposures are issues currently under review. EPA is therefore,
proposing to regulate CH in drinking water with an RSC value at the
ceiling level of 80 percent. EPA requests any additional data on known
concentrations of CH in drinking water, food, and air.
Health Effects. The health effects information in this section is
summarized from the draft Drinking Water Health Criteria Document for
Chlorinated Acetic Acids, Alcohols, Aldehydes and Ketones (USEPA,
1994e). Studies mentioned in this section are summarized in the
criteria document.
In its use as a sedative or hypnotic drug in humans, a history of
adverse effects related to CH exposure have been recorded. The acute
and toxic dose to humans is about 10 g (or 140 mg/kg), causing severe
respiratory depression and hypertension. Adverse reactions such as
central nervous system depression and gastrointestinal disturbances are
seen between 0.5 and 1.0 g CH. Cardiac arrhythmias are seen when
patients receive levels between 10 and 20 g (167-333 mg/kg). Chronic
use of CH may result in development of tolerance, physical dependence,
and addiction.
Estimates of acute oral LD<INF>50s in mice range from 1,265 to
1,400 mg/kg with central nervous system depression and inhibition of
respiration being the cause of death. Rats may be more sensitive than
mice with acute oral LD<INF>50 values ranging from 285 mg/kg in newborn
to 500 mg/kg in adults.
Short-term studies in mice indicate that the liver is the target of
CH toxicity with changes in liver weight as the primary effect. NOAELs
vary between 14 and 144 mg/kg/day.
Toxicokinetic studies of CH indicate that absorption is rapid and
complete in dogs and humans. CH is metabolized to trichloroacetic acid
(TCA) and trichloroethanol. CH is rapidly excreted primarily through
the urine as trichloroethanol glucuronide and more slowly as TCA.
Three 90-day studies in mice were considered by EPA to derive the
MCLG for CH. Each used the same dose levels (16 or 160 mg/kg/day) in
mice. The first study (Kallman et al., 1984) exposed groups of 12 male
mice to drinking water containing CH at concentrations of 70 and 700
mg/L for 90 days. These concentrations correspond to doses of 15.7 and
160 mg/kg/day. No treatment-related effects were observed for
mortality, body weight, physical appearance, behavior, locomotor
activity, learning in repetitive tests of coordination, response to
painful stimuli, strength, endurance or passive avoidance learning.
Both doses resulted in a decrease of about 1 deg. in mean body
temperature (p <0.05). The biological significance of this hypothermic
effect is uncertain.
In the second study, Sanders et al. (1982) supplied groups of 32
male and female CD-1 mice with CH in deionized drinking water (70 or
700 mg/L, corresponding to time-weighted average doses of approximately
16 mg/kg/day or 160 mg/kg/day, respectively). After 90 days, the liver
appeared to be the tissue most affected. Males appeared to be more
sensitive than females. In males, there was a dose-related hepatomegaly
and microsome proliferation, accompanied by small changes in serum
chemistry values for potassium, cholesterol, and glutathione. Females
did not show hepatomegaly, but did display changed hepatic microsomal
parameters. Based on hepatomegaly, this study identifies a LOAEL of 16
mg/kg/day for CH (the lowest dose tested).
In the third study, Kauffman et al. (1982) studied the effect of CH
on the immune system. Groups of 13 to 18 male and female CD-1 mice were
supplied with water containing 70 or 700 mg/L (corresponding to timeweighted
average doses of approximately 16 or 160 mg/kg/day,
respectively) for 90 days. In males, no effects were detected in either
humoral or cell-mediated immunity at either dose level. In females,
exposure to the high dose (160 mg/kg/day) resulted in decreased humoral
immune function (p <0.05), but no effects on cell-mediated immunity
were noted. Based on this study, a NOAEL of 16 mg/kg/day and a LOAEL of
160 mg/kg/day were identified.
CH is weakly mutagenic in Salmonella, yeast and molds. It has also
caused chromosomal aberration in yeast and nondisjunction of
chromosomes during spermatogenesis.
One study has observed neurobehavioral effects on mice pups from
female mice receiving CH at 205 mg/kg/day for three weeks prior to
breeding. Exposure of females continued until pups were weaned at 21
days of age. Pups from the high dose group (205 mg/kg/day) showed
impaired retention in passive avoidance learning tasks. This result can
be construed as a developmental effect of CH.
Two studies on the carcinogenicity of CH indicate that CH produces
mouse liver tumors. In the earlier study, Rijhsinghani et al. (1986),
B6C3F<INF>1 mice given a single oral dose of CH at 5 or 10 mg/kg
developed a significant increase in liver tumors after 92 weeks.
In a later study, Daniel et al. (1992), reported that male mice,
receiving 166 mg/kg/day CH for 104 weeks, showed a total liver tumor
prevalence of 71 percent (17/24). Proliferative liver lesions
recognized and tabulated in this study included hyperplastic nodules,
hepatocellular adenomas and hepatocellular carcinomas. No other studies
were located on the carcinogenicity of CH in other test species.
Based on the limited evidence of carcinogenicity in these two
studies and the extensive mutagenicity of CH, EPA has classified CH in
Group C: possible human carcinogen. The concentrations associated with
a 10-4, 10-5, and 10-6 excess cancer risk are 40
<greek-m>g/L, 4 <greek-m>g/L and 0.4 <greek-m>g/L, respectively.
EPA is placing CH in Category II for setting an MCLG based on liver
toxicity and limited evidence of carcinogenicity from drinking water.
EPA believes the 90-day study by Sanders et al. (1982) is most
appropriate to calculate the RfD and MCLG for CH because the liver
effects observed in this study (i.e., change to hepatic microsomal
parameters and hepatomegaly) appear to be more severe than the other
studies have indicated at similar dose levels. From the mouse LOAEL of
16 mg/kg/day and an uncertainty factor of 10,000 for use of a LOAEL
from a less than lifetime animal study, an MCLG of 0.04 mg/L is
derived.

<GRAPHIC><TIF8>TP29JY94.008

EPA is proposing to use an extra safety factor of 1 instead of 10
to account for possible carcinogenicity since an uncertainty factor of
10,000 has already been applied to the RfD. In addition, the proposed
MCLG equals the 10-4 excess cancer risk. EPA requests comment on
the Category II approach for setting an MCLG, the extra safety factor
of 1 instead of 10 for a Category II contaminant, and whether the
endpoint of liver weight increase and hepatomegaly is a LOAEL or NOAEL
given the lack of histopathology.
12. Bromate
Bromate (CAS #7789-38-0 as sodium salt) is a white crystal that is
very soluble in water. Bromate may be formed by the reaction of bromine
with sodium carbonate. Sodium bromate can be used with sodium bromide
to extract gold from gold ores. Bromate is also used to clean boilers
and in the oxidation of sulfur and vat dyes. It is formed in water
following disinfection via ozonation of water containing bromide ion.
In laboratory studies, the rate and extent of bromate formation depends
on the ozone concentration used in disinfection, pH and contact time.
Occurrence and Human Exposure. Bromide and organobromine compounds
occur in raw waters from both natural and anthropogenic sources.
Bromide can be oxidized to bromate or hypobromous acid; however, in the
presence of excess ozone, bromate is the principal product.
Table V-13 presents occurrence information available for bromate in
drinking water. Descriptions of this data are detailed in ``Occurrence
Assessment for Disinfectants and Disinfection By-Products (Phase 6a) in
Public Drinking Water,'' (USEPA, 1992a__). Significant bromate
concentrations may occur in ozonated water with bromide. More recent
occurrence data on bromate and the influence of bromide concentration
and ozone on bromate formation is discussed in Section VI of this
preamble.

Table V-13.--Summary of Occurrence Data for Bromate

Occurrence of bromate in drinking water

Concentration (<greek-m>g/L)

Survey (year)\1\ Location Sample information (No. ------------------------------------------------------------------------

of samples) Range Mean Median Other

McGuire et al., 1990\2\.. MWD Pilot Plant Studies.. Ozonation: Hydrogen Max. 60
Peroxide/Ozone. Max. 90
EPA, 1992b\2\ (1987-1991) Disinfection By-Products Finished Water, Plants <10 ........... ........... Detection
Field Studies. Not Using Ozone (33). Limit of 5 <greek-m>g/L

\1\Dates indicate period of sample collection.
\2\May not be representative of national occurrence.

EPA: Environmental Protection Agency.

Although bromate is used as a maturing agent in malted beverages,
as a dough conditioner, and in confectionery products (Borum, 1991),
monitoring data are not available to adequately characterize the
magnitude or frequency of potential bromate exposure from the diet.
Currently, the Food and Drug Administration does not have available
data for bromate in foods, as bromate is not a part of their Total Diet
Study program. Similarly, EPA's Office of Air and Radiation is not
currently measuring for bromate in air (Borum 1991).
Since only a limited number of food groups are expected to contain
bromate and no significant bromate levels are expected in ambient or
indoor air, EPA believes that drinking water is the predominant source
of intake for bromate, and contributions from air and food would be
small. Characterization of potential exposures from food and air are
issues currently under review. EPA requests any additional data on
known concentrations of bromate in drinking water, food, and air.
Health Effects. The health effects information in this section is
summarized from the Drinking Water Health Quantification of
Toxicological Effects Document for Bromate (USEPA, 1993b). Studies
mentioned in this section are summarized in the criteria document.
The noncancer effects of ingested bromate have not been well
studied. Bromate is rapidly absorbed, in part unchanged, from the
gastrointestinal tract following ingestion. It is distributed
throughout the body, appearing in plasma and urine as bromate and in
other tissues as bromide. Following exposure to bromate, bromide
concentrations were significantly increased in kidney, pancreas,
stomach, small intestine, red blood cells and plasma. Bromate is
reduced in tissues probably by glutathione or by other sulfhydrylcontaining
compounds. Excretion occurs via urine and to a lesser extent
feces.
Acute oral LD<INF>50 values range from 222 to 360 mg bromate/kg for
mice and 500 mg/kg for rats. Acute symptoms of toxicity include
decreased locomotion and ataxia, tachypnea, hypothermia, hyperemia of
the stomach mucosa, kidney damage and lung congestion. In subchronic
drinking water studies, decreased body weight gain and marked kidney
damage were observed in treated rodents. These effects were observed at
the lowest doses tested (30 mg/kg/d).
Bromate was positive in a rat bone marrow assay to determine
chromosomal aberrations. Positive findings for bromate were also
reported in a mouse micronucleus assay. Bromate has also been found to
be carcinogenic to rodents following long-term oral administration. In
these studies, an increased incidence in kidney tumors was reported for
male and female rats. Other tumors observed include thyroid follicular
cell tumor and peritoneal mesothelioma. No carcinogenic effects have
been seen in mice. Dose and time studies indicate that the minimum
exposure time to produce tumors in rats is 13 weeks.
The available data are considered insufficient to calculate an RfD.
Only one noncarcinogenic toxicity study (Nakano et al., 1989) was
located in the literature. The study failed to provide dose response
data and did not identify a NOAEL. Histopathological lesions in kidney
tubules that coincided with decreased renal function were noted in rats
exposed to 30 mg bromate/kg/d for 15 months. The available
carcinogenicity studies also do not provide sufficient information on
non-cancer related effects to determine an RfD.
In a cancer bioassay, Kurokawa et al. (1986a) supplied groups of 50
male and 50 female F344 rats (4-6 weeks old) with drinking water
containing 0, 250 or 500 mg/L (the maximum tolerated dose) of potassium
bromate (KBrO<INF>3). The high dose (500 mg/L) caused a marked
inhibition of weight gain in males, and so at week 60 this dose was
reduced to 400 mg/L. Exposure was continued through week 110. The
authors stated the average doses for low dose and high dose groups were
12.5 or 27.5 mg KBrO<INF>3/kg/day in males (equivalent to 9.6 and 21.3
mg BrO<INF>3/kg/day) and 12.5 or 25.5 mg KBrO<INF>3 in females
(equivalent to 9.6 and 21.3 mg BrO<INF>3). The incidence of renal
tumors in the three groups (control, low dose, high dose) was 6%, 60%
and 88% in males and 0%, 56% and 80% in females. The effects were
statistically significant (p <0.001) in all exposed groups. The
incidence of peritoneal mesotheliomas in males at three doses was 11%
(control), 33% (250 mg/L, p <0.05) AND 59% (500 mg/L, p <0.001). The
authors concluded that KBrO<INF>3 was carcinogenic in rats of both
sexes.
In a subsequent study, Kurokawa et al. (1986b) supplied F344 rats
with water containing KBrO<INF>3 at 0, 154, 30, 60, 125, 250 or 500 mg/
L for 104 weeks. The authors reported that these exposures resulted in
average doses of 0, 0.9, 1.7, 3.3, 7.3, 16.0 or 43.4 mg/kg/day of
KBrO<INF>3, equivalent to doses of 0, 0.7, 1.3, 2.5, 5.6, 12 or 33.4
mg/kg/day of BrO<INF>3. The incidence of renal cell tumors in these
dose groups was 0%, 0%, 4%, 21% (p <0.05), 50% (p <0.001), 95% (p
<0.001) and 95% (p <0.001). Using the linearized multistage model,
estimates of cancer risks were derived. Combining incidence of renal
adenomas and adenocarcinomas in rats, and a daily water consumption for
an adult, lifetime risks of 10-4, 105 and 106 are
associated with bromate concentrations in water at 5, 0.5 and 0.05
<greek-m>g/L, respectively. Equivalent concentrations in terms of
KBrO<INF>3, lifetime risks would be 7, 0.7 and 0.07 <greek-m>g/L,
respectively.
The International Agency for Research on Cancer placed bromate in
Group 2B, for agents that are probably carcinogenic to humans. EPA has
performed a cancer weight of evidence evaluation, and has placed
bromate in Group B2: probable human carcinogen since bromate has been
shown to produce several types of tumors in both sexes of rats
following drinking water exposures. In addition, positive mutagenicity
studies which have been reported include indications of DNA
interactions with bromate. As a result of bromate formation following
disinfection, particularly with ozone, there is a potential for
considerable exposure in drinking water. Thus, EPA is proposing an MCLG
based on carcinogenicity and a Category I approach. The resulting MCLG
is zero.
EPA is also interested in examining the mechanism of toxicity of
bromate in rats in terms of whether renal tumor formation is due to
direct action of bromate or indirectly through formation of specific
adduct in kidney DNA of rats treated with bromate.
EPA requests comment on the MCLG of zero based on carcinogenic
weight of evidence and the mechanism of action for carcinogenicity
related to DNA adduct.

VI. Occurrence of TTHMs, HAA5, and other DBPs

A. Relationship of TTHMs, HAA5 to Disinfection and Source Water Quality

Primary and Residual Disinfectant Use Patterns in U.S. and
Relationship to Formation of DBPs
A survey of 727 utilities nationwide was conducted for the American
Water Works Association Research Foundation (AWWARF) in 1987 to
determine the extent and cost of compliance with the 1979 maximum
contaminant level (MCL) for trihalomethanes (THMs) (McGuire et al.,
1988). The AWWARF survey reflected more than 67 percent of the
population represented by water utilities serving more than 10,000
customers. The survey found that chlorine remained the most common
disinfectant among water utilities. At the time of the survey, chlorine
was used by 85 percent of the flowing stream and lake surface water
systems and by 80 percent of the ground water systems. The median
chlorine dose for flowing stream and lake systems was 2.2-2.3 mg/L and
for ground water systems it was 1.2 mg/L. The range of chlorine doses
was 0.1 to >20 mg/L.
Chloramines were used by 25 percent of the flowing stream systems
and larger lake systems, but by only 13 percent of the smaller lake
systems. Chloramines were rarely used by ground water systems reporting
in the AWWARF THM survey. Typical chloramine doses for flowing stream
systems was 2.7 mg/L, compared with 1.5 mg/L for lake systems. In
addition, 10 percent of the flowing stream systems and 5 percent of the
lake systems reported using chlorine dioxide. The latter systems
typically served more than 25,000 customers. The typical chlorine
dioxide doses ranged from 0.6 mg/L for the flowing stream systems to
1.0 mg/L for the lake systems. No ground water systems reported using
this disinfectant. At the time of this survey, three utilities reported
using ozone.
The AWWA Disinfection Committee also performed nationwide surveys
on disinfectant use in 1978 (AWWA Disinfection Committee, 1983) and
1990 (AWWA Water Quality Division Disinfection Committee, 1992),
principally among systems serving >10,000 persons (<3 percent of the
surveyed systems served 10,000 persons or fewer). Chlorine has
historically been applied early in the water treatment process
(precoagulation) in order to utilize the benefit of chlorine as a
disinfectant and an oxidant and to control biological growths in
basins. In the 1978 survey, the vast majority (>85 percent) of those
who relied on surface waters prechlorinated (AWWA Disinfection
Committee, 1983). The 1990 survey found a significant reduction in the
frequency of chlorine addition prior to coagulation, along with an
increase in chlorine application after sedimentation (AWWA Water
Quality Division Disinfection Committee, 1992). The AWWARF THM survey
had found that 150 systems surveyed had changed the point of
disinfection to comply with the 0.10-mg/L THM MCL (McGuire et al.,
1988). However, the 1990 AWWA survey (AWWA Water Quality Division
Disinfection Committee, 1992) still found that 35 percent of the
utilities reported chlorination before coagulation or sedimentation.
The range and median chlorine doses in the 1990 AWWA survey were
similar to the AWWARF THM survey.
In the 1990 AWWA survey, disinfection modifications to reduce THMs
included (1) changes in prechlorination practices (24 percent of
respondents moved the first point of chlorination, 23 percent ceased
prechlorination, while 20 percent decreased the prechlorination dose),
(2) implementation of ammonia addition (19 percent added ammonia after
some free chlorine time, while nine percent added ammonia before
chlorination), (3) or changed preoxidant (10 percent switched to
potassium permanganate, five percent to chlorine dioxide, and 0.5
percent to ozone). A surprisingly large percentage of utilities
reported operational problems with disinfection modifications used for
THM reduction (e.g., 56 percent of utilities that implemented
postammoniation reported such problems; as well as 44, 36, and 28
percent of those who moved the first point of chlorination downstream,
ceased prechlorination, and decreased the prechlorination dose,
respectively). Neither the exact nature of the problems noted, nor
their duration, were defined in the survey. However, the Disinfection
Committee believed that many of the reported problems were probably
transitional and were alleviated after further experience.
The 1990 AWWA survey (Haas et al., 1990) found that disinfection
modifications for THM minimization differed between ground and surface
water utilities. For example, 13 percent of surface water systems
changed their preoxidation practices, while this option was rarely used
by ground water systems (which rarely preoxidize). Sixteen and 25
percent of surface and ground water utilities, respectively, reported
adding ammonia after some free chlorine contact as their modification
strategy to reduce THMs. Because 65 percent of the surveyed ground
waters had a THM formation potential (THMFP) (a worst-case measure of
the possible THM production rather than the amount actually produced in
the distribution system) of <100 <greek-m>g/l, most ground water
systems probably did not require modifications to meet the 1979 TTHM
rule.
AWWA established a Water Industry Data Base (WIDB) in 1990-91 (AWWA
Water Industry Data Base, 1991). The WIDB contains information from
about 500 utilities supplying water to more than 50,000 people and over
800 utilities supplying between 10,000 and 50,000 people. The utilities
in the WIDB represent a combined population of 209 million people. In
addition, a database for the Disinfectants/Disinfection By-Products (D/
DBP) negotiated regulation (``reg neg'' data base, RNDB) (JAMES M.
MONTGOMERY, CONSULTING ENGINEERS, INC., 1992) was developed for AWWA.
The RNDB comprises data on nationwide and regional DBP studies,
including data on individual THMs and haloacetic acids (HAAs), chloral
hydrate, and bromate, performed by EPA, water utilities, universities,
and engineering consultants, as well as total THM (TTHM) data from the
WIDB. The non-WIDB part of the RNDB (i.e., those studies on individual
DBP occurrence and control) includes 166 utilities serving a combined
population of about 72 million people. The majority of systems in the
non-WIDB data occurrence part of the RNDB are also in the WIDB. Thus,
the former data base represents a subset of the latter data base, in
which specialized DBP studies were conducted. In addition, many of
these studies attempted to select utilities that were representative of
source water quality, treatment plant operations, disinfectant use,
population served, and geographical locations throughout the United
States (Krasner et al., 1989). Furthermore, the RNDB includes data on
48 utilities (serving a combined population of 37 million people) which
have evaluated alternative treatments to comply with future DBP
regulations.
Figure VI-1 shows a comparison of disinfectant/oxidant uses
reported in the WIDB and the non-WIDB part of the RNDB. In general, the
current usage of disinfectants/oxidants in both data bases are
comparable, which indicates that the non-WIDB part of the RNDB is
representative of nationwide disinfectant usage. Figure VI-2 shows
disinfectants evaluated under alternative treatments in the RNDB. While
ozone is the most prevalent alternative disinfectant under
investigation in the RNDB, this data base is somewhat biased, as it
does include two AWWARF studies involving ozonation. However, Figure
VI-2 does demonstrate that ozone is an alternate disinfectant that is
being widely evaluated. While most systems currently use chlorine only,
the percentage drops when the data are population based. Figure VI-1
shows that chloramine use is higher on a population basis, probably due
to its usage by some of the larger utilities.

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<GRAPHIC><TIF9>TP29JY94.011

<GRAPHIC><TIF10>TP29JY94.012

BILLING CODE 6560-50-C
2. National Occurrence of TOC
The total organic carbon (TOC) level of a water is generally a good
indication of the amount of THM and other DBP precursors present in a
water (Singer et al., 1989). In the WIDB, 157 utilities provided TOC
data. For the 100 surface waters with TOC data, the range was ``not
detected'' (ND) to 30 mg/L. For these waters, the 25th, 50th, and 75th
percentiles were 2.6, 4.0, and 6.0 mg/L, respectively. For the 57
ground waters with TOC data, the range was ND to 15 mg/L. For these
waters, the 25th, 50th, and 75th percentiles were ND, 0.8, and 1.9 mg/
L, respectively. Typically, most ground waters are low in TOC. However,
there are some high-TOC ground waters, especially in the southeastern
part of the United States (EPA Region IV; see Figure VI-3 and Table VI-
1). For surface waters, the high-TOC waters also tend to be in the
southeastern part of the United States, although there are some
relatively high-TOC waters in the south central (EPA Region VI) and the
mountain (EPA Region VIII) states (see Figure VI-3 and Table VI-2).

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<GRAPHIC><TIF11>TP29JY94.013

BILLING CODE 6560-50-C

Table VI-1.--Statistics on Average Raw Groundwater Total Organic Carbon (mg/L) for Utilities in the AWWA Water

Industry Database

Number of Percentile
Number of utilities -----------------------------------------
EPA region utilities with missing Min value Max value
with data data 25th 50th 75th

1............ 2 48 ND 1.38 ............ ............ ............
2............ 3 72 ND 1.91 ............ ............ ............
3............ 3 96 ............ ............ ............ 2.74 ............
4............ 13 163 ND 15.00 ND 2.19 8.50
5............ 11 182 ND 4.00 0.63 1.45 1.92
6............ 4 82 ND 1.87 ............ ............ ............
7............ 5 53 ND 1.40 ............ ............ ............
8............ 4 46 0.71 2.00 ............ ............ ............
9............ 11 118 ND 1.00 ND ND 0.30
10........... 1 37 0.80 0.80 ............ ............ ............
ALL.......... 57 897 ND 15.00 ND 0.84 1.88

Table VI-2.--Statistics on Average Raw Surface Water Total Organic Carbon (mg/L) for Utilities in the AWWA Water

Industry Database

Number of Percentile
Number of utilities -----------------------------------------
EPA region utilities with missing Min value Max value
with data data 25th 50th 75th

1............ 6 44 3.00 9.00 3.48 3.50 4.50
2............ 10 65 2.10 20.00 2.50 4.55 5.00
3............ 20 79 ND 25.00 2.15 2.87 4.80
4............ 11 165 1.60 30.00 5.27 7.40 12.60
5............ 14 179 ND 9.17 2.70 4.50 5.90
6............ 10 76 2.00 10.00 3.90 5.50 6.90
7............ 2 56 7.00 10.00 ............ ............ ............
8............ 7 43 1.00 14.00 1.75 3.30 8.50
9............ 16 113 ND 5.90 1.95 3.25 3.88
10........... 4 34 1.25 3.30 ............ ............ ............
ALL.......... 100 854 ND 30.00 2.55 4.00 5.95

For surface waters that filter but do not soften, the median and
90th percentile TOC levels are 3.7 and 7.5 mg/L, respectively (see
Figure VI-4). However, when the data are flow-weighted (which would
represent more closely the distribution by population), the median and
90th percentile values drop to 2.7 and 5.1 mg/L, respectively (see
Figure VI-4). This is due, in part, to a number of large facilities
treating water with TOC levels <4 mg/L. When this same category of
surface waters is examined for choice of disinfectants between chlorine
and chloramines, the latter group has a higher TOC cumulative
probability than the former (see Figure VI-5). Switching from free
chlorine only to chloramination was one of the options utilized by
utilities with high-TOC waters to comply with the 0.10 mg/L TTHM MCL.

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<GRAPHIC><TIF13>TP29JY94.015

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As part of a ground water supply survey (GWSS), TOC was measured at
the point of entry into the distribution system (see Figure VI-6).
Because most groundwater systems do not have precursor-removal
technology as part of their treatment, these treated-water TOC levels
provide a good indication of the range of raw-water TOC levels in
ground waters. The median and 90th percentile TOC levels of systems
without softening who chlorinate were 0.7 and 2.9 mg/L, respectively.
However, the median and 90th percentile TOC levels of systems with
softening who chlorinate were 1.7 and 6.8 mg/L, respectively.

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<GRAPHIC><TIF14>TP29JY94.016

In addition, the breakdown of treated-water TOC levels of ground
waters was examined geographically (see Table VI-3). As indicated above
(see Table VI-1), the southeastern part of the United States (i.e., EPA
Region 4) has groundwaters with a relatively higher level of TOC (see
Tables VI-3A and VI-3C). In addition, the mountain states (i.e., EPA
Region 8) also tended to have a higher distribution of TOCs in the
ground waters tested (see Tables VI-3A and VI-3C). Furthermore, these
data are also broken down into those that chlorinate and those that do
not (see Table VI-3). Typically, ground waters that are currently
undisinfected tend to be ones with lower TOC levels. Thus, promulgation
of the Ground Water Disinfection Rule will probably tend to have an
impact on waters with a lower precursor level than are currently
disinfecting.

Table VI-3A.--TOC Values for GWSS Systems That Chlorinate

Number of Percentile

EPA region utilities Max value -------------------------------------------------------

with data 25th 60th 75th 90th

1............................ 19 4.3 0.4 0.5 0.95 2.3
2............................ 59 4.6 0.3 0.5 0.9 1.5
3............................ 62 4.2 0.3 0.5 0.7 1.2
4............................ 185 14 0.8 0.7 2.1 5.3
5............................ 90 8.9 0.7 1.1 1.8 2.6
6............................ 46 8 0.6 1 1.7 2.4
7............................ 103 7.8 0.8 0.8 1.8 3.7
8............................ 26 11 0.6 1.9 3.1 6.6
9............................ 39 11 <2 0.2 0.5 1.2
10........................... 25 3.3 0.3 0.9 1.4 2.2

ALL.......................... 654 14 0.3 0.7 1.7 3.3

Table VI-3B.--TOC Values for GWSS Systems That Do Not Chlorinate

Number of Percentile

EPA region utilities Max value -------------------------------------------------------

with data 25th 50th 75th 90th

1............................ 27 3.6 0.3 0.5 0.8 1.3
2............................ 14 0.8 <2 0.3 0.5 0.6
3............................ 28 5.3 <2 0.3 0.6 1.5
4............................ 34 3.2 0.3 0.5 0.8 1.7
5............................ 41 18 0.7 1.3 2.2 3.4
6............................ 26 5.6 0.2 0.6 1.5 2.9
7............................ 18 2.9 0.6 0.9 1.1 2.2
8............................ 14 5.9 0.3 0.4 1.8 2.7
9............................ 49 3.4 <2 0.3 0.4 0.9
10........................... 40 5 0.2 0.4 0.8 2

ALL.......................... 291 18 0.3 0.5 1.1 2.2

Table VI-3C.--TOC Values for all GWSS Systems

Number of Percentile

EPA region utilities Max value -------------------------------------------------------

with data 25th 50th 75th 90th

1............................ 46 4.3 0.3 0.5 0.8 1.6
2............................ 73 4.6 0.3 0.5 0.8 1.3
3............................ 90 5.3 0.3 0.4 0.7 1.2
4............................ 219 14 0.3 0.7 1.9 4.8
5............................ 131 18 0.7 1.2 1.9 3.2
6............................ 72 8 0.4 0.9 1.7 2.4
7............................ 121 7.8 0.4 0.9 1.7 3.2
8............................ 40 11 0.3 1.8 2.7 5.9
9............................ 88 11 <2 0.2 0.5 1
10........................... 65 5 0.2 0.5 1.2 2.2

ALL.......................... 945 18 0.3 0.6 1.4 2.9

3. National Occurrence of Bromide
Bromide is a concern in both chlorinated and ozonated supplies. In
chlorinated supplies, while the organic precursor level of a source
water has an impact on the amount of DBPs formed, the bromide
concentration has an impact on the speciation as well as the overall
yield (Symons et al., 1993). Typically, regardless of the organic
content in water, bromate can be formed when waters containing
sufficient levels of bromide are ozonated (Krasner et al., Jan. 1993).
In a 35-utility nationwide DBP study, bromide ranged from <0.01 to
3.0 mg/L and the median bromide level was 0.1 mg/L (Krasner et al.,
1989). Some utilities have bromide in their source water due to
saltwater intrusion (one utility had as much as 0.4 to 0.8 mg/L bromide
due to this phenomenon) (Krasner et al., 1989). However, some noncoastal
communities can have moderate-to-high levels of bromide due to
connate waters (ancient seawater that was trapped in sedimentary
deposits at the time of geological formation) or industrial and oilfield
brine discharges. The highest bromide detected in the latter
study (2.8-3.0 mg/L) (Krasner et al., 1989) was from a water in the
midsouthern part of the U.S.
Currently, a nationwide bromide survey of 70 utilities has found
bromide levels ranging from <0.005 to >3.0 mg/L (Amy et al., 1992-3).
Some waters have been sampled more than once (up to three seasonal
samples to date) in order to determine the variability in bromide
occurrence. The average raw-water bromide level per water, though,
provides an indication of the typical occurrence of bromide in each
water. Table VI-4 provides some preliminary insight into the
geographical occurrence of bromide. Ideally, more data per region are
needed; however, sufficient data are available for general trends.
Regions 6 (which includes Texas) and 9 (which includes California) have
the highest occurrence of bromide. While some California communities
have problems with saltwater intrusion, some Texas communities may have
bromide from connate waters or oil-field brines. However, most
geographical regions have at least one high-bromide water in their
area, except for the systems surveyed in the Pacific Northwest (EPA
Region 10) and the northeast (EPA Regions 1 and 2).

Table VI-4.--Statistics on Average Raw-Water Bromide (mg/L) for Utilities in the Nationwide Bromide Survey

Number of Percentile

EPA region utilities Min value Max value ---------------------------------------------------

with data 25th 50th 75th 90th

1....................... 8 0.005 0.089 0.02 0.03 0.05 0.05
2....................... 4 0.023 0.093 0.03 0.05 0.08 NA
3....................... 8 0.005 0.276 0.03 0.06 0.07 0.08
4....................... 7 0.010 0.190 0.02 0.04 0.05 0.05
5....................... 6 0.012 0.322 0.05 0.09 0.12 0.14
6....................... 7 0.014 >3.00 0.02 0.03 0.25 0.37
7....................... 6 0.042 0.206 0.06 0.08 0.09 0.10
8....................... 7 0.006 0.368 0.02 0.02 0.06 0.09
9....................... 11 0.008 0.429 0.05 0.08 0.33 0.36
10...................... 6 <0.005 0.015 <0.005 0.006 0.009 0.012

NA=Not applicable; insufficient number of utilities to determine.

Figures VI-7 and VI-8 show the cumulative probability distribution
of average raw-water bromide levels in surface and ground waters,
respectively, in the nationwide bromide survey. In surface waters in
this survey, the median, 75th, 90th, and 95th percentile bromide level
were 0.04, 0.08, 0.2, and 0.35 mg/L, respectively. In ground waters in
this survey, the median, 75th, 90th, and 95th percentile bromide level
were 0.06, 0.1, 0.25, and 0.35 mg/L, respectively. Overall, ground
waters appear to have a somewhat higher probability of bromide
occurrence than in surface waters. In the 35-utility DBP study, one
midwest utility pumped ground water into a lake to augment a low-lake
level during a drought period. Bromide rose from 0.19 to 0.68 mg/L
during this period of time.

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B. Chlorination Byproducts

TTHMs--Occurrence Studies
Prior to the promulgation of an MCL of 0.10 mg/L TTHMs in 1979, EPA
performed two surveys to obtain information on the occurrence of THMs
and other organic compounds: the National Organics Reconnaissance
Survey (NORS) in 1975 (Symons et al., 1975) and the National Organic
Monitoring Survey (NOMS) in 1976-77 (Brass et al., 1977 and The
National Organics Monitoring Survey, unpubl.). NORS and NOMS were
conducted primarily to determine the extent of THM occurrence in the
United States. These data were used, in part, in determining the 1979
THM regulation. Surveys in the 1980s were performed to provide data for
assessing a new MCL for THMs, as well as to develop regulations for
other DBPs.
The AWWARF THM survey used data from 1984-86, and these THM values
reflected the result of compliance with the 1979 THM regulation. Mean
TTHM values were computed for each of the utilities in the AWWARF THM
survey; these means, as well as data from the NORS and NOMS surveys,
are plotted (see Figure VI-9) on a frequency distribution curve. The
AWWARF survey's overall TTHM average was 42 <greek-m>g/L, which was a
40-50 percent reduction in national THM concentrations as compared to
the averages of the NORS and NOMS (all phases) results. It is important
to note that the disinfection practices of some of the utilities in the
AWWARF survey (such as the use of chloramines as a primary
disinfectant) were employed to meet the 1979 TTHM MCL, and not to meet
the requirements of the recently promulgated Surface Water Treatment
Rule (SWTR). Thus, THM and DBP levels at some utilities would most
likely be different if their current treatment practices required
modification in order to meet the new disinfection requirements of the
SWTR.

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Median TTHM concentrations in the AWWARF survey for the spring,
summer, fall, and winter seasons were 40, 44, 36, and 30 <greek-m>g/L,
respectively. THM levels were highest in the summer and lowest in the
winter, due primarily to the faster formation rates in warmer water
temperatures. In the 35-utility DBP study, the second highest THM
levels were in the fall (Krasner et al., 1989). For many utilities in
California and the southern United States, fall can be almost as warm
as summer. However, seasonal impacts may be due to changes in the
nature of naturally occurring organics or bromide levels as well.
Compliance with the THM regulation is based on a running annual average
to reflect these types of seasonal variations.
Because the 1979 regulation did not apply to systems that serve
<10,000 people, the running annual average TTHM distribution for small
systems is expected to be different. In the AWWARF THM survey, TTHM
data for small systems from 12 states were obtained (McGuire et al.,
1988). While the number of utilities (677) for which TTHM data were
received represents only a small percentage of the total number serving
fewer than 10,000 customers (55,449), some important observations can
be made. The range of TTHMs was from ND to 313 <greek-m>g/L, with a
mean of 36 <greek-m>g/L and a median of 18 <greek-m>g/L (McGuire et
al., 1988). The cumulative probability distribution differs
significantly from the NORS and NOMS data (see Figure VI-10). This lack
of agreement is probably due to many of the small systems using ground
water sources, which are generally much lower in THM precursors than
surface water sources. In addition, the overall statistics of the
AWWARF survey (for 677 cities) were markedly affected by the low TTHM
results (range of ND to 42 <greek-m>g/L with a mean of 2 <greek-m>g/L)
of the 204 systems sampled in Wisconsin. Although McGuire does not
identify a reason for low TTHMs in Wisconsin, EPA data indicate that
over 90 percent of Wisconsin systems use ground water (probably with
low precursor levels) as a primary source. Since 30 percent of the
systems in the survey were from Wisconsin, this would bias the results.

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Since the AWWARF THM survey, EPA measured DBP data in a number of
small systems. These data represent part of the non-WIDB data in the
RNDB. Figure VI-11 compares the TTHM frequency distribution for the
WIDB (large systems only) with that of the non-WIDB data on both large
and small systems. For the small systems, there is essentially a
biomodal distribution of TTHM levels: 50 percent of the small systems
have <ls-thn-eq>10 <greek-m>g/L TTHMs, while the remaining utilities
have TTHM levels of 20 to 430 <greek-m>g/L. Most likely, many of the
very low THM levels are associated with treatment of low-TOC, lowbromide
ground waters. For community water, non-purchased systems
serving <10,000 people, 4562 systems treat surface water, while 17941
disinfect ground water. For systems serving >10,000 people, 1395 treat
surface water and 1117 disinfect ground water. Thus, small systems are
utilizing ground water more than surface water.

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In the WIDB (which only includes large systems), 482 utilities that
treat surface water or a mix of surface and ground waters had TTHM
median, 75th, and 90th percentile values of 43, 59, and 74 <greek-m>g/
L, respectively. In the WIDB, 277 utilities that treat ground water
only had TTHM median, 75th, and 90th percentile values of 13, 34, and
60 <greek-m>g/L, respectively. However, systems using both types of
source waters had TTHM levels in the neighborhood of 100 <greek-m>g/L.
Thus, while ground waters in general tend to form less THMs than
surface waters, there are some ground waters with sufficient precursor
levels to form significant amounts of THMs.
2. HAAs and Other Chlorination DBPs--Occurrence Studies
a. Discovery of Additional Chlorination By-Products. In 1985, EPA
determined chlorination DBPs at 10 operating utilities, using both
target-compound and broad-screen analyses (Stevens et al., 1989). A
total of 196 compounds that can be attributed to the chlorination
process were found in one or more of the 10 utilities' finished waters.
Approximately half of the compounds contained chlorine and many were
structurally identified; however, 128 compounds were of unknown
chemical structure. The compounds which were quantifiable represented
from 30 to 60 percent of the total organic halide (TOX) of those
supplies. That study served to significantly reduce the list of
compounds that EPA considered most significant for further work.
b. Available Data on Chlorination By-Products. Taken as an example
of subsequent survey results where quantifiable target-compound
analyses were used, Figure VI-12 shows the occurrence of DBPs in the
35-utility study (Metropolitan Water District of So. Calif et al.,
1989). The figure presents an overview of the results of four seasonal
sampling quarters combined. In addition, all sampling was performed at
treatment-plant clearwell effluents. It is important to note that these
survey results do not reflect any impacts of the SWTR under which a
substantial number of systems could be expected to modify disinfection
practice to achieve compliance. On a weight basis, THMs were the
largest class of DBPs detected in this study; the second largest
fraction was haloacetic acids (HAAs). At the time of this study,
commercial standards were only available for five of the nine
theoretical species: monochloro-, dichloro-, trichloro-, monobromo-,
and dibromoacetic acid. The data indicate that the median level of THMs
(i.e., 36 <greek-m>g/L) was approximately twice that of HAAs (i.e., 17
<greek-m>g/L). The third largest fraction was the aldehydes (i.e.,
formaldehyde and acetaldehyde). These two low-molecular-weight
aldehydes were initially discovered as by-products of ozonation, but
they also appear to be by-products of chlorination. Every targetcompound
DBP was detected at some time in some utility's water during
the study; however, 2,4,6-trichlorophenol was only detected at low
levels at a few utilities during the first sampling quarter and was not
detected in subsequent samplings.

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The 35-utility DBP study assessed systems using a range of
disinfectants, a number of which used chloramines as a residual
disinfectant. In a study (in 1987-89) by EPA, primarily chlorine-only
systems were evaluated at the plant and in the distribution system
(typically a terminal location). The range of total HAAs (THAAs) (a sum
of the five aforementioned species) at the plant effluent was <1 to 86
<greek-m>g/L (representing 73 samples), with a median value of 28
<greek-m>g/L (Fair, 1992). In the distribution system (56 samples
collected), the range and median THAAs were <1-136 and 35 <greek-m>g/L,
respectively.
In a six-utility DBP survey in North Carolina (Grenier et al.,
1992), the sum of four measured HAAs--dibromoacetic acid was not
included in this study, as these waters are all low in bromide--ranged
from 14 to 141 <greek-m>g/L in the distributed waters (with utility
annual averages of 51 to 97 <greek-m>g/l). In this survey, HAA
concentrations consistently exceeded the concentration of TTHMs (which
ranged from 13 to 114 <greek-m>g/l, with utility annual averages of 34
to 72 <greek-m>g/l). The prevalence of the HAAs may be due, in
part, to chlorination of settled and finished waters with pH levels of
5.9 to 7.8. Chlorination at lower pH levels results in lower THM
formation but higher HAA concentrations (Stevens et al., 1989).
Recently, a commercial standard for bromochloroacetic acid (BCAA)
has become available. Studies to date suggest that the other mixed
bromochloroacetic acids may be unstable (Pourmoghaddas et al., 1992).
The RNDB includes the occurrence of BCAA for 25 utilities. The median,
75th and 90th percentile occurrence were 3, 5, and 8 <greek-m>g/L,
respectively. In the chlorinated distribution system of a water
containing from 0.04 to 0.31 mg/L bromide (i.e., an average- and a
high-bromide source water were being treated), BCAA was present from 6
to 17 <greek-m>g/L and accounted for 25 percent of the concentration of
the sum of the six measured HAA species (D/DBP Regulations Negotiation
Data Base (RNDB), 1992). Thus, most DBP studies which measured only
five of the HAA species will have some level of underestimation of
total HAAs present, although that should be a small error in low
bromide waters.
The RNDB includes HAA data, including from the 35-utility, EPA, and
North Carolina DBP studies. When a utility was sampled more than once
in time and space, a ``quasi'' running annual average value was
determined (RNDB). Figure VI-13 shows the cumulative probability
occurrence of THAAs (the four- to six-species sums) for large and small
systems. The median THAA for either population group is 30 <greek-m>g/
L, although the small systems have 30 percent of the utilities with
<ls-thn-eq>7 <greek-m>g/L THAAs. The difference at the low THAA levels
was probably due to treatment of low-precursor source waters in small
systems. The high end of the THAA occurrence was not significantly
different, most likely due to a lack of a HAA regulation and the fact
that pH of chlorination impacts THM and HAA formation in opposite ways.
In the RNDB, 121 of the utilities treated surface water or a ground
water/surface water mix. For those systems treating some percentage of
surface water, the median, 75th, 90th percentile, and maximum values
were 28, 50, 73, and 155 <greek-m>g/L, respectively. In the RNDB, 13 of
the utilities treated ground water only. For this limited ground water
data set, the median, 90th percentile, and maximum values were 4, 13,
and 37 <greek-m>g/L, respectively.

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3. Modeling (DBPRAM) Formation TTHMs, HAA5 and Extrapolation to
National Occurrence and Effects of SWTR
As part of the D/DBP rulemaking process, EPA developed regulatory
impact assessments of technologies that will allow utilities to comply
with possible new disinfection and DBP standards (Gelderloos et al.,
1992). As part of this process, a DBP Regulatory Assessment Model
(DBPRAM) was developed. The DBPRAM included predictive equations to
estimate DBP concentrations during water treatment (Harringon et al.,
1992). However, because reliable equations for predicting individual
DBP formation in a wide range of waters (e.g., those containing high
levels of bromide) were not available, the regulatory impact
assessments emphasized TTHM (Amy et al., 1987) and total HAA5
formation. Because BCAA was not commercially available when HAAs were
measured during the development of the HAA predictive equations, those
equations only included the formation of five HAA species (Mallon et
al., 1992). However, for a low-bromide water, the error from not
including mixed bromochloro HAA species was probably low.
The DBPRAM predicted the removal of TOC during alum coagulation,
granular activated carbon (GAC) adsorption, and nanofiltration
(Harrington et al., 1992 and Harrington et al., 1991). These equations
were developed based upon a number of bench-, pilot-, and full-scale
studies. The removal of TOC during precipitative softening, though, has
not been modeled to date. However, systems that soften represent a
small percentage of the surface-water treatment plants (about 10
percent). The DBPRAM also predicted the alkalinity and pH changes
resulting from chemical addition (Harrington et al., 1992), as well as
the decay of residual chlorine and chloramines in the plant and
distribution system (Dharmarajah et al., 1991).
In developing regulatory impact assessments, the first step was to
estimate the occurrence of relevant source-water parameters (Letkiewicz
et al., 1992). TOC data from the WIDB and bromide data from the
nationwide bromide survey formed the basis for determining the DBP
precursor levels (Wade Miller Associates, 1992). Actual water quality
data were used to simulate predicted occurrence values based upon a
statistical function such as a log-normal distribution (Letkiewicz et
al., 1992 and Wade Miller Associates, 1992). In running the DBPRAM, the
production of DBPs was restricted to surface-water plants that filtered
but did not soften. Surface waters typically have higher disinfection
criteria--and thus a greater likelihood to produce more DBPs--than
ground waters (i.e., Giardia in surface waters is more difficult to
inactivate than viruses in ground waters). As mentioned before, an
equation to predict TOC removal during softening was not available.
However, the surface water systems which were modeled represented water
treated and distributed to approximately 103 million people (Letkiewicz
et al., 1992). Another mechanism was developed for accounting for DBP
occurrence in other water systems (see below).
The second step in the regulatory impact assessment was to prepare
a probability distribution of nationwide THM and HAA occurrence if all
surface water plants that filter but do not soften used a particular
technology for DBP control (i.e., enhanced coagulation, GAC,
nanofiltration, or alternative disinfectants). Even though individual
utilities will consider a range of technologies to meet disinfection
and D/DBP rules, the DBPRAM can only predict the performance of one
technology at a time. Subsequently, a decision-making process was
employed to examine the predicted compliance choices that systems will
make (Gelderloos et al., 1992). As part of the DBPRAM, compliance with
the SWTR, a potential enhanced SWTR, the total coliform rule, and the
lead-corrosion rule were modeled. Thus, while nationwide DBP studies
typically measured DBP occurrence prior to implementation of these new
microbial and corrosion rules, the DBPRAM allowed one to assess the
impacts of meeting a multitude of rules simultaneously.
During the D/DBP negotiated rulemaking, a Technology Workgroup
(TWG) of engineers and scientists was formed. The TWG reviewed the
DBPRAM and regulatory impact assessments, and provided input to ensure
that the predicted output was consistent with real-world data. Prior
validation of the model in Southern California (where bromide
occurrence was relatively high) indicated that the central tendency was
to underpredict TTHMs by 20-30 percent (Harrington et al., 1992). In
addition, evaluation of the model in low-bromide North Carolina waters
also found that the model tended to underpredict both THM and HAA
concentrations and resulted in absolute median deviations of
approximately 25-30 percent (Grenier et al., 1992). Neither Harrington
nor Grenier were able to identify reasons for the underpredictions.
Therefore, the TWG adjusted the DBPRAM output to correct for the
underpredictions; the resultant data were confirmed against full-scale
data from throughout the United States.
Prior validation of the alum coagulation part of the model was
performed in several eastern states, as well as in Southern California.
The overall central tendency was to overpredict TOC removal by 5-10
percent. The TWG believed that utilities would implement an overdesign
factor to ensure that precursor removal technologies could consistently
meet water quality objectives. A 15 percent overdesign factor for TOC
removal compensated for a typical overprediction in TOC removal by
alum. For plants that do not filter or filter with softening, case
studies on a number of systems through the nation were used to assess
compliance choices and predicted water qualities. For ground waters,
data from the WIDB and GWSS on TOC and THM levels were used in
developing regulatory impact analyses (RIAs) for those systems.
With the revised DBPRAM output, the proposed stage 1 D/DBP rule--
i.e., MCLs of 80 <greek-m>g/L TTHMs and 60 <greek-m>g/L THAAs, as well
as a performance criteria for DBP precursor removal--would affect large
systems that filter but do not soften as follows: TTHMs would drop on a
median basis from 45 to 32 <greek-m>g/L, while the 95th percentile
would drop from 104 to 58 <greek-m>g/L; THAAs would drop on a median
basis from 27 to 20 <greek-m>g/L, and the 95th percentile would drop
from 86 to 43 <greek-m>g/L.

C. Other Disinfection Byproducts

Ozonation Byproducts
a. Identification of Ozonation Byproducts. Ozone can convert
organic matter in water to aldehydes (e.g., formaldehyde) (Glaze et
al., 1989) and assimilable organic carbon (AOC) (Van der Kooij et al.,
1982). Recent research optimized the aldehyde method in order to
quantitatively recover additional carbonyls of interest (e.g.,
dialdehydes such as glyoxal and aldo-ketones such as methyl-glyoxal
(Sclimenti et al., 1990)). AOC is the fraction of organic carbon that
can be metabolized by microorganisms; it also represents a potential
for biological regrowth in distribution systems. Polyfunctional ozone
DBPs such as ketoacids have been detected at higher levels than the
low-molecular-weight aldehydes and have been shown to correlate well
with AOC (Xie et al., 1992). Using resin columns to accumulate organics
from ozonated waters, Glaze and co-workers detected aldehydes,
carboxylic acids, aliphatic and alicyclic ketones, and hydrocarbons
(Glaze et al., August 1989). Ozone is known to produce other organic
oxygenated DBPs, such as peroxides and epoxides (Glaze et al., 1989).
Analytical methods for low-level detection are currently not available
for epoxides, but progress in detecting peroxides (inorganic and
organic) has recently been made (Weinberg et al., 1991). As with
chlorine, occurrence data for ozone DBPs are limited to compounds that
can be detected by current methods.
Although most ozone by-products are oxygenated species, the
presence of bromide will result in the formation of brominated DBPs
(Haag et al., 1983 and Dore et al., 1988). When bromide is present in a
source water, it may be oxidized by ozone to hypobromous acid (HOBr).
At common drinking-water pH levels, HOBr is in equilibrium with the
hypobromite ion, OBr-. Once produced, HOBr can react with organic
THM/DBP precursors to form bromoform and other brominated organic byproducts
(Dore et al., 1988 and Glaze et al., Jan. 1993). OBr-
(but not HOBr) can be oxidized by ozone to bromate (BrO<INF>3-)
(Krasner et al., Jan 1993 and Haag et al., 1983). Krasner and
colleagues found that ozonation of bromide-containing waters can form a
number of brominated organic DBPs that are analogous to chlorinated
DBPs (e.g., bromoform, dibromoacetic acid, tribromonitromethane
[bromopicrin], and cyanogen bromide) (Krasner et al., 1990 and Krasner
et al., 1991). Similarly, Glaze and co-workers studied the formation of
bromo-organic DBPs formed during ozone (e.g., bromoform;
dibromoacetonitrile; mono-, di-, and tribromoacetic acid; and
monobromoacetone) (Glaze et al., Jan. 1993). However, only a fraction
of the dissolved organic bromide was found as targeted brominated
organic DBPs (Glaze et al., Jan. 1993). As with chlorination, not all
of the halogenated DBPs can be accounted for with existing analytical
methodologies. However, researchers are continuing to try to uncover
new DBPs all the time, such as the bromine-substituted analogues of
chloral hydrate (trichloroacetaldehyde) formed during chlorination and/
or ozonation (Xie et al., 1993, in press).
b. National Occurrence--Trends--i. Ozone use in U.S., pre vs. post
SWTR. While ozone technology in drinking-water treatment has been in
use for more than 80 years in Europe, applications in the United States
(U.S.) have been much more limited. However, the use of this
disinfectant/oxidant is growing rapidly in the U.S. as utilities are
working to meet the requirements of the SWTR, anticipation of a D/DBP
Rule, regulations for volatile and synthetic organic chemicals, and for
taste-and-odor control (Ferguson et al., 1991 and Tate, 1991).
Virtually every surface water system use of ozone was intended to
accomplish multiple water quality objectives, such as disinfection, DBP
control, taste and odor, or any combination of these (Tate, 1991).
Ground water plants in Florida have used ozone for controlling DBPs,
color, and odor (Tate, 1991).
The first U.S. ozone plant was on-line in 1978. The number
increased to 18 by June 1990 (Tate, 1991). A recent survey has
identified an additional 11 facilities under construction, as well as
at least 37 U.S. ozone pilot-plant studies underway (Rice, Aug.-Sept.
1992). As part of the D/DBP negotiated regulation, the TWG has
evaluated compliance choices for meeting stage 1 and possible stage 2
criteria. For example, the TWG predicted that six percent of surface
water systems will use ozone/chloramines in addition to enhanced
coagulation to achieve compliance with Stage 1 requirements. Depending
on the role of precursor-removal criteria in a stage 2 Rule, it is
predicted that from 8 to 27 percent of large surface-water systems
would use ozone/chloramines as part of the treatment process. The
current and projected ozone usage is based on an existing SWTR and the
anticipation of a DBP Rule, both of which have led to the choice of
ozone, a powerful disinfectant that typically produces limited DBPs.
ii. AWWARF bromide/bromate survey and studies. In order to comply
with new and more stringent regulations, alternative treatments are
being studied. A 2-year study of ozone treatment at 10 North American
utilities was conducted at pilot and full scale (Glaze et al., 1993 in
press). For four of the six surveyed utilities where the bromide level
was <ls-thn-eq>0.06 mg/L, bromate was not detected with minimum
reporting level (MRL) values of 5-10 <greek-m>g/L at the ozone dosages
investigated (Krasner et al., Jan. 1993). For the other two low-bromide
utilities, bromate at 5-8 <greek-m>g/L was detected inconsistently over
time and space. For three of the four tested waters in which the
ambient bromide level was 0.18-0.33 mg/L, bromate was typically
detected at levels of 9-18 <greek-m>g/L. No bromate was detected at one
utility where the very high level of TOC (i.e., 26 mg/L) may have
produced an ozone demand that overwhelmed the production of bromate. In
another study, using a special, labor-intensive concentration method at
an EPA research facility, bromate was detected in seven of the nine
ozonated waters tested at an MRL of 0.4 <greek-m>g/L or higher (Sorrell
et al., 1992). In one instance, bromate was detected in the source
water at this MRL value.
Utilizing these data, as well as that of other EPA and AWWARF
investigators (Krasner et al., Jan 1993, Amy et al., 1992-93, Sorrell
et al., 1992, Hautman, 1992, and Miltner, Jan. 1993). The nationwide
distribution of bromate occurrence if all surface water plants switched
to ozone for predisinfection was estimated (Krasner et al., 1993). It
was estimated that the 20th, median, and 80th percentile for bromate
occurrence in surface waters using ozone for predisinfection might be
0.5-0.8, 1-2, and 3-5 <greek-m>g/L, respectively.
The 90th to 95th percentile occurrence of bromate could be in the
range of 5 to 20 <greek-m>g/L (Krasner et al., 1993). However, the
proposed regulation for bromate would result in either (1) some
utilities choosing not to employ ozonation or (2) other utilities
operating the ozonation process in a manner which would reduce bromate
formation. For example, demonstration-scale tests of the ozonation of a
surface water containing bromide at approximately the 90th to 95th
percentile level of occurrence (i.e., 0.17 to 0.49 mg/L) at an ambient
pH of 8 produced from <3 to 25 <greek-m>g/L bromate, depending on the
amount of ozone added (Gramith et al., 1993). In the latter tests,
Giardia inactivations from ozonation of from 0.5 to 3 logs were
achieved. When the pH of ozonation was reduced to about 6, bromate
formation in this water was consistently below 10 <greek-m>g/L and
often below 5 <greek-m>g/L. In addition, Giardia inactivations of up to
4 logs were achieved at this pH.
c. Potential DBPs not regulated at this time.--i. Aldehydes,
ketones, peroxides, and formation of precursors for other DBPs--
national occurrence. Miltner and co-workers ozonated a surface water
with 1.4 mg/L TOC at various ozone doses up to an ozone-to-TOC ratio of
2.8:1 mg/mg (Miltner et al., Nov. 1992). They found that the formation
of the three most-prevalent aldehydes (formaldehyde, glyoxal, and
methyl-glyoxal) continued to increase as the ozone dose increased, and
that these three aldehydes had not reached maximum yields before the
highest ozone-to-TOC ratio was tested. Weinberg and colleagues studied
the formation of aldehydes at 10 North American utilities at pilot- and
full-scale plants (Weinberg et al., 1993) . The interquartile range
(i.e., 25th to 75th percentile occurrence) of formaldehyde was 11 to 20
<greek-m>g/L, while the sum of aldehydes tested had an interquartile
range of 23 to 47 <greek-m>g/L. The utility with the highest TOC in the
10-utility study (8.1 mg/L in the ozonator influent) represented a
maximum outlier in aldehyde production (i.e., about 70 <greek-m>g/L
formaldehyde and up to 150 <greek-m>g/L of summed aldehydes). The
minimum outlier was the summer testing of a low-TOC water (1.0 mg/L)
which received an applied ozone dose of 1.0 mg/L. When the occurrence
data were normalized to TOC level, the interquartile ranges were 3.9 to
8.4 <greek-m>g formaldehyde per mg TOC and 9 to 20 <greek-m>g of summed
aldehydes per mg TOC. This normalization brought the water with the
highest TOC into the interquartile range. When the aldehyde formation
was further normalized for the ozone dose, the interquartile ranges per
unit TOC and per ozone dose were 1.2 to 4.2 <greek-m>g formaldehyde/(mg

mg/L) and 2.9 to 11 <greek-m>g summed aldehydes/(mg * mg/L). With
this latter normalization, the high-TOC water dropped to almost the
minimum outlier. Because the ozone demand of the latter water exceeded
the dose, it is possible that more aldehydes could have been produced
with a higher dose. These limited data suggest that either TOC or ozone
dose can be the limiting factor in aldehyde production (i.e., for the
low-TOC water in the summer testing and the high-TOC water,
respectively).
While ozonation can produce significant levels of aldehydes, the
presence of these ozone by-products in the distribution system are
highly dependent on whether the filters downstream of ozone are
operated biologically (i.e., no secondary disinfectant is applied
before the filters), as well as the choice of filter media and
filtration rate (or more exactly, the empty bed contact time [EBCT] in
the filter media) (Miltner et al., Nov. 1992, Weinberg et al., 1993,
and Krasner et al., May 1993).
Using a bioreactor, many aldehydes can be quantitatively removed
(Miltner et al., Nov. 1992). In pilot- and full-scale studies,
formaldehyde tended to be the most biodegradable of the aldehydes
tested, while the glyoxals, in some instances, were somewhat
recalcitrant (Weinberg et al., 1993, and Krasner et al., May 1993).
These aldehydes (including the glyoxals) were typically best removed at
utilities in which granular activated carbon (GAC) contactors or
filters were employed, even when the GAC was removing little or no TOC
(Weinberg et al., 1993, and Krasner et al., May 1993). When anthracite
coal/sand filters were used without a secondary disinfectant before
filtration, these aldehydes could be removed to varying degrees with
the best results at low filtration rates (or high EBCTs) (Weinberg et
al., 1993, and Krasner et al., May 1993). Because part of the proposed
D/DBP Rule sets criteria for biological filtration following ozonation
of raw water, it is anticipated that the occurrence of aldehydes, while
not directly regulated, can be minimized in the finished water.
Other oxygenated organic ozone by-products (e.g., ketoacids (Xie et
al., 1992) and organic peroxides (Weinberg et al., 1991) can also be
reduced during biological filtration. The use of biological treatment
for drinking water treatment in the United States is currently very
limited, while in Europe such processes are more common. However,
research into the incorporation of biological filtration in the United
States is now being extensively studied and its implementation is
becoming more common (Weinberg et al., 1993). In addition, some ozone
by-products are relatively unstable (e.g., peroxides and epoxides) and
may not persist in the finished water. Furthermore, because hydrogen
peroxide can reduce chlorine to chloride ions (Connick, 1947), the
addition of free chlorine should destroy a peroxide residual (Weinberg
et al., 1991). Finally, because GAC can reduce oxidant residuals, GAC
downstream of ozone should be able to destroy hydrogen peroxide.
While ozone can partially destroy the precursors of some THMs and
HAAs (Miltner et al., 1992), it can increase the formation potential of
other DBPs (e.g., chloropicrin (Miltner et al., Nov. 1992 and Hoigne et
al., 1988) and chloral hydrate (Mcknight et al., 1992)). However,
Miltner and co-workers found that ozonation followed by biotreatment
reduced chloropicrin formation potential (Miltner et al., 1992).
McKnight and Reckhow found that if acetaldehyde--an ozone by-product--
undergoes an initial chlorine substitution, then the reaction should
rapidly proceed to form the trichlorinated product chloral hydrate
(Mcknight et al., 1992). Because acetaldehyde can be reduced during
biological filtration (Miltner et al., Nov. 1992 and Weinberg et al.,
May 1993), this should minimize subsequent formation during
postchlorination. Jacangelo and colleagues found that when biological
filtration was not practiced, preozonation increased chloral hydrate
formation in postchlorinated waters (Jacangelo et al., 1989). However,
these researchers also observed that chloral hydrate production for
systems using preozonation/postchloramination was lower than that for
systems using chlorination only (Jacangelo et al., 1989). To avoid byproducts
of secondary disinfection, more research into the relative
merits of biological filtration and/or postchloramination for systems
using preozonation must be pursued.
d. Concerns with AOC in high TOC source waters. Typically a highTOC
water will have a high oxidant demand. Thus, ozonating a high-TOC
water has the potential to form a higher level of ozone by-products,
such as aldehydes (see Section VI.C.1.c. above). In addition, there are
concerns that more AOC can be formed in such a water.
Amy and colleagues found that biodegradable organic carbon (BDOC)
correlated well (r\2\=0.92) with the TOC level of ozonated waters (Amy
et al., 1992). On the average, 28 percent of the TOC was present as
BDOC after ozonation (typical ozone dose of 1:1 mg ozone/mg TOC).
However, the correlation between BDOC and AOC for the six waters
studied was poor, suggesting that individual source waters may have a
unique relationship between these constituents.
While there is a concern over forming AOC, BDOC, aldehydes, etc.,
during ozonation, current research is examining the ability of the
treatment plant to remove significant portions of the biodegradable
organic matter (e.g., through biological filtration). A question
remains as to what level AOC needs to be reduced to minimize biological
regrowth.
e. Removal of by-products. Ozonated waters may require GAC
treatment or other biological processes for removal of aldehydes, AOC,
other DBPs. There are concerns that switching to ozone may increase the
availability of AOC and potentially increase bacterial populations in
distribution systems. In addition, some ozone by-products (e.g.,
certain aldehydes and organic peroxides) may be regulated at a future
date when more data become available (USEPA, 1991).
During the 35-utility DBP study performed in 1988-1989, two
utilities switched to ozonation as the primary disinfectant
(Metropolitan Water District of So. Calif et al., 1989 and Jacangelo et
al., 1989). Both utilities applied a secondary disinfectant (chlorine
or chloramines) before the filtration step. At both plants, ozonation
produced formaldehyde and acetaldehyde (aldehydes for which analytical
methodology was being used), the levels of which were undiminished in
passing through the filters and distribution system. Subsequently, a
North American study of 10 utilities that used ozonation at a pilotand
/or full-scale in 1990-1991 (Glaze et al., 1993, in press; and
Weinberg et al., 1993) indicated the following:
<bullet> Aldehydes and aldo-ketones--especially formaldehyde,
glyoxal, and methyl-glyoxal--were ubiquitous ozone DBPs, formed in all
the surveyed utilities.
<bullet> These compounds were removed to varying extents by filters
which were allowed to operate in a biological mode (i.e., secondary
disinfection was postponed until after filtration).
<bullet> In studies where formaldehyde and acetaldehyde were
efficiently removed, glyoxals were sometimes removed to a lesser
extent.
<bullet> These aldehydes were typically best removed at utilities
in which GAC contactors or filters were employed, even when the GAC was
removing little or no TOC.
<bullet> However, GAC filters in this survey were almost always
operated at lower filtration rates (1.0 to 5.0 gpm/sf), whereas
anthracite coal filters were typically operated at higher filtration
rates (3.8 to 13.5 gpm/sf).
<bullet> In addition, secondary disinfection, which was sometimes
applied before the anthracite filters, was never applied before the GAC
filters in this survey.
Because surveys provide a ``snapshot'' of treatment practices in
use, other investigators have performed studies to better assess
individual parameters that impact the efficacy of biological
filtration. Merlet and co-workers (Merlet et al., 1991) evaluated
biological activated carbon (BAC) for the reduction in BDOC produced by
ozonation. As the EBCT of the BAC was varied up to 25 min, BDOC removal
increased up to a point, at which its efficacy plateaued out.
LeChevallier and colleagues (LeChevallier et al., 1992) also observed
that increased EBCTs increased AOC removal; however, AOC levels of <100
<greek-m>g/L could be achieved with a 5- to 10-min EBCT. In addition,
the latter researchers found that the application of free chlorine to
GAC filters did not inhibit AOC removal, whereas the application of
chloramines showed a slight inhibitory effect. Furthermore,
LeChevallier and colleagues found that GAC filter media supported
larger bacterial populations and provided better removal of AOC than
conventional filter media (LeChevallier et al., 1992).
Miltner and co-workers (Miltner et al., 1992) found that biological
activity was established within approximately one week, as evidenced by
90-percent removal of certain aldehydes. However, approximately 80 days
of filter use were required before half of the AOC could be removed.
Price and colleagues (Price et al., 1992) found that dual-media filters
(anthracite coal/sand) performed as well as GAC after time, especially
as the water temperature went up. The latter researchers also observed
that GAC/sand filters operating at 1, 3, and 5 gpm/sf provided similar
removals of AOC. Reckhow and co-workers (Reckhow et al., 1992) found
that GAC/sand filters removed less AOC and aldehydes when backwashed
with chlorinated water. As the filtration rate increased, filters
backwashed with chlorinated water achieved lower removals, whereas
filters backwashed with non-chlorinated waters were less impacted by
filtration rate.
Clearly, many researchers are investigating means of optimizing the
removal of AOC, BDOC, and aldehydes produced by ozonation through
biologically active filtration. Because many plants that are switching
to ozonation are retrofitting existing treatment plants, it is
desirable to achieve biological filtration with the same filters used
for turbidity removal. In pilot-plant testing of ozonation at
Metropolitan Water District of Southern California (Metropolitan Water
District of So. Calif. et al., 1991), dual-media (anthracite/sand)
filters operating at 3 gpm/sf were evaluated, as these were
representative of the operation at some of Metropolitan's full-scale
facilities. When secondary disinfection was delayed until after
filtration, these filters were able to remove AOC, formaldehyde, and
acetaldehyde (Paszko-Kolva et al., 1992 and Metropolitan Water District
of So. Calif. et al., 1991). However, when the aldehyde analysis was
expanded to include glyoxals at the end of the project, limited testing
indicated that glyoxals were not well removed by these filters
(Metropolitan Water District of So. Calif. et al., 1991). In addition,
there were concerns that because some of Metropolitan's facilities
operate with higher filtration rates (up to 9 gpm/sf), this could
impact the biological filtration process.
A new pilot-plant study was initiated to evaluate biological
filtration for the removal of AOC and aldehydes, including the glyoxals
. Analyzing for a wide range of aldehydes (i.e., monoaldehydes, such as
formaldehyde; the dialdehyde glyoxal; and the aldo-ketone methylglyoxal)
allowed for a more thorough investigation into the efficacy of
biological filtration. Not only may these individual carbonyls pose
different health concerns (USEPA, June 1991), but they also have the
potential to represent organic matter which is relatively biodegradable
(i.e., formaldehyde) and which is potentially somewhat recalcitrant to
biological filtration (i.e., the glyoxals).
The latter pilot testing indicated that biological activity was
established sooner on slow-filtration-rate filters with a 4.2-min EBCT,
but the high-filtration-rate filters with 2.1- and 1.4-min EBCTs
eventually were able to achieve comparable capabilities for the removal
of AOC and most aldehydes (Krasner et al., May 1993 and Paszko-Kolva et
al., 1992). However, even 111 days of operation did not allow the
anthracite coal filter operating with a 1.4-min EBCT an opportunity to
demonstrate consistently high removal (80 percent) of the glyoxals. The
latter filter, though, did remove significant amounts of AOC and
formaldehyde. Glyoxals were well removed on the anthracite filter
operated at a low filtration rate (with a 4.2-min EBCT) or the GAC
filters operated at either low or high filtration rates (with 4.2- and
1.4-min EBCTs, respectively). Note that these filters were able to
remove aldehydes and AOC efficiently at relatively short EBCTs and that
the higher EBCTs associated with GAC contactors were not required.
Use of a biological filter can produce a more biologically stable
water and can minimize the presence of aldehydes and other ozone byproducts
(e.g., ketoacids (Xie et al., 1992) and peroxides (Weinberg et
al., 1991)) of potential health and regulatory concern. As the studies
to date demonstrate, the appropriate choice of media and filtration
rate can ensure that AOC and specific organic ozone by-products can be
significantly reduced in concentration.

Chlorine Dioxide Byproducts
Chlorine dioxide is used as an alternative disinfectant to chlorine
to treat drinking water for THM control, taste-and-odor control,
oxidation of iron and manganese, and oxidant-enhanced coagulationsedimentation
(Aieta et al., 1986). In 1977, 103 facilities in the U.S.
were using or had used chlorine dioxide (Symons et al., 1979).
Currently, 500 to 900 municipalities in the U.S. use chlorine dioxide,
although some use was only seasonal (Private communication with
Chemical Manufacturers' Association, 1993). In Europe, several thousand
utilities have used chlorine dioxide, mostly to maintain a disinfectant
residual in the distribution system (Aieta et al., 1986).
Chlorine-free chlorine dioxide does not react with natural organic
matter such as humic and fulvic acids to form THMs (Symons et al.,
1981). Studies show that the TOX formed with chlorine dioxide is from 1
to 25 percent of the TOX formed with chlorine under the same reaction
conditions (Aieta et al., 1986 and Symons et al., 1981). Before the
introduction of high-yield chlorine dioxide systems that were capable
of producing nearly chlorine-free chlorine dioxide solutions,
significant amounts of chlorine could be present in the chlorine
dioxide solutions used in water treatment. Chlorine dioxide has been
used effectively by many utilities in order to comply with the 1979 THM
Rule (Aieta et al., 1986 and Lykins et al., 1986).
However, when chlorine dioxide is used, the inorganic by-products
chlorite and chlorate are produced. During water treatment,
approximately 50-70 percent of the chlorine dioxide reacted will
immediately appear as chlorite and the remainder as chlorate (Aieta et
al., 1984). The residual chlorite continues to degrade in the water
distribution system in reactions with oxidizable material in the
finished water or in the distribution system. In a study of five U.S.
utilities employing chlorine dioxide, median chlorite and chlorate
concentrations in the distribution systems tested typically ranged from
0.4 to 0.8 mg/L and between 0.1 to 0.2 mg/L, respectively (Gallagher et
al., 1993, in press). For the latter systems, the 75th percentiles for
chlorite concentrations ranged from 0.4 to 1.4 mg/L.
Data for up to 17 utilities in EPA Region 6 who employ chlorine
dioxide were obtained (Personal communication, Novatek 1993). In many
instances, data for chlorite occurrence on a monthly basis were
available. As an example, for June 1992 chlorite ranged from 0.4 to 1.2
mg/L, while in January 1993 chlorite was at values of 0.2 to 0.8 mg/L.
The higher values in June may have been due, in part, to the need for
more chlorine dioxide in warmer months to meet the oxidant demand of
the water. When the data are examined quarterly (e.g., quarter 1 is
January through March), Figure VI-14 shows that the highest occurrence
for chlorite in the systems sampled in EPA Region 6 was during the
spring and summer seasons.

BILLING CODE 6560-50-P

<GRAPHIC><TIF22>TP29JY94.024

BILLING CODE 6560-50-C
a. Potential chlorine dioxide DBPs not regulated at this time. This
proposed regulation will not include an MCLG or MCL for chlorate.
Insufficient data exist at this time to develop an MCLG for chlorate
(Orme-Zavaleta, 1992). If chlorate is regulated in the future, systems
which use hypochlorination will also need to monitor for this byproduct
(Bolyard et al., August 1992). Limited testing shows that
chlorine dioxide can form low concentrations of aldehydes (Weinberg et
al., 1993). However, studies also demonstrate that chlorine can produce
aldehydes (Krasner et al., August 1989 and Jacangelo et al., 1989).
3. Chloramination Byproducts
a. Cyanogen chloride. Typically, chloramines do not react to form
significant levels of THMs and other chlorinated DBPs. Because
monochloramine (the predominant form of chloramines in most drinkingwater
applications) is a much less potent oxidant or chlorinating agent
than chlorine, the by-products of monochloramine reactions with organic
substances are much less extensively oxidized or chlorinated (Scully,
1990). Nevertheless, chloramines appear to chlorinate natural organic
matter sufficient to produce low levels of TOX.
During the 35-utility DBP study, 14 of the 35 utilities surveyed
were utilizing chloramines (Krasner et al., 1989). Ten of these had
free-chlorine contact time prior to ammonia addition, and the remaining
four added chlorine and ammonia concurrently. The median value of
cyanogen chloride in utilities that used only free chlorine was 0.4
<greek-m>g/L. Utilities that pre-chlorinated and postammoniated had a
cyanogen chloride median of 2.2 <greek-m>g/L. The 95-percent confidence
intervals around the medians indicated that these two disinfection
schemes were statistically different with regard to the cyanogen
chloride levels detected in the clearwell effluents. Krasner and coworkers
found that a number of parameters affect the formation of
cyanogen chloride during chloramination (Krasner et al., 1991).
b. Potential other chloramination DBPs not regulated at this time.
Studies have demonstrated the formation of organochloramines by the use
of inorganic chloramines in the disinfection of water (Scully, 1982).
Recently, an analytical method has been developed to distinguish
organic chloramines from the inorganic species (Jersy et al., 1991).
Monochloramine has been shown to react with aldehydes to yield nitriles
(Le Cloirec et al., 1985). The presence of cyanogen chloride and low
concentrations of TOX in chloraminated waters indicate a need to
further identify chloramine by-products.

VII. General Basis for Criteria of Proposed Rule

A. Goals of Regulatory Negotiation

In the Federal Register ``Notice of Intent to Form an Advisory
Commitee to Negotiate the Disinfection Byproducts Rule and Announcement
of Public Meeting'' (USEPA, 1992), EPA identified key issues to be
addressed and resolved during the conduct of the negotiation. They
were:

--What disinfectants and disinfection byproducts present the greatest
risks, and how should they be grouped for regulation?
--Which categories of public water suppliers should be regulated?
--Should the regulation establish Maximum Contaminant Levels or be
technology driven?
--How effective are advanced technologies and alternative disinfectants
in the removal of disinfectants, disinfection byproducts, and microbial
risks?
--How should disinfectants, disinfection byproducts, and microbial
risks be compared, given differences in the type and certainty of their
effects?
--What levels of disinfectant, disinfection byproduct, and microbial
risks are acceptable, and at what cost?
--How should the achievement of acceptable levels of risks be defined?
--How might risk-risk models be used, if at all, in the development of
Maximum Contaminant levels within the current regulatory schedule?
--How should the needs of sensitive populations be taken into account
in the rule?
--How should Best Available Technology be defined for the removal of
disinfectants and disinfection byproducts?
--Should a comprehensive disinfectant/disinfection byproduct regulation
be issued in 1995, or should the control of certain disinfectants/
disinfection byproducts be deferred until research confirms the safety
of alternative treatment methods?
--How should affordability be factored into judgements regarding
feasibility of treatment techniques?
--How should monitoring requirements be defined?
--How can the rule be drafted to be most easily understood by both
State regulators and small system operators?

In addition to the issues identified in the Federal Register that
needed to be resolved, potential negotiating committee members
identified the following additional issues (RESOLVE, 1992a):

--How can the rule be drafted to be most easily accepted and
understandable by the general public?
--Is there a need for further regulation of DBPs?
--How should the rule account for differences in size of a system
(i.e., number of people served) or a system's water source?
--How should the rule account for differences in type of disinfection
technology and quality of source water?
--How should the rule account for the particular characteristics of
some water distribution systems that complicate efforts to minimize DBP
formation?
--How should the rule account for the cross-media environmental impacts
and ecological risks associated with DBP control technologies?
--Will the DBP rule be compatible with other EPA regulations (e.g.,
groundwater, lead, surface water)? Will current exposure and occurrence
data change with implementation of other rules? Are EPA's models good
enough to predict the effects of other regulations on the occurrence of
various DBPs in drinking water?
--To what extent are watershed protection and maintenance of source
water quality useful strategies to achieve risk reduction?
--How should analytic methods be defined? Should DBP content be
monitored at the treatment plant, within the distribution system, or at
the tap?
--How much has already been achieved by the THM rule? How can this be
taken into account in the assumptions for this rule?
--What types of research on DBP effects and controls are presently
being or should be conducted in the future?
--What are the assumptions that underlie EPA's description of
acceptable risk from exposure to microbes and DBPs in drinking water?
Is there a safe level for human exposure to DBPs? How certain are EPA's
models? Should EPA's cancer risk assessment policies be reopened in
this forum?
--How can the rule be most easily implemented?

B. Concerns for Downside Microbial Risks and Unknown Risks From DBPs of
Different Technologies

This rule is intended to limit concentrations of disinfectants and
their byproducts in public water systems. However, there is the
possibility that reducing the level of disinfection without adequately
addressing microbial risk may result in increasing microbial exposure.
The Negotiating Committee wanted to ensure that drinking water
utilities can effectively provide treatment that controls both
disinfectants and their byproducts and microbial contaminants. The
Negotiating Committee believes it accomplished this goal by developing
an additional proposed rule (Enhanced Surface Water Treatment Rule,
proposed elsewhere in today's Federal Register) to control the level of
microbial risk.
If disinfection is decreased to reduce byproduct formation, there
is the possibility that risk from pathogenic organisms could increase.
This relationship is not well understood, particularly as it applies to
the many different source waters and the various disinfectants that may
be used. To better understand and characterize this risk-risk
relationship, EPA proposed an Information Collection Rule [59 FR 6332]
to gather needed information.
In addition to concerns about increasing microbial risk, the
Negotiating Committee had concerns about large numbers of systems
switching from chlorine to an alternative disinfectant (e.g., ozone,
chlorine dioxide, chloramines) whose disinfection efficacy and
byproducts (both occurrence and health effects) are not as well
understood as those of chlorine. Chlorine has been studied far more
than the alternative disinfectants; this additional study may account
for some or all of the differences in known health risks. Chlorine has
proved to be an effective disinfectant under a wide range of
conditions. For conditions where chlorine was not adequate as a
disinfectant (e.g., high TTHM formation potential or high pH), systems
have changed to other disinfectants. However, the Committee does not
want to force large numbers of additional systems to switch
disinfectants before more information is available, since research has
indicated that health risks from alternative disinfectants may be
significant (e.g., bromate formation from ozonation).

C. Ecological Concerns

In addition to concerns about risk-risk tradeoffs and risks from
alternative disinfectants, the Technologies Working Group (TWG)
identified ecological risks that could result from a change in
technology. These concerns included:

--Moving the point of chlorination may result in problems with zebra
mussel infestation in the intake pipe.
--Increasing addition of coagulants may result in increased sludge
production and attendent disposal problems.
--Changing to ozone may require large amounts of additional energy
(electricity) for ozone generation.
--Adding GAC makes construction of on- or off-site GAC regeneration
facilities necessary.
--Adding membranes may require large amounts of additional energy
(electricity) for pressure, may cause problems in disposing of brine in
some areas, and may not be feasible in water-short areas.

D. Watershed Protection

One issue that the Negotiating Committee considered throughout the
negotiation process was the relationship and role of watershed
protection to these proposed regulations. The Committee desired to
promote watershed protection and to provide incentives to establish new
watershed protection programs and to improve existing ones. These
desires were prompted by the benefits that watershed protection
provides not only for disinfectant byproduct control, but for a wide
range of potential drinking water contaminants and related water supply
and environmental issues.
Watershed protection reduces microbial contamination in water
sources, and hence the amount of disinfectant needed to reduce
microbial risk to a specified level in a finished water supply. It also
reduces the level of turbidity, pesticides, volatile organic compounds,
and other synthetic organic drinking water contaminants found in some
water sources. Precursor (material that reacts with disinfectants to
form disinfection byproducts) levels can be lowered, which may lower
the levels of DBPs formed. Watershed protection results in economic
benefits for water supply systems by minimizing reservoir sedimentation
and eutrophication and reducing water treatment operation and
maintenance costs. Moreover, adequate watershed protection in many
cases will reduce overall organic matter (TOC) in source water and
therefore reduce DBP formation. Watershed protection also provides
other environmental benefits through improvements in fisheries and
ecosystem protection.
The types of watershed programs that the Committee wished to
encourage are those that consider agricultural controls, silvicultural
controls, urban non-point controls, point discharge controls, and land
use protections which are tailored to the environmental and human
characteristics of the individual watershed. These characteristics
include the hydrology and geology of the watershed, the nature of human
sources of contaminants, and the legal, financial and political
constraints surrounding entities which have control of aspects of the
watershed.
The Committee considered options for providing incentives for
watershed protection programs directly within these proposed
regulations through such things as reduced monitoring or reduced
requirements based on the existence of a watershed program. However,
unlike other potential contaminants whose introduction can be directly
prevented by watershed protection, disinfectant byproducts do not
directly enter the water source, but are formed in the water treatment
process.
Because of general agreement that watershed protection had
qualitative benefits, the Committee agreed that watershed protection
was desirable and included several indirect incentives for watershed
protection within these proposed regulations. The TOC levels which
trigger enhanced coagulation requirements under the proposed
Disinfectant Byproducts Rule and which trigger pilot studies under the
proposed Information Collection Rule are those that are typically
achieved in water supplies with protected watersheds. Systems which
meet the source water criteria for unfiltered systems under the Surface
Water Treatment Rule do not have to conduct virus monitoring under the
proposed Information Collection Rule [59 FR 6332], whether the system
is filtered or unfiltered. These systems are likely to have watershed
protection programs. The proposed Enhanced Surface Water Treatment Rule
(proposed elsewhere in today's FR) contains proposed options which
require less water treatment for water sources with lower levels of
microbial contamination. Such sources can achieve those levels through
watershed protection programs. The Negotiating Committee believes that
these indirect incentives will result in enhancements to watershed
protection efforts in many systems.

E. Narrowing of Regulatory Options Through Reg-Neg Process

The Negotiating Committee considered a wide range of regulatory
options during the development process. The initial approach was to
come up with several straw regulation outlines. These could generally
be classified as being either (1) MCL regulations (in which compliance
would be determined by meeting MCLs for specified disinfectants and
DBPs) or (2) treatment technique regulations (in which compliance would
be determined by meeting specified treatment parameters or surrogate
compound maximum levels).
The Negotiating Committee considered two categories of MCL options.
The first was MCLs for groups of related DBPs, such as TTHMs and HAA5.
Advantages of this approach included regulatory simplicity, avoidance
of tinkering with disinfection operations to address minor exceedances
of MCLs of individual DBPs, and the complex, not-well-understood
production relationships among related DBPs. MCLs for individual
compounds were also considered. Some members of the Negotiating
Committee felt that individual MCLs approach best met the intent of the
SDWA by regulating specific, measurable chemicals.
The Negotiating Committee also considered treatment technique
options. The first would have required systems to reduce the levels of
DBP precursors (DBPP)--compounds that react with disinfectants to form
DBPs, such as total organic carbon--to less than some specified level
before adding any disinfectant. This approach may be inappropriate for
two reasons. First, systems have different levels and types of
precursors; using a surrogate such as TOC as a trigger may result in
tremendous variation in DBP levels from system to system due to the
disinfectant used, composition and reactivity of the DBPP, and presence
of other DBPPs such as bromide. Also, many systems must add a
disinfectant as an oxidant immediately at the source water intake to
control water quality problems (e.g., zebra mussels, iron).
The second treatment technique option was enhanced coagulation,
which is the addition of higher levels of coagulant than required to
meet turbidity limits for the purpose of removing higher levels of
DBPPs. However, enhanced coagulation is practical only in systems that
operate conventional filtration treatment. Systems using other
filtration technologies (e.g., direct filtration, slow sand filtration)
or that do not filter (such as most ground water systems) cannot
operate enhanced coagulation without addition of conventional
filtration treatment. Also, some systems have water that cannot be
effectively treated by enhanced coagulation.
A final option considered was a ``risk bubble''. Under this option,
systems would be required to keep the sum of estimated risks from
levels of specified DBPs under a certain risk level. However, this
option was quickly dropped because of many problems, including failure
to account for potential synergisms and antagonisms between DBPs, data
gaps, and the evolving nature of risk assessment.

VIII. Summary of the Proposed National Primary Drinking Water
Regulation for Disinfectants and Disinfection Byproducts

The Disinfectants and Disinfection Byproducts Rule (D/DBPR)
proposal addresses a number of complex and interrelated drinking water
issues. EPA must balance the health risks from microbial organisms
(such as Giardia, Cryptosporydium, bacteria, and viruses) against risks
from compounds formed during water disinfection. Most of the DBPs that
have been measured in drinking water are byproducts from the use of
chlorine. While there is some occurrence information on even these
DBPs, the extent of exposure for systems that have not reported DBP
levels can only be estimated using available information on TOC levels
and the available models. A subset of DBPs has been studied to
determine whether long-term exposure to them presents a risk to public
health. The current lack of data on certain relatively unstudied DBPs
and on the effectiveness of certain treatment techniques has made
regulatory decisions more difficult. Water treatment facilities and
their customers potentially face significant changes to treatment
operations in response to the proposed regulations and will have to pay
more for water treatment. For these reasons, EPA is proposing the D/
DBPR in two stages. The two-stage process allows the best use of
information available during the regulatory development.
The Stage 1 D/DBPR, which will be proposed, promulgated, and
implemented concurrently with the Interim Enhanced Surface Water
Treatment Rule, will:

--Lower the maximum contaminant level (MCL) for total trihalomethanes
(the only DBPs currently regulated);
--Add new disinfectants and DBPs for regulation; and
--Extend regulations to include all system sizes.

For the Stage 2 D/DBPR, EPA will collect data on parameters that
influence DBP formation and occurrence of DBPs in drinking water
through an Information Collection Rule for large community water
systems (59 FR 6332). Based on this information and new data generated
through research, EPA will reevaluate the Stage 2 regulations and
repropose, as appropriate, depending on criteria agreed on in a second
regulatory negotiation (or similar rule development process). In
addition, Stage 2 D/DBPR MCLs for TTHMs and HAA5 are being proposed in
this Federal Register notice.

A. Schedule and Coverage

The requirements of this rule will apply to community water systems
(CWSs) and nontransient noncommunity water systems (NTNCWSs) that treat
their water with a chemical disinfectant for either primary or residual
treatment. In addition, MRDL and monitoring requirements for chlorine
dioxide will also apply to transient noncommunity water systems because
of the short-term health effects from high levels of chlorine dioxide
(see section V. for a detailed discussion of health effects).
The effective dates for compliance with these requirements will be
staggered based on system size and raw water source. The schedule is
summarized in Table VIII-1. Members of the Negotiating Commitee
reserved the right to comment on the timetable for promulgation of the
final rule and on the compliance dates of the rule.

--Subpart H systems (systems that use surface water or ground water
under the direct influence of surface water, in whole or in part)
serving 10,000 or more persons must comply with the Stage 1
requirements beginning 18 months from promulgation.
--Subpart H systems serving fewer than 10,000 persons must comply with
the Stage 1 requirements beginning 42 months from promulgation.
--A CWS or NTNCWS using only ground water not under the direct
influence of surface water serving 10,000 or more persons must comply
with the Stage 1 requirements beginning 42 months from promulgation.
--A CWS or NTNCWS using only ground water not under the direct
influence of surface water serving fewer than 10,000 persons must
comply with the Stage 1 requirements beginning 60 months from
promulgation.

Table VIII-1.--Compliance Date of Stage 1 Regulations for CWSs or

NTNCWSs

Following
Number of promulgation,

Raw water source people regulations

served become effective
after

Surface................................. <gr-thn-eq>
10,000 18 Months.

Surface................................. <10,000 42 Months.

Ground.................................. <gr-thn-eq>
10,000 42 Months.

Ground.................................. <10,000 60 Months.

In this proposal, EPA has not specified how monitoring and
compliance requirements should be split among wholesalers and retailers
of water. The Agency believes that Sec. 141.29 (consecutive systems)
provides the State adequate flexibility and authority to address
individual situations. EPA solicits comment on whether any specific
federal regulatory requirements are necessary to handle such
situations. If so, what are they?

B. Summary of DBP MCLs, BATs, and Monitoring and Compliance
Requirements

EPA is proposing to amend Subpart G, Maximum Contaminant Levels, by
adding Sec. 141.64, Maximum Contaminant Levels for Disinfection
Byproducts. Section 141.64 lists the proposed MCLs for total
trihalomethanes (TTHMs--i.e., the sum of the concentrations of
chloroform, bromodichloromethane, dibromochloromethane, and bromoform),
haloacetic acids (five) (HAA5--i.e., the sum of the concentrations of
mono-, di-, and trichloroacetic acids and mono- and dibromoacetic
acids), bromate, and chlorite. Routine monitoring requirements for all
DBPs and residual disinfectants are summarized in Table VIII-2. Reduced
monitoring requirements for all DBPs and residual disinfectants are
summarized in Table VIII-3. Members of the Negotiating Committee
reserved the right to comment on the question of whether compliance
monitoring is defined as an average of several samples across the
distribution system and over time or whether it will be based upon
monitoring at points of maximum residence time. See Section IX of this
notice for further discussion and EPA's solicitation of comments on
this issue.

Table VIII-2.--Routine Monitoring Requirements\7\

Requirement Location for Large surface Small surface Large ground Small ground
(reference) sampling systems\1\ systems\1\ water systems\2\ water systems\2\

TOC Paired 1 paired sample/ 1 paired sample/ NA............... NA.

(141.133(b)(3)). samples\3\--Only month/ plant\3\. month/plant\3\.
required for
plants with
conventional
filtration
treatment.

TTHMs 25% in dist sys 4/plant/ quarter. 1/plant/quarter\6 1/plant/quarter\6 1/plant/year6,8

(141.133(b)(1)(i at max res time, \ at maximum \ at maximum at maximum
)). 75% at dist sys residence time residence time. residence time
representative if pop. <500, during warmest
locations. then 1/plant/ month.
yr\8\.

THAAs 25% in dist sys 4/plant/ quarter. 1/plant/quarter\6 1/plant/quarter\6 1/plant/year6,8

Bromate\4\ Dist sys entrance 1/month/trt plant 1/month/trt plant 1/month/trt plant 1/month/trt plant
(141.133(b)(1)(i point. using O<INF>3. using O<INF>3. using O<INF>3. using O<INF>3.

ii)).

Chlorite\5\ 1 near first 3/month.......... 3/month.......... 3/month.......... 3/month.

(141.133(b)(1)(i cust, 1 in dist
i)). sys middle, 1 at
max res time.

Chlorine Same points as Same times as Same times as Same times as Same times as
(141.133(b)(2)(i coliform in TCR. coliform in TCR. coliform in TCR. coliform in TCR. coliform in TCR.

)).

Chlorine Entrance to dist Daily/trt plant Daily/trt plant Daily/trt plant Daily/trt plant
dioxide\5\ sys. using ClO<INF>2. using ClO<INF>2. using ClO<INF>2. using ClO<INF>2.

(141.133(b)(2)(i
i)).

Chloramines Same points as Same times as Same times as Same times as Same times as
(141.133(b)(2)(i coliform in TCR. coliform in TCR. coliform in TCR. coliform in TCR. coliform in TCR.

)).

\1\Large surface (Subpart H) systems serve 10,000 or more persons. Small surface (Subpart H) systems serving

fewer than 10,000 persons.

\2\Large systems using ground water not under the direct influence of surface water serve 10,000 or more
persons. Small systems using ground water not under the direct influence of surface water serve fewer than

10,000 persons.

\3\Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1)
source water TOC prior to any treatment and 2) treated TOC before continuous disinfection (except that systems
using ozone followed by biological filtration may sample after biological filtration) at the same time; these

two samples are called paired samples.
\4\Only required for systems using ozone for oxidation or disinfection.

\5\Only required for systems using chlorine dioxide for oxidation or disinfection. Additional chlorine dioxide

monitoring requirements apply if any chlorine dioxide sample exceeds the MRDL.

\6\Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment

plant for determining the minimum number of samples.

\7\Samples must be taken during representative operating conditions. Provisions for reduced monitoring shown

elsewhere.

\8\If the annual monitoring result exceeds the MCL, the system must increase monitoring frequency to 1/plant/
quarter. Compliance determinations will be based on the running annual average of quarterly monitoring

results.

Table VIII-3.--Reduced Monitoring Requirements\2\

Location for reduced sampling
Requirement (reference) Reduced monitoring frequency and prerequisites\1\

TOC (141.133(c)(3))........... Paired samples\3\............ Subpart H systems-reduced to 1 paired sample/

plant/quarter if 1) avg TOC <2.0mg/l for 2 years
or 2) avg TOC <1.0mg/l for 1 year.

TTHMs and THAAs In dist sys at point with max Monitoring cannot be reduced if source water TOC

(141.133(c)(1)). res time. >4.0mg/l.
Subpart H systems serving 10,000 or more-reduced
to 1/plant/qtr if 1) system has completed at
least 1 yr of routine monitoring and 2) both
TTHM and THAA running annual averages are no
more than 40 <greek-m>g/l and 30 <greek-m>g/l,
respectively.
Subpart H systems serving <10,000 and ground
water systems\6\ serving 10,000 or more-reduced
to 1/plant/yr if 1) system has completed at
least 1 yr of routine monitoring and 2) both
TTHM and THAA running annual averages are no
more than 40 <greek-m>g/l and 30 <greek-m>g/l,
respectively. Samples must be taken during month
of warmest water temperature. Subpart H systems
serving <500 may not reduce monitoring to less
than 1/plant/yr.
Groundwater systems\6\ serving <10,000-reduced to
1/plant/3yr if 1) system has completed at least
2 yr of routine monitoring and both TTHM and
THAA running annual averages are no more than 40
<greek-m>g/l and 30 <greek-m>g/l, respectively
or 2) system has completed at least 1 yr of
routine monitoring and both TTHM and THAA annual
samples are no more than 20 <greek-m>g/l and 15
<greek-m>g/l, respectively. Samples must be
taken during month of warmest water temperature.

Bromate\4\ (141.133(c)(1)).... Dist sys entrance point...... 1/qtr/trt plant using O<INF>3, if system demonstrates

avg raw water bromide <0.05 mg/l (based on
annual avg of monthly samples).
Chlorite\5\ (141.133(c)(1))... NA........................... Monitoring may not be reduced.
Chlorine, chlorine dioxide\5\, NA........................... Monitoring may not be reduced.
chloramines (141.133(c)(2)).

\1\Requirements for cancellation of reduced monitoring are found in the regulation.
\2\Samples must be taken during representative operating conditions. Provisions for routine monitoring shown
elsewhere.
\3\Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1)
source water TOC prior to any treatment and 2) treated TOC before continuous disinfection (except that systems
using ozone followed by biological filtration may sample after biological filtration) at the same time; these
two samples are called paired samples.
\4\Only required for systems using ozone for oxidation or disinfection.
\5\Only required for systems using chlorine dioxide for oxidation or disinfection.
\6\Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment
plant for determining the minimum number of samples.

Maximum Contaminant Levels for Total Trihalomethanes and Total
Haloacetic Acids
The formation rate of DBPs is affected by type and amount of
disinfectant used, water temperature, pH, amount and type of precursor
material in the water, and the length of time that water remains in the
treatment and distribution systems. For this reason, the proposed rule
specifies the point in the distribution system (and in some cases, the
time) where samples must be taken.
In this action today, EPA proposes to lower the MCL for TTHMs from
0.10 mg/l to 0.080 mg/l. In addition, EPA proposes to set the Stage 1
MCL for HAA5 at 0.060 mg/l. EPA believes that by meeting MCLs for TTHMs
and HAA5, water suppliers will also control the formation of other DBPs
not currently regulated that may also adversely affect human health.
a. Subpart H Systems Serving 10,000 or More People.
Routine Monitoring: CWSs and NTNCWSs using surface water (or ground
water under direct influence of surface water) (Subpart H systems) that
treat their water with a chemical disinfectant and serve 10,000 or more
people must routinely take four water samples each quarter for both
TTHMs and HAA5 for each treatment plant in the system. At least 25
percent of the samples must be taken at the point of maximum residence
time in the distribution system. The remaining samples must be taken at
representative points in the distribution system. This monitoring
frequency is the same as the frequency required under the current TTHM
rule (Sec. 141.30).
Reduced Monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Figure VIII-1). Systems eligible for
reduced monitoring may reduce the monitoring frequency for TTHMs and
HAA5 to one sample per quarter. Systems on a reduced monitoring
schedule may remain on that reduced schedule as long as the average of
all samples taken in the year is no more than 75 percent of each MCL.
Systems that do not meet these levels revert to routine monitoring.
Compliance Determination: A public water system (PWS) is in
compliance with the MCL when the running annual average of quarterly
averages of all samples, computed quarterly, is less than or equal to
the MCL. If the running annual average computed for any quarter exceeds
the MCL, the system is out of compliance.

Figure VIII-1.--Eligibility for Reduced Monitoring: All Systems Serving
10,000 or More People and Surface Water Systems Serving 500 or More

People

All systems serving
10,000 or more
people, and
surface water
systems serving
500 or more
people, may reduce
monitoring of
TTHMs and HAA5 if
they meet all of
the following
conditions:
--The annual
average for
TTHMs is no more
than 0.040 mg/l.
--The annual
average for HAA5
is no more than
0.030 mg/l.
--At least one
year of routine
monitoring has
been completed.
--Annual average
source water
Total Organic
Carbon (TOC)
level is no more
than 4.0 mg/l
prior to
treatment.

b. Ground Water Systems Serving 10,000 or More People.
Routine Monitoring: CWSs and NTNCWSs using only ground water
sources not under the direct influence of surface water that treat
their water with a chemical disinfectant and serve 10,000 or more
people are required to take one water sample each quarter for each
treatment plant in the system. Samples must be taken at points that
represent the maximum residence time in the distribution system. For
purposes of this regulation, multiple wells drawing raw water from a
single aquifer may, with State approval, be considered one plant for
determining the minimum number of samples. Systems may take additional
samples if they desire. If additional samples are taken, at least 25
percent of the total number of samples must be taken at the point of
maximum residence time in the distribution system. The remaining
samples must be taken at representative points in the distribution
system.
Reduced Monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Figure VIII-1). Systems eligible for
reduced monitoring may reduce the monitoring frequency to one sample
per treatment plant per year. Systems that are on a reduced monitoring
schedule may remain on that reduced schedule as long as the average of
all samples taken in the year is no more than 75 percent of the MCLs.
Systems that do not meet these levels must revert to routine
monitoring.
Compliance Determination: A PWS is in compliance with the MCL when
the running annual average of quarterly averages of all samples,
computed quarterly, is less than or equal to the MCL. If the running
annual average for any quarter exceeds the MCL, the system is out of
compliance.
c. Subpart H Systems Serving 500 to 9,999 People.
Routine Monitoring: Systems are required to take one water sample
each quarter for each treatment plant in the system. All samples must
be taken at the point of maximum residence time in the distribution
system.
Reduced Monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Figure VIII-1). Systems eligible for
reduced monitoring may reduce the monitoring frequency for TTHMs and
HAA5 to one sample per year per treatment plant. Systems that are on a
reduced monitoring schedule may remain on that reduced schedule as long
as the average of all samples taken in the year is no more than 75
percent of the MCLs. Systems that do not meet these levels must revert
to routine monitoring.
Compliance Determination: A PWS is in compliance with the MCL when
the running annual average of quarterly averages of all samples,
computed quarterly, is less than or equal to the MCL. If the average
for any quarter exceeds the MCL, the system is out of compliance.
d. Subpart H Systems Serving Fewer than 500 People.
Routine Monitoring: Subpart H systems serving fewer than 500 people
are required to take one sample per year for each treatment plant in
the system. The sample must be taken at the point of maximum residence
time in the distribution system during the month of warmest water
temperature. If the annual sample exceeds the MCL, the system must
increase monitoring to one sample per treatment plant per quarter,
taken at the point of maximum residence time in the distribution
system.
Reduced Monitoring: These systems may not reduce monitoring.
Systems on increased monitoring may return to routine monitoring if the
annual average of quarterly samples is no more than 75 percent of the
TTHM and HAA5 MCLs.
Compliance Determination: A PWS is in compliance when the annual
sample (or average of annual samples, if additional sampling is
conducted) is less than or equal to the MCL. If the annual sample
exceeds the MCL, the system must increase monitoring to one sample per
treatment plant per quarter. If the running annual average of the
quarterly samples then exceeds the MCL, the system is out of
compliance.
e. Ground Water Systems Serving Fewer than 10,000 People.
Routine Monitoring: CWSs and NTNCWSs using only ground water
sources not under the direct influence of surface water that treat
their water with a chemical disinfectant and serve fewer than 10,000
people are required to sample once per year for each treatment plant in
the system. The sample must be taken at the point of maximum residence
time in the distribution system during the month of warmest water
temperature. If the sample (or the average of all annual samples, when
more than the one required sample is taken) exceeds the MCL, the system
must increase monitoring to one sample per treatment plant per quarter.
Reduced Monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Figure VIII-2). Systems eligible for
reduced monitoring may reduce the monitoring frequency for TTHMs and
HAA5 to one sample per three-year monitoring cycle. Systems on a
reduced monitoring schedule may remain on that reduced schedule as long
as the average of all samples taken in the year is no more than 75
percent of the MCLs. Systems that do not meet these levels must resume
routine monitoring. Systems on increased monitoring may return to
routine monitoring if the annual average of quarterly samples is no
more than 75 percent of the TTHM and HAA5 MCLs.

Figure VIII-2.--Eligibility for Reduced Monitoring: Ground Water Systems

Serving Fewer than 10,000 People

Systems using
ground water not
under the direct
influence of
surface water that
serve fewer than
10,000 people may
reduce monitoring
for TTHMs and HAA5
if they meet
either of the
following
conditions:
1. The average of
two consecutive
annual samples
for TTHMs is no
more than 0.040
mg/l, the
average of two
consecutive
annual samples
for HAA5 is no
more than 0.030
mg/l, at least
two years of
routine
monitoring has
been completed,
and the annual
average source
water Total
Organic Carbon
(TOC) level is
no more than 4.0
mg/l prior to
treatment.
2. The annual
sample for TTHMs
is no more than
0.020 mg/l, the
annual sample
for HAA5 is no
more than 0.015
mg/l, at least
one year of
routine
monitoring has
been completed,
and the annual
average source
water Total
Organic Carbon
(TOC) level is
no more than 4.0
mg/l prior to
treatment.

Compliance Determination: A PWS is in compliance when the annual
sample (or average of annual samples) is less than or equal to the MCL.
f. Best Available Technology.
EPA has identified the best technology available for achieving
compliance with the MCLs for both TTHMs and HAA5 as enhanced
coagulation or treatment with granular activated carbon with a ten
minute empty bed contact time and 180 day reactivation frequency
(GAC10), with chlorine as the primary and residual disinfectant.
Enhanced coagulation means the addition of excess coagulant for
improved removal of disinfection byproduct precursors by conventional
filtration treatment.
2. Maximum Contaminant Level for Bromate
Bromate is one of the principal byproducts of ozonation in bromidecontaining
source waters. The proposed MCL for bromate is 0.010 mg/l.
Routine Monitoring: CWSs and NTNCWSs using ozone, for disinfection
or oxidation, are required to take at least one sample per month for
each treatment plant in the system using ozone. The sample must be
taken at the entrance to the distribution system when the ozonation
system is operating under normal conditions.
Reduced Monitoring: If a system's monthly measurements for one year
indicate that the average raw water bromide concentration is less than
0.05 mg/l, the system may reduce the monitoring frequency to once per
quarter.
Compliance Determination: A PWS is in compliance if the running
annual average of samples, computed quarterly, is less than or equal to
the MCL.
Best Available Technology: EPA has identified the best technology
available for achieving compliance with the MCL for bromate as control
of ozone treatment process to reduce production of bromate.
3. Maximum Contaminant Level for Chlorite
Chlorite is an inorganic DBP formed when drinking water is treated
with chlorine dioxide. The proposed MCL for chlorite is 1.0 mg/l.
Routine Monitoring: CWSs and NTNCWSs using chlorine dioxide for
disinfection or oxidation are required to take three samples each month
in the distribution system. One sample must be taken at each of the
following locations: as close as possible to the first customer, in a
location representative of average residence time, and as close as
possible to the end of the distribution system (reflecting maximum
residence time in the distribution system).
Reduced monitoring: Systems required to monitor for chlorite may
not reduce monitoring.
Compliance Determination: A PWS is in compliance if the monthly
average of samples is less than or equal to the MCL.
Best Available Technology: EPA has identified as the best means
available for achieving compliance with the chlorite MCL as control of
treatment processes to reduce disinfectant demand, and control of
disinfection treatment processes to reduce disinfectant levels.

C. Summary of Disinfectant MRDLs, BATs, and Monitoring and Compliance
Requirements

Disinfectants are added during water treatment to control
waterborne microbial contaminants. Some residual disinfectants will
remain in water after treatment. MRDLs protect public health by setting
limits on the level of residual disinfectants in drinking water. MRDLs
are similar in concept to MCLs--MCLs set limits on contaminants and
MRDLs set limits on residual disinfectants. MRDLs, like MCLs, are
enforceable.

MRDL for Chlorine
Chlorine is a widely used and highly effective water disinfectant.
The proposed MRDL for chlorine is 4.0 mg/l.
Routine Monitoring: As a minimum, CWSs and NTNCWSs must measure the
residual disinfectant level at the same points in the distribution
system and at the same time as total coliforms, as specified in
Sec. 141.21. Subpart H systems may use the results of residual
disinfectant concentration sampling done under the SWTR
(Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3) for
systems that filter) in lieu of taking separate samples.
Reduced monitoring: Monitoring for chlorine may not be reduced.
Compliance Determination: A PWS is in compliance with the MRDL when
the running annual average of monthly averages of all samples, computed
quarterly, is less than or equal to the MRDL. Notwithstanding the MRDL,
operators may increase residual chlorine levels in the distribution
system to a level and for a time necessary to protect public health to
address specific microbiological contamination problems (e.g.,
including distribution line breaks, storm runoff events, source water
contamination, or cross-connections).
Best Available Technology: EPA has identified the best means
available for achieving compliance with the MRDL for chlorine as
control of treatment processes to reduce disinfectant demand, and
control of disinfection treatment processes to reduce disinfectant
levels.
MRDL for Chloramines
Chloramines are formed when ammonia is added during chlorination.
The proposed MRDL for chloramines is 4.0 mg/l (as total chlorine).
Routine Monitoring: As a minimum, CWSs and NTNCWSs must measure the
residual disinfectant level at the same points in the distribution
system and at the same time as total coliforms, as specified in
Sec. 141.21. Subpart H systems may use the results of residual
disinfectant concentration sampling done under the SWTR
(Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3) for
systems that filter) in lieu of taking separate samples.
Reduced monitoring: Monitoring for chloramines may not be reduced.
Compliance Determination: A PWS is in compliance with the MRDL when
the running annual average of monthly averages of all samples, computed
quarterly, is less than or equal to the MRDL. Notwithstanding the MRDL,
operators may increase residual chloramine levels in the distribution
system to a level and for a time necessary to protect public health to
address specific microbiological contamination problems (e.g.,
including distribution line breaks, storm runoff events, source water
contamination, or cross-connections).
Compliance Determination: A PWS is in compliance with the MRDL when
the running annual average of samples, computed quarterly, is less than
or equal to the MRDL. EPA recognizes that it may be appropriate to
increase residual disinfectant levels in the distribution system of
chloramines significantly above the MRDL for short periods of time to
address specific microbiological contamination problems (e.g.,
distribution line breaks, storm runoff events, source water
contamination, or cross-connections).
Best Available Technology: EPA identifies the best means available
for achieving compliance with the MRDL for chloramines as control of
treatment processes to reduce disinfectant demand, and control of
disinfection treatment processes to reduce disinfectant levels.
MRDL for Chlorine Dioxide
Chlorine dioxide is used primarily for the oxidation of taste and
odor-causing organic compounds in water. It can also be used for the
oxidation of reduced iron and manganese and color, and is also a
powerful disinfectant and algicide. Chlorine dioxide reacts with
impurities in water very rapidly, and is dissipated very quickly. EPA
is proposing an MRDL of 0.80 mg/l for chlorine dioxide.
Routine Monitoring: CWSs and noncommunity systems must monitor for
chlorine dioxide only if chlorine dioxide is used by the system for
disinfection or oxidation. If monitoring is required, systems must take
daily samples at the entrance to the distribution system. If the MRDL
is exceeded, the system must go to increased monitoring.
Increased Monitoring: If any daily sample taken at the entrance to
the distribution system exceeds the MRDL, the system is required to
take three additional samples in the distribution system on the next
day. Samples must be taken at the following locations.
<bullet> Systems using chlorine as a residual disinfectant and
operating booster chlorination stations after the first customer. These
systems must take three samples in the distribution system: One as
close as possible to the first customer, one in a location
representative of average residence time, and one as close as possible
to the end of the distribution system (reflecting maximum residence
time in the distribution system).
<bullet> Systems using chlorine dioxide or chloramines as a
residual disinfectant or chlorine as a residual disinfectant and not
operating booster chlorination stations after the first customer. These
systems must take three samples in the distribution system as close as
possible to the first customer at intervals of not less than six hours.
Reduced monitoring: Monitoring for chlorine dioxide may not be
reduced.
Compliance Determination: Acute violations. If any daily sample
taken at the entrance to the distribution system exceeds the MRDL and
if, on the following day, any sample taken in the distribution system
exceeds the MRDL, the system will be in acute violation of the MRDL and
must take immediate corrective action to lower the occurrence of
chlorine dioxide below the MRDL and issue the required acute public
notification. Failure to monitor in the distribution system on the day
following an exceedance of the chlorine dioxide MRDL shall also be
considered an acute MRDL violation.
Nonacute violations. If any two consecutive daily samples taken at
the entrance to the distribution system exceed the MRDL, but none of
the samples taken in the distribution system exceed the MRDL, the
system will be in nonacute violation of the MRDL and must take
immediate corrective action to lower the occurrence of chlorine dioxide
below the MRDL. Failure to monitor at the entrance to the distribution
system on the day following an exceedance of the chlorine dioxide MRDL
shall also be considered a nonacute MRDL violation.
Important note. Unlike chlorine and chloramines, the MRDL for
chlorine dioxide may not be exceeded for short periods of time to
address specific microbiological contamination problems.
Monitoring for CT credit: Subpart H systems required to operate
enhanced coagulation or enhanced softening may receive credit for
compliance with CT requirements in Subpart H if the following
monitoring is completed and the required operational standards are met.

--For each chlorine dioxide generator, the system must demonstrate that
the generator is achieving at least 95 percent yield and producing no
more than five percent free chlorine by testing a minimum of once per
week.
--On any day that a generator fails to achieve at least 95 percent
yield, and on subsequent days until at least 95 percent yield is
achieved, and/or any day that the generator produces more than five
percent free chlorine and on subsequent days until no more than five
percent free chlorine is produced, the system may not receive credit
for compliance with CT requirements.
--On any day that a generator achieves at least 90 percent, but less
than 95 percent, yield, and/or any day that a generator produces more
than five percent, but less than 10 percent, free chlorine, the system
may take immediate corrective action to achieve a minimum of 95 percent
yield and no more than five percent free chlorine. If subsequent
testing conducted on the same day demonstrates at least 95 percent
yield and no more than five percent free chlorine, the system may
receive credit for compliance with CT requirements on that day. If the
generator continues to fail to demonstrate at least 95 percent yield
and/or continues to produce more than five percent free chlorine, the
system may not receive credit for compliance with CT requirements on
that day.
--Measurements must be made at least every seven days. If, in the
interim, the system changes generator conditions (e.g., change in
chlorine dose, change conditions to match changing plant flow rate), it
shall remeasure for chlorine dioxide yield and free chlorine.

To calculate compliance with Sec. 141.133(b)(2)(ii)(C) in order to
receive credit for CT compliance, Method 4500-ClO<INF>2 E (Standard
Methods for the Examination of Water and Wastewater, 18th Ed. 1992)
must be used to determine concentrations of chlorine dioxide, chlorine,
and related species in the generator effluent. Calculations are
performed as demonstrated below.

Perform titration on generator sample aliquots as required by
Method 4500-ClO<INF>2 E. Record the titration readings for A through E
below, the normality (N) of the titrant used, and the sample dilution.

--A (ml titrant/ml sample) for titration of chlorine and one-fifth of
ClO<INF>2.
--B (ml titrant/ml sample) for titration of four-fifths of ClO<INF>2
and of chlorite.
--C (ml titrant/ml sample) for titration of nonvolatilized chlorine.
--D (ml titrant/ml sample) for titration of chlorite.
--E (ml titrant/ml sample) for titration of chlorine, ClO<INF>2,
chlorate, and chlorite.
--N (normality of the titrant used in equivalents per liter).

2. Determine chlorine dioxide generator performance (yield). The
calculations in a. through c. below must be corrected for the sample
dilution.
a. Calculate chlorine dioxide concentration.

[ClO<INF>2 (mg/l)]=13490 x 5/4 x (B-D) x N

b. Calculate chlorite concentration.

[ClO<INF>2 (mg/l)] = 16863 x D x N

c. Calculate chlorate concentration.

[ClO<INF>3 (mg/l)] = 13909 x [E-(A+B)] x N

d. Calculate yield (in %).

<GRAPHIC><TIF23>TP29JY94.009

3. Determine excess chlorine. This calculation must be corrected
for sample dilution.
a. Calculate chlorine concentration.

[Cl<INF>2 (mg/l)] = {A - [(B-D)/4]} x N x 35453

b. Using the concentrations of chlorine dioxide, chlorite, and
chlorate calculated above (2.a.-c.), calculate excess chlorine.

<GRAPHIC><TIF24>TP29JY94.010

4. Determine whether CT credit can be taken.
a. If % Yield <gr-thn-eq> 95% and % Excess Chlorine <ls-thn-eq> 5%,
CT credit may be taken.
b. If % Yield <gr-thn-eq> 90% but < 95%, and/or % Excess chlorine >
5% but < 10%, the system may take immediate corrective action and then
remeasure. CT credit may be taken if a subsequent measurement performed
on the same day shows a yield <gr-thn-eq> 95% and % Excess Chlorine
<ls-thn-eq> 5%.
c. If % Yield < 90% or excess chlorine > 10%, the system may not
take CT credit for that day and for any subsequent days until a
subsequent measurement shows a yield <gr-thn-eq> 95% and % Excess
Chlorine <ls-thn-eq> 5%.
Best Available Technology: EPA identifies the best means available
for achieving compliance with the MRDL for chlorine dioxide as control
of treatment processes to reduce disinfectant demand, and control of
disinfection treatment processes to reduce disinfectant levels.

D. Enhanced Coagulation and Enhanced Softening Requirements

In addition to meeting MCLs and MRDLs, some water suppliers must
also meet treatment requirements to control the organic material
(disinfection byproduct precursors (DBPPs)) in the raw water that
combines with disinfectant residuals to form DBPs. Subpart H systems
using conventional treatment are required to control for DBPPs
(measured as total organic carbon (TOC)) by using enhanced coagulation
or enhanced softening. A system must remove a certain percentage of TOC
(based on raw water quality) prior to the point of continuous
disinfection. Systems using ozone followed by biologically active
filtration or chlorine dioxide which meets specific criteria would be
required to meet the TOC removal requirements prior to addition of a
residual disinfectant. Systems able to reduce TOC by a specified
percentage level have met the DBPP treatment technique requirement. If
the system does not meet the percent reduction, it must determine its
alternative minimum TOC removal level, which is further explained in
Section IX. The State approves the alternative minimum TOC removal
possible for the system on the basis of the relationship between
coagulant dose and TOC in the system.

Applicability
Subpart H systems using conventional treatment must use enhanced
coagulation or enhanced softening to remove TOC unless they meet one of
the criteria in a. through d. below. Systems using chlorine dioxide
that achieve a 95 percent yield of chlorine dioxide and have no more
than five percent excess chlorine would be required to meet the TOC
removal requirements prior to the addition of another residual
disinfectant.
a. The system's treated water TOC level, prior to the point of
continuous disinfection, is less than 2.0 mg/l.
b. The system's source water TOC level, prior to any treatment, is
less than 4.0 mg/l; the alkalinity is greater than 60 mg/l; and not
later than the effective dates for compliance for the system, either
the TTHM annual average is no more than 0.040 mg/l and the THAA annual
average is no more than 0.030 mg/l, or the system has made a clear and
irrevocable financial commitment not later than the effective date for
compliance for Stage 1 to technologies that will limit the levels of
TTHMs and THAAs to no more than 0.040 mg/l and 0.030 mg/l,
respectively. Systems must submit evidence of the clear and irrevocable
financial commitment, in addition to a schedule containing milestones
and periodic progress reports for installation and operation of
appropriate technologies, to the State for approval not later than the
effective date for compliance for Stage 1. These technologies must be
installed and operating not later than the effective date for Stage 2.
c. The system's TTHM annual average is no more than 0.040 mg/l and
the THAA annual average is no more than 0.030 mg/l and the system uses
only chlorine for disinfection.
d. Systems practicing softening and removing at least 10 mg/l of
magnesium hardness (as CaCO<INF>3), except those that use ion exchange,
are not subject to performance criteria for the removal of TOC.
Enhanced Coagulation Performance Requirements
Systems Not Practicing Softening. Systems that use either (1) ozone
followed by biological filtration or (2) chlorine dioxide and meet the
performance requirements for CT credit must reduce TOC by the amount
specified in Table VIII-4 before the addition of a residual
disinfectant. All other systems must reduce the percentage of TOC in
the raw water by the amount specified in Table VIII-4 prior to
continuous disinfection, unless the State approves a system's request
for an alternative minimum TOC removal level.
Required TOC reductions for Subpart H systems, indicated in Table
VIII-4, are based upon the specified source water parameters.
Systems Practicing Softening. Systems that use either (1) ozone
followed by biological filtration or (2) chlorine dioxide and meet the
performance requirements for CT credit must reduce TOC by the amount
specified in the far-right column of Table VIII-4 (Source Water
Alkalinity >120 mg/l) for the specified source water TOC before the
addition of a residual disinfectant. All other systems practicing
softening are required to meet the percent reductions in the far-right
column of Table VIII-4 (Source Water Alkalinity >120 mg/l) for the
specified source water TOC prior to continuous disinfection, unless the
State approves a system's request for an alternative minimum TOC
removal level. Systems removing more than 10 mg/l of magnesium hardness
(as CaCo<INF>3) are considered to be practicing enhanced softening, and
are not subject to performance criteria for the removal of TOC (see
paragraph D.1.(d) above).

Table VIII-4.--Required Removal of TOC by Enhanced Coagulation for
Subpart H Systems Using Conventional Treatment\1\

[In percent]

Source water alkalinity (mg/l)

Source water total organic carbon (mg/ --------------------------------

l) 0-60 >60-120 >120\2\

>2.0-4.0............................... 40.0 30.0 20.0
>4.0-8.0............................... 45.0 35.0 25.0
>8.0................................... 50.0 40.0 30.0

\1\Systems meeting at least one of the conditions in Sec.
141.135(a)(1)(i)-(iv) are not required to operate with enhanced

coagulation.

\2\Systems practicing softening must meet the TOC removal requirements

in this column.

3. Alternative Performance Criteria
a. Non-softening systems. Non-softening Subpart H conventional
treatment systems that cannot achieve the TOC removals required above
due to unique water quality parameters or operating conditions must
apply to the State for alternative performance criteria. The system's
application to the State must include, as a minimum, results of benchor
pilot-scale testing for alternate performance criteria. Alternative
TOC removal criteria may be determined as follows:
(1) bench- or pilot-scale testing used to determine alternative TOC
removal criteria must be based on quarterly measurements and must be
conducted at pH levels no greater than those indicated in Table VIII-5,
dependent on the alkalinity of the water,
(2) the alternative TOC removal criteria will be no less than the
percent removal determined by the alternative enhanced coagulation
level (AECL), where an incremental addition of 10 mg/l of alum (or an
equivalent amount of ferric salt) results in a TOC removal of 0.3 mg/l
(determined as a slope),
(3) once approved by the State, this new requirement (alternative
TOC removal criteria) supersedes the minimum TOC removal required in
Table VIII-4 and remains effective until the State approves a new
value, and
(4) if the TOC removal is consistently less than 0.3 mg/l of TOC
per 10 mg/l of incremental alum dose at all dosages of alum, the water
is deemed to contain TOC not amenable to enhanced coagulation and the
system may then apply to the State for a waiver of enhanced coagulation
requirements.

Table VIII-5.--Alternate Enhanced Coagulation Level Maximum pH

Alkalinity (mg/l as CaCO<INF>3) Maximum pH

0-60....................................................... 5.5
60-120..................................................... 6.3
>120-240................................................... 7.0
>240....................................................... 7.5

The system may then operate at any coagulant dose or pH necessary
to achieve the minimum TOC removal determined under the testing. For
example, a system may choose to use lower levels of alum and depress
the pH further instead of adding higher levels of alum at the higher
pH.
b. Softening systems. During the negotiation, the Committee was not
able to develop alternative performance criteria for Subpart H
softening systems. In Section IX of this Notice, EPA solicits comments
on what these criteria should include.
4. Compliance Determinations
Compliance for systems required to operate with enhanced
coagulation or enhanced softening is based on a running annual average,
computed quarterly, of normalized monthly TOC percent reductions. A
system is in compliance if the normalized running annual average is at
least 1.00. For Subpart H systems using conventional treatment but not
required to operate enhanced coagulation or enhanced softening,
compliance with the DBPP treatment technique is based on continuing to
meet the avoidance criteria in paragraph 1 above. Example VIII-1 below
shows how to determine compliance with the enhanced coagulation (or
enhanced softening) requirements for systems that do not require
alternative TOC removal requirements.

Example VIII-1

The system conducts the required monitoring for 12 months.
Complete data are included only for the most recent quarter of
monitoring.
(1) Using the procedure explained in Sec. 141.135(b), the system
determines the percent TOC removal, which is equal to:

(1 - (treated water TOC/source water TOC)) x 100

(2) Determine the required monthly TOC percent removal (from
either the table in Sec. 141.135(a)(2)(i) or from
Sec. 141.135(a)(3). Note that seasonal water quality variations may
require systems to determine required TOC removals from both
sections (i.e., both Step 1 and Step 2 levels) during any one year.
(3) Divide 1) by 2).
(4) Add together the results of 3) for the last 12 months and
divide by 12.
(5) If 4) <1.00, the system is not in compliance.

In the report below, the system is in compliance with the TOC
removal requirements.

Source

Month Treated Source (1-a./b.) water Reqd. TOC c./d.

TOC(mg/l) TOC(mg/l) x 100 alkalinity removal (%)
a. b. c. d. e.

January........................... ........... ........... ........... ........... ........... 1.10
February.......................... ........... ........... ........... ........... ........... 0.94
March............................. ........... ........... ........... ........... ........... 1.03
April............................. ........... ........... ........... ........... ........... 1.07
May............................... ........... ........... ........... ........... ........... 0.98
June.............................. ........... ........... ........... ........... ........... 1.24
July.............................. ........... ........... ........... ........... ........... 1.10
August............................ ........... ........... ........... ........... ........... 1.07
September......................... ........... ........... ........... ........... ........... 1.02
October........................... 4.6 8.2 44 70 40 1.10
November.......................... 4.0 6.1 34 75 35 0.98
December.......................... 4.4 6.2 29 85 35 0.83
Last 12 mos....................... N/A N/A N/A N/A N/A <greek-S>=

12.48<divid
e(=f.)
f./12 = 1.04 (=g.)
If g <gr-thn-eq> 1.00, the system is in compliance.

EPA solicits comment on how the following situations should be
handled in compliance determinations.

--when the monthly source water TOC is less than 2.0 mg/l and enhanced
coagulation is not required.
--when seasonal variations cause the system to determine that TOC is
not amenable to any level of enhanced coagulation and the system would
be eligible for a waiver of enhanced coagulation requirements.

EPA believes that assigning a value of 1.00 for these months is a
reasonable approach.
5. CT Credit.
Systems required to operate with enhanced coagulation or enhanced
softening may not take credit for compliance with CT requirements prior
to sedimentation unless they meet one of the following criteria:
a. Systems may include CT credit during periods when the water
temperature is below 5 deg.C and the TTHM and HAA5 quarterly averages
are no greater than 40 <greek-m>g/l and 30 <greek-m>g/l, respectively.
b. Systems receiving disinfected water from a separate entity as
their source water shall be allowed to include credit for this
disinfectant in determining compliance with the CT requirements. If the
TTHM and HAA5 quarterly averages are no greater than 40 <greek-m>g/l
and 30 <greek-m>g/l, respectively, systems may use the measured ``C''
(residual disinfectant concentration) and the actual contact time (as
T<INF>10). If the TTHM and HAA5 quarterly averages are greater than 40
<greek-m>g/l and 30 <greek-m>g/l, respectively, systems must use a
``C'' (residual disinfectant concentration) of 0.2 mg/l or the measured
value, whichever is lower; and the actual contact time (as T<INF>10).
This credit shall be allowed from the disinfection feed point, through
a closed conduit only, and ending at the delivery point to the
treatment plant.
c. Systems using chlorine dioxide as an oxidant or disinfectant may
include CT credit for its use prior to enhanced coagulation or enhanced
softening if the following standards are met: the chlorine dioxide
generator must generate chlorine dioxide on-site at a minimum 95
percent yield from sodium chlorite; and the generated chlorine dioxide
feed stream applied from the chlorine dioxide generator must contain
less than five percent (by weight) chlorine, measured as the weight
ratio of chlorine to chlorine dioxide, chlorite, and chlorate in such
feed stream. Compliance with these standards must be demonstrated by
monitoring.

E. Requirement for Systems to Use Qualified Operators

Under the proposed rule, each PWS must be operated by qualified
personnel who meet the requirements specified by the State. This
proposed requirement is similar to the requirement in the Surface Water
Treatment Rule. States must develop operator qualifications if they do
not already have them and they must require that systems be operated by
personnel who meet these qualifications. In addition, the State must
maintain a register of qualified operators. The appropriate criteria
for determining if an operator is qualified depend upon the type and
size of the system.

F. Analytical Method Requirements

Disinfection By-Products. Disinfection by-products must be measured
by the methods listed in Table VIII-6:

Table VIII-6.--Proposed Methods for Disinfection By-products

Contaminant Methods

Trihalomethanes (4)......................... \1\502.2, \2\524.2,

\3\551.

Haloacetic Acids (5)........................ \2\552.1, \4\6233 B.
Bromate, Chlorite........................... \5\300.0.

\1\EPA Method 502.2 is in the manual ``Methods for the Determination of
Organic Compounds in Drinking Water'', EPA/600/4-88/039, July 1991,

NTIS publication PB91-231480.

\2\EPA Methods 524.2 and 552.1 are in the manual ``Methods for the
Determination of Organic Compounds in Drinking Water--Supplement II'',

EPA/600/R-92/129, August 1992, NTIS PB92-207703.

\3\EPA Method 551 is in the manual ``Methods for the Determination of
Organic Compounds in Drinking Water--Supplement I'', EPA/600/4-90/020,

July 1990, NTIS PB91-146027.

\4\Standard Method 6233 B is in ``Standard Methods for the Examination
of Water and Wastewater,'' 18th Edition, American Public Health
Association, American Water Works Association, and Water Environment

Federation, 1992.

\5\EPA Method 300.0 is in the manual ``Methods for the Determination of
Inorganic Substances in Environmental Samples'', EPA/600/R/93/100,
August 1993, with revisions. See Section IX for revisions.

All measurements listed in this section must be conducted by a
laboratory certified by EPA or the State. To receive certification, the
laboratory must:
(1) Use the promulgated method(s).
(2) On an annual basis, successfully analyze appropriate
performance evaluation (PE) samples provided by EPA or the State.
Disinfectant Residuals. The three disinfectant residuals are
measured and reported as follows: chlorine as free or total chlorine;
chloramines as combined or total chlorine; and chlorine dioxide as
chlorine dioxide. Residual disinfectant concentrations must be measured
by the methods listed in Table VIII-7.

Table VIII-7.--Proposed Methods for Disinfectants

Disinfectant measurement Proposed methods\1\

Chlorine as free or total residual 4500-Cl DAmperometric Titration.
chlorine, chloramines as combined 4500-Cl FDPD Ferrous Titrimetric.
or total residual chlorine. 4500-Cl GDPD Colorimetric.
Chlorine as free residual chlorine. 4500-Cl HSyringaldazine (FACTS).
Chlorine or Chloramines as total 4500-Cl ELow-Level Amperometric.
residual chlorine. 4500-Cl IIodometric Electrode.
Chlorine Dioxide as residual 4500-ClO<INF>2 CAmperometric Titration.

chlorine dioxide. 4500-ClO<INF>2 DDPD.
4500-ClO<INF>2 EAmperometric Titration.

\1\Proposed methods are in ``Standard Methods for the Examination of
Water and Wastewater,'' 18th Edition, American Public Health
Association, American Water Works Association, and Water Environment

Federation, 1992.

Residual disinfectant concentrations for chlorine and chloramines
may also be measured by using DPD colorimetric test kits if their use
is approved by the State. Measurement for disinfectant residual
concentration must be conducted by a party approved by the State.
Other Parameters--Total Organic Carbon, Alkalinity and Bromide.
Other parameters that are monitored to meet treatment technique
requirements must be measured using the methods listed in Table VIII-8.

Table VIII-8.--Proposed Analytical Methods for Other Parameters

Parameter Method

Total Organic Carbon............... 5310 CPersulfate-Ultraviolet

Oxidation\1\
5310 DWet Oxidation\1\

Alkalinity......................... 2320 B\1\, 310.1\2\, D-1067-

88BTitrimetric\3\
I-1030-85Electrometric\4\

Bromide............................ 300.0Ion Chromatography\5\

\1\Standard Methods 2320 B, 5310 B and 5310 C are in Standard Methods
for the Examination of Water and Wastewater, 18th Edition, American
Public Health Association, American Water Works Association, and Water

Environment Federation, 1992.

\2\EPA Method 310.1 is in the manual ``Methods for Chemical Analysis of
Water and Wastes'', EPA/600/4-79-020, March 1983, NTIS PB84-128677.
\3\Method D-1067-88B is in the ``Annual Book of ASTM Standards'', Vol.
11.01, American Society for Testing and Materials, 1993.
\4\Method I-1030-85 is in Techniques of Water Resources Investigations
of the U.S. Geological Survey, Book 5, Chapter A-1, 3rd ed., U.S.

Government Printing Office, 1989.

\5\EPA Method 300.0 is in the manual ``Methods for the Determination of
Inorganic Substances in Environmental Samples'', EPA/600/R/93/100--

Draft, June 1993.

Measurement for these parameters must be conducted by a party
approved by the State.

G. Public Notice Requirements

Standard provisions for public notice apply to this rule. These
provisions are explained in Section XIV of this preamble. There is only
one acute violation, which occurs when the chlorine dioxide MRDL is
exceeded in the distribution system (or if the system fails to take the
required samples in the distribution system).

H. Variances and Exemptions

Standard provisions for variances and exemptions apply to this
rule. These provisions are explained in Section XI of this preamble.

I. Reporting and Recordkeeping Requirements for PWSs

Reporting: EPA has proposed reporting requirements designed to
document compliance with the treatment and monitoring requirements
described above. These requirements are specified in Sec. 141.134(b) of
the proposed rule. Systems required to sample quarterly or more
frequently must report monitoring information to the State within 10
days after the end of each quarter in which samples were collected.
Systems required to sample less frequently than quarterly must report
monitoring information to the State within 10 days after the end of
each required monitoring period in which samples were collected.
Recordkeeping: There are no additional recordkeeping requirements
for systems.

J. State Implementation Requirements

Records Kept by States: EPA is proposing to add several
requirements to Sec. 142.14, Records Kept by States. These include
records of the currently applicable or most recent State
determinations, including supporting information and an explanation of
the technical basis for each decision.

--Records of systems that are installing GAC or membrane technology.
--Records of systems that are required, by the State, to meet
alternative TOC performance criteria (alternate enhanced coagulation
level).
--Records of Subpart H systems using conventional treatment meeting any
of the enhanced coagulation or enhanced softening exemption criteria.
--Register of qualified operators.
--Records of systems with multiple wells considered to be one treatment
plant.

Reports by States: EPA is proposing to add several requirements to
Sec. 142.15, Reports by States. These requirements include:

--Reports of systems that must meet alternative minimum TOC removal
levels.
--Reports of extensions granted for compliance with MCLs in Sec. 141.64
and the date by which compliance must be achieved.
--A list of systems required to monitor for various disinfectants and
disinfection byproducts.
--A list of all systems using multiple ground water wells which draw
from the same aquifer and are considered a single source for monitoring
purposes.

Special Primacy Requirements: EPA is proposing to add several
requirements to Sec. 142.16, Special Primacy Requirements. These
requirements include how the State will:

--Determine the interim treatment requirements for those systems
electing to install GAC or membrane filtration.
--Qualify operators of community and nontransient-noncommunity public
water systems subject to this regulation.
--Approve alternative TOC minimum removal levels.
--Approve parties to conduct pH, alkalinity, temperature and residual
disinfectant concentration measurements.
--Approve DPD colorimetric test kits for free and total chlorine
measurements.
--Define the criteria to use to determine if multiple wells are being
drawn from a single aquifer and therefore be considered a single source
for compliance with monitoring requirements.

IX. Basis for Key Specific Criteria of Proposed Rule

A. 80/60 TTHM/HAA5 MCLs, Enhanced Coagulation Requirements, and BAT

Basis for Umbrella Concept vs. Individual MCLs
The proposed rule would establish limits for two DBP class sums
(i.e., TTHMs and the sum of five HAA species [HAA5]) rather than
individual DBPs. In performing the regulatory impact analysis (RIA),
TTHM and HAA5 data were generated that were believed to represent
occurrence data with conventional drinking water treatment as well as
that achievable with the use of advanced technologies. However,
individual DBPs could not be reliably predicted over the range of TOC
and bromide levels that are found in surface waters before and after
treatment.
In addition to the inability to characterize individual DBP
formation, the Negotiating Committee was concerned that individual DBPs
cannot all be controlled simultaneously without adverse impacts. While
precursor removal processes (i.e., coagulation, precipitative
softening, GAC, and nanofiltration) can remove TOC, they do not remove
bromide (except for nanofiltration to a limited extent). Such processes
are best for controlling the formation of chloroform and least
effective for controlling the formation of bromoform (Summers et al.,
1993). Amy and colleagues found that increasing the bromide-to-TOC
ratio (e.g., by reducing TOC with a precursor-removal technology)
yielded a higher percentage of brominated THM species (Amy et al.,
1991). Symons and colleagues speculated that this phenomenon is due to
the following: (1) after treatment to lower TOC, a water may be
``precursor-limited''; (2) THM formation kinetics favor bromine
incorporation; (3) thus bromine consumes most of the active precursor
sites, leaving few for chlorine substitution (Symons et al., 1993).
In an enhanced coagulation study of 16 waters nationwide, the
median reduction in TTHMs was 50 percent (JAMES M. MONTGOMERY,
CONSULTING ENGINEERS, INC., 1991 and Means et al., 1993). Because this
technology removed TOC but not bromide, chloroform levels were well
reduced (median of 65 percent), while bromodichloromethane values were
not as well reduced (for 15 of the waters the median reduction was 28
percent; this THM level, though, went up six percent in the sixteenth
water). For the more brominated species (dibromochloromethane and
bromoform), the THM levels decreased in some waters and increased in
others. Again, the increase in formation of these brominated THMs was
attributed to the change in bromide-to-TOC ratio and/or competition
between bromine and chlorine for precursors. For the raw waters in this
study (median TOC of 4.3 mg/L and bromide of 0.09 mg/L), chlorination
(at 20 deg.C for 16 hr) yielded median values of 77 <greek-m>g/L
chloroform, 17 <greek-m>g/L bromodichloromethane, 6 <greek-m>g/L
dibromochloromethane, 0.2 <greek-m>g/L bromoform, and 124 <greek-m>g/L
TTHMs. For the coagulated/settled waters, chlorination yielded median
values of 26 <greek-m>g/L chloroform, 12 <greek-m>g/L
bromodichloromethane, 6 <greek-m>g/L dibromochloromethane, 0.3
<greek-m>g/L bromoform, and 56 <greek-m>g/L TTHMs. These data
demonstrate that enhanced coagulation can reduce TTHMs, with varying
impacts on individual species. While not all chemical species were
significantly reduced, the overall theoretical cancer risk from THMs is
lower. This may also apply to HAA5 and other byproducts.
In the aforementioned coagulation study, the median raw- and
settled-water DCAA levels were 28 and 14 <greek-m>g/L, respectively
(JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC., 1991 and Means et
al., 1993). For the waters tested, the median reduction in DCAA was 61
percent, which was comparable to the reduction in chloroform. For
dibromoacetic acid (DBAA), the median raw- and settled-water levels
were 1.2 and 1.6 <greek-m>g/L, respectively (JAMES M. MONTGOMERY,
CONSULTING ENGINEERS, INC., 1991). For the three waters in this study
with very high bromide levels, DBAA was reduced from a range of 16 to
52 <greek-m>g/L in the chlorinated raw waters to a range of 11 to 30
<greek-m>g/L in the chlorinated coagulated/ settled waters.
These types of data indicate that while it is feasible for systems
utilizing enhanced coagulation to reduce TTHM and HAA5 levels, it is
not possible to reduce all of the individual THMs and HAAs to the same
extent. Using precursor control technologies, which can remove TOC but
not bromide, there is a feasible limit on being able to minimize the
formation of each individual THM or HAA. Alternatively, using
alternative disinfectants (e.g., ozone/chloramines), one can
significantly reduce the formation of all THMs and HAAs. However, as
discussed in Section VI.C., there are concerns with the byproducts of
alternative disinfectants.
Utilizing the DBP class sums, though, the Technologies Working
Group (TWG) was able to evaluate the benefits of enhanced coagulation
with the DBPRAM. For surface waters that filter but do not soften,
using conventional filtration treatment and chlorine, it was determined
that the median, 75th, and 90th percentile TTHMs are 46, 68, and 90
<greek-m>g/L, respectively. With enhanced coagulation for all surface
water systems that filter but do not soften, it was predicted that
median, 75th, and 90th percentile TTHMs would drop to 29, 41, and 58
<greek-m>g/L, respectively. Similarly, using conventional treatment and
chlorine, it was determined that the median, 75th, and 90th percentile
HAA5 levels are 28, 47, and 65 <greek-m>g/L, respectively. With
enhanced coagulation, it was predicted that median, 75th and 90th
percentile HAA5 levels would drop to 17, 26, and 37 <greek-m>g/L,
respectively.
In order to comply with MCLs of 80 <greek-m>g/L TTHMs and 60
<greek-m>g/L HAA5, the TWG assumed that a utility would design the
treatment process to achieve levels less than 80 percent of the MCL
values (i.e., 64 <greek-m>g/L TTHMs and 48 <greek-m>g/L HAA5) as an
operating margin of safety. Such TTHM and HAA5 levels should be
attainable for approximately 90 percent of the systems when using
enhanced coagulation with chlorine, based upon the predicted 90th
percentile levels above. Similarly, GAC10 with chlorine was predicted
to result in comparable levels of TTHMs and HAA5. Note, though, that
for some waters the HAA levels may exceed the THM concentrations
(Grenier et al., 1992) and that compliance with both sets of DBP
classes may require additional treatment changes. For example, the
DBPRAM predicted that for these surface-water systems using enhanced
coagulation, the maximum TTHM would be 80 <greek-m>g/L while the
maximum HAA5 level would be 81 <greek-m>g/L.
Enhanced coagulation can be used to remove the precursors for other
DBPs as well as those associated with THMs and HAAs. Reckhow and Singer
demonstrated that the formation potential (a measure of precursor
levels) of THMs, di-, and trichloroacetic acid, dichloroacetonitrile,
1,1,1-trichloropropanone, and TOX could all be reduced with enhanced
coagulation (Reckhow et al., 1990). Thus, enhanced coagulation can be
used to control other DBPs as well, even though they are not part of
this proposed D/DBP Rule.
In a full-scale evaluation of enhanced coagulation performed during
the 35-utility DBP study, the alum dose was raised from 10 to 40 mg/L
(Metropolitan Water District of So. Calif. et al, 1989). Removal of TOC
(raw water TOC of 3 mg/L--a low-alkalinity water) through coagulation
and settling increased from 25 to 50 percent. Chlorination (at 25
deg.C for 24 hr) of settled/filtered water during the low-alum-dose
test yielded 86 <greek-m>g/L TTHMs, 50 <greek-m>g/L HAA5, and 9.4
<greek-m>g/L chloral hydrate. Chlorination of settled/filtered water
during the high-alum-dose test yielded 55 <greek-m>g/L TTHMs, 29
<greek-m>g/L HAA5, and 6.0 <greek-m>g/L chloral hydrate. By enhancing
the coagulation process at this utility, the levels of TTHMs, HAA5, and
chloral hydrate were all reduced (compared to the low-alum-dose test)
by 36-42 percent. In the 35-utility study, the overall correlation
between the occurrence of chloral hydrate and chloroform in the
treatment plant effluents of all the systems was good (correlation
coefficient of 0.85) (Metropolitan Water District of So. Calif. et al.,
1989). Chloral hydrate has been postulated to form as an intermediate
in the conversion of ethanol to chloroform (Beibar et al., 1973). By
removing THM and HAA precursors during enhanced coagulation, chloral
hydrate should be controlled as well.
Basis for Level of Stringency in MCLs, BAT, and Concurrent Enhanced
Coagulation Requirements
The Safe Drinking Water Act directs EPA to set the MCL as close to
the MCLG as is technically and economically feasible to achieve and to
specify in the rule such best available technology (BAT). Systems
unable to meet the MCL after application of BAT can get a variance (see
Section XI for a discussion of variances). Systems that obtain a
variance must meet a schedule approved by the State for coming into
compliance. Systems are not required to use BAT in order to comply with
the MCL but can use other technologies as long as they meet all
drinking water standards and are approved by the State.
For chemicals classified as B2 carcinogens, EPA must set standards
as close to zero (the MCLG) as is technically and economically feasible
to achieve by the BAT. EPA has classified three THMs (chloroform,
bromodichloromethane, and bromoform) and one of the HAAs
(dichloroacetic acid) as probable human carcinogens (i.e., B2
carcinogens) based on evidence of carcinogenicity in animals. EPA is
also concerned with the potential risks of chlorination byproducts
other than THMs or HAAs, indicated in part by the presence of THMs and
HAAs. A TTHM MCL and HAA MCL would limit exposure from different THMs
and HAAs as well as other chlorinated DBPs.
EPA is proposing a combined limit for only five of the HAAs
(HAA5)--monochloroacetic acid, dichloroacetic acid, trichloroacetic
acid, monobromoacetic acid, and dibromoacetic acid--because currently
available data enable EPA to predict only their combined occurrence.
How BAT is defined determines the level at which MCLs are set for
TTHMs and HAA5. Per agreement with the Negotiating Committee, EPA is
proposing either enhanced coagulation or shallow bed GAC (GAC10) with
chlorine as the primary and residual disinfectant. The TWG considered
GAC10 as roughly equivalent to enhanced coagulation in removing organic
precursors to DBPs. The Negotiating Committee considered it appropriate
to define chlorination for primary and residual disinfection within the
BAT definition because 1) chlorine is an effective disinfectant for
inactivating most microbial pathogens originating in the source water
and for limiting contamination in the distribution system, and 2)
health risks from DBPs from use of alternate disinfectants are not as
yet as well characterized as they are for DBPs of chlorination.
However, as noted above, alternate disinfectants (such as ozone) may be
used to achieve D/DBPR compliance.
As discussed previously, based on model predictions by the DBPRAM,
most systems in the U.S. would be able to achieve a TTHM level of 80
<greek-m>g/l or an HAA5 level of 60 <greek-m>g/l if they were to apply
the proposed BATs. The Negotiating Committee agreed to propose the MCLs
accordingly. Alternative BATs and corresponding MCLs were considered
but not included for the reasons discussed below.
Including a more effective precursor removal technology such as
GAC20 or membrane filtration in the BAT would result in significantly
lower MCLs. Setting such MCLs would probably result in much greater use
of alternative disinfectants, such as ozone and chloramines because
these technologies would be significantly less expensive than the BAT
for achieving the MCL. While much greater use of such technology may be
appropriate, some members of the Negotiating Committee did not consider
this increased use desirable, at least until more was known concerning
health risk associated with DBPs formed from use of alternative
disinfectants. For the same reasons, alternative disinfectants were not
included in the BAT definition(s).
Setting the MCLs for TTHMs and HAA5 at 80 and 60 <greek-m>g/l,
respectively, should lead to substantially lower TTHM and HAA levels
than those being achieved under the existing TTHM MCL. The TWG
estimated that, for surface water systems serving over 10,000 people
that do not soften, the median concentration for TTHMs and HAA5 would
drop from about 46 <greek-m>g/l to 31 <greek-m>g/l and 28 <greek-m>g/l
to 20 <greek-m>g/l, respectively, as a result of such regulations. As
part of today's proposal, EPA is also proposing that all systems using
surface water sources which use sedimentation and filtration must
operate with either enhanced coagulation or enhanced softening unless
they meet certain water quality conditions (discussed in the following
section of the preamble). This requirement was set in conjunction with
the MCLs for TTHMs and HAA5 for the following reasons:
(1) A substantial amount of precursors to disinfection DBPs could
be removed at low cost and within a short period of time, regardless of
which disinfectants were used. Thus, any health effects associated with
DBPs that might otherwise be formed would be reduced quickly and at low
costs.
(2) Reducing precursors would lead to lower TTHM and HAA5 levels
and thereby diminish the incentive for many systems to shift toward use
of alternative disinfectants in order to comply with the new MCLs,
thereby limiting concerns from any potential associated health risks.
(3) Enhanced coagulation and enhanced softening will also
significantly reduce disinfectant demand, thereby allowing utilities to
use less disinfectant while still maintaining a residual in the
distribution system. Maintaining a residual is important for
identifying when contamination occurs into the distribution system
(indicated by the absence of a residual) and for limiting bacterial
growth.
While lowering DBP precursors and disinfectant demand can provide
obvious benefits, there are also associated potential downside risks.
Since water treatment plant operators often apply disinfectant dosages
in order to maintain a residual in the distribution system, if the
disinfectant demand is lowered, lower disinfectant dosages could
inadvertently lead to lower levels of inactivation of pathogens
originating in the source water and increased microbial risk. To
prevent such risks, compensating treatment must be provided where
appropriate. EPA is therefore concurrently proposing possible
amendments to the SWTR to address such concerns in today's Federal
Register.
Another concern with precursor removal is that, in waters with high
bromide concentrations, it is possible (as previously discussed) to
increase the concentrations of certain brominated DBPs even though the
group concentrations of the TTHMs and HAA5 may decrease. Since the
health risks associated with many of the brominated DBPs are currently
unknown, it remains unclear whether the benefits of lowering the
concentrations of chlorinated DBPs outweigh the possible downside risks
of increasing certain brominated DBPs. Nevertheless, since only a small
percentage of systems may experience increased concentrations of
certain brominated DBPs from enhanced coagulation, the Negotiating
Committee reached a consensus that setting a national requirement for
precursor removal by enhanced coagulation or enhanced softening would
be appropriate.
The Committee could not reach consensus on whether to require
systems to use technologies such as GAC20 or membrane technology in
conjunction with setting lower MCLs, as was done for enhanced
coagulation with the proposed Stage 1 MCLs. Some members did not
consider it appropriate without a better understanding of the impacts
of such a requirement. Installation and use of GAC20 or membrane
technology involve greater costs and time to begin implementing than
enhanced coagulation. Some Committee members believed that, depending
on source water quality, use of alternative disinfectants may be
significantly more cost-effective for reducing health risks from DBP
levels than GAC20 or membrane technology. Also, these members believed
that use of alternative disinfectants instead of GAC20 or membranes may
pose fewer ecological impacts. However, other members believed that
GAC20 or membranes would substantially improve water quality and should
be required. The Committee did not reach consensus.
If GAC20 or membrane technology were required under Stage 1, benchand
pilot-scale studies would need to be conducted prior to design and
installation. Such studies would probably require at least several
years to complete for most systems. Under the ICR (59 FR 6332), large
systems with high TOC levels will be required to conduct bench- or
pilot-scale studies to evaluate the treatment effectiveness of GAC or
membrane technology. These studies will enable systems to design and
install GAC or membrane technologies, if required by the Stage 2 D/
DBPR, in a shorter time than otherwise would be possible under the
Stage 2 rule. Bench- or pilot-scale studies initiated under the ICR
will in part simulate the same initial actions that many utilities will
take in the future and reduce the time needed to come into compliance
if GAC20 or membrane technology are required.

Basis for enhanced coagulation and softening criteria

a. Enhanced coagulation. Removal of organic carbon in conventional
drinking water treatment by the addition of alum or iron salts has been
demonstrated by laboratory research, pilot-scale, demonstration plant,
and full-scale studies. Until recently, there have been limited data
available on the removal of organic carbon (measured as TOC) using
natural organic carbon matrices. Much of the developmental work for the
removal of TOC by coagulation and sedimentation has been done in the
laboratory using synthetic mixtures of humic materials. Researchers
have demonstrated that natural TOC exhibits a wide range of responses
to treatment with high doses of alum and iron salts. A key indication
of the ability of TOC to be removed by coagulation is the molecular
weight distribution of the organic carbon. A large proportion of high
molecular weight organic carbon is much easier to remove than an
organic carbon that is predominantly low molecular weight material.
Unfortunately, the procedure to determine TOC molecular weight
distribution is cumbersome, is only being used in research
applications, and is not generally available in water treatment plants
or to consulting firms.
Even though TOC removal has been practiced for some time at
conventional, full-scale plants, there has not been a standard method
to evaluate the potential for a water treatment plant to remove TOC
during the coagulation/sedimentation process. As a result of the work
of the TWG of the Negotiating Committee, a number of alternatives for
defining enhanced coagulation have been evaluated. The term optimized
coagulation was not used to describe the process of incremental removal
of TOC by coagulants to avoid confusion with optimized coagulation for
particle removal practiced by many water utilities.
The majority of the data for removal of TOC in drinking water
treatment has been developed with the use of aluminum sulfate
(AlSO<INF>4 <bullet> 14H<INF>2O). Iron salts are also effective for
removing TOC and equivalent dosages for iron salts were developed on
the basis of TOC removal by alum. Research has demonstrated that
polyaluminum chloride and cationic polymers are not effective for
removing the same degree of TOC as either alum or iron salts. Cationic
polymers (as well as anionic and nonionic polymers) have been proven to
be valuable in creating settlable floc when high dosages of alum or
iron salts are used. Specific organic polymers have been shown to
remove color in water treatment applications, but significant TOC
removal by organic polymers has not been demonstrated on a widespread
basis. Other coagulation process arrangements that result in the
required removals for enhanced coagulation are acceptable. For example,
sludge blanket clarifiers with or without powdered activated carbon
have been shown to remove significant levels of TOC.
The TWG attempted to define what percent TOC removals could be
achieved by most systems treating surface water and using coagulation/
sedimentation processes using elevated, but not unreasonable, amounts
of coagulant dose. The intent was to define enhanced coagulation in
such a manner that (a) significant TOC reductions would be achieved and
(b) the criteria could easily be enforced with minimal State
transactional costs. A TOC-based performance standard was therefore
desirable. It was not considered appropriate to base a performance
standard on what all systems would be expected to be able to achieve
since some waters are especially difficult to treat. Under such a
standard many systems with easier to treat waters might not be
motivated to reduce their TOC to the extent that was reasonably
achievable. On the other hand, setting a standard based on what many
systems would not be able to readily achieve would introduce large
transactional costs to States enforcing the rule. To address these
concerns the TWG developed a two-step standard for enhanced
coagulation. The first step includes performance criteria which, if
achieved, would define compliance. The second step would allow systems
that have difficult to treat waters to demonstrate to the State,
through a specific protocol, alternative performance criteria for
achieving compliance.
The TWG examined case histories of TOC removal with alum and
developed the 4X3 matrix shown below (Table IX-1) as the initial step
for defining enhanced coagulation. The TWG members and other experts
consulted during this process attempted to specify criteria by which
about 90 percent of the water utilities employing conventional
treatment and required to operate enhanced coagulation would be able to
meet the TOC removal percentages listed, without unreasonable addition
of alum. While limited empirical data were used to develop these
criteria, the 90 percent compliance objective with the step 1 criteria
is not statistically based. Establishing criteria at the anticipated 90
percent level, versus (for example) a 50 percent level with more
stringent percent TOC removal requirements, was expected to result in
much lower transactional costs to the State (because fewer evaluations
of experimental data to establish alternative criteria would be
required) without significantly higher TOC levels in treated waters
nationally.
Systems not practicing conventional treatment were excluded from
enhanced coagulation requirements because they were generally expected
to (a) have higher quality source waters with lower TOC levels than
waters treated by conventional water treatment plants, and (b) not have
treatment that could be expected to achieve significant TOC reduction
(e.g., most ground water supplies, direct filtration, diatomaceous
earth filtration, and slow sand filtration).

Table IX-1.--Required Removal of TOC by Enhanced Coagulation for Subpart
H Systems Using Conventional Treatment\2\

[In percent]

Source Water Alkalinity(mg/l)

Source Water Total Organic Carbon (mg/ --------------------------------

l) 0-60 >60-120 >120\1\

>2.0-4.0............................... 40.0 30.0 20.0
>4.0-8.0............................... 45.0 35.0 25.0
>8.0................................... 50.0 40.0 30.0

\1\Systems practicing softening must meet the TOC removal requirements

in this column.

\2\Systems meeting at least one of the conditions in Sec.
141.135(a)(1)(i)-(iv) are not required to operate with enhanced

coagulation.

The percent removals required as part of the initial compliance
determination were developed in recognition of the general trends in
TOC coagulation research that removals of TOC were more difficult the
higher the alkalinity (due to the difficulty of reaching the optimum
coagulation pH for TOC, usually between 5.5 and 6.5). It is also fairly
well established that TOC removal by coagulation is generally easier
the higher the initial TOC in the water. More information on the
practice of removing TOC in a wide variety of source waters would have
been helpful for developing the proposed criteria. EPA solicits comment
on whether the TOC percent removal levels in Table IX-1 indicated above
are representative of what 90 percent could be expected to achieve with
elevated, but not unreasonable, coagulant addition.
About 10 percent of the utilities required to operate enhanced
coagulation are not expected to achieve the percent removals in Table
IX-1. The purpose of the second step in the definition of enhanced
coagulation is to determine the point of diminishing returns for the
addition of coagulant for TOC removal.
Some waters contain TOC composed mostly of highly mineralized
organic carbon with most of the molecular weight fraction in the low
range. It is known that this kind of TOC can be very difficult to
remove. It is not the intent of this rule to require the addition of
very high concentrations of coagulants with little removal of TOC.
Therefore, the second step in the definition of enhanced coagulation
allows utilities to avoid such a situation. It requires the evaluation
of incremental addition of coagulant in a bench- or pilot-scale test
and measurement of the amount of TOC removed by 10 mg/L increments of
coagulant. Per recommendation of the TWG, EPA is proposing that the
point of diminishing returns for coagulant addition be defined as the
alternate enhanced coagulation level (AECL) at 0.3 mg/L of TOC removed
per 10 mg/L of alum added or equivalent addition of iron coagulant, and
that the percent TOC removal achieved at this point be defined, if
approved by the State, as the alternative minimum TOC removal level (to
that indicated in Table IX-1) that could be met for demonstrating
compliance.

Table IX-1a.--Coagulant Dose Equivalents

[mg/l]

Coagulant Dose

Aluminum sulfate<bullet> 14H<INF>2O............................. 10
Ferric chloride<bullet> 6H<INF>2O............................... 9.1
Ferric chloride............................................ 5.5
Ferric sulfate<bullet> 9H<INF>2O................................ 9.5

The guidance manual contains a bench-scale method for demonstrating
alternative performance criteria under step 2 of the enhanced
coagulation definition (EPA, 1994). The method described therein is
patterned after the ASTM D 2035-80 method for ``Standard Practice for
Coagulation-Flocculation Jar Test of Water.''
The bench-/pilot-scale procedure for determining alternative
percent TOC removal requirements does not require the use of a
laboratory filtration step. Experience has shown that most TOC is
removed during coagulation/sedimentation. Also, not requiring
laboratory filtration eliminates a point of possible contamination. TOC
is known to leach from some commercially available filters. Not
specifying laboratory filtration also avoids the issue of requiring a
particular type of filter for the bench-scale studies. During the
development of this proposed rule, no consensus could be reached on the
use of membrane filters with various pore diameters versus glass fiber
filters.
If a utility wishes to include the TOC removal in the filtration
process as part of compliance with enhanced coagulation, under step 2,
filtration would then have to be part of the bench-/pilot-scale study.
Using filtration in the treatment plant as part of compliance with
enhanced coagulation TOC removal would also require that continuous
disinfection for CT credit would not be allowed until after the
filters.
EPA solicits comment on whether filtration should be required as
part of the bench-/pilot-scale procedure for determination of Step 2
enhanced coagulation. If so, what type of filter should be specified
for bench-scale studies?
Figure IX-1 shows three examples of the types of curves anticipated
to result from a step 2 analysis and are based on actual data collected
during the TWG evaluation. Curve A represents a water containing a TOC
highly susceptible to removal by coagulation/sedimentation. Step 2 is
met at an alum dosage of 40 mg/L. Note that due to its low alkalinity
(<60 mg/L), the percent removal of TOC at this point (57%) is actually
more than is required under step 1 (45%). In this case, the utility is
only required to remove TOC to the level specified in step 1, 45%,
although removal of higher levels of easily removed TOC is encouraged.

BILLING CODE 6560-50-P

<GRAPHIC><TIF25>TP29JY94.025

BILLING CODE 6560-50-C
Curve B is probably more typical of waters that fall into the step
2 evaluation (alkalinity <gr-thn-eq>60-120). Note that the slope of
0.3/10 is located at a dosage of 25 mg/L of alum and results in a TOC
removal of 26%. The method used to determine the actual slopes of
portions of Curve B was to draw it on graph paper and count squares.
Curve fitting programs with instantaneous slope determinations may be
available to improve the precision of this task. If the specified TOC
removal in Table IX-1 had been followed, 31 mg/L of alum would have
been added to achieve the required 30% removal. Curve C shows a water
with a TOC that is not amenable to removal by coagulation. A slope of
0.3/10 is never reached.
Once a TOC percent removal is established at the slope of 0.3/10, a
utility may operate its water treatment plant with any combination of
acid and coagulant to achieve that percent TOC removal. Utilities may
find that the least-cost approach to achieving a specific TOC percent
removal may be with both sulfuric acid and a metal salt coagulant.
Other utilities may wish to avoid the concerns with handling sulfuric
acid and use alum or ferric salts to depress pH and produce a metal
hydroxide precipitate.
EPA solicits comment on whether a slope of 0.3 mg/L of TOC removed
per 10 mg/L of alum added should be considered representative of the
point of diminishing returns for coagulant addition under Step 2. EPA
also solicits comment on how the slope should be determined (e.g.,
point-to point, curve-fitting). If the slope varies above and below
0.3/10, where should the Step 2 alternate TOC removal requirement be
set--at the first point below 0.3/10? At some other point?
The requirement to add alum at 10 mg/L increments until the
``maximum pH'' is reached was developed to ensure that enough alum was
added to adequately test if TOC removal was feasible and to add it in
small enough increments to notice significant changes in the slope of
the coagulant dose-TOC removal curve. The maximum pH varies depending
on the alkalinity due to the difficulty in changing pH at the higher
alkalinities. Because alum coagulation of natural organic material is
most effective at a pH level between 5.5 and 6.5, large amounts of acid
would be required for high alkalinity waters to achieve this optimal
pH, followed by large amounts of base to raise the pH of the water up
to 8.0 before distributing to ensure compliance with the lead/copper
rule.
It is well demonstrated that the concentrations and characteristics
of TOC in source waters will change over time. In some source waters,
the rate of change could be rapid (such as during storm events). Other
source waters have a generally consistent TOC concentration and
characteristic due to storage of source water in reservoirs. EPA
proposes that, under guidance, the bench- or pilot-scale evaluation of
enhanced coagulation be performed on at least a quarterly basis, for
one year, to reflect seasonal changes in source water quality.
Currently, the proposed rule does not specify the frequency at which
the bench- or pilot-scale evaluation should be conducted because such
frequency of testing may not be warranted for all waters.
EPA solicits comment on how often bench- or pilot-scale studies
should be performed to determine compliance under step 2. Should such
frequency and duration of testing be included in the rule or left to
guidance (i.e., allow the State to define what testing would be needed
on a case by case basis for each system)? Is quarterly monitoring
appropriate for all systems? What is the best method to present the
testing data to the primacy agency that reflects changing influent
water quality conditions and also keeps transactional costs to a
minimum? How should compliance be determined if the system is not
initially meeting the percent TOC reduction requirements because of a
difficulty to treat waters and a desire to demonstrate alternative
performance criteria?
b. Enhanced softening. In general, there is much less data on the
removal of TOC during the softening process when compared to
conventional treatment. Based on the data available to the TWG, the
definition of enhanced softening is (a) the percent TOC removals
indicated for high alkalinity waters (> 120 mg/l) in Table IX-1, or (b)
the achievement of 10 mg/L magnesium removal during the softening
process. There are limited data on the use of ferrous salts at the high
pH levels of softening, but not enough to specify in this rule.
The calcium carbonate precipitate typically created during
softening is relatively dense and completely unlike the amorphous
aluminum and ferric hydroxide precipitates created in conventional
coagulation processes. It is the amorphous or gelatinous nature of the
aluminum and ferric hydroxides with their high surface areas that give
them their ability to absorb and remove TOC. Softening is carried out
at a wide range of pH levels, generally between 9.5 and 11.0. Above a
pH of about 10.5, magnesium precipitates as magnesium hydroxide (which
has very similar characteristics to alum and ferric precipitates). The
TWG determined that if a softening process could not achieve the
percent TOC removals shown in Table IX-1 under the alkalinity column of
>120 mg/L and it was practicing magnesium precipitation, there was
little more that could be done to enhance TOC removal. It is
anticipated that the vast majority of softening utilities will be able
to comply with these enhanced softening requirements. Not enough data
were available to the TWG to determine whether alternative enhanced
coagulation criteria needed to be defined and, if so, what they should
be.
EPA solicits comment on whether data are available on the use of
ferrous salts in the softening process which can help define a step 2
for enhanced softening. For softening plants, is enhanced softening
properly defined by the percent removals in Table IX-1 or by 10 mg/L
removal of magnesium hardness reported as CaCO<INF>3? Is there a step 2
definition? Can ferrous salts be used at softening pH levels to further
enhance TOC removals?
c. Preoxidation credit. Except for the conditions described below,
disinfection credit for the purpose of complying with the ESWTR is not
allowed prior to enhanced coagulation. The reason for these limitations
is the production of higher levels of DBPs when disinfectants are used
prior to the precursor removal step.
A number of water treatment plants add oxidants to the influent to
the treatment plant to control a variety of water quality problems. The
regulation allows the continuous addition of oxidants to control these
problems. The limitation on disinfection credit prior to enhanced
coagulation, except for the conditions described below, is expected to
keep the addition of disinfectants to the minimum necessary to control
the water quality problems that can be controlled by oxidation.
EPA solicits comments on whether preoxidation is necessary in water
treatment to control water quality problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams, taste and odor. Will allowing
preoxidation before precursor removal by enhanced coagulation generate
excessive DBP levels?
Ozone. Disinfection credit for ozone is allowed prior to enhanced
coagulation if it is followed by biologically active filtration (BAF)
because many of the organic DBPs formed by ozone are generally removed
by a biological process. In order to maintain a filter in a
biologically active mode, virtually no chlorine, chlorine dioxide, or
chloramines can be added to the filter influent.
EPA solicits comments on whether biologically active filtration
following ozonation is sufficient to remove most byproducts believed to
result from ozonation. What parameters, if any, should be measured in
and/or out of the filter to demonstrate a biologically active filter,
or alternatively, that ozone byproducts are adequately being removed?
For example, would it be sufficient to demonstrate greater than 90
percent removal of formaldehyde to establish that a filter is
biologically active and that predisinfection credit could therefore be
given?
Chlorine dioxide. Due to the wide variation in the application of
chlorine dioxide generation technology, it is common for water
treatment plants to apply chlorine dioxide along with an excess of free
chlorine. Technologies do exist to produce high purity chlorine
dioxide, but these technologies are not universally used. EPA is
proposing to allow disinfection credit for chlorine dioxide prior to
enhanced coagulation in the same manner as for ozone and BAF if the
system can demonstrate the generation of high purity chlorine dioxide.
Under the proposal, a system using chlorine dioxide could get
disinfection credit if the following standards are met: the chlorine
dioxide generator must generate chlorine dioxide on-site at a minimum
95 percent conversion efficiency (yield) from sodium chlorite; and the
generated chlorine dioxide feed stream applied from the chlorine
dioxide generator must contain less than five percent (by weight) free
chlorine residual, measured as the weight ratio of free residual
chlorine (i.e., hypochlorous acid) to chlorine dioxide in such feed
stream. Compliance with these standards must be demonstrated on an
ongoing basis for each generator in use. By meeting these standards,
chlorite and chlorate (chlorine dioxide generation byproducts) will be
limited and free residual chlorine will not be available to react with
the organic precursors prior to TOC removal and the potential for
halogenated organic DBP production is limited.
EPA solicits comments on whether disinfection credit should be
allowed for chlorine dioxide used prior to enhanced coagulation if
virtually no halogenated organic DBPs are formed. Should some other
limit, in addition to or in lieu of that proposed, be set (e.g., 5
<greek-m>g/L TTHMs) on DBPs formed by high purity chlorine dioxide to
ensure sufficient control for the production of excessive halogenated
organic DBPs if disinfection credit were to be allowed with chlorine
dioxide prior to enhanced coagulation?
Disinfection credit during cold water months. It is well
established that temperature plays a critical role in the production of
DBPs and that DBP concentrations are the lowest in winter months. The
cold water temperature months are also the most difficult time for
utilities to meet CT requirements, because longer contact times with a
disinfectant are needed to overcome the poorer inactivation
efficiencies.
Figure IX-2 plots the required CT values for inactivation of
Giardia cysts for free chlorine at various pH and log inactivation
levels. The family of curves clearly indicates a significant change in
slope below a temperature of 5 deg. C indicating that it is much more
difficult to achieve a log inactivation of Giardia cysts in water below
this temperature.

BILLING CODE 6560-50-P

<GRAPHIC><TIF26>TP29JY94.026

BLLING CODE 6560-50-C
NSERT FIGURE IX-2 HERE.
EPA is proposing that systems be allowed to add a disinfectant
before enhanced coagulation when water temperatures are less than or
equal to 5 deg.C. In order to ensure that excessive DBPs are not
produced by this special case and to more cost effectively balance
chemical and microbial risks, exercise of this provision would only be
allowed if the TTHM and HAA5 winter quarterly averages in the
distribution system served by the treatment plant are less than 40 and
30 ug/l, respectively.
EPA solicits comment on the appropriateness of this provision or
alternative means for addressing this issue.
d. Basis for Avoiding Enhanced Coagulation or Enhanced Softening
Requirements. The purpose of the treatment technique for control of
disinfection byproduct precursors (DBPPs) is to remove one of the
factors which result in the production of DBPs upon subsequent
disinfection. Criteria have been established which allow systems to
forgo the requirement to implement enhanced coagulation for control of
DBPPs. These criteria were generally established to either recognize
low potential of certain waters to produce DBPs or to account for types
of water which contain TOC that is difficult to remove by enhanced
coagulation. Implementation of enhanced coagulation in difficult to
treat waters generally costs much more than the average case used to
develop the national costs for this rule, and may introduce other water
quality problems.
TOC <2.0 mg/L. If a water contains less than 2.0 mg/L TOC before
continuous disinfection, it does not have to implement enhanced
coagulation. This level is calculated each quarter as a running annual
average, based on monthly (or quarterly, if the system has qualified
for reduced monitoring) treated water (i.e., prior to continuous
disinfection) TOC measurements. The basis for this criterion is related
to the purpose of the enhanced coagulation requirement (which is to
reduce the presence of organic matter when chlorine or other
disinfectants are added to the water). A TOC of less than 2.0 mg/L
would be expected, in general, to produce TTHM and HAA5 levels upon
chlorination that are less than 40 and 30 <greek-m>g/L, respectively.
This criterion would apply to high quality source waters and to systems
with water treatment plants which have installed a precursor removal
process other than enhanced coagulation prior to continuous
disinfection. High quality surface waters with TOC levels less than 2.0
mg/L account for less than 20 percent of the total number of utilities
using surface water in the U.S.
Systems with other installed precursor removal technologies include
a water treatment plant with granular activated carbon in a post-filter
adsorber configuration, e.g., Cincinnati, Ohio. As long as the TOC is
less than 2.0 mg/L before continuous disinfection, it is not important
which precursor removal technology is employed.
40/30/<4/>60. It is harder to remove organic matter by enhanced
coagulation in waters with alkalinities greater than 60 mg/L as
CaCO<INF>3 and TOC levels less than 4.0 mg/L. To compensate for this
phenomenon, systems with these water quality characteristics are
permitted to apply alternate disinfectants before any precursor removal
step and, if the TTHM and HAA5 levels produced are less than 40 and 30
<greek-m>g/L, respectively, the utility would not have to implement
enhanced coagulation. Source water TOC, source water alkalinity and
TTHM and HAA5 levels are calculated each quarter as running annual
averages, based on monthly measurements.
In addition to allowing systems that already meet these criteria to
avoid enhanced coagulation, the Committee also agreed to allow systems
that were installing alternative disinfection technology that would
allow the system to meet these criteria to avoid enhanced coagulation.
The technology must be installed prior to the compliance date for Stage
2 D/DBPR. For example, a system that already had a TOC of less than 4.0
mg/l and an alkalinity of greater than 60 mg/l would be allowed to
avoid enhanced coagulation if the system committed to installation of
ozonation. This commitment must include a clear and irrevocable
financial commitment not later than the effective date for compliance
with Stage 1 D/DBPR to technologies that will limit the levels of TTHMs
and HAA5 to no more than 0.040 mg/l and 0.030 mg/l, respectively.
Systems must submit evidence of the financial commitment, in addition
to a schedule containing milestones for installation and operation of
appropriate technologies, to the State for approval. Violation of the
approved schedule will constitute a violation of the National Primary
Drinking Water Regulation.
The schedule must be enforceable, but should only contain
significant milestones. Types of schedule items that should be included
as enforceable include award contract, begin construction, end
construction, pilot operations, and full compliance. The schedule
should allow for minor slippage, but must require compliance by the
compliance date for Stage 2. The State may also require periodic
progress reports, but EPA recommends that these not be part of the
enforceable schedule (and thus be a basis for finding the system in
violation for late submission or failure to submit).
The cost of employing enhanced coagulation to waters of this type
is higher than the base case examined as part of the regulatory impact
analysis for this rule. It is assumed that systems with this type of
water quality will, in general, achieve more cost effective reduction
of DBPs by use of alternative treatment strategies than by use of
enhanced coagulation. The overall purpose of this rule is to reduce the
levels of both DBPs that are known and DBPs which are not known. The
criterion in this section is expected to accomplish these goals.
40/30 with Chlorine. It is possible that some types of TOC do not
produce significant levels of DBPs upon chlorination. To account for
this fact, systems which use chlorine (and meet the CT requirements
under the SWTR or ESWTR) and which achieve running annual averages of
less than 40 and 30 <greek-m>g/L for TTHM and HAA5, respectively, do
not have to employ enhanced coagulation. The type of precursors
normally encountered in surface waters will produce TTHMs and THAAs
higher than the concentrations of 40 and 30 <greek-m>g/L if the TOC
level is greater than 2.0 mg/L and CT requirements are met. It is
expected that this criterion will not be applicable to many surface
water systems.
4. Basis for GAC Definitions
Treatment with granular activated carbon (GAC) has been found by
many researchers to remove organic DBP precursors. For water treatment
applications, GAC is typically placed in a gravity filter, not unlike
granular media filters for particle removal, and operated in a downflow
mode. The design parameters most often specified for the use of GAC are
empty bed contact time (EBCT) and regeneration frequency (or
equivalently, carbon use rate). During the development of this proposed
rule, GAC was defined at two levels of treatment to facilitate the
development of national cost data as well as project expected national
DBP levels resulting from the use of GAC treatment.
GAC10 means granular activated carbon filter beds with an empty-bed
contact time of 10 minutes based on average daily flow and a carbon
regeneration frequency of every 180 days. The GAC10 definition, which
was recommended by the TWG, was meant to specify the design and
operating conditions of GAC that would be necessary to remove
approximately the same amount of DBP precursors (measured as TOC) as
that achieved by enhanced coagulation. As discussed previously, the
Negotiating Committee agreed that enhanced coagulation or GAC10, used
in conjunction with chlorine as the sole disinfectant, should be the
BATs corresponding to the Stage 1 MCLs of 80 and 60 <greek-m>g/l for
TTHMs and HAA5, respectively.
GAC20 means granular activated carbon filter beds with an empty-bed
contact time of 20 minutes based on average daily flow and a carbon
regeneration frequency of every 60 days. The GAC20 definition,
recommended by the TWG, was meant to specify the conditions by which at
least 90% of the systems in the U.S. would be able to use this
technology, with chlorine as the sole disinfectant, and comply with the
Stage 2 MCLs of 40 and 30 <greek-m>g/l for TTHMs and HAA5,
respectively. The ability of systems to use GAC20 and achieve such
performance was tested and confirmed by the TWG using national TOC
occurrence data obtained from the Water Industry Data Base (WIDB) and
the Water Treatment Plant Simulation Model (USEPA 1992; USEPA, 1994).
The Water Treatment Plant Simulation Model predicts the production
of TTHMs and HAA5 based on water quality and treatment conditions. GAC
performance in the model is based on equation parameters developed as
part of a TOC removal study at Jefferson Parish, Louisiana. Jefferson
Parish is proposed as representative of the ``general case'' for TOC
removal. TOC removal has been demonstrated to be higher at Jefferson
Parish than at Manchester, NH; Miami, FL; and the Metropolitan Water
District of Southern California. TOC removal was lower at Jefferson
Parish than at Philadelphia, PA; Cincinnati, OH; and Shreveport, LA.
The TWG participants who developed these definitions also thought
that it would be conceivable for GAC10 to be employed in a filter media
replacement mode. GAC20 was clearly not compatible in a filter media
replacement mode and would have to be applied as post-filter adsorbers.
EPA solicits comment on whether GAC10 and GAC20 are reasonable
definitions of GAC performance? Do they span the expected level of GAC
applications in drinking water treatment for the control of TTHMs and
HAA5? Is it appropriate to consider Jefferson Parish, Louisiana, TOC
removal by GAC representative of the ``general case'' of TOC removal?
5. Basis for Monitoring Requirements
Monitoring for disinfection byproducts, disinfectant residuals, and
total organic carbon must be conducted during normal operating
conditions. Systems may not change their operating conditions for the
sole purpose of meeting an MCL or MRDL and then change back to an
operating regime that would not meet limits. For example, a system may
not reduce disinfectant feed temporarily to meet the chlorine MRDL and
the TTHM and HAA5 MCLs (or chlorine dioxide MRDL and chlorite MCL) and
then immediately revert to a higher feed. However, systems are allowed
to modify operations to address changing conditions and to protect
human health. For example, systems must modify operations to address
changes in source water quality or emergency conditions (such as
earthquakes and floods). Such modifications have been made for
legitimate reasons and are included as ``normal operations''.
Failure to monitor in accordance with the monitoring plan is a
monitoring violation. Where compliance is based on a running annual
average of monthly or quarterly samples or averages and the system's
failure to monitor makes it impossible to determine compliance with
MCLs or MRDLs, this failure to monitor will be treated as a violation
for the entire period covered by the annual average. Systems whose
monitoring is substantially complete will not be in violation for the
entire period covered by the annual average. Substantially complete
means that the State is able to determine MCL/MRDL compliance. For
example, a system that missed a few percent of its MRDL compliance
samples due to inability to sample at required locations (or took all
necessary samples, but had minor deviations from its monitoring plan)
would be able to determine compliance. These systems would be in
violation of monitoring requirements, but only for the month or quarter
(depending on the particular requirement). A system that did not take
samples or took samples at locations that would be expected to produce
results that are not representative (e.g., not taking TTHM samples at
the point of maximum residence time) is in violation for the entire
period covered by the annual average.
a. TTHMs and HAA5. In general, monitoring requirements for TTHMs
and HAA5 follow closely the requirements contained in the 1979 TTHM
rule. In that rule, there were provisions for routine and reduced
monitoring. In this proposal, the Agency has included the same
frequency of monitoring for routine monitoring for Subpart H systems
serving at least 10,000 people as in the 1979 TTHM rule, although the
Committee did not reach consensus on these specific requirements. See
below for (1) further discussion and (2) requests for comment on the
monitoring requirements. Subpart H systems serving 10,000 or more
persons must take four water samples each quarter for each treatment
plant in the system, with at least 25 percent of the samples taken at
locations within the distribution system that represent the maximum
residence time of the water in the system. The remaining samples must
be taken at locations within the distribution system that represent the
entire system, taking into account the number of persons served,
different sources of water, and different treatment methods employed.
Initial monitoring for ground water systems serving at least 10,000
people will be less than what is required under the 1979 TTHM rule,
because of the generally lower byproduct formation shown over the life
of the 1979 rule. Systems that use a chemical disinfectant must take
one water sample each quarter for each treatment plant in the system,
taken at locations within the distribution system that represent the
maximum residence time of the water in the system. Routine samples must
be taken at locations meant to reflect the highest possible TTHM and
HAA5 levels (i.e., at the maximum residence time in the distribution
system). If those samples are below the MCL, the Agency believes that
the system should be considered in compliance.
The Agency is also requiring systems not regulated under the 1979
TTHM rule to meet the requirements of this proposed rule. Community
water systems serving fewer than 10,000 people will be covered, as will
nontransient noncommunity water systems, a category that did not exist
in 1979. Nontransient noncommunity water systems must sample at the
same frequency and location as community water systems of the same
size.
Routine samples for these systems must be taken at locations meant
to reflect the highest TTHM and HAA5 levels (i.e., at the maximum
residence time in the distribution system). If those samples are below
the MCL, the Agency believes that the system should be considered in
compliance. Subpart H systems serving from 500 to 9,999 persons must
take one water sample each quarter for each treatment plant in the
system, taken at a point in the distribution system that represents the
maximum residence time in the distribution system.
Subpart H systems serving fewer than 500 persons must take one
sample per year for each treatment plant in the system, taken at a
point in the distribution system reflecting the maximum residence time
in the distribution system and during the month of warmest water
temperature, when the formation rate of TTHMs and HAA5 is the fastest.
This monitoring requirement will allow for a worst case sample, but
will limit the monitoring burden for these very small systems.
Systems using only ground water sources not under the direct
influence of surface water that use a chemical disinfectant and serve
less than 10,000 persons must sample once per year for each treatment
plant in the system, taken at a point in the distribution system
reflecting the maximum residence time in the distribution system and
during the month of warmest water temperature, as with very small
Subpart H systems.
All ground water systems may, with State approval, consider
multiple wells drawing water from the same aquifer as one plant for the
purposes of determining monitoring frequency. This provision is the
same as was in the 1979 TTHM rule. EPA requests comment on whether any
additional regulatory requirements, guidance, or explanation is
required to define ``multiple wells''. It was the intention of the
Committee that multiple wells include both individual wells and well
groups. This was done because many ground water systems are extremely
decentralized, with multiple entry points to the distribution system,
unlike most Subpart H systems with only one or several entry points.
Also, EPA requests comment on whether there should be an upper limit of
sampling frequency for systems that either cannot determine that they
are drawing water from a single aquifer or are drawing water from
multiple aquifers. For example, should a system that must draw water
from many aquifers to satisfy demand be allowed to limit monitoring as
if they were drawing from no more than four aquifers (routine sampling
would thus be limited to four samples per quarter from systems serving
at least 10,000 people or to four samples per year for systems serving
fewer than 10,000 people)? Does EPA need to develop any additional
guidance for any other aspect of this requirement?
Systems monitoring less frequently than one sample per quarter per
plant must increase monitoring to one sample per treatment plant per
quarter until the system meets criteria for reduced sampling if the
sample (or the average of the annual samples, when more than one sample
is taken) exceeds the MCL.
Systems may sample more frequently than one sample per quarter and
more frequently than required, but must take at least 25 percent of the
samples at a location reflecting the maximum residence time in the
distribution system. The remaining samples must be taken at locations
representative of at least average residence time in the distribution
system. Any public water system that samples once per quarter or less,
but more frequently than the frequency required in this section, must
take all of its samples at a location reflecting the maximum residence
time in the distribution system.
Taken together, these requirements attempt to balance TTHM and HAA5
formation, system size and source characteristics, and system
monitoring costs. As the number of required samples decreases, the
system is required to take samples at locations (and times, in some
cases) where the highest levels would be expected.
Reduced TTHM and HAA5 Monitoring. Some systems are not able to
reduce monitoring. Any Subpart H system which has a source water TOC
level, before any treatment, of greater than 4.0 mg/l may not reduce
its monitoring. Subpart H systems serving fewer than 500 people may not
reduce their monitoring to less than one sample per plant per year.
Should there be any exceptions that would allow systems with a TOC> 4.0
mg/l to reduce monitoring (e.g., the system has installed
nanofiltration)?
Systems may reduce monitoring (1) if they have a running annual
averages for TTHMs and HAA5 that are no more than 0.040 mg/l and 0.030
mg/l, respectively, or (2) for systems using ground water not under the
direct influence of surface water that serve fewer than 10,000 persons
and are required to take only one sample per year, if either (a) the
average of two consecutive annual samples is no more than 0.040 mg/l
and 0.030 mg/l, respectively, for TTHMs and HAA5 or (b) any annual
sample is less than 0.020 mg/l and 0.015 mg/l, respectively, for TTHMs
and HAA5. Systems must meet these requirements for both TTHMs and HAA5
to qualify for reduced monitoring. The system may reduce monitoring
only after the system has completed at least one year of monitoring.
This standard is more stringent than that in the TTHM rule, in which
the system had only to demonstrate that the TTHM concentrations would
be ``consistently below'' the MCL. The Negotiating Committee felt that
a more objective set of criteria were necessary.
Reduced monitoring frequency. Subpart H systems serving 10,000
persons or more that are eligible for reduced monitoring may reduce the
monitoring frequency for TTHMs and HAA5 to one sample per quarter per
treatment plant, with samples taken at a point in the distribution
system reflecting the maximum residence time in the distribution
system. Subpart H systems serving between 500 to 9,999 persons that are
eligible for reduced monitoring may reduce the monitoring frequency for
TTHMs and HAA5 to one sample per year per treatment plant, with samples
taken at a point in the distribution system reflecting the maximum
residence time in the distribution system and during the month of
warmest water temperature.
Systems using only ground water not under the direct influence of
surface water and serving 10,000 persons or more that are eligible for
reduced monitoring may reduce the monitoring frequency for TTHMs and
HAA5 to one sample per year per treatment plant, with samples taken at
a point in the distribution system reflecting the maximum residence
time in the distribution system and during the month of warmest water
temperature. Systems using only ground water sources not under the
direct influence of surface water and serving fewer than 10,000 persons
may reduce the monitoring frequency for TTHMs and HAA5 to one sample
per three-year monitoring cycle, with samples taken at a point in the
distribution system reflecting the maximum residence time in the
distribution system and during the month of warmest water temperature.
EPA believes that this procedure of taking worst-case samples less
frequently will adequately identify systems with TTHM and HAA5
problems, since systems have to meet relatively stringent criteria to
be eligible for reduced monitoring. Systems which are on a reduced
monitoring schedule may remain on that reduced schedule as long as the
average of all samples taken in the year (for systems which must
monitor quarterly) or the result of the sample (for systems which must
monitor no more frequently than annually) is no more than 75 percent of
the MCLs. Systems that do not meet these levels must resume monitoring
at routine frequency. Also, the State may return a system to routine
monitoring at the State's discretion.
During the negotiated rulemaking, the Association of State Drinking
Water Administrators (ASDWA) expressed the opinion that the reduced
monitoring for ground water systems serving fewer than 10,000 people
could be expanded beyond what is in the proposal. These are the systems
usually having multiple ground water sources, whose quality is unlikely
to change with respect to DBP precursors and are most likely to benefit
from reduced monitoring. The additional options presented below both
have as a basis the demonstration that the ground water source in
question has a minimal likelihood of having precursor material that
could combine with chlorine to form any significant concentrations of
THMs or HAA5s. Each option would rely on having each entry point of the
system go through three years of routine monitoring to qualify for
reduced monitoring. After this period, if the entry points meet
additional criteria, then the entry points would be subject to minimal
additional monitoring. Option one would reduce the monitoring to once
every nine years for THMs and HAA5s in the distribution system. This
option would minimize the expense of THM and HAA5 monitoring for these
systems. Option two, which specifies even more restrictive criteria,
would exempt systems from any additional THM and HAA5 monitoring as
long as the TOC criteria are met. This option offers the largest cost
savings and eliminates the need for tracking and enforcing monitoring
requirements on those systems that have historically had the poorest
monitoring compliance records and are least likely to have significant
levels of DBPs. The Agency would like to receive comments on the
following two options.
Option One: Any ground water system serving fewer than 10,000
people that has a raw water TOC of less than 1.0 mg/l, and has both
TTHM and HAA5 values less than 25 percent of the MCLs (20 <greek-m>g/l
and 15 <greek-m>g/l, respectively) after three years of routine and
reduced monitoring, can reduce the monitoring for TTHMs and HAA5s to
one sample every nine years, taken at the maximum distribution system
residence time during the warmest month.
Option Two: Any ground water system serving fewer than 10,000
people that has a raw water TOC of less than 0.5 mg/l, and has both
TTHM and HAA5 values less than 25 percent of the MCLs (20 <greek-m>g/l
and 15 <greek-m>g/l, respectively) after three years of routine and
reduced monitoring, is exempt from the distribution system monitoring
requirements for TTHMs and HAA5s for as long as TOC monitoring is
conducted once every three years and the raw water TOC remains less
than 0.5 mg/l.
These options are not mutually exclusive, that is, both could be
used simultaneously or some hybrid could be developed. The Agency seeks
comment on whether either or both of these options are reasonable in
adequately protecting the public health and should therefore be
considered as criteria for reduced monitoring. Are there other options
for reduced monitoring that should be considered? What are they?
Consensus was not reached on certain key aspects of monitoring and
compliance determination. Some members of the Negotiating Committee
expressed concerns about the following issues, especially (but not
solely) as related to TTHMs and HAA5 monitoring:

--Is the monitoring frequent enough to adequately determine variations
in sample results caused by time and/or location in the distribution
system? If not, what is a more appropriate monitoring schedule? Should
requirements differ for systems based on population served, raw water
source, or other factors? If so, should the proposed requirements be
changed? How should they be changed? If requirements should not be
based on these factors, what should the requirements be?
--Does averaging of sample results taken in various locations and
averaging over the course of a year to determine compliance adequately
protect individuals that are in locations that may regularly have
higher than average levels? If it does not, how should the proposed
requirements be changed?

EPA solicits comment on the above issues.
b. Basis for TOC Monitoring Requirements With Enhanced Coagulation
or Enhanced Softening. In order to demonstrate that the necessary DBPP
removal is accomplished (either the percentage specified in Table IX-1
or the alternative minimum TOC removal level determined by the AECL),
systems must monitor TOC on a monthly basis, with both source water and
treated water (prior to continuous disinfection) samples taken. At the
same time, systems must monitor for source water alkalinity. Compliance
is based on a running annual average, computed quarterly. Specifics on
compliance calculations are included in Section VIII.

B. Bromate MCL and BAT

During the D/DBP negotiated regulation, ozone was evaluated as an
alternative disinfectant to chlorine. In particular, the use of ozone
for primary disinfection and chloramines for residual disinfection were
considered as a disinfection scenario to significantly minimize the
formation of THMs, HAAs, and TOX (Metropolitan Water District of So.
Calif. et al., 1989; Ferguson et al., 1991; Glaze et al., 1993, in
press; Miltner, 1993; and Jacangelo et al., 1989). In addition, when a
``cancer-risk bubble'' was evaluated by examining the theoretical risks
contributed by five compounds that have been classified as B2 (i.e.,
``probable human'') carcinogens (i.e., chloroform,
bromodichloromethane, bromoform, dichloroacetic acid [DCAA], and
bromate), it was shown that the production of bromate during ozonation
may present less of a theoretical cancer risk than the sum of the risks
from the individual chlorination DBPs. However, such a determination
largely depended upon the risk attributed to DCAA (which had not been
finally established by EPA). Also, the ability to detect bromate at
risk levels equivalent to risk levels for chlorinated DBPs greatly
obscures this analysis.
As part of the TWG evaluation of different technologies that might
be used to comply with the D/DBP Rule, ozone/chloramines were evaluated
under a possible enhanced SWTR scenario for large systems using surface
waters that filter but do not soften. It was predicted that TTHMs would
range from 4 to 62 <greek-m>g/L, with median, 75th, and 90th percentile
values of 15, 23, and 30 <greek-m>g/L, respectively. In addition, it
was predicted that HAA5 would range from 2 to 133 <greek-m>g/L, with
median, 75th, and 90th percentile values of 16, 26, and 41 <greek-m>g/
L, respectively. The TWG believed that use of alternative disinfectants
would provide a feasible means of not only achieving the Stage 1
criteria of 80 <greek-m>g/L TTHMs and 60 <greek-m>g/L HAA5 but also
allow some systems the means of complying with a proposed Stage 2
criteria of 40 <greek-m>g/L TTHMs and 30 <greek-m>g/L HAA5. As
discussed previously (Section VI.C.1.b.ii), the TWG also conducted an
analysis of bromate occurrence with use of ozone technology and
determined that most systems, allowing for modifications in treatment
if necessary, such as lowering of pH, could achieve a bromate level of
10 <greek-m>g/L (Krasner et al., 1993).
A major issue, however, is the ability to determine low levels of
bromate during compliance monitoring and concern that the risk from
bromate could exceed the risk from chlorinated DBPs for which risk
estimates are available. While Haag and Hoigne discussed the
theoretical basis for the formation of bromate in their 1983 paper
(Haag et al., 1983), an analytical method sensitive enough to determine
if bromate was indeed formed in ozonated drinking water was not
available until a few years ago (Pfaff et al., 1990). In addition, the
initial ion chromatography (IC) method was unable to adequately resolve
low levels of bromate from very high amounts of chloride. Because most
waters high in bromide can have very high levels of chloride
(Metropolitan Water District of So. Calif. et al., 1989), Kuo and
colleagues developed a modification to the IC method in order to remove
chloride prior to bromate analysis (Kuo et al., 1990). This
modification permitted quantitation of bromate down to a concentration
of 10 <greek-m>g/L; subsequently quantitation has been lowered in
several research laboratories to 3 or 5 <greek-m>g/L (Gramith et al.,
1993). Using two different labor-intensive concentration methods prior
to IC analysis at EPA research facilities, quantitation for bromate was
lowered to less than 1.0 <greek-m>g/L (Sorrell et al., 1992 and
Hautman, 1992).
Currently, though, a minimum quantitation level for bromate by
conventional IC is probably about 10 <greek-m>g/L in laboratories that
might perform compliance monitoring. During the D/DBP negotiated
rulemaking, some members of the Negotiating Committee expressed concern
that setting an MCL at 10 <greek-m>g/L would exceed the theoretical
10-4 risk level for bromate of 5 <greek-m>g/L. The regulation of
bromate, at this time, represents an unresolved issue. However, the
Negotiating Committee was willing to propose an MCL for bromate of 10
<greek-m>g/L with the following qualifications and reservations:

EPA is seeking data to show that a lower quantitation level (at
least down to 5 <greek-m>g/L) can be obtained by those laboratories
that will perform compliance monitoring for bromate in natural drinking
water matrices. Whether this improvement in sensitivity is accomplished
by improvements to the official EPA method 300.0 (USEPA, 1993) or an
alternative analytical method, such data would need to demonstrate
appropriate precision and accuracy, including a linear calibration
curve for the range of values to be measured, quantitative and precise
measurements at the MCL (U.S. Office of the Federal Register, 1987),
intra- and interlaboratory reproducibility, as well as freedom from
potential interferences in natural matrices (e.g., other anions in
water such as chloride, and other ozone byproducts such as organic
acids). In addition, this methodology would need to be demonstrated in
a number of ozonated drinking water matrices and tested in several
laboratories nationwide. If the improved methodology uses equipment
and/or reagents that are not currently required for EPA method 300.0,
data to indicate the commercial availability and costs of these items
would also need to be presented.
In addition, EPA is soliciting comments on a treatment technique
that could ensure that bromate can be kept below 5 <greek-m>g/L, even
if quantitation at 5 <greek-m>g/l is not achievable under routine
laboratory conditions. A possible treatment technique that could ensure
that all systems be able to produce <ls-thn-eq>5 <greek-m>g/L bromate
(the theoretical 10-4 risk level), would be to construct a matrix
of predicted bromate concentration as a function of bromide
concentration levels, ozone disinfection conditions (CT), and pH levels
under which ozonation occurs. As the bromide and/or inactivation
criterion increased, the pH of ozonation might need to be decreased to
ensure that the bromate concentration was kept below 5 <greek-m>g/l.
Under a treatment requirement, if a system used ozone, it would be
required to operate within the specified matrix conditions for bromide,
CT, and pH levels to achieve compliance. This matrix would need to
consider ozone residuals sufficient to meet CT criteria for a possible
ESWTR.
Other treatment techniques which allow ozone to meet disinfection
and oxidation requirements while minimizing bromate formation are also
solicited. In addition, any proposed treatment technique must be fieldtested
in a number of representative natural water matrices. A number
of parameters which can affect bromate formation and must be evaluated
in establishing a treatment technique include TOC, bromide, alkalinity,
pH, ammonia, and hydrogen peroxide levels of the water, as well as the
temperature and ozone contact time (Krasner et al., Jan. 1993; Amy et
al., 1992-3; Haag et al., 1983; Glaze et al., Jan. 1993; Krasner et
al., 1991; Miltner, Jan. 1993; Krasner et al., 1993; Gramith et al.,
1993; Miltner et al., 1992; Siddiqui et al., 1993; and Von Gunten et
al., 1992). Because the hydrodynamics of the ozone contactor can
significantly affect bromate formation (Krasner et al., Jan. 1993;
Krasner et al., 1991; and Gramith et al., 1993), the treatment
technique may need to be evaluated at pilot-, demonstration-, and/or
full-scale. (Bench-scale testing can be used in preliminary evaluations
of ozone/bromide/bromate chemistry, but such experiments cannot provide
the sole basis for determining an appropriate treatment technique.)
Evaluation of the treatment technique will also require
quantitation of bromate concentrations that are <ls-thn-eq>5
<greek-m>g/L. Thus, appropriate quality assurance and control will be
required to ensure that the data are precise and accurate.
Because the proposed bromate MCL of 10 <greek-m>g/L was
determined to be feasible based upon studies performed to date, if
sufficient data are presented to EPA to indicate that a lower MCL and/
or an appropriate treatment technique can be obtained, the feasibility
and nationwide regulatory impact would need to be considered. For
example, the cost of chemical addition to lower the pH of water before
ozonation and to raise the pH prior to distribution was not considered
in developing the national cost data for systems using ozone to meet
the D/DBP Rule. This cost for pH adjustment could be significant for
systems with high alkalinity. EPA requests comment on the cost impact
that this requirement would have on systems with both high alkalinity
and high bromide levels. The effect of a treatment technique would also
need to be evaluated in terms of other water quality impacts.
Therefore, if a treatment technique is developed, EPA would revise the
regulatory impact analysis to reflect new costs and other water quality
impacts. EPA requests comment on the relative costs of adjusting pH to
reduce bromate formation versus the costs of other technologies to meet
the MCLs in this proposed rule.
The following limited data suggest that a significant increase in
sensitivity of the method for measuring bromate may indicate that other
disinfectant/oxidants produce bromate, and/or that bromate may be a
contaminant in some source waters. In a study conducted to test a more
sensitive method for measuring bromate (Hautman, 1992), a bromate
concentration of 0.4 <greek-m>g/L was measured in one of the nine
source waters tested (i.e., before the point of disinfection/
oxidation). However, the researcher did not rule out the possibility of
sample contamination of this source water. Theoretical and limited data
suggest that chlorine dioxide can react with bromide in the presence of
sunlight to form brominated DBPs, including possibly bromate (Cooper,
1990 and Kruithof, 1992). Likewise, under alkaline conditions, bromide
reacts with hypochlorite to form hypobromite which then
disproportionates to bromate (Bailar et al, 1973). When the
hypochlorite solutions from 14 drinking water utilities were surveyed
for the presence of oxyhalides (Bolyard et al., 1992), bromate was
measured in nine of the hypochlorite solutions, at levels of 4 to 51
mg/L. However, the chlorinated drinking water samples did not contain
bromate at concentrations above the 10 <greek-m>g/L quantitation level.
Based on this information, if the MCL for bromate is lowered, analyses
for the occurrence of bromate may need to be extended to sources other
than ozonated water.
EPA plans to convene a second meeting of interested parties to
develop a consensus on the second stage of the D/DBP Rule in 1998. It
is anticipated that by that time, measurement for bromate at
concentrations <10 <greek-m>g/L may be practical, more health effects
data on this DBP will be available, and the treatment to control
bromate formation will be appropriately developed and field tested. EPA
solicits comments on the feasibility of developing a treatment
technique requirement for bromate, lowering the MCL based upon improved
analytical techniques, and the time frame under which such alternative
standards could be developed.
In the proposed D/DBP Rule, bromate compliance will be based on a
running annual average value. This schedule is analogous to that used
for THMs and HAAs. Because carcinogens represent a risk based upon a
lifetime exposure, temporary peaks in exposure should not affect the
lifetime cancer risk. Unlike THMs and HAAs, though, bromate will be
measured monthly rather than quarterly and at the entry point to the
distribution system rather than in the distribution system. THMs and
HAAs can increase in a distribution system as DBP precursors continue
to react with the residual disinfectant, especially if free chlorine is
used. Because ozone and other active oxidant residuals (e.g., hydroxyl
radicals) are short-lived, bromate formation should be complete within
the treatment plant. Once in the distribution system, bromate should be
stable (Glaze et al., 1993, in press), so analyzing samples in the
distribution system will provide no additional information. Because
there are many water quality parameters and treatment plant operations
that can affect bromate formation, it was not clear whether quarterly
monitoring would be adequate to capture the variability in bromate
formation (Krasner et al., Jan. 1993, Miltner, Jan. 1993, and Gramith
et al., 1993). However, EPA is proposing reduced bromate monitoring
where a utility's average raw water bromide level is less than 0.05 mg/
L. This reduction is based on limited data to date to suggest that
under typical drinking water ozonation conditions of water with
<ls-thn-eq>0.05 mg/L bromide (based on pilot- and full-scale data) that
bromate will typically not be formed at levels of 5 to 10 <greek-m>g/L
or higher (Krasner et al., 1993).

C. Chlorite MCL and BAT

Chlorite is formed as a result of treating source water with
chlorine dioxide. Many utilities use chlorine dioxide because of
specific water quality characteristics that make the water difficult to
treat. These characteristics include high hardness, TOC, and bromide
concentrations. For example, at high pHs (above 9.0), chlorine is much
less effective as a disinfectant and ozone residuals cannot be
maintained in solution long enough for effective disinfection. Systems
now using chlorine dioxide may not be able to meet the standards
proposed in this regulation, since in some cases, even expensive
precursor removal technologies such as GAC or membrane technology may
not be able to remove precursors adequately to meet DBP MCLs and, in
other cases, systems may not be able to use the technologies due to
site restrictions (e.g., membranes not feasible due to water limits--
system cannot afford loss of significant amounts of water as membrane
reject).
While research is underway on how to reduce chlorite residuals at
the treatment plant, e.g., using ferrous iron (Griese et al., 1992),
additional work is required. At this time, the only means for reducing
chlorite levels is to control the use of chlorine dioxide.
During the negotiations, EPA had not yet established a reference
dose for chlorite and, therefore, no MCLG was considered at that time.
However, EPA's Office of Water staff stated that they interpreted the
available health effects data to indicate the toxicological endpoint of
concern as oxidative stress to red blood cells. This effect is
considered reversible, lasting a matter of a few weeks or months.
Based on considerations that the health effect was of relatively
short duration, and that some systems might require chlorine dioxide,
the Negotiating Committee agreed to propose a conditional MCL of 1.0
mg/l. This MCL was selected based on a recommendation from the TWG that
1.0 mg/l is the lowest level achievable by typical systems using
chlorine dioxide, and taking into consideration the monitoring
requirements to determine compliance.
In agreeing to propose 1.0 mg/l as the MCL for chlorite, the
Negotiating Committee set certain qualifications and reservations:
(1) If EPA proposed a MCLG for chlorite of 1.0 mg/l or higher, the
proposed MCL would be set at the MCLG value. If EPA proposed a MCLG for
chlorite of less than 1.0 mg/l based on EPA's reference dose, the
proposed MCL would be set at 1.0 mg/l based on technological
feasibility considerations.
(2) Additional research would be conducted including a twogeneration
reproductive effects study in animals and a clinical study
of humans exposed to chlorite to determine what minimum levels of
exposure can be considered safe. It was agreed that these studies would
be completed in time for consideration of possible changes to the MCL
under the final Stage 1 rule. If the studies indicate that a level of
1.0 mg/l of chlorite is safe, the MCL would remain at 1.0 mg/l. If the
studies indicate that a level of 1.0 mg/l of chlorite is not safe or,
if such a study is not conducted, the MCL would be reevaluated.
Based on a consideration that the health effect is reversible and
relatively short term in duration, the Negotiating Committee agreed
that systems would determine compliance by monitoring for chlorite
three times per month. Samples would be taken at the following
locations: one near the first customer, one in a location
representative of average residence time, and one near the end of the
distribution system reflecting maximum residence time. Monitoring would
be conducted in the distribution system since the concentration of
chlorite is likely to increase in the distribution system. If the
monthly average of the three distribution system samples exceeded the
MCL, the system would be in violation for that month. In agreeing to
propose these requirements, the Negotiating Committee assumed that, if
a system were out of compliance during one month but achieved
compliance during the following month, that any health effects that
might occur from the short term exposure would cease once the system
achieved compliance.
After the Negotiating Committee agreed to propose the above MCL and
monitoring requirements at its last meeting in June, 1993, EPA's
Reference Dose Committee met and determined a different toxicological
endpoint for chlorite. The Reference Dose Committee determined that
chlorite poses an acute developmental heath effect, which is a
neurobehavioral effect: depressed exploratory behavior. Based on the
new reference dose, the MCLG for chlorite would be 0.08 mg/l (see
section V of this preamble). The derivation of the MCLG includes a
1,000-fold uncertainty factor to account for use of a LOAEL instead of
a NOAEL from an animal study. EPA does not believe that the proposed
MCL of 1.0 mg/l and monitoring requirements agreed to by the
Negotiating Committee are adequate to protect the public from the acute
developmental health effect, unless new data indicate otherwise.
EPA is concerned about proposing an MCL significantly above the
MCLG, especially since the MCLG is based on acute health risks. EPA is
proposing this level to honor the agreement of the Negotiating
Committee. However, EPA solicits comment on the following approaches
for promulgating a final rule.
(1) EPA could promulgate an MCL at the MCLG. Based on currently
available information, an MCL of 0.08 mg/l would probably rule out the
use of chlorine dioxide as a disinfectant, since it does not appear
possible for systems to meet simultaneously disinfection requirements
and the resultant chlorite MCL. If new data become available indicating
a NOAEL of 1 mg/kg/day, the highest resultant MCLG and corresponding
MCL would likely be no more than 0.3 mg/l. An MCL of 0.3 mg/l for
chlorite ion would allow some systems to be able to use chlorine
dioxide. However, other water systems, because of water quality
parameters that affect chlorine dioxide demand and chlorite ion
control, will not be able to find a feasible operating region to use
chlorine dioxide, at least on a year-round basis. EPA would be
concluding that other technologies besides chlorine dioxide are
feasible for those systems for meeting the Stage 1 D/DBPR and SWTR (or
ESWTR, if such a rule is necessary), taking cost into consideration for
systems currently using chlorine dioxide. A regulatory impact analysis
will have to be prepared to evaluate technical feasibility, production
of other DBPs based on a different disinfectant, and cost
considerations.
(2) EPA could promulgate an MCL lower than the proposed MCL of 1.0
mg/l, but above the MCLG, depending upon all data that became available
in the near term. In doing so, EPA would be concluding that risks from
other alternatives are commensurate at this level, or that other
technologies, taking costs into consideration, are not available at the
0.08 mg/l level, but are available at a higher level. EPA would thus be
indicating that some systems must use chlorine dioxide to meet
disinfection requirements, but can maintain compliance by making
operational modifications that are not available to all systems. This
approach would more narrowly limit the use of chlorine dioxide to
systems with very specific source water or other characteristics if use
of chlorine dioxide were considered essential versus use of other
disinfectants.
(3) Depending on new data that become available, EPA could
promulgate an MCL at the proposed MCL of 1.0 mg/l if the Agency
determined that the systems currently using chlorine dioxide could not
meet disinfection requirements in any other feasible manner, taking
cost into consideration.
As part of any of the above approaches, EPA could accelerate the
promulgation of NPDWRs for chlorine dioxide and chlorite if the Agency
believed it necessary to avoid acute health effects. Also, as part of
the final rule, EPA would consider the appropriateness of the proposed
monitoring requirements and public notification language in light of
the acute health effect. Monitoring changes could include increasing
the sampling frequency, changing the location of monitoring, and/or
changing the determination of compliance. These changes may result in
requirements similar to those for chlorine dioxide (e.g., daily
measurements within the distribution system to determine compliance).
In making its final decision, EPA will consider a number of
factors: the risk which would be posed from chlorite and chlorine
dioxide compared to the risk from other contaminants if chlorine
dioxide were not used, the uncertainty in those risk estimates, the
feasibility of using other means of control, and the cost of those
other control mechanisms.
EPA requests comments on the above approaches for regulating
chlorite. Specifically, EPA requests comment on the following:

--Is the basis for EPA's MCLG and concern for acute health effects
appropriate? See Section V. for a complete discussion.
--In light of the proposed MCLG and concern for acute health risks that
were not apparent during the negotiations, should EPA accelerate the
promulgation of NPDWRs for chlorine dioxide and chlorite? If so, should
EPA set the MCL at the proposed MCLG? Should EPA wait until more data
become available, as agreed upon during the negotiations, before
promulgating an MCL? Such data will be available through CMA. CMA is
conducting health effects studies to fill data gaps for chlorine
dioxide and chlorite. EPA will evaluate these data (which are scheduled
to be available prior to rule promulgation) to help determine what
changes to the MRDLG and MRDL may be warranted.
--Are there any particular water quality characteristics for systems
currently using chlorine dioxide which make it ineffective to use any
other disinfection technology?
What are the lowest chlorite levels these systems can achieve? What
technologies would need to be adopted and at what costs if such systems
with these particular water quality characteristics would no longer use
chlorine dioxide to meet the other regulatory criteria proposed herein?
--Should EPA set the chlorite MCL at a level so that chlorine dioxide
remains a viable disinfection alternative for some systems even if this
level is above the MCLG? If so, what would be the rationale for doing
so?
--Is 1.0 mg/l the lowest level that systems needing chlorine dioxide
can reliably achieve?
--How should EPA change the compliance monitoring requirements for
chlorite to reflect concern about acute effects? Should such changes
include increasing the frequency or changing the location of monitoring
to be similar to those for chlorine dioxide? How would the MCL be
affected by changes in the monitoring requirements?
--How should EPA change the public notification requirements for
chlorite to reflect concern about acute effects?

D. Chlorine MRDL and BAT

The chlorine MRDL has been set at the MRDLG of 4.0 mg/l, with
compliance being based on a running annual average of monthly averages
of samples taken in the distribution system. A running annual average
was used as the basis for compliance because health effects are long
term (see Section V.).
There will be no additional monitoring required by Subpart H
systems to comply with this requirement, since samples that are already
required to be taken by systems to comply with the Surface Water
Treatment Rule (see 40 CFR 141.74) may be used to demonstrate
compliance with the MRDL. The samples required under the SWTR are used
to demonstrate compliance with the requirement for maintenance of a
residual in the distribution system (in effect, a floor or minimum);
the samples required under this rule would set a maximum or ceiling for
chlorine levels.
Additional monitoring is required for systems that use only ground
water not under the direct influence of surface water to comply with
this requirement, since samples are not already required to be taken by
these systems. However, this sampling may be required to comply with
the forthcoming Ground Water Disinfection Rule (GWDR) to be proposed at
a later date. If such monitoring is required by the GWDR, one set of
samples will be allowed to be used to demonstrate compliance with both
the MRDL in this rule and the distribution system monitoring
requirements in the GWDR.
Since compliance is based on an annual average, the MRDL does not
apply to individual samples, which are allowed to be higher than the
MRDL. In addition, allowing individual samples to exceed the MRDL gives
the system operator the flexibility to address short-term
microbiological problems caused by distribution system line breaks,
storm runoff events, source water contamination, or cross connections.
EPA believes that it is essential that system operators are aware
of the flexibility that this rule gives them in addressing specific
microbiological threats without worrying about violating an MRDL. For
this reason, the definition of ``maximum residual disinfectant level''
proposed today in Sec. 141.2 specifically allows higher disinfectant
levels for the two disinfectants with long-term, but not short-term,
effects (chlorine and chloramines), while pointing out that increasing
levels of chlorine dioxide to address short-term problems is not
allowed (because of the short-term health effects--see Section V.). The
Agency believes that even if systems must increase disinfectant levels
to address specific contamination problems, they will be able to meet
the MRDL on an annual basis.

E. Chloramine MRDL and BAT

The chloramine MRDL has been set at the MRDLG of 4.0 mg/l, with
compliance based on a running annual average of monthly averages of
samples taken in the distribution system. A running annual average was
used as the basis for compliance because health effects are long term
(see Section V.). The Negotiating Committee considered a range of 4 to
6 mg/l and chose 4 mg/l. This decision was based on compliance being
determined by a running annual average rather than by individual
samples. Also, 4 mg/l was thought to be the lowest feasible MRDL for
some systems that would not compromise microbial protection. Residual
disinfectant demand could be reduced by additional precursor removal,
but the Negotiating Committee agreed that precursor removal beyond that
achieved by enhanced coagulation or enhanced softening should not be
required in Stage 1. EPA requests comment on what level would be
feasible to achieve by most systems without increasing microbial risk.
There will be no additional monitoring required by Subpart H
systems to comply with this requirement, since samples that are already
required to be taken by systems to comply with the Surface Water
Treatment Rule (see 40 CFR 141.74) may be used to demonstrate
compliance with the MRDL. The samples required under the SWTR are used
to demonstrate compliance with the requirement for maintenance of a
residual in the distribution system (in effect, a floor or minimum);
the samples required under this rule would set a maximum or ceiling for
chloramine levels.
Additional monitoring is required for systems that use only ground
water not under the direct influence of surface water to comply with
this requirement, since samples are not already required to be taken by
these systems. However, this sampling may be required to comply with
the forthcoming Ground Water Disinfection Rule (GWDR) to be proposed at
a later date. If such monitoring is required by the GWDR, one set of
samples will be allowed to be used to demonstrate compliance with both
the MRDL in this rule and the distribution system monitoring
requirements in the GWDR.
Since compliance is based on an annual average, the MRDL does not
apply to individual samples, which are allowed to be higher than the
MRDL. In addition, allowing individual samples to exceed the MRDL gives
the system operator the flexibility to address short-term
microbiological problems caused by distribution system line breaks,
storm runoff events, source water contamination, or cross connections.
EPA believes that it is essential that system operators are aware
of the flexibility that this rule gives them in addressing specific
microbiological threats without worrying about violating an MRDL. For
this reason, the definition of ``maximum residual disinfectant level''
proposed today in Sec. 141.2 specifically allows higher disinfectant
levels for the two disinfectants with long-term, but not short-term,
effects (chlorine and chloramines), while pointing out that increasing
levels of chlorine dioxide to address short-term problems is not
allowed (because of the short-term health effects--see Section V.). The
Agency believes that even if systems must increase disinfectant levels
to address specific contamination problems, they will be able to meet
the MRDL on an annual basis.

F. Chlorine Dioxide MRDL and BAT

EPA has proposed the MRDLG for chlorine dioxide at 0.3 mg/L (see
section V of this preamble). The derivation of the MRDLG includes an
uncertainty factor of three to address one data gap (i.e., lack of a 2-
generation reproduction study). In the near future, it is tentatively
planned that health effects studies on the impact of chlorine dioxide
in drinking water will be performed to resolve the data gap concerning
reproductive effects.
Chlorine dioxide is used in Europe as a residual disinfectant,
while in the U.S. it is used for disinfection or oxidation within the
treatment plant. Because chlorine dioxide residuals are short-lived,
they are typically not detected in distribution systems. When chlorine
dioxide residuals are analyzed, the presence of other oxidants (e.g.,
chlorine, chlorite, and chlorate) must be subtracted out from a total
oxidant measurement. In a method where the value is obtained by
difference, there is a limit to how low a quantitative measurement can
be made. The PQL for chlorine dioxide residuals is probably in the
range of 0.5 to 1.0 mg/L.
Systems must monitor for chlorine dioxide daily since there are
acute health effects. Monitoring must be conducted at the entrance to
the distribution system, since the concentration of chlorine dioxide
will not increase in the distribution system. If monitoring indicates
that the concentration of chlorine dioxide exceeds the MRDL, the system
is then required to conduct additional monitoring in the distribution
system. This monitoring consists of three samples taken the day
following an exceedance of the MRDL at specific locations within the
distribution system considered to be those most likely to have the
highest levels and depend on the type and location of residual
disinfection. For systems that use chlorine dioxide or chloramines to
maintain a residual in the distribution system, or that use chlorine
with no booster chlorination after the water enters the distribution
system, three samples must be taken as close as possible to the first
customer at intervals of at least six hours. For systems that use
chlorine to maintain a disinfectant residual in the distribution
system, and have one or more locations within the distribution system
where additional chlorine is added (i.e., booster chlorination),
samples must be taken at the following locations: One as close as
possible to the first customer, one in a location representative of
average residence time, and one near the end of the distribution system
reflecting maximum residence time. These additional samples must be
taken each day following any sample taken at the entrance to the
distribution system that exceeds the MRDL.
Compliance is based on samples taken both at the entrance to the
distribution system and in the distribution system. If one or more of
the samples taken in the distribution system exceed the MRDL, the
system has an acute violation and must take immediate corrective action
to lower the level of chlorine dioxide and make appropriate public
notification. If two consecutive samples taken at the entrance to the
distribution system exceed the MRDL (and none of the required samples
taken in the distribution system exceed the MRDL), the system has a
nonacute violation and must take corrective action to lower the level
of chlorine dioxide and make appropriate public notification. If a
required sample is not taken, the system must treat it as if the sample
had been taken and exceeded the MRDL. Therefore, failure to take one or
more of the additional distribution system samples the day following a
sample taken at the entrance to the distribution system that exceeds
the MRDL is considered an acute violation. Failure to take a sample at
the entrance to the distribution system the day following a sample
taken at the entrance to the distribution system that exceeds the MRDL
is considered a nonacute violation.
The Negotiating Committee agreed to propose 0.8 mg/L as the MRDL
for chlorine dioxide with certain qualifications and reservations:
(1) A two-generation reproductive study would be completed for
consideration in the final Stage 1 rule. If this study indicates there
is no concern from reproductive effects at the proposed MRDL, unless
public comments otherwise influence the Agency, then the proposed MRDL
would remain the same as proposed (0.8 mg/l).
(2) If no new health effects studies become available on
reproductive effects, the chlorine dioxide MRDL will be reassessed. It
will be necessary to re-examine the tradeoffs and regulatory impacts of
a lower chlorine dioxide MRDL in light of the positive aspects of
chlorine dioxide disinfection and control of chlorination DBPs. EPA
would probably promulgate a final MRDL that is the higher of the MRDLG
or the detection level because the health effects are acute. Issues
that would be considered include new information on health effects of
other disinfectants.
As part of the above approaches, EPA could accelerate the
promulgation of an NPDWRs for chlorine dioxide if the Agency believed
it necessary to avoid acute health effects. In making its final
decision, EPA will consider a number of factors: The risk which would
be posed from chlorite and chlorine dioxide compared to the risk from
other contaminants if chlorine dioxide were not used, the uncertainty
in those risk estimates, the feasibility of using other means of
control, and the cost of those other control mechanisms.
EPA requests comments on the above approaches for regulating
chlorite. Specifically, EPA requests comment on the issues identified
earlier in the chlorite subsection.
Regardless of the final MRDL value, the Negotiating Committee
agreed on the following monitoring program to protect against the risk
of a reproductive endpoint due to short-term exposure to a high dose of
chlorine dioxide: the entry point to the distribution system will be
measured daily. If any day's value exceeds the MRDL, sampling will be
initiated in the distribution system. If the second-day plant effluent
is also above the MRDL, but distribution system samples are less than
the MRDL, then the utility will be in violation (but this would not be
considered an acute violation); the lower concentration of chlorine
dioxide in the distribution system will minimize the risk to consumers
due to the lower level of exposure. If chlorine dioxide is detected at
a level greater than the MRDL in the distribution system, then the
utility would be considered in acute violation because the risk to
susceptible consumers (i.e., pregnant women) is higher. By monitoring
chlorine dioxide residuals daily in the treatment plant, utilities can
work best at minimizing exposure in the distribution system.

G. Basis for Analytical Method Requirements

The SDWA directs EPA to set an MCL for a contaminant ``if, in the
judgment of the Administrator, it is economically and technologically
feasible to ascertain the level of such contaminant in water in public
water systems.'' [SDWA section 1401(1)(c)(ii)] To make this threshold
determination for the disinfectants and disinfection by-products (DBPs)
proposed today, EPA evaluated the availability, costs, and performance
of analytical techniques which measure these disinfectants and DBPs.
This evaluation is discussed below. EPA also considered the ability of
laboratories to measure consistently and accurately at the maximum
residual disinfectant level (MRDL) or the maximum contaminant level
(MCL) of each contaminant. The ability to measure consistently and
accurately at 25 and 50 percent of the total trihalomethane (TTHM) and
haloacetic acid (HAA5) MCLs was also evaluated in order to ensure that
measurements for allowing reduced monitoring can be made reliably.
The reliability of analytical methods is critical at the MRDL or
MCL and at levels which allow reduced monitoring. Therefore, each
analytical method was evaluated for lack of bias (i.e. accuracy or
recovery) and precision (good reproducibility) at these concentrations
for each contaminant. The primary purpose of the evaluation was to
determine: (1) Whether analytical methods exist to measure
disinfectants and DBPs; (2) reasonable expectations of technical
performance by analytical laboratories at the MRDL or MCL levels and at
the levels which allow reduced monitoring for TTHMs and HAA5; and (3)
analytical costs.
In selecting analytical methods, EPA considered the following
factors:
(a) Reliability (i.e., precision/accuracy) of the analytical
results;
(b) Specificity in the presence of interferences;
(c) Availability of enough equipment and trained personnel to
implement a national monitoring program (i.e., laboratory
availability);
(d) Rapidity of analysis to permit routine use; and
(e) Cost of analysis to water supply systems.
Several analytical methods are described and discussed below. EPA
refers readers to the published methods for additional information on
the precision, accuracy and quality control requirements of the
proposed analytical methods.

Disinfectants
Today's rule proposes monitoring requirements to ensure compliance
with proposed maximum residual disinfectant levels for chlorine,
chloramines, and chlorine dioxide. Analytical methods, most of which
have been in use for years, exist to measure these residuals. There are
additional analytical techniques available for measuring disinfectant
residuals (AWWARF, 1992) that are not proposed in today's rule because
they are not written in a standard format that is readily available to
the public. Nine disinfectant methods are proposed in today's rule
(Table IX-2). Most of the proposed methods are in use, because they
were promulgated with the Surface Water Treatment Rule (SWTR). (54 FR
27486, June 29, 1989)

Table IX-2.--Proposed Methods for Disinfectants

Disinfectant measurement Proposed methods

chlorine dioxide. 4500-ClO<INF>2 DDPD.
4500-ClO<INF>2 EAmperometric Titration.

Proposed methods are in ``Standard Methods for the Examination of Water
and Wastewater,'' 18th Edition, American Public Health Association,
American Water Works Association, and Water Environment Federation,

1992.

The disinfectant residual methods proposed in today's rule were
selected based on evaluations that included the results of an
evaluation made for the methods that were promulgated with the SWTR. In
today's rule, EPA proposes to withdraw Standard Method 408F, which was
promulgated for measurement of chlorine residual under the SWTR. EPA is
also proposing two methods (Standard Methods 4500-Cl H and 4500-Cl I)
that were inadvertently omitted from the SWTR. Methods 4500-Cl H and I
would be approved for compliance monitoring under the SWTR and the D/
DBP rule. In addition, EPA proposes to update all of the disinfectant
methods, which were promulgated in 1989 with the SWTR, to the versions
that will be promulgated with the D/DBP rule. This update will allow
laboratories to use the most recent versions of these methods for all
compliance monitoring of disinfectant residuals.
Standard Method 408F was dropped from the 17th and subsequent
editions of Standard Methods because it is difficult to use, and
because there are several other available methods that are superior to
it. Since EPA believes few, if any, laboratories use Method 408F,
withdrawal should have little effect on the regulated community.
In evaluating disinfectant residual methods for use under the SWTR
EPA considered, but did not promulgate, five EPA and two Standard
Methods. The seven methods were rejected for the following reasons. EPA
methods 330.1 to 330.5 for free and total chlorine measurement were not
promulgated because equivalent methods published by Standard Methods,
which contained more up-to-date and complete descriptions of required
analytical procedures, were available. The five EPA methods have not
been updated since 1979, while new editions of Standard Methods are
issued periodically to include all applicable improvements made to the
methods during the interim. Standard Method 4500-Cl B (Iodometric I)
was not promulgated with the SWTR because it cannot measure chlorine
accurately at concentrations of less than 1 mg/L. Standard Method 4500-
Cl C (Iodometric II) was not promulgated because it is not sensitive
enough for drinking water analyses. For these same reasons, EPA is not
proposing these seven methods in today's rule.
EPA is aware that all of the disinfectant methods proposed today
are subject to interferences, especially when used to measure low
concentrations of disinfectant residuals. However, when procedures
specified in the methods are followed, the methods can be used to
indicate compliance with the minimum disinfectant residual
concentrations proposed in today's rule (AWWARF, 1992). EPA is
soliciting information on improvements which may have been made to
these methods, but that are not reflected in the 18th edition of
Standard Methods. EPA is also seeking information on new methodology
that may be applicable for compliance monitoring. New methods must
provide demonstrated advantages over the current methods and have the
potential for being distributed in a standard format in the time frame
of this regulation.
EPA is aware that several vendors manufacture or may manufacture
test kits that are based on DPD colorimetric Standard Methods 4500-Cl G
and 4500-ClO<INF>2 D. If Methods 4500-Cl G and 4500-ClO<INF>2 D are
promulgated under the D/DBP rule, EPA proposes that kits using the same
chemistry as these methods be approved for compliance monitoring for
chlorine and chlorine dioxide, respectively, provided the State also
approves of their use.
EPA believes that the analytical methods being proposed today are
within the technical and economic capability of many laboratories. For
example, utility laboratories are currently using the proposed
disinfectant methods to measure disinfectant residuals under the SWTR.
The analytical cost is estimated at $10 to $20 per sample. Costs will
vary with the laboratory, analytical technique selected, number of
samples, and other factors. EPA believes these costs are affordable.
Below is a description of the analytical methods proposed for
compliance with the proposed MRDLs. The three disinfectant residuals
are measured and reported as follows: chlorine as free or total
chlorine; chloramines as combined or total chlorine; and chlorine
dioxide as chlorine dioxide. For information on the precision and
accuracy of these methods, EPA refers the readers to the written
methods and to AWWARF, 1992. EPA requests public comments on the
technical adequacy of these proposed analytical techniques.
a. Amperometric Titration Method (SM 4500-Cl D) for chlorine and
chloramines. Free residual chlorine is measured by adjusting the pH of
the sample to between 6.5 and 7.5 followed by titration to the endpoint
with a phenylarsine oxide reducing solution. Total residual chlorine is
measured by adding potassium iodide to the sample, adjusting the pH to
between 3.5 and 4.5, and titrating with phenylarsine oxide to the
endpoint. Chloramines, as combined chlorine, are determined by
subtracting the result of the free residual chlorine measurement from
the total residual chlorine measurement in the same sample. A
microammeter is used to detect the endpoints in each titration.
Commercial titrators are considered to have detection limits as low as
20 <greek-m>g/L (as Cl<INF>2), but the limit of detection depends on
the type of water sample (AWWARF, 1992). Since interferences may
account for a high percentage of the instrument response at low
concentrations, results in samples with low concentrations of free or
total chlorine should be used with caution (AWWARF, 1992). EPA believes
the working range for this method adequately covers the proposed MRDLs
for free, combined, and total chlorine residuals.
b. Low Level Amperometric Titration Method (SM 4500-Cl E) for
chlorine and chloramines measured as total residual chlorine. This
method utilizes the same principle as the amperometric titration method
listed above. This method modifies SM 4500-Cl D by using a more dilute
concentration of phenylarsine oxide titrant and a graphical procedure
to determine the endpoint. Use of this method is recommended when the
total chlorine residual is less than or equal to 0.2 mg/L as Cl<INF>2.
This method will show a positive bias if other oxidizing reagents are
present in the water sample. Since SM 4500-Cl E is only applicable to
measuring total residual chlorine, it cannot be used to differentiate
between free and combined residual chlorine.
c. DPD Ferrous Titrimetric Method (SM 4500-Cl F) for chlorine and
chloramines. When the proper sample pH is chosen, this method can
differentiate between free chlorine, monochloramine, dichloramine, and
total chlorine. The color produced by the reaction of the chlorine
species with the DPD dye slowly disappears as the sample is titrated
with ferrous ammonium sulfate. The amount of titrant corresponds to the
concentration of chlorine species being measured. This method is
proposed for the determination of free, combined, and total residual
chlorine.
d. DPD Colorimetric Method (SM 4500-Cl G) for chlorine and
chloramines. The method utilizes the same principle as SM4500-Cl F
except that the color produced is read by a colorimeter and the
concentrations of free and total chlorine are calculated after
standardization. Combined residual chlorine is the sum of the
monochloramine and dichloramine measurements. Total residual chlorine
is the sum of free and combined residual chlorine. This method is
proposed for the determination of free, combined, and total residual
chlorine.
e. Syringaldazine (FACTS) Method (SM 4500-Cl H) for chlorine. The
reagent, syringaldazine, is oxidized by free chlorine on a 1:1 basis to
produce a color which is determined colorimetrically. The pH of the
sample must be maintained at approximately 6.7 to stabilize the color
formed. This method is proposed for the determination of free residual
chlorine.
f. Iodometric Electrode Technique (SM 4500-Cl I) for chlorine and
chloramines. This method involves the direct potentiometric (electrode)
measurement of iodine released when potassium iodide is added to an
acidified sample containing chlorine. A platinum-iodide electrode pair
is used in combination to measure the liberated iodine. This method is
proposed for the determination of total residual chlorine.
g. Amperometric Method I (SM 4500-ClO<INF>2 C) for chlorine dioxide
residuals. This titration method is an extension of SM 4500-Cl D (which
measures chlorine). By sequentially performing four titrations at
different sample pH with phenylarsine oxide, four chemicals (free
chlorine, monochloramine, chlorite, and chlorine dioxide) may be
determined by a method of differences. This method is proposed for the
determination of chlorine dioxide residuals.
h. DPD Method (SM 4500-ClO<INF>2 D) for chlorine dioxide. This
method is an extension of the DPD method for chlorine (SM 4500-Cl F).
Chlorine dioxide appears in the first step of this procedure, but only
to the extent of one-fifth of its available oxidation/reduction
potential. This potential arises from the reduction of chlorine dioxide
in the sample to chlorite. After a pH adjustment and the addition of a
buffer, a color is produced which corresponds to the chlorine dioxide
content of the sample. This method is proposed for the determination of
chlorine dioxide residuals.
i. Amperometric Method II (4500-ClO<INF>2 E) for chlorine dioxide.
This titration method is similar to SM 4500-ClO<INF>2 C which is
described above. The method can measure chlorine dioxide in samples
which contain free chlorine and other interfering compounds. The method
can measure a wide range of chlorine dioxide concentrations in drinking
water samples. Dilute (0.1 to 10 mg/L) and concentrated (10 to 100 mg/
L) concentrations of chlorine dioxide are measured by varying the size
of the drinking water sample and the concentration of the titrating
solution. This method is proposed for the determination of chlorine
dioxide residuals.
2. By-Products
Six analytical methods for measurement of inorganic and organic
disinfection by-products (Table IX-3) are proposed and discussed in
parts 3 and 4.

Table IX-3.--Proposed Methods for Disinfection By-products

Contaminant Methods\1\

Trihalomethanes............................. 502.2, 524.2, 551.
Haloacetic Acids............................ 552.1, 6233 B.

Bromate, Chlorite........................... 300.0.

\1\EPA Method 502.2 is in the manual ``Methods for the Determination of
Organic Compounds in Drinking Water'', EPA/600/4- 88/039, July 1991,
NTIS publication PB91-231480. EPA Method 551 is in the manual
``Methods for the Determination of Organic Compounds in Drinking
Water--Supplement I'', EPA/600/4-90/020, July 1990, NTIS PB91-146027.
EPA Methods 524.2 and 552.1 are in the manual ``Methods for the
Determination of Organic Compounds in Drinking Water--Supplement II'',
EPA/600/R-92/129, August 1992, NTIS PB92-207703. EPA Method 300.0 is
in the manual ``Methods for the Determination of Inorganic Substances
in Environmental Samples'', EPA/600/R/93/100--Draft, June 1993.
Standard Method 6233 B is in ``Standard Methods for the Examination of
Water and Wastewater,'' 18th Edition, American Public Health
Association, American Water Works Association, and Water Environment

Federation, 1992.

3. Organic By-Product Methods
EPA is proposing five methods (Table IX-3) for the analysis of two
classes of organic disinfection by-products--total trihalomethanes
(TTHMs) and haloacetic acids (five) (HAA5). Compliance with the 0.08
mg/L TTHM MCL will be determined by summing the concentration of each
of four trihalomethanes (bromoform, chloroform, dibromochloromethane
and bromodichloromethane) as measured in a drinking water sample by EPA
Methods 502.2 or 524.2 or 551. EPA is also proposing to withdraw
approval of two EPA methods which use older technology and have been
superseded by Methods 502.2 and 551.
Compliance with the HAA5 MCL of 0.060 mg/L will be determined by
summing the concentration of each of five haloacetic acids (mono-, di-,
and trichloroacetic acids; mono- and dibromoacetic acids) as measured
in a drinking water sample with EPA Method 552.1 or Standard Method
6233 B. The haloacetic analytical methods can also measure a sixth
haloacetic (bromochloroacetic) acid. Since this acid may be considered
in a future disinfection by-product control regulation, EPA encourages,
but does not require, water systems to measure and report occurrences
of bromochloroacetic acid in samples analyzed for HAA5 MCL compliance
monitoring.
EPA believes the analytical methods being proposed today are within
the technical capability of many laboratories and within the economic
capability of the regulated community. The analytical cost for
trihalomethane (THM) analysis is estimated to be from $50 to $100 per
sample. There is generally no additional cost for THM measurements if
Method 502.2 or 524.2 is used to measure volatile organic compounds
(VOCs) in the same sample. The analytical cost for haloacetic acid
analysis is estimated at $150 to $250 per sample; adding
bromochloroacetic acid to the analysis should not significantly change
the cost. Actual costs may vary with the laboratory, analytical
technique selected, the total number of samples, and other factors.
Today's proposed requirements would impose little or no extra
trihalomethane monitoring on community water systems serving
populations of 10,000 or more because most of these systems must
routinely monitor for THMs under the Trihalomethane rule [44 FR 68264,
November 29, 1979]. Monitoring for haloacetic acids will increase each
system's analytical costs but EPA believes these costs are affordable.
With the exception of EPA Method 551, the proposed methods for
measuring trihalomethanes are in widespread use. More than 700
laboratories are presently certified to measure THMs. Many of these
laboratories use Methods 502.2 and 524.2 to comply with VOC and THM
monitoring requirements and MCLs. EPA believes there is adequate
laboratory capacity for trihalomethane analysis. EPA expects that many
of these laboratories will become certified to conduct analysis of
haloacetic acids in drinking water samples.
The methods for measuring haloacetic acids are new and not in
widespread use. These compounds have been included in several of EPA's
Water Supply (WS) performance evaluation (PE) studies, and the number
of participants has increased with each successive study. In the WS 31
study, twenty-five laboratories reported data for all five of the
haloacetic acids covered in today's proposed rule, compared to sixteen
laboratories in the WS 29 study. These data were produced using a
liquid-liquid extraction method. Based on the available PE data, EPA
believes the haloacetic acid methods can provide reliable data at the
proposed MCLs. EPA is aware that many utility laboratories are
developing analytical capability for haloacetic acids, and commercial
laboratories are receiving requests from utilities for haloacetic acid
analyses. Therefore, EPA believes there will be adequate laboratory
capability by the time compliance monitoring for haloacetic acids is
required.
a. Trihalomethane Methods. Presently EPA Methods 501.1, 501.2,
502.2, and 524.2 are approved for compliance with total trihalomethane
monitoring requirements under 40 CFR 141.30. For reasons discussed
below, EPA proposes to withdraw Methods 501.1 and 501.2, and to approve
a new method (EPA Method 551) for trihalomethane compliance
measurements.
Method 502.2, Volatile Organic Compounds in Water by Purge and Trap
Capillary Column Gas Chromatography with Photoionization and
Electrolytic Conductivity Detectors in Series, and Method 524.2,
Measurement of Purgeable Organic Compounds in Water by Capillary Column
Purge and Trap Capillary Column Gas Chromatography/Mass Spectrometry,
are widely used for THM and VOC analyses. Readers are referred to
previous notices, 52 FR 25690 (July 8, 1987) and 56 FR 3548 (January
30, 1991), for discussions and descriptions of these methods. Method
502.2 requires a photoionization detector and an electrolytic
conductivity detector, configured in series, to measure aromatic or
unsaturated VOCs by photoionization, and other VOCs and THMs by
electrolytic conductivity. If only THMs are to be determined in a
sample, Method 502.2 may be used without the photoionization detector.
EPA proposes to withdraw approval of EPA Methods 501.2 and 501.1
for TTHM compliance monitoring. Method 501.2, which uses a liquidliquid
extraction technique, and Method 501.1, which uses a purge-andtrap
sparging technique, have not been updated since 1979. Both methods
use packed column technology. Packed columns have less resolving power
than capillary columns, which often limits their use to very simple
analyses. This is one of the reasons that Methods 501.1 and 501.2 are
only promulgated for trihalomethane monitoring.
Packed column technology is becoming obsolete, and capillary
columns are required in most modern gas chromatographic methods that
have been developed for compliance monitoring. In a rule which was
published on August 3, 1993 (58 FR 41344), EPA encourages the use of
capillary column methods for THM analysis, and announces discontinuance
of technical support for packed column methods. As laboratories replace
their gas chromatographs over the next few years, EPA believes most, if
not all, laboratories will acquire capillary column instruments because
they offer greater flexibility in the number of analytes that can be
measured [W.L. Budde, 1992].
The Agency has promulgated (58 FR 41344) two capillary column
methods (EPA Methods 502.2 and 524.2) that can replace Method 501.1.
Today EPA is proposing a capillary column method (EPA Method 551) for
trihalomethane monitoring that can replace Method 501.2. Withdrawal of
EPA Methods 501.1 and 501.2 would not become effective until 18 months
after today's rule is promulgated, so laboratories would be able to use
these methods for several more years. EPA does not believe that
withdrawal of the methods will adversely affect laboratories over this
time frame.
EPA Method 551, Determination of Chlorination Disinfection
Byproducts and Chlorinated Solvents in Drinking Water by Liquid- Liquid
Extraction and Gas Chromatography with Electron Capture Detection, is
proposed for THM compliance measurements. It is a liquid-liquid
extraction method applicable to the determination of a variety of
halogenated organic compounds.
In Method 551 the ionic strength of a 35-mL drinking water sample
aliquot is adjusted using sodium chloride, and the sample is extracted
with 2-mL of methyl-tert-butyl ether. If only THMs are to be measured,
pentane can be used as the extracting solvent provided the quality
control requirements specified in Method 551 are met. When pentane is
used, Method 551 is very similar to liquid-liquid extraction Method
501.2. EPA believes laboratories wishing to use liquid-liquid
extraction to measure THMs will prefer Method 551 to Method 501.2.
b. THM-Sample Dechlorination. All of the promulgated and proposed
methods for THM compliance analysis require that the THM formation
reaction be halted by addition of a reagent that removes all free
chlorine from the sample. EPA provides the following guidance to help
laboratories correctly preserve samples for compliance with proposed
and existing (40 CFR 141.30 and 141.133) THM monitoring requirements.
The Agency believes that this guidance is warranted because many
preservation procedures are available, depending on the method, and
because laboratories may wish to measure VOCs and THMs in a single
analysis.
Laboratories must carefully follow the preservation procedure
described in each method, especially the order in which reagents are
added to the sample. The methods allow analysts to choose among four
reagents (ammonium chloride, ascorbic acid, sodium sulfite, or sodium
thiosulfate) to dechlorinate a water sample. These reagents remain
available for use but, with one exception, EPA strongly recommends the
use of sodium thiosulfate for the analyses of THMs, since EPA has the
most performance data with this chemical. The exception is that
ascorbic acid should be used when sulfur dioxide will interfere with
analyses that are performed using a mass spectrometer. Samples
dechlorinated with ascorbic acid must be acidified immediately, as
directed in the method.
c. Haloacetic Acid Methods. Standard Method 6233 B and EPA Method
552.1 are relatively new, use capillary columns, and are proposed today
for measurement of five haloacetic (monochloroacetic, dichloroacetic,
trichloroacetic, monobromoacetic and dibromoacetic) acids. As discussed
above, EPA recommends that bromochloroacetic acid also be measured with
these methods.
Standard Method 6233 B, Micro Liquid-Liquid Extraction Gas
Chromatographic Method for Haloacetic Acids, was developed by several
laboratories, including EPA. The analytical procedures used in Method
6233 B are equivalent and very similar to those used in the 30-mL
extraction option, which is described in EPA Method 552, Determination
of Haloacetic Acids in Drinking Water by Liquid-Liquid Extraction,
Derivatization, and Gas Chromatography with Electron Capture Detection.
EPA considered proposing both methods; however, Method 552 contains a
30-mL and a 100-mL extraction option. EPA believes that the 100-mL
extraction option uses a quantitation and calibration procedure that
will not produce acceptable results for compliance with today's
monitoring requirements. Also, the performance data for the 30-mL
extraction option is more completely presented in Method 6233 B. For
purposes of today's rule, EPA believes that Method 6233 B is more
complete and easier to use than Method 552. Laboratories, which have
been using the 30-mL extraction option in Method 552, will have no
trouble switching to Method 6233 B. If EPA revises Method 552, it may
be approved in the final rule.
In Method 6233 B, the pH of a 30-mL drinking water sample is
adjusted to 0.5 or less, and the ionic strength of the sample is
increased by adding sodium sulfate. The acids are extracted into 3-mL
of methyl-tert-butyl ether (MTBE). Exactly 2-mL of the extract is
transferred to a volumetric flask and the volume is reduced to
approximately 1.7-mL.
The haloacetic acids, which have been concentrated in the MTBE
extract, are converted to methyl esters using a dilute solution of
diazomethane in MTBE. The extract, which now contains the methyl esters
of the haloacetic acids, is analyzed using capillary column gas
chromatography with electron capture detection.
The analytical method is calibrated and the haloacetic acids are
quantitated using standards with a known concentration of each
haloacetic acid. These standards are called aqueous procedural
standards because they are prepared in reagent water and treated
exactly like a drinking water sample. This means that the standards are
carried through the extraction, derivatization, and chromatographic
steps of the method. Aqueous standards which are analyzed in this way
automatically correct for the method bias that occurs when any of the
haloacetic acids are not completely extracted from the drinking water
sample with the solvent MTBE.
EPA Method 552.1, Determination of Haloacetic Acids and Dalapon in
Drinking Water by Ion-Exchange Liquid-Solid Extraction and Gas
Chromatography with an Electron Capture Detector, is a liquid-solid
extraction method which does not require the use of diazomethane. It is
proposed today for five haloacetic acids.
In Method 552.1, a 100-mL sample aliquot is adjusted to pH 5.0 and
extracted with a preconditioned miniature anion exchange column. The
haloacetic acids are eluted from the column with small aliquots of
acidic methanol. After the addition of a small volume of MTBE as a cosolvent,
the acids are converted to their methyl esters directly in the
acidic methanol. The methyl esters are partitioned into the MTBE phase
and identified and measured by capillary column gas chromatography with
electron capture detection.
4. Inorganic By-Product Method
EPA is proposing Method 300.0, Determination of Inorganic Anions by
Ion Chromatography, for analysis of the inorganic disinfection byproducts
covered in today's proposed rule--bromate and chlorite (Table
IX-3). Method 300.0 must be modified as specified below to adequately
measure bromate at the MCL proposed in today's rule. This method is
presently approved for the analysis of nitrate and nitrite in drinking
water under 40 CFR 141.23. The method is described below; additional
information may be found in the May 22, 1989 notice [54 FR 22097].
Method 300.0 requires an ion chromatograph and an ion
chromatographic column. Ion chromatography is conducted in many
laboratories because it can simultaneously measure many anions of
interest--bromide, chloride, fluoride, nitrate, nitrite,
orthophosphate, sulfate, bromate, chlorite, and chlorate. Method 300.0
specifies the two columns that are required to separate and measure the
ions of interest. The AS9 column is used to measure chlorite, chlorate,
and bromate. This column has the advantage that it separates the
chlorate ion from the nitrate ion.
EPA believes that Method 300.0 is within the technical capability
of many laboratories and within the economic capability of the
regulated community. The analytical cost of bromate and chlorite
analysis is estimated to range from $50 to $100 per sample. Actual
costs may vary with the laboratory, the total number of samples, and
other factors. EPA believes the analytical costs for bromate and
chlorite ion monitoring are affordable.
Under the requirements set forth in this proposed rule, monitoring
for the bromate ion would apply to water systems using ozone in the
treatment train. Monitoring for the chlorite ion would apply to systems
using chlorine dioxide. Since utilities rarely use both ozone and
chlorine dioxide, most systems will use Method 300.0 to measure only
bromate or only chlorite for compliance with the MCLs proposed in
today's rule.
EPA WS PE studies indicate that an increasing number of
laboratories have the capability to measure bromate and chlorite. The
lowest concentration of the bromate ion in a PE sample to date was 30
<greek-m>g/L in WS 31. Twenty-three laboratories reported data and 65%
of them were within <plus-minus>50% of the true value. Chlorite ion
concentrations have ranged from 100 to 460 <greek-m>g/L in studies WS
29 through WS 31. The percentage of laboratories successfully meeting
<plus-minus>50% of the true value acceptance criteria ranged from 85 to
96%. These data indicate that adequate laboratory capacity will be
available by the time the compliance monitoring requirements proposed
in this rule become effective.
EPA has evaluated Method 300.0, modifications to the method, and
the results from PE studies to determine the feasibility of obtaining
reliable measurements at the MCLs proposed in today's rule for chlorite
and bromate. Based on this evaluation, EPA believes that Method 300.0
can easily provide reliable data at the proposed MCL for chlorite. To
reliably measure bromate at the proposed MCL, Method 300.0 must be
modified to improve the sensitivity of the analysis. The modifications,
which are discussed below, involve changes to the injection volume and
to the eluent.
a. Bromate Ion. EPA is aware that the current version of Method
300.0 is not sensitive enough to measure bromate ion concentrations at
the proposed MCL. Method 300.0 is more sensitive to bromate if a weaker
ion chromatographic eluent is used. In a recent EPA study, Hautman &
Bolyard [1992] successfully used a borate, rather than a carbonate,
eluent to chromatographically measure bromate ion concentrations in
drinking water. This alternate eluent reduced baseline noise, thereby
increasing the method sensitivity. The detection limit for bromate can
be further reduced by increasing the volume of sample that is injected
into the ion chromatograph (from 50 to 200 <greek-m>L) and by further
decreasing the concentration of the borate eluent to 18mM NaOH/72 mM
H<INF>3BO<INF>3 [Hautman, 1993]. These are acceptable modifications to
Method 300.0. The quality control requirements, which must be met when
a weaker eluent or a larger sample injection volume is used, are
specified in the method.
A few utility, university, and commercial laboratories are
analyzing ozonated drinking water for low concentrations of the bromate
ion. According to verbal communications with EPA, some of these
laboratories are able to quantitate bromate down to concentrations of 5
to 10 <greek-m>g/L, and they can detect bromate down to concentrations
of 1 to 2 <greek-m>g/L. In order to achieve this sensitivity, the
laboratories are using the modifications mentioned above and, in some
cases, the laboratories are also treating the samples to remove a
chloride interference [Kuo et al., 1990].
Based on the information presented above, EPA believes that Method
300.0 with the appropriate modifications can be used to reliably
determine compliance with the proposed MCL for bromate. Whether
laboratories are able to reliably measure bromate ion concentrations at
levels below the proposed MCL under routine operating conditions is
presently unknown. Laboratory performance data will be collected as
part of the proposed Information Collection Rule (ICR) (59 FR 6332) so
EPA will be able to more accurately determine laboratory capabilities
for measuring bromate prior to promulgation of today's proposed rule.
EPA is aware of efforts to develop more sensitive techniques for
measuring bromate ion concentrations in drinking water. Two studies
have demonstrated the capability to measure bromate levels of <1
<greek-m>g/L using sample concentration techniques prior to injection
into the ion chromatograph [Hautman, 1992; Sorrell & Hautman, 1992].
However, these techniques are labor-intensive and not generally
available to laboratories that do routine analyses using ion
chromatography. Efforts are underway to develop an automated sample
concentration technology which may be applicable to routine analyses
[Joyce & Dhillon, 1993]. EPA solicits comments on whether use of a
sample concentration technology prior to ion chromatographic analysis
should be considered as a new methodolgy or a modification to Method
300.0 under today's rule. EPA also solicits comments on the
applicability of sample concentration technology to today's proposed
MCL for bromate.
EPA is aware that high concentrations of the chloride ion interfere
with the measurement of the bromate ion. There are currently two
solutions to this interference problem. The first solution is based on
a recent study [Hautman & Bolyard, 1992] that successfully used a
borate eluent to chromatographically separate bromate and chloride. The
study demonstrated that these conditions can be used to measure other
anions for which ion chromatography is an approved compliance
monitoring technique. The second solution to the chloride interference
is to remove chloride from the sample by filtering it through a silver
filter before injecting it into the ion chromatograph [Kuo et al.,
1990]. Both of these solutions are permitted as part of EPA Method
300.0 provided the quality control requirements, which are specified in
the method, are met.
EPA prefers the first solution (borate as eluent) to the chloride
interference problem, because it lowers the baseline noise, thereby
increasing the method's sensitivity for all anions in the analytical
scope of the method. However, in some waters, chloride ion
concentrations are too high, and a silver filter must be used to remove
excess chloride. EPA cautions that silver will leach from the filters
into the sample. If the leachate is not removed from the sample, it
will contaminate the ion chromatographic column. Since a contaminated
column cannot be used to measure chloride or bromide ion
concentrations, the leachate must be removed by filtering the sample
through an ion chromatographic chelate cartridge prior to injection
into the ion chromatograph [Hautman, 1992]. Another alternative is to
dedicate an ion chromatographic column to bromate analysis, since
silver interferes only with the analysis of chloride and bromide, not
bromate, ions.
Compliance with the bromate MCL under today's rule is determined by
analyzing samples collected at the entrance point to the distribution
system. EPA does not believe an ozone residual will exist at this
sampling point, so the reactions that cause bromate formation should be
complete. Bromate does not decompose after it is produced. As a result,
Method 300.0 does not require the use of a preservative for bromate
samples. EPA is soliciting any data that demonstrate the need for a
preservative in samples collected at this sampling point for
measurement of bromate.
b. Chlorite Ion. EPA considered other available methods for the
measurement of the chlorite ion. For example, chlorite ion, chlorate
ion, and the disinfectant chlorine dioxide can be measured by
amperometric or potentiometric measurements of iodine, which is formed
from the reaction of these chemicals with iodide ion. EPA recognizes
that these methods may be useful to utility operators for routine
operational monitoring of unit processes. Their use is encouraged for
such work when an ion chromatograph is not available at the treatment
plant. However, EPA does not believe that these methods are suitable
for compliance monitoring, because chlorite is determined by a method
of differences rather than direct measurement. EPA believes that the
ion chromatography method is the compliance technique of choice,
because it provides a direct measurement of each inorganic DBP anion.
Method 300.0 is also a very versatile method with an analytical scope
that includes several other ions that are commonly present in drinking
water samples. Therefore, Method 300.0 is the only method proposed for
chlorite ion monitoring in today's rule.
Utilities using chlorine dioxide as a disinfectant or oxidant will
have the ions, chlorite and chlorate, in the treated water. Using
Method 300.0, chlorate can be measured along with chlorite at little or
no extra cost. Since chlorate may be considered in a future
disinfection by-product control regulation, utilities are encouraged,
but not required, to obtain data on chlorate concentrations in their
water.
Since the chlorite ion reacts with free residual chlorine and with
metal ions such as nickel and iron, it is not stable in some drinking
water matrices [Hautman & Bolyard, 1992]. Method 300.0 addresses this
problem by requiring the addition of ethylenediamine (EDA) as a
preservative, if samples cannot be analyzed for the chlorite ion within
10 minutes of sample collection. If the chlorite ion is measured in
samples with a chlorine dioxide residual, the sample must also be
sparged with nitrogen at the time of collection to remove the chlorine
dioxide residual. EPA is interested in learning whether there are
vendors who are willing, or would be willing in the future, to sell
high purity chlorite standards to laboratories performing analyses for
chlorite.

. Other Parameters--Total Organic Carbon, Alkalinity and Bromide

Table IX-4.--Proposed Analytical Methods for Other Parameters

Parameter Method\1\

Total Organic Carbon............... 5310 CPersulfate-Ultraviolet

Oxidation.
5310 DWet Oxidation.

Alkalinity......................... 2320 B, 310.1, D-1067-

88BTitrimetric.
I-1030-85Electrometric.

Bromide............................ 300.0Ion Chromatography.

\1\EPA Method 300.0 is in the manual ``Methods for the Determination of
Inorganic Substances in Environmental Samples'', EPA/600/R/93/100--
Draft, June 1993. EPA Method 310.1 is in the manual ``Methods for
Chemical Analysis of Water and Wastes'', EPA/600/4-79-020, March 1983,
NTIS PB84-128677. Standard Methods 2320B, 5310B and 5310C are in
Standard Methods for the Examination of Water and Wastewater, 18th
Edition, American Public Health Association, American Water Works
Association, and Water Environment Federation, 1992. Method D-1067-88B
is in the ``Annual Book of ASTM Standards'', Vol. 11.01, American
Society for Testing and Materials, 1993. Method I-1030-85 is in
Techniques of Water Resources Investigations of the U.S. Geological
Survey, Book 5, Chapter A-1, 3rd ed., U.S. Government Printing Office,

1989.

Total organic carbon, alkalinity, and bromide are not covered by
proposed MRDLs or MCLs in today's rule. As explained in Sections VIII
and IX of this notice, EPA is proposing monitoring requirements for
some or all of these parameters at systems that need to use the results
to comply with certain treatment requirements. To ensure accurate
measurement of these parameters, EPA proposes the following analytical
methods.
a. Total organic carbon (TOC) methods. Several analytical methods
exist to measure total organic carbon; two Standard Methods are
proposed in today's rule (Table IX-4). TOC measurements are conducted
in many laboratories. In a recent EPA Water Pollution PE study (WP 30),
541 laboratories reported TOC data. EPA believes this response
indicates an adequate potential laboratory capability to comply with
the requirements of today's rule. EPA believes these methods are within
the technical and economic capability of many laboratories. The
analytical cost for TOC analyses is estimated to range from $50 to $75
per sample. Actual costs may vary with the laboratory, analytical
technique selected, the total number of samples, and other factors. EPA
believes that the costs for TOC monitoring are affordable.
Today's rule proposes monitoring for TOC, not dissolved organic
carbon (DOC). TOC is the sum of the undissolved and dissolved organic
carbon in the water sample. DOC is differentiated from TOC by filtering
the sample with a very fine (0.45-<greek-m>m) filter. Today's rule
specifies that TOC samples are not to be filtered except to remove
turbidity, which is known to interfere with accurate TOC measurement
when the sample turbidity is greater than 1 NTU. A TOC sample can be
filtered to remove turbidity provided a prewashed, glass-fiber filter
with a large (5- to 10-<greek-m>m) pore size is used. As an alternative
to filtering, the TOC sample can be diluted with organic-free reagent
water in order to reduce the turbidity interference. EPA solicits
comments on the proposed turbidity threshold, and on the sample
filtration procedure as described above and in the proposed methods.
EPA has evaluated several methods to determine the feasibility of
obtaining reliable TOC measurements. To meet today's proposed
requirements, a TOC method must have a detection limit of at least 0.5
mg/L, and more importantly achieve a reproducibility of <plus-minus>0.1
mg/L over a range of approximately 2 to 5 mg/L. This reproducibility is
required because some systems will have to reliably measure 0.3 mg/L
differences in TOC removal in several jar test samples to which
progressively greater amounts of coagulant have been added [R. Miltner,
1993]. Reliable measurement of 0.3 mg/L differences requires that the
error bars on the analysis approach <plus-minus>0.1 mg/L. When
calculated as a percent, this precision requirement becomes
<plus-minus>5% at 2 mg/L of TOC, and <plus-minus>2% at 5 mg/L of TOC.
Data presented in Standard Method 5310 C indicate that this is
feasible, and Standard Method 5310 D is close to this level of
performance.
In a PE sample prepared for EPA's Water Pollution WP 27 study, 26
EPA and State laboratories achieved a precision of <plus-minus>0.33 mg/
L on a TOC sample spiked at about 5 mg/L. In WP 30, a mean value of
8.74 <plus-minus>0.79 mg/L was measured by the 541 laboratories that
reported results. A subset of 27 EPA and State laboratories in WP 30
reported a precision of <plus-minus>0.4 mg/L on the same sample. EPA
solicits comment on what precision can be routinely expected on
differential TOC measurements of jar test samples. EPA is also
interested in new methods or modifications to the methods proposed
today that would improve the reproducibility of TOC measurement.
EPA considered, but is not proposing, Standard Method 5310 B
because the stated detection limit is 1 mg/L, which is 0.5 mg/L greater
than the required TOC detection limit. EPA is aware that the
instrumentation used in Method 5310 B is being improved. If this work
is successful, EPA will consider the next version of Method 5310 B (or
its equivalent) for promulgation in the final rule. The two methods
proposed today for TOC measurements are described below.
Persulfate-Ultraviolet Oxidation Method (SM 5310 C) measures
organic carbon via infrared absorption of the carbon dioxide gas that
is produced when the organic carbon in the sample is simultaneously
reacted with a persulfate solution and irradiated with ultraviolet
light. Inorganic carbon is removed from the sample prior to analysis by
acidification with phosphoric or sulfuric acid. Chloride and low sample
pH can impede the analysis; precautions are specified in the method.
The lower limit of detection of the method is 0.05 mg/L.
Wet-Oxidation Method (SM 5310 D) has a detection limit of 0.10 mg/L
and is subject to the same interferences as the persulfate-ultraviolet
method. Persulfate and phosphoric acid are added to the sample; the
sample is then purged with pure oxygen to remove inorganic carbon. The
purged sample is sealed in an ampule and combusted for four hours in an
oven at a temperature that causes persulfate to oxidize organic carbon
to carbon dioxide. The ampule is opened inside a TOC-analyzer, and TOC
is measured via infrared absorption of carbon dioxide.
b. Alkalinity Methods. With two minor exceptions, EPA is proposing
all of the methods (Table IX-4) which are currently approved under 40
CFR 141.89 for measurement of alkalinity. The exceptions are that EPA
is proposing more recent versions of the alkalinity methods, which are
published by Standard Methods and the American Society of Testing and
Materials (ASTM). In today's rule, EPA is proposing Method 2320 B,
which is in the 18th edition of Standard Methods, and Method D1067-88B,
which is in the 1993 Annual Book of ASTM Standards, in lieu of the
versions cited at 40 CFR 141.89. There are no technical difference
between the proposed versions and the currently approved versions.
EPA is also aware that EPA Method 310.1, which uses the same
technology as Methods 2320 B and D1067-88B, has not been updated since
1983. The references in the EPA method are becoming obsolete, and the
equivalent methods from ASTM and Standard Methods are updated more
regularly. To allow laboratories the use of only the most current
versions of equivalent methods, EPA may not promulgate Method 310.1
with the final D/DBP rule, and EPA also may withdraw approval of it
under 40 CFR 141.89.
To accurately measure alkalinity, the sample pH at the source where
the sample was collected must be recorded. It is important to
accurately measure carbon dioxide gas, which is dissolved in the sample
and is a major contributor to the alkalinity of the sample. To minimize
loss of carbon dioxide, the sample is collected in an air tight
container, and agitation of the sample is kept to a minimum.
EPA believes that the proposed alkalinity methods, which have been
used for years, are within the technical and economic capability of
many laboratories. The analytical cost of alkalinity analysis is
estimated to range from $5 to $10 per sample. Actual costs may vary
with the laboratory, analytical technique selected, the total number of
samples and other factors. EPA believes the analytical costs for
alkalinity monitoring are affordable.
EPA believes the working range for each method adequately covers
the requirements proposed for alkalinity monitoring in today's rule.
All procedures and precautions listed below and in the methods must be
followed carefully. Descriptions and more information on the methods
are in the notices of August 18, 1988 [53 FR 31516] and October 19,
1990 [55 FR 42409].
c. Bromide Method. EPA Method 300.0, Determination of Inorganic
Anions by Ion Chromatography, is proposed for measurement of bromide
ion. This method is described above under inorganic by-product methods
for chlorite and bromate. EPA believes the working range for this
method adequately covers the requirements proposed for bromide
monitoring in today's rule.
EPA believes that Method 300.0 is within the technical and economic
capability of many laboratories. The analytical cost of bromide
analysis is estimated to range from $50 to $100 per sample. However, if
other anions, such as fluoride or chloride, are measured in the same
sample, the additional cost for bromide analysis should be minimal.
Actual costs may vary with the laboratory, analytical technique
selected, the total number of samples, and other factors. EPA believes
the analytical costs for bromide ion monitoring are affordable.
6. Sources and Scope of Future Analytical Methods
The Standard Methods proposed in today's rule are published in the
18th edition of Standard Methods. EPA is aware that these methods will
be updated when the 19th edition is published. EPA is also gathering
additional performance data on several EPA methods which are proposed
in today's rule. EPA will obtain these data from occurrence studies,
from laboratory certification performance evaluation sample analyses
and from other sources. To support pollution prevention goals and to
generally improve the safety and efficiency of analytical methods, EPA
is working to reduce the volume of solvents and the amounts of
potentially hazardous reagents in EPA methods. Thus, EPA may revise,
improve, or expand several EPA methods prior to promulgation of the D/
DBP rule. Examples of methods that EPA or other organizations might
change are discussed below.
EPA may refine the solvent extraction and sample preservation
procedures in Method 551, which is proposed today for trihalomethanes.
EPA may also extend approval of EPA Method 551 to compliance
measurements of six chemicals currently regulated under 40 CFR 141.24.
The six contaminants are: carbon tetrachloride, trichloroethylene,
tetrachloroethylene, 1,2-dibromoethane (EDB), 1,2-dibromo-3-
chloropropane (DBCP), and 1,1,1-trichloroethane. EPA may revise Method
552, merge it with Method 552.1, and approve it for the analysis of
haloacetic acids. EPA may revise Method 300.0 to improve the detection
limits for bromate and to further eliminate some of the interference
problems in the method. The Standard Methods organization may
incorporate more sensitive instrumentation in later versions of TOC
method 5310 B.
To accommodate future improvements in analytical methods, EPA
proposes that the methods in the then current editions of books
published by Standard Methods and ASTM and the then current versions of
EPA methods be cited in the final D/DBP rule provided no unacceptable
changes are in the later versions of these methods.

H. Basis for Compliance Schedule and Applicability to Different Groups
of Systems, Timing With Other Regulations

Under the negotiated rulemaking the Negotiating Committee agreed to
propose three rules: (a) an information collection requirements rule
(ICR) (59 FR 6332), (b) an ``interim'' enhanced surface water treatment
rule (ESWTR) (proposed in today's Federal Register), and c)
Disinfection/Disinfection By-products (D/DBP) regulations, proposed
herein today. Table IX-5 indicates the schedule agreed to by the
Negotiating Committee by which these rules would be proposed,
promulgated, and become effective. Compliance dates for the ICR are
indicated under the columns of the Stage 2 D/DBP rule and ESWTR to
reflect the relationship between these rules.
The Negotiating Committee agreed that more data, especially
monitoring data, should be collected under the ICR to assess possible
shortcomings of the SWTR and develop appropriate remedies, if needed,
to prevent increased risk from microbial disease when systems began
complying with the Stage 1 D/DBP regulations. It was also agreed that
EPA would propose an interim ESWTR (proposed elsewhere in today's
Federal Register) pertaining to systems serving greater than 10,000
people, including a wide range of regulatory options. Data gathered
under the ICR would form the basis for (a) promulgating the most
appropriate criteria among the options presented in the proposed
interim ESWTR, and (b) proposing at a later date a long-term ESWTR
pertaining to all system sizes. Both of these rules, if needed, would
be proposed and promulgated so as to be in effect at the same time that
systems of the respective size categories would be required to comply
with new regulations for D/DBPs.
The Negotiating Committee also agreed that additional data on the
occurrence of disinfectants, disinfection byproducts (DBPs), potential
surrogates for DBPs, source water and within treatment conditions
affecting the formation of DBPs, and bench-pilot scale information on
the treatability for removal of DBP precursors would be beneficial for
developing the Stage 2 D/DBP regulatory criteria.
Prior to promulgating the interim ESWTR, EPA intends to issue a
Notice of Availability to: (a) discuss the pertinent data collected
under the ICR rule, (b) discuss additional research that would
influence determination of appropriate regulatory criteria, (c) discuss
criteria EPA considered appropriate to promulgate in the interim ESWTR
(which would be among the regulatory options of the proposed interim
ESWTR) and (d) solicit public comment on the intended criteria to be
promulgated.
The Negotiating Committee believed that the December 1996 scheduled
date for promulgating the Stage 1 D/DBP Rule was within the shortest
time possible by which the interim ESWTR, if necessary, could also be
promulgated. EPA is proposing that the Stage 1 D/DBP regulations and
the interim ESWTR (if necessary) become effective on the same date of
June 30, 1998 for systems using surface water and serving greater than
10,000 people.

TABLE IX-5.--Proposed D/DBP, ESWTR, ICR Rule Development Schedule

Time line Stage 1 DBP rule Stage 2 DBP rule ESWTR

12/93....... .................. Propose Propose

information information
collection collection
requirements for requirements for
systems >100k. systems >10k.

3/94........ Propose required Propose Stage 2. Propose interim
enhanced MCLs for TTHMs ESWTR for systems
coagulation for (40 <greek-m>g/ >10k.

systems with l), HAA5 (30
conventional <greek-m>g/l),
treatment. MCLs- BAT is precursor
TTHMs (80<greek- removal with
m>g/l), HAA5 chlorination.
(60<greek-m>g/l),
bromate,
chlorite.
Disinfectant
limits.

6/94........ .................. Promulgate ICR.... Promulgate ICR.
8/94........ Close of public .................. Public comment

comment period. period for
proposed ESWTR
closes.

10/94....... .................. Systems >100k Systems >100k

begin ICR begin ICR
monitoring. monitoring.

1/95........ .................. .................. Systems 10-100k

begin source
water monitoring.

10/95....... .................. SW systems >100k, ..................

GW systems >50k
begin bench/pilot
studies unless
source water
quality criteria
met.

11/95....... .................. .................. NOA for monitoring

data, direction
of interim ESWTR.

1/96........ .................. .................. Systems >10k

complete ICR
monitoring. End
NOA public
comment period.

3/96........ .................. Systems complete Systems >100k

ICR monitoring. complete ICR
monitoring.

12/96....... Promulgate Stage 1 .................. Promulgate interim

ESWTR for systems
>10k.

6/97........ .................. Notice of Propose long-term

availability for ESWTR for systems
Stage 2 <10k, possible
reproposal. changes for
systems >10k.

10/97....... .................. Complete and ..................

submit results of
bench/pilot
studies.

12/97....... .................. Initiate ..................

reproposal--begin
with 3/94
proposal.

6/98........ Effective. Close of public Interim ESWTR
Effective for SW comment period. effective for

systems serving systems >10k.
greater >10k, 1994-6 monitoring
extended data used to
compliance date determine
for GAC or treatment level.
membrane
technology.

12/98....... .................. Propose for CWSs, Publish long-term

NTNCWSs. ESWTR.

6/00........ Stage 1 limits Promulgate Stage 2 Long-term ESWTR
effective for for all CWSs, effective for all
surface water NTNCWSs. system sizes.

systems <10k, GW
systems <10k.

1/02........ Stage 1 limits Stage 2 effective, ..................

effective for GW compliance for
systems >10k GAC/membranes by
unless Stage 2 2004.
criteria
supersede.

Although the Agency anticipates that the ICR will be promulgated
later than the date indicated in Table IX-5, EPA believes that the
long-term schedule will be adhered to and the final D/DBPR will be
promulgated in December, 1996.
EPA is proposing that systems using surface water and serving fewer
than 10,000 people comply with the Stage 1 D/DBP regulations by June
30, 2000 to allow such systems to also come into compliance with the
final ESWTR. EPA believes that the June 30, 2000 compliance date
reflects the shortest time possible that would allow for the final
ESWTR to be proposed, promulgated, and become effective; thereby
providing the necessary protection from any downside microbial risk
that might otherwise result when systems of this size attempt to
achieve compliance with the Stage 1 D/DBP rule.
EPA is also proposing that systems using ground water and serving
greater than 10,000 people would be required to achieve compliance with
the Stage 1 D/DBP rule by June 30, 2000. EPA believes this is the
earliest date possible by which all ground water systems of this size
could be expected to achieve compliance with both the GWDR and the
Stage 1 D/DBP rule. Many ground water systems would be expected to be
able to achieve compliance by an earlier date but others, due to
recently installing or upgrading disinfection to meet the GWDR, would
require some period of monitoring for DBPs in order to adjust their
treatment processes to also meet the Stage 1 D/DBP standards.
For the same reasons as stated above, EPA is proposing that systems
using ground water and serving 10,000 or less people be required to
meet the Stage 1 D/DBP rule beginning January 1, 2002. The delayed date
for the ground water systems serving 10,000 or less people is because
of the much large number of such systems in this size category, and the
time necessary for States and systems to implement the GWDR.

I. Basis for Qualified Operator Requirements and Monitoring Plans

EPA believes that systems that must make treatment changes to
comply with requirements to reduce the microbiological risks and risks
from disinfectants and disinfection byproducts should be operated by
personnel who are qualified to recognize and react to problems.
Therefore, in today's proposal, the Agency is requiring that all
systems regulated under this rule be operated by an individual who
meets State-specified qualifications, which may differ based on size
and type of the system. Subpart H systems already are required to be
operated by qualified operators under the provisions of the SWTR (40
CFR 141.70(c)). Current qualification programs developed by the States
should, in many cases, be adequate to meet this requirement for Subpart
H systems. In the upcoming Ground Water Disinfection Rule, the Agency
may require some or all ground water systems to also be operated by
qualified operators. If so, the qualification programs for Subpart H
systems may be modified to account for the differences between Subpart
H systems and ground water systems. Also, States must maintain a
register of qualified operators.
EPA encourages States which do not already have operator license
certification programs in effect to develop such programs. The
Negotiating Committee and Technologies Working Group believed that
properly trained personnel were an essential first step in ensuring
safer drinking water.
Also, systems are required to develop and follow monitoring plans
for monitoring required under this proposed rule. Systems may update
these plans for reasons including changes to the distribution system or
changes in treatment.

J. Basis for Stage 2 Proposed MCLs

EPA is proposing lower MCLs for TTHMs and total haloacetic acids
(THAAs) for Stage 2 to indicate the desire to further decrease exposure
from these chemicals but also to lower the exposure from other
byproducts resulting from chlorine reacting with naturally occurring
organics. Systems which lower the levels of TTHMs and THAAs are also
likely to lower the levels of many other chlorination byproducts, some
of which may pose additional health risks.
The proposed 40/30 MCL is based on what would be achievable by most
systems if they were to use the ``best available technology'' (BAT)
proposed for Stage 2. The Negotiating Committee agreed that the BAT in
Stage 2 for controlling TTHMs and THAAs include either enhanced
coagulation and shallow bed granular activated carbon (GAC10) or deep
bed granular activated carbon (GAC20) and chlorine as the primary and
residual disinfectant.
One of the major reasons for defining BAT as including chlorine
versus, for example, defining BAT as including alternative
disinfectants, is to recognize the many benefits of chlorine as a
disinfectant, especially in preventing microbial disease. In addition
to being a strong primary disinfectant, a chlorine residual in the
distribution system helps prevent bacterial growth and is an excellent
marker (when there is an absence of chlorine) for indicating potential
contamination from outside sources into the distribution system. EPA
believes that chlorine should be included in the BAT definition at
least until there is more health effects information on byproducts
formed by use of alternative disinfectants.
Currently it is not clear whether risks from chlorination
byproducts are more significant than those formed from use of
alternative disinfectants. The Negotiating Committee agreed that EPA
would repropose Stage 2 requirements in 1998 to consider new
information that would become available, especially data on the health
effects of alternative disinfectants.

X. Laboratory Certification and Approval

EPA recognizes that the effectiveness of today's proposed
regulations depends on the ability of laboratories to reliably analyze
the regulated disinfectants and disinfection byproducts at the proposed
MRDL or MCL, respectively. Laboratories must also be able to measure
the trihalomethanes and haloacetic acids at the proposed monitoring
trigger levels, which are between 25 and 50 percent of the proposed
MCLs for these compound classes. EPA has established a drinking water
laboratory certification program that States must adopt as a part of
primacy. (40 CFR 142.10(b)). EPA has also specified laboratory
requirements for analyses, such as alkalinity and disinfectant
residuals, that must be conducted by approved parties. (40 CFR 141.89
and 141.74). EPA's ``Manual for the Certification of Laboratories
Analyzing Drinking Water'', EPA/570/9-90/008, specifies the criteria
which EPA uses to implement the drinking water laboratory certification
program.
Today EPA is proposing MCLs for total trihalomethanes, total
haloacetic acids (HAA5), bromate, and chlorite. EPA is proposing that
only certified laboratories be allowed to analyze samples for
compliance with the proposed MCLs. For the disinfectants and other
parameters in today's rule, which have MRDLs or monitoring
requirements, EPA is requiring that analyses be conducted by a party
acceptable to the State.
Performance evaluation (PE) samples, which are an important tool in
EPA's laboratory certification program, are provided by EPA or the
States to laboratories seeking certification. To obtain and maintain
certification, a laboratory must use a promulgated method and at least
once a year successfully analyze an appropriate PE sample. In the
drinking water PE studies, EPA has samples for bromate, chlorite, five
haloacetic acids, four trihalomethanes, free chlorine, and alkalinity.
EPA has total chlorine and total organic carbon samples in the
wastewater PE studies and has the potential to provide these samples
for drinking water studies. Due to the lability of chlorine dioxide,
EPA does not expect a suitable PE sample can be designed for chlorine
dioxide measurements.

A. PE-Sample Acceptance Limits for Laboratory Certification

Historically, EPA has set minimum PE acceptance limits based on one
of two criteria: statistically derived estimates or fixed acceptance
limits. Statistical estimates are based on laboratory performance in
the PE study; fixed acceptance limits are ranges around the true
concentration of the analyte in the PE sample. Today's proposed rule
combines the advantages of these approaches by specifying
statistically-derived acceptance limits around the study mean, within
specified minimum and maximum fixed criteria.
EPA believes that specifying statistically-derived PE acceptance
limits with upper and lower bounds on acceptable performance will
provide the flexibility necessary to reflect improvement in laboratory
performance and analytical technologies. The proposed acceptance
criteria will maintain minimum data quality standards (the upper bound)
without artificially imposing unnecessarily strict criteria (the lower
bound). Therefore, EPA is proposing the following acceptance limits for
measurement of bromate, chlorite, each haloacetic acid, and each
trihalomethane in a PE sample.
EPA proposes to define acceptable performance for each chemical
measured in a PE sample from estimates derived at a 95% confidence
interval from the data generated by a statistically significant number
of laboratories participating in the PE study. However, EPA proposes
that these acceptance criteria not exceed <plus-minus>50% nor be less
than <plus-minus>15% of the study mean. If insufficient PE study data
are available to derive the estimates required for any of these
compounds, the acceptance limit for that compound will be set at
<plus-minus>50% of the study true value. The true value is the
concentration of the chemical that EPA has determined was in the PE
sample.
EPA recognizes that when using multianalyte methods, the data
generated by laboratories that are performing well will occasionally
exceed the acceptance limits. Therefore, to be certified to perform
compliance monitoring using a multianalyte method, laboratories are
required to generate acceptable data for at least 80% of the regulated
chemicals in the PE sample that are analyzed with the method. If fewer
than five compounds are included in the PE sample, data for each of the
analytes in that sample must meet the minimum acceptance criteria in
order for the laboratory to be certified.

B. Approval Criteria for Disinfectants and Other Parameters

Today's rule proposes MRDLs for the three disinfectants--chlorine,
chloramines, and chlorine dioxide. In addition, monitoring requirements
(under conditions explained in sections VIII and IX of this notice) are
being proposed for total organic carbon (TOC), alkalinity, and bromide;
there are no MCLs proposed for these parameters. In previous rules (40
CFR 141.28, .74, and .89), EPA has required that measurements of
alkalinity, disinfectant residuals, pH, temperature, and turbidity be
made with an approved method and conducted by a party approved (not
certified) by the State. In today's rule, EPA proposes that samples
collected for compliance with today's requirements for alkalinity,
bromide, residual disinfectant, and TOC only be conducted with approved
methods and by a party approved by the State.

C. Other Laboratory Performance Criteria

For all contaminants and parameters proposed for monitoring in
today's rule, the States may impose other requirements for a laboratory
to be certified or a party to be approved to conduct compliance
analyses. EPA solicits suggestions for other optional or mandatory
performance criteria that EPA or the States should consider for
certification or approval of laboratories.

XI. Variances and Exemptions

A. Variances

Under section 1415(a)(1)(A) of the SDWA, a State which has primary
enforcement responsibility (primacy), or EPA as the primacy agent, may
grant variances from MCLs to those public water systems that cannot
comply with the MCLs because of characteristics of the water sources
that are reasonably available. At the time a variance is granted, the
State must prescribe a compliance schedule and may require the system
to implement additional control measures. The SDWA requires that
variances only be granted to those systems that have installed BAT (as
identified by EPA in the regulations). Furthermore, before EPA or the
State may grant a variance, it must find that the variance will not
result in an unreasonable risk to health (URTH) to the public served by
the public water system. The levels representing an URTH for each of
the contaminants and disinfectants in this proposal will be addressed
in subsequent guidance. In general, the URTH level would reflect acute
and subchronic toxicity for shorter term exposures and high
carcinogenic risks for long-term exposures (as calculated using the
linearized multistage model in accordance with the Agency's risk
assessment guidelines; see URTH Guidance, 55 FR 40205, October 2,
1990).
Under section 1413(a)(4), States that choose to issue variances
must do so under conditions, and in a manner, that are no less
stringent than EPA allows in section 1415. Of course, a State may adopt
standards that are more stringent than the EPA standards. Before a
State may issue a variance, it must find that the system is unable to
(1) Join another water system or (2) develop another source of water
and thus comply fully with all applicable drinking water regulations.
EPA specifies BATs for variance purposes. EPA may identify as BAT
different treatments under section 1415 for variances than BAT under
section 1412 for MCLs. EPA's section 1415 BAT findings may vary
depending on a number of factors, including the number of persons
served by the public water system, physical conditions related to
engineering feasibility, and the costs of compliance with MCLs. In this
proposal, EPA is not proposing a different BAT for variances under
section 1415.

B. Exemptions

Under section 1416(a), EPA or a State may exempt a public water
system from any requirements related to an MCL or treatment technique
of an NPDWR, if it finds that (1) Due to compelling factors (which may
include economic factors), the PWS is unable to comply with the
requirement; (2) the exemption will not result in an unreasonable risk
to health; and (3) the PWS was in operation on the effective date of
the NPWDR, or for a system that was not in operation by that date, only
if no reasonable alternative source of drinking water is not available
to the new system.
If EPA or the State grants an exemption to a public water system,
it must at the same time prescribe a schedule for compliance (including
increments of progress) and implementation of appropriate control
measures that the State requires the system to meet while the exemption
is in effect. Under section 1416(a)(2), the schedule must require
compliance within one year after the date of issuance of the exemption.
However, section 1416(b)(2)(B) states that EPA or the State may extend
the final date for compliance provided in any schedule for a period not
to exceed three years, if the public water system is taking all
practicable steps to meet the standard and one of the following
conditions applies: (1) The system cannot meet the standard without
capital improvements that cannot be completed within the period of the
exemption; (2) in the case of a system that needs financial assistance
for the necessary implementation, the system has entered into an
agreement to obtain financial assistance; or (3) the system has entered
into an enforceable agreement to become part of a regional public water
system. For public water systems which serve less than 500 service
connections and which need financial assistance for the necessary
improvements, EPA or the State may renew an exemption for one or more
additional two-year periods if the system establishes that it is taking
all practicable steps to meet the requirements above.
Under section 1416(d), EPA is required to review State-issued
exemptions at least every three years and, if the Administrator finds
that a State has, in a substantial number of instances, abused its
discretion in granting exemptions or failed to prescribe schedules in
accordance with the statute, the Administrator, after following
established procedures, may revoke or modify those exemptions and
schedules. EPA will use these procedures to scrutinize exemptions
granted by States and, if appropriate, may revoke or modify exemptions.
In addition to the conditions stated above, EPA solicits comment on
whether exemptions to this rule should be granted if a system could
demonstrate to the State, that due to unique water quality
characteristics, it could not avoid through the use of BAT the
possibility of increasing its total health risk by complying with the
Stage 1 regulations. EPA solicits comment on when such situations might
occur. For example, such situations might occur for systems with
elevated bromide levels in raw water. In this case, it is possible that
the use of BAT could result in the increase of total risk due to
increased concentrations of brominated byproducts in the finished
water. EPA also solicits comment on what specific conditions, if any,
should be met for a system to be granted an exemption under such a
provision. What provisions should EPA require of States to grant these
exemptions? Should such exemptions be granted for a limited period but
be renewable by the State if no new health risk information became
available?

XII. State Implementation

The Safe Drinking Water Act provides that States may assume primary
implementation and enforcement responsibilities. Fifty-five out of 57
jurisdictions have applied for and received primary enforcement
responsibility (primacy) under the Act. To implement the federal
drinking water regulations, States must adopt their own regulations
which are at least as stringent as the federal regulations. This
section describes the regulations and other procedures and policies
that States must adopt to implement this proposed rule.
To implement this proposed rule, States are required to adopt the
following regulatory requirements:

--Section 141.32, Public Notification;
--Section 141.64, MCLs for Disinfection Byproducts;
--Section 141.65, MRDLs for Disinfectants;
--Subpart L, Disinfectant Residuals, Disinfectant Byproducts, and
Disinfection Byproduct Precursors.

In addition to adopting regulations no less stringent than the
federal regulations, EPA is proposing that States adopt certain
requirements related to this regulation in order to have their program
revision applications approved by EPA. In several instances, the
proposed NPDWRs provide flexibility to States in implementing of the
monitoring requirements of this rule.
EPA is also proposing changes to State recordkeeping and reporting
requirements. EPA's proposed changes are discussed below.

A. Special Primacy Requirements

To ensure that a State program includes all the elements necessary
for an effective and enforceable program, a State application for
program revision approval must include a description of how the State
will:
(1) Determine the interim treatment requirements for systems
granted additional time to install GAC and membrane filtration.
(2) Qualify operators of community and nontransient noncommunity
water systems subject to this regulation. Qualification requirements
established for operators of systems subject to 40 CFR Part 141 Subpart
H (Filtration and Disinfection) may be used in whole or in part to
establish operator qualification requirements for meeting Subpart L
requirements if the State determines that the Subpart H requirements
are appropriate and applicable for meeting Subpart L requirements.
(3) Approve percentage reduction of TOC levels lower than those
required in Sec. 141.135(a)(3) (i.e., how the State will approve
alternate enhanced coagulation levels).
(4) Approve parties to conduct analyses of water quality parameters
(pH, alkalinity, temperature, bromide, and residual disinfectant
concentration measurements). The State's process for approving parties
performing water quality measurements for systems subject to Subpart H
requirements may be used for approving parties measuring water quality
parameters for systems subject to Subpart L requirements, if the State
determines the process is appropriate and applicable.
(5) Approve alternate analytical methods for measuring residual
disinfectant concentrations for chlorine and chloramines. State
approval granted under Subpart H (Sec. 141.74(a)(5)) for the use of DPD
colorimetric test kits for free chlorine testing would be considered
acceptable approval for the use of DPD test kits in measuring free
chlorine residuals as required in Subpart L.
(6) Define criteria to use in determining if multiple wells are to
be considered as a single source. Such criteria will be used in
determining the monitoring frequency for systems using only ground
water not under the direct influence of surface water.

B. State Recordkeeping

The current regulations in Sec. 142.14 require States with primacy
to keep various records, including analytical results to determine
compliance with MCLs, MRDLs, and treatment technique requirements;
system inventories; sanitary surveys; State approvals; enforcement
actions; and the issuance of variances and exemptions. In this rule,
States would be required to keep additional records of the following,
including all supporting information and an explanation of the
technical basis for each decision:
(1) Records of determinations made by the State when the State has
allowed systems additional time to install GAC or membrane filtration.
These records must include the date by which the system is required to
have completed installation.
(2) Records of systems that apply for alternative TOC performance
criteria (alternate enhanced coagulation levels). These records must
include the results of testing to determine alternative limits.
(3) Records of systems that are required to meet alternative TOC
performance criteria (alternate enhanced coagulation levels). These
records must include the alternative limits and rationale for
establishing the alternative limits.
(4) Records of Subpart H systems using conventional treatment
meeting any of the enhanced coagulation or enhanced softening exemption
criteria.
(5) Records of systems with multiple wells considered to be one
treatment plant for purposes of determining monitoring frequency.
(6) Register of qualified operators.
Pursuant to Sec. 141.133(d), Subpart H systems serving more than
3,300 people are required to submit monitoring plans to the State. EPA
solicits comment on whether the State should be required to keep this
plan on file at the State after submission to make it available for
public review.

C. State Reporting

EPA currently requires in Sec. 142.15 that States report to EPA
information such as violations, variance and exemption status, and
enforcement actions. In addition to the current reporting requirements,
EPA is proposing under Sec. 142.15(c) that States also report:
(1) A list of all systems required to monitor for various
disinfectants and disinfection byproducts;
(2) A list of all systems for which the State has granted
additional time for installing GAC or membrane technology and the basis
for the additional time;
(3) A list of laboratories that have completed performance sample
analyses and achieved the quantitative results for TOC, TTHMs, HAA5,
bromate, and chlorite;
(4) A list of all systems using multiple ground water wells which
draw from the same aquifer and are considered a single source for
monitoring purposes;
(5) A list of all Subpart H systems using conventional treatment
which are not required to operate with enhanced coagulation, and the
reason why enhanced coagulation is not required for each system, as
listed in Sec. 141.135(a)(1)(A)-(D); and
(6) A list of all systems with State-approved alternate performance
standards (alternate enhanced coagulation levels).
EPA believes that the State reporting requirements contained in
this proposal are necessary to ensure effective oversight of State
programs. Public comments on these proposed reporting requirements are
requested. EPA particularly requests comment from the States on whether
the proposed reporting requirements are reasonable.

XIII. System Reporting and Recordkeeping Requirements

The current system reporting regulations, 40 CFR 141.31, require
public water systems to report monitoring data to States within ten
days after the end of the compliance period. No changes are proposed to
those requirements.
Specific data required by this rule to be reported by public water
systems are included in Sec. 141.134. These data are required to be
submitted quarterly for any monitoring conducted quarterly or more
frequently, and within 10 days of the end of the monitoring period for
less frequent monitoring. Systems that are required to do extra
monitoring because of the disinfectant used have additional reporting
requirements specified. This applies to systems that use chlorine
dioxide (must report chlorine dioxide and chlorite results) and ozone
(must report bromate results).
Subpart H systems that use conventional treatment are required to
report either compliance/noncompliance with disinfection byproduct
precursor (TOC) removal requirements or report which of the enhanced
coagulation/enhanced softening exemptions they are meeting. There are
additional requirements for systems that cannot meet the required TOC
removals and must apply for an alternate enhanced coagulant level.
These requirements are included in Sec. 141.134(b)(6).
Calculation of compliance with the TOC removal requirements is
based on normalizing the percent removals over the most recent four
quarters, since compliance is based on that period. Normalization is
necessary since source water quality changes will change the percent
removal requirements. To illustrate this process, EPA has developed a
sample reporting and compliance calculation sheet that will be included
in the (to be developed) guidance manual. An example of calculations
using the sheet is included in Section VIII (Description of the
Proposed D/DBP Rule).

XIV. Public Notice Requirements

Under Section 1414(c)(1) of the Act, each owner or operator of a
public water system must give notice to persons served by it of: (1)
Any violation of any MCL, treatment technique requirement, or testing
provision prescribed by an NPDWR; (2) failure to comply with any
monitoring requirement under section 1445(a) of the Act; (3) existence
of a variance or exemption; and (4) failure to comply with the
requirements of a schedule prescribed pursuant to a variance or
exemption.
The 1986 Amendments required that EPA amend its current public
notification regulations to provide for different types and frequencies
of notice based on the differences between violations which are
intermittent or infrequent and violations which are continuous or
frequent, taking into account the seriousness of any potential adverse
health effects which may be involved. EPA promulgated regulations to
revise the public notification requirements on October 28, 1987 (52 FR
41534). The regulations state that violations of an MCL, treatment
technique, or variance or exemption schedule (``Tier 1 violations'')
contain health effects language specified by EPA which concisely and in
non-technical terms conveys to the public the adverse health effects
that may occur as a result of the violation. States and water utilities
remain free to add additional information to each notice, as deemed
appropriate for specific situations. Today's proposed rule contains
specific health effects language for the contaminants which are in
today's proposed rulemaking. EPA believes that the mandatory health
effects language is the most appropriate way to inform the affected
public of the health implications of violating a particular EPA
standard. The proposed mandatory health effects language in
Sec. 141.32(e) describes in non-technical terms the health effects
associated with the proposed contaminants.
Under this rule, Sec. 141.135 prescribes treatment technique
requirements. Violations of these requirements are considered Tier 1
violations. Tier 2 violations include monitoring violations, failure to
comply with an analytical requirement specified by an NPDWR, and
operating under a variance or exemption.
EPA requests comment on its proposed rule language. Of particular
interest is the acute violation language in Sec. 141.32(e)(85) for
violations of the chlorine dioxide MCL. Also of interest is the
language in Sec. 141.32(e)(86) for violations of the TTHM and HAA5 MCLs
and the enhanced coagulation treatment technique requirement.

XV. Economic Analysis

A. Executive Order 12866

Under Executive Order 12866 (58 FR 51735, October 4, 1993), the
Agency must determine if the regulatory action is ``significant'' and
therefore subject to OMB review and the requirements of the Executive
Order. The Order defines ``significant regulatory action'' as one that
is likely to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
Pursuant to the terms of Executive Order 12866, it has been
determined that this rule is a ``significant regulatory action''
because it will have an annual effect on the economy of $100 million or
more. As such, this action was submitted to OMB for review. Changes
made in response to OMB suggestions or recommendations will be
documented in the public record.

B. Predicted Cost Impacts On Public Water Systems

Compliance Treatment Cost Forecasts
Compliance treatment cost forecasts were estimated by the TWG. The
basis for these estimates presented herein are described in the
Regulatory Impact Analysis (USEPA, 1994). Tables XV-1 through XV-3
present summaries of the estimated total national costs of installing
and operating treatment to comply with both Stage I and Stage II
requirements. Table XV-1 is a summary of estimated cost impacts for all
public water supplies affected (i.e., community and nontransient
noncommunity systems) and represents a combination of the estimates
indicated in Table XV-2 for community systems and Table XV-3 for
nontransient noncommunity systems.

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The rule would affect about 51,500 ``non-purchased'' community
water systems and 24,500 ``non-purchased'' nontransient noncommunity
water systems. Non-purchased water systems are those that produce and/
or treat water for distribution. Of the affected community water
systems, about 95% serve fewer than 10,000 persons. It is estimated
that all but four of the affected nontransient noncommunity water
systems serve fewer than 10,000 persons. As a group, the systems
serving fewer than 10,000 persons are projected to account for about 40
percent of the total annual cost of installing and operating treatment
to comply with the rule and about 55 percent of the total cost of
monitoring and reporting to comply with the rule. In terms of the
Regulatory Flexibility Act, this rule will have a significant impact on
a substantial number of small systems. Following EPA guidance, the
Regulatory Flexibility Act Analysis will be presented within the
Regulatory Impact Analysis.
The Stage II DBP Rule--as proposed--would apply only to nonpurchased
community and NTNC surface water systems serving more than
10,000 persons. The impact of the Stage II requirements on these
systems will result in a combined total annual cost (Stage I + Stage
II) for installing and operating treatment facilities of $1.77 billion
per year. If the Stage II requirements were extended to cover all
systems, the result would be a combined total annual cost (Stage I +
Stage II) for installing and operating treatment facilities of $2.56
billion per year. Monitoring and state implementation costs have not
been estimated for Stage II. Under this extended Stage II scenario,
systems serving fewer than 10,000 persons would account for nearly 40
percent of the total annual cost of installing and operating treatment.
In terms of the total annual cost of installing and operating
treatment, the Stage II extended scenario would be about one-and-onehalf
times as expensive as Stage I. The same ratio applies to both size
categories of systems, i.e., those serving greater or fewer than 10,000
people.
2. Compliance Treatment Forecast
Tables XV-4 and XV-5 present summaries of the national forecasts of
treatment choices that were made to support the development of the
national treatment cost estimates. The DBPRAM, a Monte Carlo simulation
model of influent variability combined with a treatment model to
predict treatment performance, was used to seed this analysis.
Initially, the DBPRAM provided a default set of most likely compliance
choices based on a least cost algorithm based on estimated costs of
different unit processes (Gelderloos et al., 1992; Cromwell et al.,
1992; USEPA, 1992). These choices were then adjusted via a consensus
process reflecting the combined judgement of the TWG (USEPA, 1994).
While some technologies, such as chlorine dioxide, were recognized as
possible means for achieving compliance, insufficient data were
available to predict such compliance choices. However, the TWG believed
that failure to consider compliance choices other than those listed in
Tables XV-4 and XV-5 would not significantly affect the total national
cost compliance cost estimates.

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Regarding Table XV-4, the DBPRAM predicted that 60 percent of all
systems using surface water would at least use enhanced coagulation to
comply with the Stage 1 requirements. Among the systems using enhanced
coagulation, 10% would also use chloramines as their residual
disinfectant (with chlorine used as the primary disinfectant), 6% would
also use ozone as their primary disinfectant and chloramines as their
residual disinfectant, 1% would also use GAC10, and 1% would also use
GAC20. Among the systems not using enhanced coagulation, 3% would use
chloramines as a residual disinfectant (with chlorine as the primary
disinfectant), 5% would use ozone as their primary disinfectant and
chloramines as their residual disinfectant, and 4% would use membrane
technology. The predicted compliance choices for systems serving 10,000
people or less are almost the same as those for systems serving greater
than 10,000 people. One notable difference is that because of large
economies of scale for GAC20, no systems serving 10,000 people or less
are predicted to use GAC20; rather all such systems (6%) requiring
substantial precursor removal are predicted to use membrane technology.
Regarding Table XV-5, the DBPRAM predicted that for systems using
ground water and seeking to comply with the Stage 1 requirements, 8%
would use chloramines as their residual disinfectant (with chlorine as
the primary disinfectant), 4% would use membrane technology, and 0.04%
would use ozone for primary disinfection with chloramines for residual
disinfection. While 2% of systems serving greater than 10,000 people
were predicted to use ozone and chloramines, no systems serving 10,000
people or less were predicted to use this technology (for these sized
systems membranes were considered a preferred option to ozone and
chloramines because of the likely lower system level cost and ease of
use).
Unlike for surface water supplies, all large ground water systems
with high DBP precursor levels are predicted to use membrane technology
in lieu of GAC. This is because large ground water systems are assumed
to use multiple wells, each being of small enough size to be more cost
effectively treated with membrane technology than by GAC.
The percentage of systems affected by the DBP regulations is
markedly less among those using ground waters than those using surface
waters. This is because (1) Most ground waters have much lower levels
of DBP precursors than surface waters, and (2) most ground waters
(i.e., those not under the direct influence of surface water as assumed
in this analysis) are not considered vulnerable to contamination by
protozoa and therefore require much less disinfection. Also, some
ground water systems which are adequately protected will be able to
avoid disinfection altogether and thereby avoid needing to meet any
regulatory requirements pertaining to DBPs.
3. DBP Exposure Estimates
Table XV-6 presents three computer generated profiles of exposure
reflecting the baseline condition, the Stage I rule, and the Stage II
rule. The change in exposure is characterized in terms of TOC, TTHMs,
and HAA5. These data are applicable only to large systems (>10,000
population) which filter but do not soften. The median and 95th
percentile values for effluent TOC are shown to be reduced from 2.5 and
4.9 mg/l under baseline conditions to 2.2 and 3.8 mg/l at Stage I, and
2.0 and 3.3 mg/l at Stage II. The median and 95th percentile values for
TTHMs are shown to be reduced from 46 and 104 <greek-m>g/l under
baseline conditions to 31 and 58 <greek-m>g/l at Stage I, and 22 and 30
<greek-m>g/l at Stage II. The median and 95th percentile values for
effluent HAA5 are shown to be reduced from 28 and 86 ug/l under
baseline conditions to 20 and 43 <greek-m>g/l at Stage I, and 14 and 22
<greek-m>g/l at Stage II.

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Quantitative changes in exposure from TOC and DBPs were not
predicted for ground water systems because of insufficient data.
Treatment changes that ground water systems make to comply with the DBP
regulations are likely to result in lower reductions of national median
TOC and DBP levels than in surface water supplies. This is because of
the much smaller percentage of ground water systems that are affected.
However, the resultant change from the DBP regulations on the 95th
percentile of TOC and DBP levels in ground water systems may be more
significant than in surface water systems. This is because membrane
filtration, which would be used in the systems with poorest quality,
can remove greater than 90% of TOC, resulting in probably similar
reductions of TTHMs and HAA5 (USEPA 1992).
4. System Level Cost Estimates
Tables XV-7 and XV-8 present the unit cost estimates that were
utilized for each of the different treatment technologies in each
system size category. The unit cost estimates were derived from a cost
model described in the Cost and Technology document (USEPA 1992) and
adjusted per discussion among TWG to reflect site specific factors
(USEPA 1994). For systems in size categories serving greater than
10,000 people the estimated system level costs for achieving compliance
ranged from $0.01/1000 gallons (chlorine/chloramines) to $1.87/1000
gallons (membrane technology). For systems in size categories serving
less than 10,000 people the estimated system level costs for achieving
compliance ranged from $.03/1000 gallons (chlorine/chloramines) to
$3.49/1000 gallons. Although some technologies are listed as costing
more than $3.49/1000 gallons in the smallest size categories (because
of large economies of scale), no such technologies would be used
because compliance could be achieved with membrane technology.

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5. Effect on Household Costs
Table XV-9 summarizes cost impacts at the household level contained
in Figures XV-1 through XV-4 for systems having to install and operate
treatment. The impacts presented for Stage II represent the cumulative
cost per household of both Stage I and Stage II. The household impacts
are based solely upon the community water system analysis since the
nontransient noncommunity systems typically do not serve households.
These household impacts do include, however, the households in
purchased water systems that are served by the affected non-purchased
water systems. These household costs reflect only the cost of treatment
and do not include the cost of monitoring. Note also that costs of an
Enhanced Surface Water Treatment Rule, if such a rule should become
necessary, are not included.

Table XV-9.--Stage 1 and Stage 2 Household Cost Impact Summary

Large Small Large Small
Type of system surface surface ground ground Totals
water\1\ water\1\ water\1\ water\1\

Number of systems.............................. 1395 4562 1316 44,310 51,583
Number of households (in millions)............. 56 6.4 19 12.3 93.7

$/household/yr.
(4) Number of households expected to pay
specific increased costs for compliance with
stage 1 (in millions)

0.......................................... 16.8 1.8 16.0 10.6 45.2
>0-10...................................... 30.8 2.4 2.0 1.0 36.2
>10-20..................................... 4.5 1.1 0.2 None 5.8
>20-40..................................... 2.2 0.1 0.2 0.1 2.6
>40........................................ 1.7 1.0 0.6 0.6 3.9

(4) Number of households expected to pay
specific increased costs for compliance with
stage 1 and stage 2 (in millions)

0.......................................... 13.4 (\2\) (\2\) (\2\) 13.4
>0-10...................................... 25.2 (\2\) (\2\) (\2\) 25.2
>10-20..................................... 6.2 (\2\) (\2\) (\2\) 6.2
>20-40..................................... 6.7 (\2\) (\2\) (\2\) 6.7
>40........................................ 4.5 (\2\) (\2\) (\2\) 4.5

\1\Large systems serve 10,000 or more persons. Small systems serve fewer than 10,000 persons. Surface water
systems are Subpart H systems. Ground water systems are systems using only ground water not under the direct

influence of surface water.

\2\Today's Stage 2 D/DBP Rule proposal only applies to Subpart H systems serving at least 10,000 persons. As

proposed, there are no household compliance costs for other systems.

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EPA estimates that about 45 million households (48% of the total
served by community water systems) will incur no treatment costs for
compliance with Stage I. Of 49 million households incurring treatment
costs for compliance with Stage I, 45.5 million will incur costs of
less than $50 per year, 1.3 million will incur costs of $50 to $100 per
year, 1.0 million will incur costs of $100 to $200 per year, 0.8
million will incur costs of $200 to $300 per year, and 0.2 million will
incur costs of more than $300 per year.
EPA estimates that 13.4 million of the 56 million households served
by large surface water systems (24% of the total) will incur no
treatment costs for compliance with Stage II as proposed (applying only
to large surface water systems). Of the nearly 43 million households
incurring treatment costs for compliance with Stage II as proposed,
39.8 million will incur costs of less than $50 per year, 2.2 million
will incur costs of $50 to $100 per year, and 0.8 million will incur
costs of $100 to $200 per year.
EPA estimates that 36.3 million households (39% of the total served
by community water systems) will incur no treatment costs for
compliance with Stage II if extended to all systems. Of the 57.2
million households incurring treatment costs for compliance with an
extended Stage II, 48.6 million will incur costs of less than $50 per
year, 2.7 million will incur costs of $50 to $100 per year, 2.6 million
will incur costs of $100 to $200 per year, 2.5 million will incur costs
of $200 to $300 per year, and 0.8 million will incur costs of more than
$300 per year. Annual household costs above $200 are projected
predominantly for small systems that may be required to install
membrane treatment. Some of these systems could find that there are
less expensive options available, such as connecting into a larger
regional water system.
Impacts on Low Income Families. The Negotiating Committee had
several discussions of the impact of the DBP regulatory proposals on
low income households and reviewed the impact estimates specifically in
this light. An analysis was presented that focused exclusively on the
impact on low income households, using data on families enrolled in the
Aid to Families with Dependent Children (AFDC) program as an
illustration.
Based on the 1992 Statistical Abstract of the United States, there
were 4.2 million AFDC families (this represents about one- third of all
families below the poverty line). In the absence of information to
suggest otherwise, it was assumed that these families are distributed
across water system types and sizes in the same proportion as the total
population. The analysis was performed to illustrate the impact of the
Stage II DBP requirements under the assumption that the 40/30
requirement was extended to all water systems. Results are presented in
Figure XV-5.
The results in Figure XV-5 show the distribution of impacts in
terms of the number of households that would have a given level of
impact on their household income in terms of the percent of AFDC
income. Based on the current level of AFDC payments, a $22 per year
increase in the water bill is equivalent to 0.5 percent of AFDC income.

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With the given assumptions about the distribution of AFDC
households, it is projected that 1.7 million of the 4.2 million AFDC
families would be served by water systems that are unaffected by the
DBP regulations. This reflects a general characteristic of the
regulation of DBPs--that it is not going to be a problem in many
systems that have fortunate circumstances regarding raw water
characteristics.
Another 1.8 million of the 4.2 million AFDC families are projected
to be served by water systems that will incur costs of less than $22
per household per year, or less than 0.5 percent of AFDC income. This
reflects another feature of the DBP rule--that impacts might not be too
severe in many large urban water systems with moderate levels of DBPs
and economies of scale. It is noted, however, that the current Stage II
cost estimates are based upon generous use of alternative
disinfectants. If use of alternative disinfectants becomes unacceptable
or inadequate for meeting other concurrent criteria (such as DBP
precursor removal), greater use of alternative precursor removal
technologies becomes necessary as a means of achieving compliance and
utilities could incur expenses several times as great.
About one-sixth of the 4.2 million AFDC households (0.7 million)
are projected to be served by water systems that will incur costs of
more than $22 per household per year, or more than 0.5 percent of AFDC
income. These estimates are also based on an assumption of extensive
use of alternative disinfectants that are less expensive than precursor
removal technologies.
Important patterns are illustrated in Figure XV-5. Most of the
700,000 households are concentrated in large systems near the low end
of the scale. Nearly 75 percent (514,000 of the total 700,000
households) are projected to be served by large water systems. Among
these 514,000 households, over 75 percent (390,000) will face costs of
less than 2 percent of AFDC income; nearly half (248,000) will face
costs of less than 1 percent of AFDC income. Less than one-quarter of
AFDC households in large systems (124,000) will face costs between 2
percent and 4.5 percent of AFDC income. None will face costs greater
than 4.5 percent of AFDC income. Again, these estimates assume use of
alternate disinfectants rather than more costly precursor removal
technologies.
At the extreme right-hand side of Figure XV-5, the most extreme
impacts on AFDC households are indicated to occur in small water
systems. Given the assumptions of this analysis, it is projected that
there will be 147,000 AFDC households in small communities that will
face costs of between 6.0 and 7.0 percent of AFDC income. This impact
is more likely to occur in small rural communities in declining
economic regions. Realistically, it is not clear that such communities
could raise the required capital without some form of government
assistance that might reduce the final cost per household.
6. Monitoring and State Implementation Costs, Labor Burden Estimates
Table XV-10 summarizes the monitoring and state implementation cost
and labor burden estimates. In compliance with the Paperwork Reduction
Act, EPA estimates the total labor burden of complying with monitoring
and reporting requirements to be 1.5 million hours over six years,
averaging 250,000 hours per year. This estimate equates to an average
of 4 hours per system per year. The labor burden for State program
implementation is estimated to total 2.5 million hours over six years,
averaging 416,666 hours per year. This estimate implies a per State
average of 7,440 hours per year. However, the implementation work load
will not be staggered evenly over the six year period or by State.

BILLING CODE 6560-50-P

<GRAPHIC><TIF41>TP29JY94.040

BILLING CODE 6560-50-C
The total cost of compliance with the monitoring requirements is
estimated to be $283 million over six years, averaging $47 million per
year. The total cost of state implementation is estimated to be $82
million over six years, averaging $14 million per year. The cost of
monitoring and of state implementation will not be evenly spread over
the six year period.

C. Concepts of Cost Analysis

The Negotiating Committee reviewed the cost of capital assumptions
normally employed by EPA in analyzing drinking water regulations. EPA
typically assumes a 7 percent interest rate and a 20-year term. These
assumptions result in a Capital Recovery Factor of 0.09439. The Capital
Recovery Factor is multiplied times the capital cost to arrive at the
amount of the annual payment required including principal and interest.
During the negotiation, it was pointed out that the standard EPA
assumption is too low for investor owned utilities considering other
carrying costs of capital investment (e.g., taxes, depreciation),
although it be reasonable for municipal utilities considering current
interest rates. It was also noted that the standard EPA assumption is
too low an estimate for the cost of capital in small investor owned
systems and other small private systems (e.g., homeowner's
associations, trailer parks, etc.) considering differences in credit
risk and access to capital.
An analysis was presented by a member of the Negotiating Committee
indicating that a Capital Recovery Factor of 0.17172 is appropriate for
large investor owned utilities and that a Capital Recovery Factor of
0.20105 is appropriate for small privately owned water systems. Based
on current interest rates for municipal bonds, the TWG determined that
Capital Recovery Factors of 0.09439 and 0.10185 are appropriate for
large and small municipally owned water systems, respectively. EPA and
NAWC data on the mix of ownership types by system size were then used
to develop weighted composite Capital Recovery Factors for use in the
analysis. The results are summarized as follows:

Capital

Category Ownership of recovery Composite

systems factors factors

<1,000...................... priv 87......... 0.20105 0.18815

publ 13......... 0.10185

1,000-10,000................ priv 25......... 0.20105 0.12665

publ 75......... 0.10185

10,000-100,000.............. priv 14......... 0.17172 0.10522

publ 86......... 0.09439

100,000+.................... priv 17.5....... 0.17172 0.10792

publ 82.5....... 0.09439

Capital costs are based on the EPA Cost and Technology Document which
represents fourth quarter 1991 costs. These costs were not adjusted for
inflation, but very little inflation has occurred since then.

D. Benefits

Despite the enormous uncertainties for estimating reductions in
risk resulting from different regulatory strategies, the Negotiating
Committee recognized that the existing risks could be large, and
therefore should be reduced. The Negotiating Committee reached a
consensus that the Stage 1 requirements were of sufficient benefit to
be proposed for all system sizes, but could not agree on Stage 2
reductions. Until extensive epidemiological and toxicological studies
have been completed, it is not possible to draw definitive quantitative
conclusions regarding the precise extent of cancer and non-cancer
adverse health effects resulting from disinfection byproducts.
Nevertheless, based on exposure estimates described above, an
analysis was developed to provide some quantitative indication of the
range of possibilities implied by the Stage I and Stage II proposals in
terms of the cost-per-case-of-cancer-avoided. Toxicological and
epidemiological analyses can be applied to the exposures predicted by
the DBPRAM to suggest a range of annual cancer incidence that might be
avoided if systems were to comply with the proposed D/DBP regulations.
During the regulatory negotiations, some negotiators argued that
the national baseline incidence of cancer attributed to DBPs in
drinking water may be less than 1 case per year; others argued that
over 10,000 cases per year are linked to DBPs. The lower bound baseline
risk estimate was based on the maximum likelihood estimates of
toxicological risk (best case estimates as opposed to upper 95%
confidence bound estimates) associated with THM levels (i.e.,
chloroform, bromoform, bromodichloromethane, and dibromochloromethane)
predicted by the DBPRAM (USEPA, 1994). Not included in the lower bound
estimate were any risks resulting from exposure to HAAs or other DBPs.
Although dichloroacetic acid has been classified as a probable human
carcinogen (see Section V of this preamble), risks have not been
included for this chemical because the Agency has not yet quantified
its carcinogenic potential. Also, since cancer bioassays are only
currently underway for the brominated HAAs, potential risks from their
exposure could not be quantified. No national risk estimates were
possible for bromate because of the lack of national occurrence data or
model to predict bromate formation.
An upper bound base-line estimate of over 10,000 cancer cases per
year was considered based upon the central tendency estimate of the
pooled relative risks from a meta-analysis study which statistically
combined the results of ten previously published epidemiology studies
(Morris et al. 1992). The basis for estimating risks from the metaanalysis
was questioned by some members of the Negotiating Committee,
including EPA, because (a) the studies used in the meta-analysis were
of different design and thus not subject to a meta-analysis and (b)
potential confounding factors or bias may not have been adequately
controlled (Farland and Gibb, 1993; Craun 1993; Murphy 1993). Also, the
epidemiologic studies used in the meta-analysis considered exposure to
populations before the advent of the 1979 MCLs for TTHMs; that
regulation significantly reduced exposure to chlorinated DBPs (McGuire
et al 1989). Other members of the Negotiating Committee, however,
commented that many of the ``biases'' noted in studies used in the
meta-analysis would tend to underestimate cancer risks and that, taken
as a whole, these studies are highly suggestive of a link between DBPs
and certain cancers. They also noted that current THM rules do not
apply to most public water systems (those serving fewer than 10,000
people) which serve about 20% of the U.S. population. Also, these rules
do not necessarily control many other DBPs which may be of health risk
significance.
While research is needed to establish better risk estimates
associated with disinfected water, the above estimates appear to
reasonably bound the potential for cancer risk (it should be noted,
however, using the upper bound of the meta-analysis estimate would have
resulted in a higher baseline cancer risk estimate). In order to
estimate the benefits of reducing DBP exposure, EPA made certain
assumptions. All assumptions are based on results of DBPRAM estimates
of conditions in large surface water systems that filter but do not
soften. These systems represent about 80 percent of the population
served by surface water systems and over 50 percent of the population
served by all public water systems. However, this analysis does not
address the benefits to consumers using smaller systems. One approach
used was to assume that the percent reduction in TTHM and HAA5 median
effluent concentrations reflects an equivalent percent reduction in
cancer risk. A second approach was to assume that the percent reduction
in median TOC effluent concentration reflects an equivalent percent
reduction in cancer risk. These alternatives were evaluated under the
assumption that there would be no compromising the SWTR risk goal of no
more than one case of giardiasis per 10,000 people per year. In other
words, this microbial treatment objective was used to constrain the
DBPRAM model while predicting a) the baseline levels of TTHMs, HAA5,
and TOC under the existing SWTR, and b) the new concentrations of
TTHMs, HAA5, and TOC resulting from systems attempting to meet the
Stage 1 and Stage 2 requirements (USEPA, 1994). This modeling
constraint, which is in effect an ESWTR consistent with the objectives
of the SWTR, avoids increases in microbial risk and simplifies the
benefits analysis. The preamble to the proposed ESWTR, elsewhere in
today's Federal Register, discusses how the DPBRAM has also been used
to predict increases in microbial risk that might result if systems
complied with more stringent DBP standards without an ESWTR.
In Stage 1, the DBPRAM predicted that the baseline median TTHM and
HAA5 effluent concentrations would be reduced by 33 and 29 percent,
respectively, while the TOC effluent concentration would be reduced by
12 percent. Assuming that the change in the median effluent TTHM and
HAA5 levels reflects the same changes in exposure from cancer risk
(relative to the respective toxicological and epidemiological baseline
risk levels previously alluded to), the Stage I proposal would result
in avoidance of between 0.29 to 0.33 cases per year and 2,900 to 3,300
cases per year. The lower bound of cancer cases avoided per year is
likely to be understated because, in the absence of risk estimates
available for other DBPs, it is assumed that all cancer cases caused by
exposure to DBPs can be represented by the maximum likelihood
toxicological risk estimate from exposure to THMs alone.
Under the assumptions described above and assuming that the change
in median effluent TOC reflects the same changes in exposure from
cancer risk, the Stage I proposal would result in avoidance of between
0.12 and 1,200 cases of cancer per year. In Stage 2, the change in
median TTHM and HAA5 effluent concentrations was a reduction of 48 and
50 percent, respectively, from the baseline prior to Stage 1, while the
change in TOC effluent concentration was a reduction of 18 percent.
Assuming the change in median effluent TTHM and HAA5 levels reflects
the same change in exposure from cancer risk, the Stage II proposal
would result in a cumulative (Stage 1 plus 2) avoidance of between 0.50
to 0.52 cases per year and 5,000 to 5,200 cases per year. Assuming the
change in median effluent TOC reflects the change in exposure from
cancer risk, the Stage II proposal would result in cumulative avoidance
of between 0.2 and 2,000 cases of cancer per year.
If the total annual cost of treatment is $1.04 billion to meet
Stage I targets, then the cost per case of cancer avoided ranges
between $8.67 billion and $867,000 per case, based on changes in median
effluent TOC. If based on Stage I changes in median effluent TTHMs and
THAAs, the cost per case of cancer avoided ranges between $3.59 billion
and $359,000. Assuming that DBPs other than THMs pose some cancer risk,
the upper bound cost estimates per cancer case avoided are likely to be
overstated. Similarly, until more conclusive epidemiology data become
available, the lower bound cost estimate per case will remain highly
controversial. If one were to assume there is a 10 percent chance that
the baseline cancer risks suggested by Morris et al. (1992) were true,
then the estimated costs per case of cancer avoided would range from
$8.67 million per case (based on changes in median TOC) to $3.59
million per case (based on changes in median TTHMs). The lack of better
evidence for causality in the epidemiological studies would indicate
there is a possibility that the associations cited in the Morris study
are due to omitted variables or deficiencies in the data, in which case
the cost effectiveness may be even worse than these estimates.
In principle, the cost-effectiveness of the rule should be
evaluated in terms of the expected (mean) outcome and the likelihood of
this and other outcomes. Quantitative data on the likelihood of
different outcomes are unavailable, however, and as a result EPA has
been able to quantify the expected cost effectiveness only in terms of
the ranges reported here. EPA believes that likely cost-effectiveness
outcomes will fall in this range. Whether the expected cost
effectiveness of the proposal is closer to the high-end or low-end
estimates depends primarily on whether future epidemiological or
toxicological studies can provide stronger evidence of a causal effect
of exposure to disinfected (e.g., chlorinated) water on cancer risks.
Cost-effectiveness will be affected by the size and the water
quality of a particular system, and the technology used for achieving
compliance. Economies of scale for technologies used to achieve
compliance will make household compliance costs higher in smaller
systems than in larger systems (see Table XV-8). However, because many
large systems will already have reduced exposure from DBPs under the
existing TTHM standard (which only pertains to systems serving greater
than 10,000 people), reductions in exposure from DBPs in many small
systems is also likely to be greater than in larger system. Although
the data are limited, this presumption appears to be supported by
Figures VI-11 and VI-13 in section VI of this preamble. Figures VI-11
and VI-13 suggest that a substantial number of systems serving less
than 10,000 people have much higher TTHM (and DBP) concentrations than
systems serving 10,000 people or greater. EPA solicits data and comment
on the extent to which reductions in exposure can be expected to differ
between systems serving 10,000 people or more and systems serving less
than 10,000 people.
For systems using enhanced coagulation, the technology most likely
to be used to achieve compliance among surface water supplies (see
Table XV-4), there are relatively small differences in economies of
scale (see Tables XV-6 and XV-7) and small differences in cost
effectiveness between small and large systems. Table XV-4 indicates
that approximately 17% of the surface water supplies serving fewer than
10,000 people will use technologies (ozone or membrane technology) that
would result in significantly higher household costs than those
expected in most larger-sized systems. Similarly, Table XV-5 indicates
that approximately 4% of the ground water supplies serving fewer than
10,000 people will use a technology (membrane technology) that would
result in significantly higher household costs than in most largersized
systems. Depending on the reductions in exposure, which would be
very significant in systems using membrane technology, the costeffectiveness
in some small systems is likely to be substantially less
than in larger-sized systems. EPA solicits comments on what data and
approaches could be used for estimating differences in costeffectiveness
for large versus small systems complying with Stage 1
requirements.
Maintaining the assumptions as described above, if the total annual
cost of treatment is $2.56 billion to meet Stage II targets (extended
to all systems), then the cost per case of cancer avoided ranges
between $5.3 billion and $512,000 if based on changes in median TTHM
and HAA5 effluent concentrations. If based on Stage II changes in
median effluent TOC, the cost per case of cancer avoided ranges between
$12.8 billion and $1.28 million per case.
Under the above assumptions, the Stage 1 requirements are
significantly more cost effective than the Stage 2 requirements for
reducing risk, whatever that risk may be. Despite the enormous
uncertainties for estimating reductions in risk resulting from
different regulatory strategies, the Negotiating Committee believed
that the Stage 1 requirements were of sufficient benefit to be proposed
for all system sizes. Some negotiators argued that Stage 2 controls
should only be proposed now for larger systems and revisited when more
information became available; others argued that such controls should
be put in place sooner. The ultimate decision was to propose Stage 2
rules but to provide an opportunity for consideration of more data at a
second regulatory negotiation (or similar proceeding) before Stage 2 is
finalized.

XVI. Other Requirements

A. Consultation with State, Local, and Tribal Governments

Two Executive Orders (E.O. 12875, Enhancing Intergovernmental
Partnerships, and E.O 12866, Regulatory Planning and Review) explicitly
require Federal agencies to consult with State, local, and tribal
entities in the development of rules and policies that will affect
them, and to document what they did, the issues that were raised, and
how the issues were addressed.
As described in section II of today's rule, SDWA section 1412
requires EPA to promulgate NPDWRs for at least 25 contaminants every
three years. The contaminants listed in today's rule are being proposed
in response to that Congressional mandate.
To comply with this rule, PWSs will need to meet specified levels
for total trihalomethanes, haloacetic acids, certain other byproducts,
and certain disinfectants. To meet these standards, certain systems
will need to employ enhanced coagulation, enhanced precipitative
softening, and/or other treatment technologies. The total annual cost
of the rule, including monitoring, is expected to be about $1.1 billion
per year. Systems serving more than 10,000 persons are expected to come
into compliance in 1998 and 2000 and bear $700 million of the cost.
Systems serving fewer than 10,000 persons are expected to come into
compliance in the years 2000 to 2002 and bear about $400 million of the
total cost.
The Agency first sought public input to the rule in a strawman rule
published in October 1989. Comments received in response to the
strawman rule are summarized in section IV of today's rule. In June
1991 EPA issued a status report designed to update the public on the
Agency's thinking on rule criteria. Comments were also received on the
status report; they, too, are summarized in section IV.
In 1992, EPA considered entering into a negotiated rulemaking on
this rule primarily because no clear path for addressing all the major
issues associated with the rule was apparent. EPA hired a facilitator
to explore this option with external stakeholders and, in November
1992, decided to proceed with the negotiation. The 18 negotiators,
including EPA, met from November 1992 until June 1993 at which time
agreement was reached on the content of the proposed rule. Today's
proposed regulatory and preamble language has been agreed to by the 17
negotiators who remained at the table through June 1993. A summary of
those negotiations is contained in section IV.
The negotiators included persons representing State and local
governments. At the table were:
(1) Association of State Drinking Water Administrators, a group
representing state government officials responsible for implementing
the regulations,
(2) Association of State and Territorial Health Officials, a group
representing statewide public health interests and the need to balance
spending on a variety of health priorities,
(3) National Association of Regulated Utilities Commissioners, a
group representing funding concerns at the state level,
(4) National Association of County Health Officials, a group
representing local government general public health interests,
(5) National League of Cities, a group representing local elected
and appointed officials responsible for balancing spending needs across
all government services,
(6) National Association of State Utility Consumer Advocates, a
group representing consumer interests at the state level, and
(7) National Consumer Law Center, a group representing consumer
interests at the local level.
In addition, several associations representing public municipal and
investor-owned water systems also served on the committee.
As part of the negotiation process, each of these representatives
was responsible for obtaining endorsement from their respective
organization on the positions they took at the negotiations and on the
final signed agreement. During the negotiations, the group heard from
many other parties who attended the public negotiations and were
invited to express their views. As is true with any negotiation, all
sides presented initial positions which were ultimately modified to
obtain consensus from all sides. However, all parties mentioned above
signed the final agreement on behalf of their associations. This
agreement reflected basic consensus that the cost of the rule was
offset by its public health benefits and its promotion of responsible
drinking water treatment practices.
The only original negotiator who did not sign the agreement left
the negotiations in March 1993. That negotiator represented the
National Rural Water Association (NRWA), a group representing primarily
small public and private water systems. NRWA believed that since
systems serving populations under 10,000 persons are not subject to the
current trihalomethane standard, it would be more reasonable to require
that small systems comply with the current trihalomethane standards
rather than the standards proposed today. NRWA objected to the costs of
the rule on small systems given its belief that the risks to humans
from D/DBP are poorly understood. NRWA in its letter of resignation
stated that ``[t]here is insufficient good, reliable scientific data
showing clear risks to human health from the levels of D/DBP found on
average in drinking water.'' It should be noted that although NRWA
objected to the cost of the rule, they had supported an option with
approximately the same estimated cost earlier in the negotiation
process. The NRWA position that small systems should meet the current
trihalomethane standard was rejected by the remaining negotiators,
several of whom also represent small water systems.
The contents of today's proposed rule has been available to the
public for several months as part of the regulatory negotiation
signature process. EPA has briefed numerous groups, including
government organizations, on its contents. The Agency has received
several letters from public water systems objecting to the cost of the
proposed rule and questioning its potential health benefit. These
letters are contained in the public docket supporting today's rule. The
Agency recognizes that many persons are concerned whether the proposed
rule is warranted. The technical issues are complex. The process needed
to develop a common level of understanding among the negotiators as to
what was known and unknown and what are reasonable estimates of
potential costs and benefits was time-consuming. It is unreasonable to
expect persons not at the negotiating table to have that same level of
understanding and to all share the same view. However, the discussions
throughout the negotiated rulemaking process were informed by a broad
spectrum of opinions. The Agency believes this consensus proposal is
not only the preferred approach but one which will generate informed
debate and comment.

B. Regulatory Flexibility Act

The Regulatory Flexibility Act, 5 U.S.C. 602 et eq., requires EPA
to explicitly consider the effect of proposed regulation on small
entities. By policy, EPA has decided to consider regulatory
alternatives if there is any economic impact on any number of small
entities. The Small Business Administration defines a ``small water
utility'' as one which serves fewer than 3,300 people. If there is a
significant effect on a substantial number of small systems, the Agency
must seek means to minimize the effects.
In accordance with the Regulatory Flexibility Act EPA has conducted
a Regulatory Flexibility Analysis indicating what the predicted impacts
on small systemns could be and how such impacts could be minimized. A
detailed description of this effort is available in the Regulatory
Impact Analysis (USEPA, 1994). Following is a summary of the key
elements of the Regulatory Flexibility Analysis.
Throughout the negotiated rulemaking process, small systems were
defined as those serving fewer than 10,000 persons. This definition was
used because there is an existing SDWA standard of 0.10 mg/l for total
trihalomethanes that applies only to systems serving at least 10,000
persons. Systems serving fewer than 10,000 persons are presently
unregulated with respect to disinfection byproducts. There are, as a
result, two different baseline conditions from which water systems will
approach additional disinfection byproduct control. The major impact
will be the requirement to install and operate water treatment
equipment to meet specific standards of quality in the delivered water.
These requirements pertain primarily to systems that actually treat
water. Systems that purchase treated water from another source may see
an increase in their wholesale costs, but a data base sufficient to
track all the wholesale treated water transactions in the country does
not exist. Impacts are therefore evaluated in terms of the systems that
treat water. The data with which to characterize the capacities and
flows of these facilities does exist and provides an adequate basis for
assessing total capital and operating costs.
EPA estimates that there are a total of 76,051 community and
nontransient noncommunity water systems that treat water. Of these, an
estimated 73,336 (96%) serve fewer than 10,000 persons. Despite their
overwhelming dominance in terms of industry structure, these systems
provide water to only 22 percent of the total population served by
public water supplies.
Of the total 68,171 small groundwater systems, it is estimated that
8,324 (12%) will have to modify treatment to comply with the Stage 1
proposal. The TWG forecast that 5,403 (8%) systems will comply with the
very inexpensive technology of chloramines while 2,921 (4%) systems
will require more expensive membrane treatment systems. Use of these
technologies by small systems will result in total capital costs of
$1.1 billion.
Of the total 5,165 small surface water systems, it is estimated
that 3,611 (70%) will have to modify treatment to comply with the Stage
1 proposal. The TWG forecast that 3,318 (64%) systems will comply with
cost effective combinations of enhanced coagulation, chloramines, and
ozone. Another 293 (6%) systems will require more expensive membrane
treatment systems. This will result in total capital costs of $0.6
billion.
EPA believes that the proposed rule could have a significant impact
on a substantial number of small systems. Therefore, the Agency has
attempted to provide less burdensome alternatives to achieve the rule's
goals for small systems wherever possible. These considerations,
discussed in greater detail in Section IX of this preamble and in the
Regulatory Impact Analysis (USEPA, 1994), include:
(a) Less routine monitoring. Small systems are required to monitor
less frequently for such contaminants as TTHMs and HAA5. Also, ground
water systems (the large majority of small systems) are required to
monitor less frequently than Subpart H systems of the same size.
(b) Reduced monitoring. There are reduced monitoring provisions for
systems that meet specified prerequisites. EPA believes that many small
systems will qualify for this reduced monitoring.
(c) Extended compliance dates. Systems that use only ground water
not under the direct influence of surface water serving at least 10,000
people and Subpart H systems serving fewer than 10,000 people have 42
months from promulgation of this rule to comply. Systems that use only
ground water not under the direct influence of surface water serving
fewer than 10,000 people have 60 months from promulgation of this rule
to comply. These staggered compliance dates will allow smaller systems
to learn from the experience of larger systems on how to most cost
effectively comply with the Stage 1 D/DBP rule. Larger systems will
generate a significant amount of treatment and cost effectiveness data
under the Information Collection Rule and in their efforts to achieve
compliance with the Stage 1 requirements. EPA intends to summarize this
information and make it available through guidance documents that will
assist smaller systems in achieving compliance with both the Stage 1 D/
DBP rule and long-term ESWTR.
The staggered compliance dates for smaller systems will also enable
them to consider any new Stage 2 requirements, scheduled to be proposed
in 1998, while achieving compliance with the Stage 1 requirements. The
delayed compliance schedule should facilitate the selection of the most
cost effective means for achieving compliance with both the Stage 1 and
Stage 2 requirements.
(d) The Negotiating Committee considered other options for systems
serving less than 10,000 people. These ranged from requiring smaller
systems to meet the same compliance schedule as for larger systems to
only extending the existing TTHM standard to systems serving less than
10,000 people. The Negotiating Committee rejected the former option for
the above reasons and to enable the development of an ESWTR (i.e., the
long-term ESWTR rather than the interim ESWTR) that would be more
reasonable for smaller systems to comply with (see proposed ESWTR in
today's Federal Register, and the proposed Information Collection Rule,
59 FR 6332; February 10, 1994). The Negotiating Committee rejected the
latter option, over the objections of the National Rural Water
Association, because it believed that all systems should be subject to
the same level of protection. Also, setting only a TTHM standard in the
absence of other criteria could lead to increased exposure from other
DBPs that might pose greater health risks.

C. Paperwork Reduction Act

The information collection requirements in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An
Information Collection Request document has been prepared by EPA (ICR
No. 270.33) and a copy may be obtained from Sandy Farmer, Information
Policy Branch (MC:2136), EPA, 401 M Street SW., Washington, DC 20460,
or by calling (202) 260-2740.
The reporting and recordkeeping burden for this proposed collection
of information will be phased-in starting in 1997. The specific burden
anticipated for each category of respondent, by year, is shown below:

1997

Public Water Systems--monitoring and reporting
Hours per respondent: 0
Total hours: 0
Public Water Systems--recordkeeping
Hours per respondent: 0
Total hours: 0
State Program Costs--reporting
Hours per respondent: 2,650
Total hours: 148,424
State Program Costs--recordkeeping
Hours per respondent: 1,500
Total hours: 84,000

1998

Public Water Systems--monitoring and reporting
Hours per respondent: 5.3
Total hours: 328,605
Public Water Systems--recordkeeping
Hours per respondent: .05
Total hours: 3,319
State Program Costs--reporting
Hours per respondent: 11,643
Total hours: 652,032
State Program Costs--recordkeeping
Hours per respondent: 600
Total hours: 33,640

1999

Public Water Systems--monitoring and reporting
Hours per respondent: 3.9
Total hours: 239,424
Public Water Systems--recordkeeping
Hours per respondent: .04
Total hours: 2,418
State Program Costs--reporting
Hours per respondent: 9,119
Total hours: 510,672
State Program Costs--recordkeeping
Hours per respondent: 0
Total hours: 0

Send comments regarding the burden estimate or any other aspect of
this collection of information, including suggestions for reducing this
burden, to Chief, Information Policy Branch (MC:2136), EPA, 401 M
Street, SW, Washington, DC 20460; and to the Office of Information and
Regulatory Affairs, OPM, Washington, DC 20503, marked ``Attention: Desk
Officer for EPA.'' The final rule will respond to any OMB or public
comments on the information collection requirements contained in the
proposal.

D. National Drinking Water Advisory Council and Science Advisory Board

In accordance with section 1412 (d) and (e) of the Act, the Agency
has submitted this proposed rule to the Science Advisory Board,
National Drinking Water Advisory Council (NDWAC), and the Secretary of
Health and Human Services for their review. The Agency will take their
comments into account in developing the final rule. NDWAC supported the
use of regulatory negotiation to develop this rule.

XVII. Request for Public Comment

The proposed rule represents criteria that were agreed to be
proposed by the Negotiating Committee. Part A of this Section lists the
parts of the rule for which members of the Negotiating Committee,
including EPA, requested comment. Part B of this Section lists the
parts of the rule that pertain to small systems for which EPA requests
public comments but which were not requested by Members of the
Negotiating Committee. Members of the Negotiating Committee agreed not
to file negative comments on the settled portions of the proposed rule
or the preamble to the extent that they have the same substance and
effect as the recommended rule and preamble. Each member of the
Negotiating Committee may comment in support of the settled portions of
the proposed rule. Each member of the Negotiating Committee may comment
fully on or respond to comments solicited in the preamble or on issues
that were not the subject of negotiations. The public at large is
invited to comment on all aspects of the rule or preamble including the
appropriateness of numerical criteria, monitoring requirements, and
applicability. EPA will consider all public comments received in
developing the final rule.

A. Request for Comment

Section V
The appropriateness of adopting the term ``MRDLG'' in lieu of MCLGs
for disinfectants in the final rule.

--Any additional data on known concentrations of chlorine in drinking
water, food, and air.
--The following issues concerning chlorine: placing chlorine in
Category III for developing an MRDLG, selection of the specified study
and NOAEL as the basis for the MRDLG, the 80% RSC, the appropriateness
of the UF of 100, and the cancer classification for chlorine.
--Any additional data on known concentrations of chloramines in
drinking water, food, and air.
--The following issues concerning chloramines: the proposed MRDLG for
chloramines and the RSC of 80%, the significance of the findings of
immunotoxicity for setting the RfD instead of the NTP study, the
significance of the finding of mononuclear cell leukemia in female F344
rats, the significance of the finding of tubular cell neoplasms in
high-dose exposed mice, and whether the adjusted MRDLG, which takes
into account the measurement of monochloramine as total chlorine, is
appropriate.
--The significance of the epidemiological studies with chlorine and
chloramines as indicators of risk. EPA recognizes that there are
different interpretations of these epidemiological studies and
specifically solicits comment on the rationale for EPA's
interpretations. EPA further requests comments on the studies
suggesting a reproductive risk related to disinfectant byproduct
exposure.
--Any additional data on known concentrations of chlorine dioxide,
chlorate, and chlorite in drinking water, food, and air.
--For chlorine dioxide, the SAB's suggestion that a child's body weight
of 10 kg and water consumption of 1 L/d may be more appropriate for
setting the MRDLG than the adult parameters, given the acute nature of
the toxic effect. EPA also requests comment on the appropriateness of
the 300-fold uncertainty factor, the studies selected as the basis for
the RfD, and the 80% relative source contribution.
--For chlorite, the SAB's suggestion that EPA consider basing the MCLG
on the child body weight of 10 kg and water consumption of 1 L/day
instead of the adult default values. EPA requests comments on the SAB's
suggestion, along with the study selected as the basis for the MCLG,
the uncertainty factor and the RSC of 80%.
--The decision not to propose an MCLG for chlorate at this time.
--Any additional data on known concentrations of chloroform in drinking
water, food, and air.
The basis for the proposed MCLG for chloroform.

--Any additional data on known concentrations of BDCM in drinking
water, food, and air.
--The basis of the proposed MCLG for BDCM and the use of tumor data of
large intestine and kidney, but not liver, in quantitative estimation
of carcinogenic risk of BDCM from oral exposure.
--Any additional data on known concentrations of DBCM in drinking
water, food, and air.
--The basis for the proposed MCLG for DBCM, the RSC of 80%, and the
cancer classification for DBCM.
--Any additional data on known concentrations of bromoform in drinking
water, food, and air.
--The different viewpoints between IARC and EPA regarding bromoform's
carcinogenic potential.
--The basis for the proposed MCLG for bromoform.
--Any additional data on known concentrations of DCA in drinking water,
food, and air.
--The basis for the proposed MCLG for DCA in drinking water and the
cancer classification of Group B2.
--Any additional data on known concentrations of TCA in drinking water,
food, and air.
--The basis for the MCLG and the cancer classification for TCA.
--Any additional data on known concentrations of CH in drinking water,
food, and air.
--For CH, the Category II approach for setting an MCLG, the extra
safety factor of 1 instead of 10 for a Category II contaminant, and
whether the endpoint of liver weight increase and hepatomegaly is a
LOAEL or NOAEL given the lack of histopathology.
--Any additional data on known concentrations of bromate in drinking
water, food, and air.
--The MCLG of zero for bromate based on carcinogenic weight of evidence
and the mechanism of action for carcinogenicity related to DNA adduct.
Section VIII
--The timetable for promulgation of the final rule and the compliance
dates therein.
--How monitoring and compliance requirements should be split among
wholesalers and retailers of water. Does Sec. 141.29 (consecutive
systems) provide the State adequate flexibility and authority to
address individual situations? Are any specific federal regulatory
requirements necessary to handle such situations? If so, what are they?
--How the following situations should be handled in compliance
determinations.
--When the monthly source water TOC is less than 2.0 mg/l and enhanced
coagulation is not required.
--When seasonal variations cause the system to determine that TOC is
not amenable to any level of enhanced coagulation and the system would
be eligible for a waiver of enhanced coagulation requirements.

EPA believes that assigning a value of 1.00 for these months is a
reasonable approach.
Section IX
--Whether exemptions to this rule should be granted if a system could
demonstrate to the State, that due to unique water quality
characteristics, it could not avoid through the use of BAT the
possibility of increasing its total health risk by complying with the
Stage 1 regulations. When might such situations occur? What specific
conditions, if any, should be met for a system to be granted an
exemption under such a provision. What provisions should EPA require of
States to grant these exemptions? Should such exemptions be granted for
a limited period but be renewable by the State if no new health risk
information became available?
--Whether the TOC percent removal levels in Table IX-1 are
representative of what 90 percent of systems required to use enhanced
coagulation could be expected to achieve with elevated, but not
unreasonable, coagulant addition.
--Whether filtration should be required as part of the bench-/pilotscale
procedure for determination of Step 2 enhanced coagulation. If
so, what type of filter should be specified for bench-scale studies?
--Whether a slope of 0.3 mg/L of TOC removed per 10 mg/L of alum added
should be considered representative of the point of diminishing returns
for coagulant addition under Step 2. EPA also solicits comment on how
the slope should be determined (e.g., point-to point, curve-fitting).
If the slope varies above and below 0.3/10, where should the Step 2
alternate TOC removal requirement be set--at the first point below 0.3/
10? At some other point?
--Whether any additional regulatory requirements, guidance, or
explanation is required to define ``multiple wells''. EPA requests
comment on whether there should be an upper limit of sampling frequency
for systems that either cannot determine that they are drawing water
from a single aquifer or are drawing water from multiple aquifers. For
example, should a system that must draw water from many aquifers to
satisfy demand be allowed to limit monitoring as if they were drawing
from no more than four aquifers (routine sampling would thus be limited
to four samples per quarter from systems serving at least 10,000 people
or to four samples per year for systems serving fewer than 10,000
people)? Does EPA need to develop any additional guidance for any other
aspect of this requirement?
--How often bench-or pilot-scale studies should be performed to
determine compliance under step 2. Should such frequency of testing be
included in the rule or left to guidance? Is quarterly monitoring
appropriate for all systems? What is the best method to present the
testing data to the primacy agency that reflects changing influent
water quality conditions and also keeps transactional costs to a
minimum? How should compliance be determined if the system is not
initially meeting the percent TOC reduction required because of
difficult to treat water and a desire to demonstrate alternative
performance criteria?
--Whether data are available on the use of ferrous salts in the
softening process which can help define a step 2 for enhanced
softening. For softening plants, is enhanced softening properly defined
by the percent removals in Table IX-1 or by 10 mg/L removal of
magnesium? Is there a step 2 definition? Can ferrous salts be used at
softening pH levels to further enhance TOC removals?
--Whether preoxidation is necessary in water treatment to control water
quality problems such as iron, manganese, sulfides, zebra mussels,
Asiatic clams, taste and odor. Will allowing preoxidation before
precursor removal by enhanced coagulation generate excessive DBP
levels?
--Whether biologically active filtration following ozonation is
sufficient to remove most byproducts believed to result from ozonation?
What parameters should be measured in and/or out of the biologically
active filter to demonstrate that ozone byproducts are being removed?
For example, would it be sufficient to demonstrate greater than 90
percent removal of formaldehyde to establish that a filter is
biologically active?
--Whether disinfection credit should be allowed for chlorine dioxide
used prior to enhanced coagulation if virtually no halogenated organic
DBPs are formed. Should some other limit, in addition to or in lieu of
that proposed, be set (e.g., 5 <greek-m>/L TTHMs) on DBPs formed by
high purity chlorine dioxide to ensure sufficient control for the
production of excessive halogenated organic DBPs if disinfection credit
were to be allowed with chlorine dioxide prior to enhanced coagulation?
--The appropriateness of allowing systems to add a disinfectant before
enhanced coagulation when water temperatures are less than or equal to
5 deg.C if excessive DBPs are not produced or identification of
alternative means for addressing this issue.
--Whether GAC10 and GAC20 reasonable definitions of GAC performance? Do
they span the expected level of GAC applications in drinking water
treatment for the control of TTHMs and THAAs? Is the Jefferson Parish,
Louisiana TOC removal representative of the ``general case'' of TOC
removal?
--Whether any Subpart H systems with a TOC >4.0 mg/l should be allowed
to reduce monitoring? Under what conditions (e.g., system has installed
nanofiltration)?
--Whether reduced monitoring for ground water systems serving fewer
than 10,000 people could be expanded beyond what is in the proposal.
The additional options presented below would rely on having each entry
point of the system go through three years of routine monitoring to
qualify for reduced monitoring. After this period, if the entry points
meet additional criteria, then the entry points would be subject to
minimal additional monitoring.

Option One: Any ground water system serving fewer than 10,000
people that has a raw water TOC of less than 1.0 mg/l, and has both
TTHM and HAA5 values less than 25 percent of the MCLs (20 <greek-m>g/l
and 15 <greek-m>g/l, respectively) after three years of routine and
reduced monitoring, can reduce the monitoring for TTHMs and HAA5s to
one sample every nine years, taken at the maximum distribution system
residence time during the warmest month.
Option Two: Any ground water system serving fewer than 10,000
people that has a raw water TOC of less than 0.5 mg/l, and has both
TTHM and HAA5 values less than 25 percent of the MCLs (20 <greek-m>g/l
and 15 <greek-m>g/l, respectively) after three years of routine and
reduced monitoring, is exempt from the distribution system monitoring
requirements for TTHMs and HAA5s for as long as TOC monitoring is
conducted once every three years and the raw water TOC remains less
than 0.5 mg/l.
These options are not mutually exclusive, that is, both could be
used simultaneously or some hybrid could be developed. The Agency seeks
comment on whether either or both of these options are reasonable in
adequately protecting the public health and should therefore be
considered as criteria for reduced monitoring. Are there other options
for reduced monitoring that should be considered? What are they?

--Comment on the cost impact of pH adjustment on systems with both high
alkalinity and high bromide levels.
--Comment on the relative costs of adjusting pH to reduce bromate
formation versus the costs of other technologies to meet the MCLs in
this proposed rule.
--Whether the monitoring is frequent enough to adequately determine
variations in sample results caused by time and/or location in the
distribution system? If not, what is a more appropriate monitoring
schedule? Should requirements differ for systems based on population
served, raw water source, or other factors? If so, should the proposed
requirements be changed? How should they be changed? If requirements
should not be based on these factors, what should the requirements be?
Does averaging of sample results taken in various locations over the
course of a year to determine compliance adequately protect individuals
that are in locations that may regularly have higher than average
levels? If it does not, how should the proposed requirements be
changed?
--Data to show that a lower quantitation level (at least down to 5
<greek-m>g/L) can be obtained by those laboratories that will perform
compliance monitoring for bromate in natural drinking water matrices.
If the improved methodology uses equipment and/or reagents that are not
currently required for EPA method 300.0, data to indicate the
commercial availability and costs of these items would also need to be
presented.
--A treatment technique that could ensure that bromate can be kept
below 5 <greek-m>g/L, even if quantitation at 5 <greek-m>g/l is not
achieveable under routine laboratory conditions.
--Other treatment techniques which allow ozone to meet disinfection and
oxidation requirements while minimizing bromate formation.
--The feasibility of developing a treatment technique requirement for
bromate, lowering the MCL based upon improved analytical techniques,
and the time frame under which such alternative standards could be
developed.
--The following approaches for promulgating a final rule for chlorite:

(1) An MCL at the MCLG.
(2) An MCL lower than the proposed MCL of 1.0 mg/l, but above the
MCLG, depending upon all data that became available in the near term.
(3) Depending on new data that become available, EPA could
promulgate an MCL at the proposed MCL of 1.0 mg/l if the Agency
determined that the systems currently using chlorine dioxide could not
meet disinfection requirements in any other feasible manner, taking
cost into consideration.
--The approaches for regulating chlorite. Specifically, EPA requests
comment on the following:
--Is the basis for EPA's MCLG and concern for acute health effects
appropriate? See Section V. for a complete discussion.
--Are there any particular water quality characteristics for systems
currently using chlorine dioxide which make it ineffective to use any
other disinfection technology? What are the lowest chlorite levels
these systems can achieve? What technologies would need to be adopted
and at what costs if such systems with these particular water quality
characteristics would no longer use chlorine dioxide to meet the other
regulatory criteria proposed herein?
--Should EPA set the chlorite MCL at a level so that chlorine dioxide
remains a viable disinfection alternative for some systems even if this
level is above the MCLG? If so, what would be the rationale for doing
so?
--Is 1.0 mg/l the lowest level that systems needing chlorine dioxide
can reliably achieve?
--How should EPA change the compliance monitoring requirements for
chlorite to reflect concern about acute effects? Should such changes
include increasing the frequency or changing the location of monitoring
to be similar to those for chlorine dioxide? How would the MCL be
affected by changes in the monitoring requirements?
--How should EPA change the public notification requirements for
chlorite to reflect concern about acute effects?
--What level of residual chloramine would be feasible to achieve by
most systems without increasing microbial risk.
--Information on improvements which may have been made to disinfectant
methods to measure low concentrations of disinfectant residuals, but
that are not reflected in the 18th edition of Standard Methods. EPA is
also seeking information on new methodology that may be applicable for
compliance monitoring.
--The technical adequacy of the analytical methods proposed for
compliance with the proposed MRDLs.
--For bromate, whether use of a sample concentration technology prior
to ion chromatographic analysis should be considered as a new
methodolgy or a modification to Method 300.0 under today's rule. EPA
also solicits comments on the applicability of sample concentration
technology to today's proposed MCL for bromate.
--Data that demonstrate the need for a preservative in samples
collected at the entrance point to the distribution system for
measurement of bromate.
--The proposed turbidity threshold of 1 NTU to remove turbidity, which
is known to interfere with accurate TOC measurement when the sample
turbidity is greater than 1 NTU, and on the sample filtration procedure
described in Section IX and in the proposed methods.
--What precision can be routinely expected on differential TOC
measurements of jar test samples. EPA is also interested in new methods
or modifications to the methods proposed today that would improve the
reproducibility of TOC measurement.
Section X
--Other optional or mandatory performance criteria that EPA or the
States should consider for certification of laboratories, or approval
of analysts.
Section XI
--Whether exemptions to this rule should be granted if a system could
demonstrate to the State, that due to unique water quality
characteristics, it could not avoid through the use of BAT the
possibility of increasing its total health risk by complying with the
Stage 1 regulations. When might such situations occur? What specific
conditions, if any, should be met for a system to be granted an
exemption under such a provision. What provisions should EPA require of
States to grant these exemptions? Should such exemptions be granted for
a limited period but be renewable by the State if no new health risk
information became available?
Section XII
--The proposed State reporting requirements. EPA particularly requests
comment from the States on whether the proposed reporting requirements
are reasonable.
--Whether the State should be required to keep the monitoring plan on
file at the State after submission to make it available for public
review?
Section XIV
--The proposed public notification rule language. Of particular
interest is the acute violation language in Sec. 141.32(e)(85) for
violations of the chlorine dioxide MCL. Also of interest is the
language in Sec. 141.32(e)(86) for violations of the TTHM and HAA5 MCLs
and the enhanced coagulation treatment technique requirement.
Section XV
--Data and comment on the extent to which reductions in exposure to
TTHMs and DBPs can be expected to differ between systems serving 10,000
people or more and systems serving less than 10,000 people.
Section XVI
--The burden estimate or any other aspect of this collection of
information, including suggestions for reducing this burden.

B. Request for Additional Public Comments by EPA

The Negotiating Committee considered several regulatory options for
systems serving less than 10,000 people. These ranged from requiring
smaller systems to meet the same compliance schedule as for larger
systems to only extending the existing TTHM standard to systems serving
less than 10,000 people. The Negotiating Committee rejected the former
option for reasons discussed in Section XVI of this preamble. The
Negotiating Committee rejected the latter option, over the objections
of the National Rural Water Association (which was initially
represented on the Negotiating Committee but then withdrew from the
negotiations), because it believed that all systems should be subject
to the same level of protection. Also, setting only a TTHM standard in
the absence of other criteria could lead to increased exposure from
other DBPs that might pose greater health risks.
EPA recognizes that several factors still make it significantly
more difficult for smaller systems than larger systems to achieve
compliance with the Stage 1 requirements. Because the larger systems
already have substantial experience with lowering TTHM levels, they
will be more familiar than smaller systems with available technologies
and operating conditions for lowering DBP levels. Because of economies
of scale, the costs for systems to achieve the same incremental
reduction in DBPs is substantially greater in smaller systems than in
larger systems. For about 4% of systems serving less than 3,300 people
(and less than 1% of the U.S. population receiving public drinking
water), costs for compliance are estimated to be about $300 per
household per year. For these reasons, EPA remains concerned about the
ability of small communities to afford compliance and is interested in
comments on this issue as well. Specifically, EPA is interested in
further comment on alternative regulatory approaches for various small
and medium system sizes.
The parties reached consensus on the approach for staggered
compliance schedules for systems serving fewer than 10,000 people
(i.e., June 2000 for systems using surface water and ground water under
the direct influence of surface water that serve fewer than 10,000
people and January 2002 for ground water systems serving fewer than
10,000 people). EPA is interested in comments on these important
issues. Again, EPA recognizes the problems faced by small- and mediumsized
systems and is interested in further comment on alternative
compliance approaches and possible solutions for various small and
medium system sizes (e.g., <1,000; 1,000-3,300; >3,300-10,000).
Because of the Agency's commitment to develop rules based on the
best reasonably available scientific data, EPA intends to conduct
research on the best way to reduce exposure from both DBPs and
pathogens in small systems cost effectively. Based on information
collected under the ICR, EPA intends to also refine models to more
accurately predict occurrence of DBPs as a function of different
treatment technologies, including those used by small systems. EPA
intends to use available data in refining its estimates and solicits
additional data on the occurrence of DBPs in drinking water systems,
the concentration of pathogens in source water, and the effectiveness
of treatment on microbial contaminants, especially for smaller systems.
Also, as part of the major research effort leading to negotiation of
the Stage 2 D/DBP rule, EPA intends to investigate technologies to
determine whether small systems will be able to comply with D/DBP
regulations at lower costs in future years.

XVIII. References and Public Docket

References in this section are organized by type. Subsection A
lists Federal Register references. Subsection B lists analytical method
references. Subsection C lists health criteria document references.
Subsection D lists other references.

A. Federal Register References

U.S. Environmental Protection Agency. National Interim
Primary Drinking Water Regulations; Control of Trihalomethanes in
Drinking Water. Vol. 44, No. 231. November 29, 1979. pp. 68624-
68707.
U.S. Environmental Protection Agency. National Revised
Primary Drinking Water Regulations, Volatile Synthetic Organic
Chemicals in Drinking Water; Advanced Notice of Proposed Rulemaking.
Vol. 47, No. 43, Thursday, Mar. 4, 1982--Part IV. pp. 9350-9358.
U.S. Environmental Protection Agency. National Interim
Primary Drinking Water Regulations; Trihalomethanes. Vol. 48, No.
Monday, Feb. 28, 1983. pp. 8406-8414.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations; Synthetic Organic Chemicals, Inorganic
Chemicals and Microorganisms: Proposed Rule. Vol. 50, No. 219.
Wednesday, Nov. 13, 1985--Part IV. pp. 46936-47025.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations--Synthetic Organic Chemicals; Monitoring
for Unregulated Contaminants; Final Rule. Vol. 52, No. 130. July 8,
1987--Part II. pp. 25690-25717.
Federal Register. U.S. Environmental Protection Agency.
Drinking Water Regulations; Public Notification; Final Rule. Vol.
52, No. 208. Wednesday, Oct. 28, 1987--Part II. pp. 41534-41550.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations. Maximum Contaminant Level Goals and
National Primary Drinking Water Regulations for Lead and Copper.
Vol. 53, No. 160. Thursday, Aug. 18, 1988. pp. 31516-31578.
U.S. Environmental Protection Agency. National Primary and
Secondary Drinking Water Regulations; Proposed Rule. Vol. 54, No.
Monday, May 22, 1989. pp. 22062-22160.
U.S. Environmental Protection Agency. Drinking Water;
National Primary Drinking Water Regulations; Filtration,
Disinfection; Turbidity, Giardia lamblia, Viruses, Legionella, and
Heterotrophic Bacteria; Final Rule. Part II. Vol. 54, No. 124.
Thursday, June 29, 1989. pp. 27486-27541.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations; Synthetic Organic Chemicals and
Inorganic Chemicals; Proposed Rule. Vol. 55, No. 143. Wednesday,
July 25, 1990--Part II. pp. 30370-30448.
U.S. Environmental Protection Agency. Notice of Availability
of Proposed Guidance for Determining Unreasonable Risk to Health.
Vol. 55, No. 191. Tuesday, Oct. 2, 1990. p. 40205.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations: Lead and Copper. Notice of Availability
with Request for Comments. Vol. 55, No. 203. Friday, Oct. 19, 1990.
pp.42409-42413.
U.S. Environmental Protection Agency. National Revised
Primary Drinking Water Regulations--Synthetic Organic Chemicals and
Inorganic Chemicals; Monitoring for Unregulated Contaminants;
National Primary Drinking Water Regulations Implementation; National
Secondary Drinking Water Regulations. Vol. 56, No. 20. Wednesday,
Jan. 30, 1991. pp. 3526-3597.
U.S. Environmental Protection Agency. National Primary and
Secondary Drinking Water Regulations; Synthetic Organic Chemicals
and Inorganic Chemicals; Final Rule. Vol. 57, No. 138. Friday, July
17, 1992--Part III. pp. 31776-31849.
U.S. Environmental Protection Agency. Intent to Form an
Advisory Committee to negotiate the Drinking Water Disinfection ByProducts
Rule and Announcement of Public Meeting. Vol. 57, No. 179.
September 15, 1992. pp. 42533-42536.
U.S. Environmental Protection Agency. Establishment and Open
Meeting of the Negotiated Rulemaking Advisory Committee for
Disinfection By-Products. Vol. 57, No. 220. November 13, 1992. p.
53866.
U.S. Environmental Protection Agency. National Primary
Drinking Water Regulations: Analytical Techniques (Trihalomethanes);
Final Rule. Vol. 58, No. 147. August 3, 1993. pp. 41344-41345.
U.S. Environmental Protection Agency. Executive Order 12866:
Regulatory Planning and Review. Vol. 58, No. 190. October 4, 1993.
51735-51744.

B. Analytical Methods

APHA. 1992. American Public Health Association. Standard
Methods for the Examination of Water and Wastewater (18th ed.).
Washington, D.C. (Including: 4500 Cl D,E,F,G,H,I; 4500 ClO<INF>2
C,D,E; 5310 C,D; 6233B; 2320 B)
ASTM. 1993. Methods D-1067-88B, D-2035-80. Annual Book of
ASTM Standards. Vol. 11.01, American Society for Testing and
Materials.
U.S. EPA. 1993. EPA Method 300.0. The Determination of
Inorganic Anions by Ion Chromatography in the manual ``Methods for
the Determination of Inorganic substances in Environmental
Samples,'' EPA/600/R/93/100.
U.S. EPA. 1983. EPA Method 310.1. Methods of Chemical
Analysis of Water and Wastes. Envir. Monitoring Systems Laboratory,
Cincinnati, OH. EPA 600/4-79-020. 460 pp.
U.S. EPA. 1988. EPA Method 502.2. Methods for the
Determination of Organic Compounds in Drinking Water. EPA 600/4-88-
PB91-231480. Revised July 1991.
U.S. EPA. 1992. EPA Methods 524.2, 552.1. Methods for the
Determination of Organic Compounds in Drinking Water--Supplement II.
EPA 600/R-92/129. PB92-207703.
U.S. EPA. 1990. EPA Methods 551, 552. Methods for the
Determination of Organic Compounds in Drinking Water--Supplement I.
EPA 600/4-90-020. PB91-146027.
USGS. 1989. Method I-1030-85. Techniques of Water Resources
Investigations of the U.S. Geological Survey. Book 5, Chapter A-1,
3rd ed., U.S. Government Printing Office.

C. Health Criteria Documents

USEPA. 1993b. Draft Drinking Water Health Criteria Document
for Bromate. Office of Science and Technology, Office of Water. Sep.
30, 1993.
USEPA. 1994b. U.S. Environmental Protection Agency. Draft
Drinking Water Health Criteria Document for Chloramines. Office of
Science and Technology, Office of Water.
USEPA. 1994e. U.S. Environmental Protection Agency. Draft
Drinking Water Health Criteria Document for Chlorinated Acetic
Acids/Alcohols/Aldehydes and Ketones. Office of Science and
Technology, Office of Water.
USEPA. 1994a. U.S. Environmental Protection Agency. Draft
Drinking Water Health Criteria Document for Chlorine, Hypochlorous
Acid and Hypochlorite Ion. Office of Science and Technology, Office
of Water.
USEPA. 1994c. U.S. Environmental Protection Agency. Final
Draft Drinking Water Health Criteria Document for Chlorine Dioxide,
Chlorite and Chlorate. Office of Science and Technology, Office of
Water. March 31, 1994.
U.S. Environmental Protection Agency. 1994d. Health and
Ecological Criteria Div., OST. Final Draft for the Drinking Water
Criteria Document on Trihalomethanes. Apr. 8. 1994.

D. Other References

Aieta, E. M., & Berg, J. D. 1986. A Review of Chlorine
Dioxide in Drinking Water Treatment. Jour. AWWA, 78:6:62 (June
1986).
Aieta, E. M.; Roberts, P. V.; & Hernandez, M. 1984.
Determination of Chlorine Dioxide, Chlorine, Chlorite, and Chlorate
in Water. Jour. AWWA, 76:1:64 (Jan. 1984).
Alavanja M, Goldstein I, Susser M. 1978. A Case-Control Study
of gastrointestinal and urinary tract cancer mortality and drinking
water chlorination. In: Water Chlorination: Environmental Impact and
Health Effects, Vol. 2. R.L. Jolley et al., editors. (Ann Arbor: Ann
Arbor Science Publishers). pp. 395-409.
Amy, G., et al. Nation-wide Survey of Bromide Ion
Concentrations in Drinking Water Sources. Progress reports to
AWWARF, University of Colorado at Boulder, Dept. of Civil,
Environmental, and Architectural Engineering, Boulder, Colo. (1992-
93).
Amy, G. L.; Chadik, P. A.; & Chowdhury, Z. 1987. Developing
Models for Predicting Trihalomethane Formation Potential and
Kinetics. Jour. AWWA, 79:7:89 (July 1987).
Amy, G. L.; Tan, L.; & Davis, M. K. 1991. The Effects of
Ozonation and Activated Carbon Adsorption on Trihalomethane
Speciation. Water Res., 25:2:191 (Feb. 1991).
Amy, G., et al. Biodegradability of Natural Organic Matter: A
Comparison of Methods (BDOC and AOC) and Correlations with Chemical
Surrogates. Proc. 1992 AWWA Ann. Conf. (Water Research), pp. 523-
542, Vancouver, B.C.
Aschengrau A, Zierler S, Cohen A. 1993. Quality of Community
Drinking Water and the Occurrence of Late Adverse Pregnancy
Outcomes. Arch Env Health 48:105-113.
Atlas, E.; Schauffler, S. 1991. Analysis of Alkyl Nitrates
and Selected Halocarbons in the Ambient Atmosphere Using a Charcoal
Preconcentration Technique, Environ. Sci. Technol., Vol. 25, No. 1,
pp. 61-7.
AWWA Water Industry Data Base (WIDB). 1990. American Water
Works Association. User's Guide.
AWWA Water Industry Data Base (WIDB). 1991. AWWA, Denver,
CO.
AWWA Water Quality Division Disinfection Committee. 1992.
Survey of Water Utility Disinfection Practices. Jour. AWWA, 84:9:121
(Sept. 1992).
AWWA Disinfection Committee. 1983. Disinfection, Water
Quality Control, and Safety Practices of the Water Utility Industry
in 1978 in the United States. Jour. AWWA, 75:1:51 (Jan. 1983).
AWWA. 1991. American Water Works Association Disinfection
Survey. Data Base.
AWWARF, 1992. AWWA Research Foundation. Disinfectant
Residual Measurement Methods. Second Ed. Denver, CO.
Bailar, J.C., Jr., et al, Eds. 1973. Comprehensive Inorganic
Chemistry (Vol. 2, p.1407). Pergamon Press Ltd., Oxford, England.
Bellar, TA, Lichtenberg, JJ, and Kroner, RC. 1974. ``The
Occurrence of Organohalides in Chlorinated Drinking Water'', Jour.
AWWA, 66(12):703-706.
Bercz J.P., L. Jones, L. Murray et al. 1982. Subchronic
toxicity of chlorine dioxide and related compounds in drinking water
in nonhuman primates. Environ. Health Persp. 46:47-55.
Boland, P.A. 1981. ``National Screening Program for Organics
in Drinking Water Part II: Data''; SRI International. Prepared for
U.S. Environmental Protection Agency under Contract No. 68-01-4666;
March, 1981.
Bolyard, M.; Fair, P. S.; & Hautman, D. P. 1992. Occurrence
of Chlorate in Hypochlorite Solutions Used for Drinking Water
Disinfection. Environ. Sci. Technol., 26:8:1663 (Aug. 1992).
Borum, D. 1991. U.S. Environmental Protection Agency,
Washington, D.C. Phone Conversation with Greg Diachenko, Food and
Drug Administration, Washington, D.C.; December 17, 1991.
Bove F, Fulcomer M, Klotz J, Esmart J, Dufficy E, Zagraniski
R, Savrin JE. 1992b. Public Drinking Water Contamination and
Birthweight, and Selected Birth Defects: A Case-Control Study (Phase
IV-B), New Jersey Department of Health. May 1992.
Bove F, Fulcomer M, Klotz J, Esmart J, Dufficy E, Zagraniski
R, Savrin JE. 1992a. Public Drinking Water Contamination and
Birthweight, Fetal Deaths, and Birth Defects: A Cross-Sectional
Study (Phase IV-A), New Jersey Department of Health. April 1992.
Brass, H.J. 1981. Rural Water Surveys Organics Data;
Drinking Water Quality Assessment Branch, Technical Support
Division, Office of Drinking Water, U.S. Environmental Protection
Agency. Memo to Hugh Hanson, Science and Technology Branch, CSD,
ODW, U.S. Environmental Protection Agency.
Brass, H.J.; Weisner, M.J.; Kingsley, B.A. 1981. Community
Water Supply Survey: Sampling and Analysis for Purgeable Organics
and Total Organic Carbon (Draft); American Water Works Assoc. Annual
Meeting, Water Quality Division; June 9, 1981.
Brass, H. J., et al. 1977. The National Organic Monitoring
Survey: Samplings and Analyses for Purgeable Organic Compounds. In
Drinking Water Quality Enhancement Through Source Protection (R. B.
Pojasek, editor). Ann Arbor Sci. Publ., Inc., Ann Arbor, MI.
Brenniman GR, Vasilomanolakis-Lagos J, Amsel J, Tsukasa N,
Wolff AH (1980). Case-Control Study of Cancer Deaths in Illinois
Communities Served by Chlorinated or Non- chlorinated Water. In:
R.L. Jolley et al., editors, Water Chlorination: Environmental
Impact and Health Effects, Vol. 3. (Ann Arbor: Ann Arbor Science
Publishrs). pp. 1043-1057.
Brodzinsky, R.; Singh, H.B. 1983. Volatile Organic Chemicals
in the Atmosphere; An Assessment of Available Data; U.S.
Environmental Protection Agency, Office of Research and Development,
Research Triangle Park, North Carolina; 1983. Cited in Howard, 1990.
Budde, W.L., Memorandum on capillary column technology,
September 22, 1992.
Bull, R.J.; Kopfler, F.C. 1991. Health Effects of
Disinfectants and Disinfectant By-Products. Prepared for: AWWA
Research Foundation; August, 1991.
Bull, R.J., I.M. Sanchez, M.A. Larson and A.J. Lansing.
Liver tumor induction in B6C3F1 mice by dichloroacetate and
trichloroacetate. Toxicol. 63:341-359.
Cantor, K.P., R. Hoover, P. Hartge, T.J. Mason, D.T.
Silverman, and L.I. Levin. 1985. Drinking Water Source and Bladder
Cancer: A Case-control Study. Chapter 12 in: Water Chlorination:
Chemistry, Environmental Impact and Health Effects, Vol. 5. R.L.
Jolley, R.J. Bull, W.P. Davis, S. Katz, M.H. Roberts, Jr., and V.A.
Jacobs, editors. (Chelsea, MI: Lewis Publishers, Inc.). pp. 145-152.
Cantor, K.P., R. Hoover, P. Hartge, T.J. Mason, D.T.
Silverman, R. Altman, D.F. Austin, M.A. Child, C.R. Key, L.D.
Marrett, M.H. Myers, A.S. Narayana, L.I. Levin, J.W. Sullivan, G.M.
Swanson, D.B. Thomas, and D.W. West. 1987. Bladder Cancer, Drinking
Water Source, and Tap Water Consumption: A Case-control Study. J.
Natl. Cancer Inst. 79: 1269-1279.
Cantor, K.P., R. Hoover, P. Hartge, T.J. Mason, and D.
Silverman. Bladder Cancer, Tap Water Consumption, and Drinking Water
Source. 1990. Chapter 33 in: Water Chlorination: Chemistry,
Environmental Impact and Health Effects, Vol. 6. R.L. Jolley, L.W.
Condie, J.D. Johnson, S. Katz, R.A. Minear, J.S. Mattice, and V.A.
Jacobs, editors. (Chelsea, MI: Lewis Publishers, Inc.). pp. 411-419.
Chemical Manufacturers' Association. 1993. Personal
communication with Stuart Krasner.
Cicmanec, J.L., L.W. Condie, G.R. Olson, and Shin-Ru Wang.
90-Day toxicity study of dichloroacetate in dogs. Fundam.
Appl. Toxicol. 17: 376-389.
Coleman, W.E. et al. 1990. Analysis and Identification of
Organic Substances in Water; L. Keith Ed., Ann Arbor Michigan; Ann
Arbor Press; 1976; pp. 305-27. Cited in Howard, 1990.
Connick, R.E. 1947. The Interaction of Hydrogen Peroxide and
Hypochlorous Acid in Acidic Solutions Containing Chloride Ion. Jour.
Amer. Chem. Soc., 69:1509.
Connor, MS, and D. Gillings. 1974. Am J Publ. Health.
74:555.
Cooper, W.J. 1990. Bromide Ion--Oxidant Chemistry in
Drinking Water: A Review. Preprints of papers presented at the 200th
Amer. Chem. Soc. Nat'l Meet., Div. of Environ. Chem., Washington, DC
(Aug. 1990).
Cragle, D.L., C.M. Shy, R.J. Struba, and E.J. Siff. 1985. A
Case-control Study of Colon Cancer and Water Chlorination in North
Carolina. Chapter 13 in: Water Chlorination: Chemistry,
Environmental Impact and Health Effects, Vol. 5. R.L. Jolley, R.J.
Bull, W.P. Davis, S. Katz, M.H. Roberts, Jr., and V.A. Jacobs,
editors. (Chelsea, MI: Lewis Publishers, Inc.) pp. 153-159.
Craun, G.F. 1988. Surface Water Supplies and Health. Journal
AWWA (Feb): 40-52.
Craun, G.F., P.A. Murphy, and J.A. Stober. 1989. Review of
the Epidemiologic Studies of Cancer and Cardiovascular Disease Risks
Which may be Associated with the Disinfection of Drinking Water in
the United States. Part IV in: Development of Drinking Water
Standards for Disinfectants and Disinfection By-products for the
Office of Drinking Water. Internal report from the Office of Health
Research, Office of Research and Development, USEPA, September,
1989.
Craun, G.F. 1991. Epidemiology study of organic
micropollutants in drinking water. In: The Handbook of Environmental
Chemistry. Vol 5. part A. Water Pollution. O. Hutzinger (ed).
Springer-Verlag. Berlin.
Craun, G.F. 1993. Epidemiology studies of water
disinfectants and disinfection by-products. In: Proceedings: Safety
of Water Disinfection: Balancing Chemical and Microbial Risks. p.
277-303, International Life Sciences Institute Press, Washington,
DC.
Cromwell, JE, Zhang X, Letkiewicz FJ, et al. 1992. Analysis
of potential tradeoffs in regulation of disinfection by-products.
Office of Ground Water and Drinking Water Resource Center.
Washington, DC EPA-811-R-92-008.
Crump, K.S. and H.A. Guess. 1982. Drinking Water and Cancer:
Review of Recent Epidemiological Findings and Assessment of Risks.
Ann. Rev. Publ. Health 3: 339-357.
D/DBP Regulations Negotiation Database. Draft final report
to AWWA, JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC., Applied
Research Dept., Pasadena, Calif. (Oct. 1992).
Daft, J.L. 1989. Determination of Fumigants in Fatty and
Nonfatty Foods, J. Agric. Food Chem., Vol. 37, No. 2, pp. 560-4.
Daft, J.L. 1988. Rapid Determination of Fumigant and
Industrial Chemical Residues in Food, J. Assoc. Off. Anal. Chem.,
Vol. 71, No. 4, pp. 748-760.
Daft, J.L. 1987. Determining Multifumigants in Whole Grains
and Legumes, Milled and Low-Fat-Grain Products, Spices, Citrus
Fruits, and Beverages, J. Assoc. Off. Anal. Chem., Vol. 70, No. 4,
pp. 734-739.
Daniel, F.B., A.B. DeAngelo, J.A. Stober, G.R. Olson, and
N.P. Page. 1992. Hepatocarcinogenicity of Chloral Hydrate, 2-
Chloroacetaldehyde, and Dichloroacetic Acid in the B6C3F1 Mouse.
Fundam. Appl. Toxicol. 19(2):159-168.
DeAngelo, A.B., F.B. Daniel, J.A. Stober, and G.R. Olson.
The carcinogenicity of dichloroacetic acid in the male B6C3F1
mouse. Fundam. Appl. Toxicol. 16:337-347.
Devesa, S.S., D.T. Silverman, J.K. McLaughlin, C.C. Brown,
R.R. Connelly, and J.T. Fraumeni, Jr. 1990. Comparison of the
Descriptive Epidemiology of Urinary Tract Cancers. Cancer Causes and
Control 1: 133-141.
Dharmarajah, H., et al. Empirical Modeling of Chlorine and
Chloramine Residual Decay. Proc. 1991 AWWA Ann. Conf. (Water Quality
for the New Decade), Philadelphia, Penn., pp. 569-588.
Dore, M.; Merlet, N.; Legube, B.; & Croue, J. Ph. 1988.
Interactions Between Ozone, Halogens and Organic Compounds. Ozone
Sci. & Engrg., 10:2:153.
Druckrey, H. 1968. Chlorinated Drinking Water, Toxicity
Tests, Involving Seven Generation of Rats. Food and Cosmetics
Toxicology, Vol. 6, Pergamon Press. 147-154.
Entz, R.C.; Thomas, K.W.; Diachenko, G.W. 1982. Residues of
Volatile Halocarbons in Foods Using Headspace Gas Chromatography, J.
Agric. Food Chem., Vol. 30, No. 5, 1982, pp. 846-9.
Fair, P. S. 1992. Technical Support Division Disinfection
By-Products Field Study Data Base. Private communication to Wade
Miller Associates. Technical Support Division, Office of Ground
Water and Drinking Water, USEPA, Cincinnati, Ohio (Feb. 14, 1992).
Farland WH and HJ Gibb. 1993. U.S. perspective on balancing
chemical and microbial risks of disinfection. In: Proceedings:
Safety of Water Disinfection: Balancing Chemical and Microbial
Risks. pp. 3-10, International Life Sciences Institute Press,
Washington D.C.
Ferguson, D. W.; Gramith, J. T.; & McGuire, M. J. 1991.
Applying Ozone for Organics Control and Disinfection: A Utility
Perspective. Jour. AWWA, 83:5:32.
Gallagher, D. L.; Hoehn, R. C.; & Dietrich, A. M. 1993.
Sources, Occurrence, and Control of Chlorine Dioxide By-Product
Residuals in Drinking Water. Report for AWWARF, Denver, Colo.
Gelderloos, A. B., et al. Simulation of Compliance Choices
for the Disinfection By-Products Regulatory Impact Analysis. Proc.
1992 AWWA Ann. Conf. (Water Quality), Vancouver, B.C., pp. 49-79.
Glaze, W. H., et al. 1993. Determining Health Risks
Associated With Disinfectants and Disinfection By-products: Research
Needs. Jour. AWWA, 85:3:53.
Glaze, W. H.; Weinberg, H. S.; & Cavanagh, J. E. 1993.
Evaluating the Formation of Brominated DBPs During Ozonation. Jour.
AWWA, 85:1:96.
Glaze, W. H., et al. Identification and Occurrence of
Ozonation By-Products in Drinking Water. Report for AWWARF, Denver,
Colo. (1993, in press). 285 pp.
Glaze, W. H.; Koga, M.; & Cancilla, D. 1989. Ozonation
Byproducts. 2. Improvement of an Aqueous Phase Derivatization Method
for the Detection of Formaldehyde and Other Carbonyl Compounds
Formed by the Ozonation of Drinking Water. Environ. Sci. Technol.,
23:7:838.
Glaze, W. H., et al. 1989. Evaluation of Ozonation Byproducts
from Two California Surface Waters. Jour. AWWA, 81:8:66.
Glaze, W. H., et al. 1989. Ozone as a Disinfectant and
Oxidant in Water Treatment. In Disinfection By-Products: Current
Perspectives, AWWA, Denver, CO.
Gottlieb MS, Carr JK, Clarkson JR. 1982. Drinking water and
cancer in Louisiana--a retrospective mortality study. Am J Epidemiol
116:652.
Gramith, J. T., et al. Demonstration-Scale Evaluation of
Bromate Formation and Control Strategies. Proc. 1993 AWWA Ann.
Conf., San Antonio, Texas.
Greiner, A. D.; Obolensky, A.; & Singer, P. C. 1992.
Technical Note: Comparing Predicted and Observed Concentrations of
DBPs. Jour. AWWA, 84:11:99.
Griese, M. H.; Kaczur, J. J.; & Gordon, G. 1992. Combining
Methods for the Reduction of Oxychlorine Residuals in Drinking
Water. Jour. AWWA, 84:11:69.
Haag, W. R., & Hoigne, J. 1983. Ozonation of BromideContaining
Waters: Kinetics of Formation of Hypobromous Acid and
Bromate. Envir. Sci. & Technol., 17:5:261.
Haas, C. N., et al. 1990. AWWA Disinfection Survey.
Preliminary final report to AWWA, Drexel University, Environmental
Studies Institute (Dec. 20, 1990).
Harrington, G. W.; Chowdhury, Z. K.; & Owen, D. M. 1992.
Developing a Computer Model to Simulate DBP Formation During Water
Treatment. Jour. AWWA, 84:11:78.
Harrington, G. W.; Chowdhury, Z. K.; & Owen, D. M.
Integrated Water Treatment Plant Model: A Computer Model to Simulate
Organics Removal and Trihalomethane Formation. Proc. 1991 AWWA Ann.
Conf. (Water Quality for the New Decade), Philadelphia, Penn., pp.
589-624.
Hartwell, T.D.; Pellizzari, E.D.; Perritt, R.L.; Whitmore,
R.W.; Zelon, H.S.; Sheldon, L.S.; Sparacino, C.M.; Wallace, L. 1987.
Results from the Total Exposure Assessment Methodology (TEAM) Study
in Selected Communities in Northern and Southern California, Atmos.
Environ., Vol. 21, No. 9, pp. 1995-2004.
Hautman, D. P. Analysis of Trace Bromate in Drinking Water
Using Selective Anion Concentration and Ion Chromatography. Proc.
1992 AWWA WQTC, Toronto, Canada.
Hautman, D.P. ``Low-level Measurements of Bromate Ion Using
Selective Anion Concentration'' AWWA WQTC Proceedings, Toronto,
Ontario, November 1992.
Hautman, D.P. & Bolyard, M. 1992. ``Analysis of Oxyhalide
Disinfection By-Products and Other Anions of Interest in Drinking
Water by Ion Chromatography.'' J. of Chromatography, 602:65.
Hautman, D., Memorandum on modified eluant conditions, April
13, 1993.
Heffernan W. P., C. Guion and R.J. Bull. 1979. Oxidative
damage to the erythrocyte induced by sodium chlorite in vivo. J.
Environ. Pathol. and Tox. 2:1487-1499.
Heikes, D.L.; Hopper, M.L. 1990. J. Assoc. Off. Anal. Chem.;
Vol. 69; 1986; pp. 990-8. Cited in Howard, 1990.
Heikes, D.L. 1987. Purge and Trap Method for Determination
of Volatile Halocarbons and Carbon Disulfide in Table-Ready Foods;
J. Assoc. Off. Anal. Chem; Vol. 70; No. 2; 1987; pp. 215-26.
Heywood R, Sortwell RJ, Noel PRB, Street AE, Prentice DE,
Roe FJC, Wadsworth PF, Worden AN, Van Abbe NJ. 1979. Safety
evaluation of toothpaste containing chloroform. III. Long-term study
in beagle dogs. J. Environ. Pathol. Toxicol. 2:835-851.
Ho, et al. 1983. Cited in USEPA, 1985.
Hoehn, R. C., et al. Household Odors Associated With the Use
of Chlorine Dioxide. Jour. AWWA, 82:4:166 (Apr. 1990).
Hoigne, J., & Bader, H. 1988. The Formation of
Trichloronitromethane and Chloroform in a Combined Ozonation/
Chlorination Treatment of Drinking Water. Water Res. 22:3:313.
Howard, P.H. 1990. Handbook of Environmental Fate and
Exposure Data for Organic Chemicals; Lewis Publishers, Chelsea, MI;
Vol. 2; 1990; pp. 40-47.
IARC. 1982. International Agency for Research on Cancer.
Chloroform. Monographs on the Evaluation of Carcinogenic Risk of
Chemicals to Humans. Supplement 4. Chloroform. Vols. 1-29. World
Health Organization (WHO). pp. 87-88.
IARC. 1991. International Agency for Research on Cancer
Monographs on the Evaluation of Carcinogenic Risks to Humans:
Summary of Final Evaluations. Vol. 52. World Health Organization
(WHO). p.473.
IARC. 1991. International Agency for Research on Cancer.
Bromodichloromethane. In: IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans: Chlorinated drinking water;
chlorination byproducts; some other halogenate compounds; cobalt and
cobalt compounds. Volume 52. Lyon, France: World Health Organization
(WHO), International Agency for Research on Cancer. pp. 179-268.
IRIS. 1985. Integrated Risk Information System (December).
Washington, DC.: US Environmental Protection Agency.
IRIS. 1990. Integrated Risk Information System (December).
Washington, DC.: US Environmental Protection Agency.
IRIS. 1991. Integrated Risk Information System (December).
Washington, DC.: US Environmental Protection Agency.
IRIS. 1993. Chronic Health Hazard Assessment for
Noncarcinogenic Effects. Rev. Jan. 20, 1992.
Ijsselmuiden CB, Gaydos C, Feighner B, Novakoski WL,
Serwadda D, Caris LH, Vlahov D, Comstock GW. 1992. Cancer of the
Pancreas and Drinking Water: a Population-based Case-Control Study
in Washington County, Maryland. Am J Epidemiol 136:836-842.
Jacangelo, J. G., et al. 1989. Ozonation: Assessing Its Role
in the Formation and Control of Disinfection By-products. Jour.
AWWA, 81:8:74.
James M. Montgomery, Consulting Engineers, Inc. 1991.
Effect of Coagulation and Ozonation on the Formation of Disinfection
By-Products. Report submitted to AWWA Govt. Affairs Ofce.,
Washington, D.C.
Jersey, J. A., & Johnson, J. D. Analysis of N-Chloramines
in Chlorinated Wastewater and Surface Water by On-Line Enrichment
HPLC with Post-Column Reaction Electrochemical Detection. Proc. 1991
AWWA WQTC, pp. 1071-1081, Orlando, Florida.
Jorgenson TA, Meierhenry EF, Rushbrook CJ. Bull RJ,
Robinson M. 1985. Carcinogenicity of chloroform in drinking water to
male Osborne-Mendel rats and female B6C3F<INF>1 mice. Fundam. Appl.
Toxicol. 5:760-769.
Joyce, R.J. & Dhillon, H.S. 1993. Part-Per-Billion Level
Determination of Bromate in Ozonated Drinking Water Using Ion
Chromatography International Ion Chromatography Symposium,
Baltimore, MD.
Kallman, M.J., G.L. Kaempf and R.L. Balster. 1984.
Behavioral toxicity of chloral in mice: an approach to evaluation.
Neurobehav. Toxicol. Teratol. 6(2):137-146.
Kauffman, B.M., K.L. White, V.M. Sanders, K.A. Douglas,
L.E. Sain, J.F. Borzelleca and A.E. Munson. 1982. Humoral and cellmediated
immune status in mice exposed to chloral hydrate. Environ.
Health Perspect. 44:147-151.
Kelley, R.D. 1989. Synthetic Organic Compounds Sampling
Survey of Public Water Supplies, NTIS PB85-214427, 1985, p. 1-32.
Cited in USEPA, 1989.
Kelsey, JL, WD Thompson, and AS Evans. Methods in
Observational Epidemiology. Oxford Univ Press, NY. 1986. pp.148-149.
Kramer MD, Lynch CF, Isacson P, Hanson JW. 1992. The
Association of Waterborne Chloroform with Intrauterine Growth
Retardation. Epidemiology 3:407-413.
Krasner, S.W.; Barrett, S.E.; Dale, M.S.; Hwang, C.J.
1989a. Free Chlorine Versus Monochloramine for Controlling OffTastes
and Off-Odors; Journal AWWA; February, 1989; pp. 86-93.
Krasner, S.W.; McGuire, M.J.; Jacangelo, J.G.; Patania,
N.L.; Reagan, K.M.; Aieta, E.M. 1989b. The Occurrence of
Disinfection By-Products in U.S. Drinking Water; Journal AWWA;
August, 1989; pp. 41-53.
Krasner, S. W., et al. Development of a Bench-Scale Method
To Investigate the Factors that Impact Cyanogen Chloride Production
in Chloraminated Waters. Proc. 1991 AWWA WQTC, pp. 1207-1218,
Orlando, Florida.
Krasner, S. W., et al. Formation and Control of Brominated
Ozone By-Products. Proc. 1991 AWWA Ann. Conf., Philadelphia, Penn.,
pp. 945-971.
Krasner, S. W.; Chinn, R.; Hwang, C. J.; & Barrett, S. E.
Analytical Methods for Brominated Organic Disinfection By-Products.
Proc. 1990 AWWA WQTC, San Diego, CA.
Krasner, S. W.; Sclimenti, M. J.; & Coffey, B. M. 1993.
Testing Biologically Active Filters for Removing Aldehydes Formed
During Ozonation. Jour. AWWA, 85:5:62.
Krasner, S.W. et al. 1993. Formation and Control of Bromate
During Ozonation of Water Containing Bromide. Jour. AWWA, 85:1:73.
Krasner, S. W., et al. Bromate Occurrence and Control:
Pilot- and Full-Scale Studies. Proc. 1993 AWWA Ann. Conf., San
Antonio, Texas.
Krasner, S. W., et al. 1993. Formation and Control of
Bromate During Ozonation of Waters Containing Bromide. Jour. AWWA,
85:1:73.
Kruithof, J. C. 1992. Formation, Restriction Formation and
Removal of Bromate. Metropolitan Water District of Southern
California/KIWA Workshop, La Verne, Calif.
Kuo, C.Y.; Krasner, S. W.; Stalker, G. A.; & Weinberg, H.
S. Analysis of Inorganic Disinfection By-Products in Ozonated
Drinking Water by Ion Chromatography. Proc. 1990 AWWA WQTC, San
Diego, CA.
Kurokawa et al. 1986b. Dose-response studies on the
carcinogenicity of potassium bromate in F344 rats after long-term
oral administration. J. Natl. Cancer Inst. 77:977-982.
Kurokawa et al. 1986a. Long-term in vitro carcinogenicity
tests of potassium bromate, sodium hypochlorite and sodium chlorite
conducted in Japan. Environ. Health Perspect. 69:221-236.
Lawrence CE, Taylor PR, Trock BJ, Reilly AA. 1984.
Trihalomethanes in Drinking Water and Human Colorectal Cancer. J.
Natl. Cancer Inst. 72:563-569.
LeChevallier, M.W., et al. 1992. Evaluating the Performance
of Biologically Active Rapid Filters. Jour. AWWA, 84:4:136.
Le Cloirec, C. & Martin, G. 1985. Evolution of Amino Acids
in Water Treatment Plants and the Effect of Chlorination on Amino
Acids. In Water Chlorination: Chemistry, Environmental Impacts and
Health Effects, Vol. 5 (Jolley, R.L., et al, eds), Lewis Publishers,
Inc. Chelsea, MI.
Letkiewicz, F. J., et al. Simulation of Raw Water and
Treatment Parameters in Support of the Disinfection By-Products
Regulatory Impact Analysis. Proc. 1992 AWWA Ann. Conf. (Water
Quality), Vancouver, B.C., pp. 1-48.
Lieu, N. I.; Wolfe, R. L; & Means, E.G., III. 1993.
Optimizing Chloramine Disinfection for the Control of Nitrification.
Jour. AWWA, 85:2:84.
Lubbers, J.L. et al. 1982. Controlled Clinical Evaluations
of Chlorine Dioxide, Chlorite and Chlorate in Man. Environ. Health
Persp. Vol. 46.
Lykins, B.W., Griese, M.H. 1990. Using Chlorine Dioxide for
Trihalomethane Control, Jour. Am. Water Works Assoc., Vol. 78, 1986,
pp. 88-93.
Mallon, K., et al. Mathematical Modeling of the Formation
of THMs and HAAs in Chlorinated Natural Waters. Proc. 1992 AWWA Wat.
Qual. Tech. Conf. (WQTC), Toronto, Canada, pp. 1801-1813.
Masschelein, W.J. 1990. Historic and Current Overview of
Chlorine Dioxide. In: Chlorine Dioxide: Scientific, Regulatory and
Application Issues, Chemical Manufacturers Assoc., 2501 M St., NW,
Washington, D.C., 20037; 1989; pp. 4-40. Cited in Bull and Kopfler,
1990.
Mather, G.G., J.H. Exon and L.D. Koller. 1990. Subchronic
90-day toxicity of dichloroacetic acid and trichloroacetic acid in
rats. Toxicol. 64:71-80.
McGuire, M.J.; Meadow, R.G. 1988. AWWARF Trihalomethane
Survey; Journal AWWA; January, 1988; pp. 61-68.
McGuire, M.J.; Krasner, S.W.; Gramith, J.T. 1990. Comments
on Bromide Levels in State Project Water and Impacts on Control of
Disinfection By-Products; Metropolitan Water District of Southern
California, Los Angeles, California; September, 1990.
McGuire, M.J.; Krasner, S.W.; Reagan, K.M; Aieta, E.M.;
Jacangelo, J.G. Patania, N.L.; Gramith, K.M. 1990. Final Report for
Disinfection By-Products in United States Drinking Waters, Vol. 1,
U.S. Environmental Protection Agency and California Dept. of Health
Services, 1989. Cited in Bull and Kopfler, 1990.
McKnight, A., & Reckhow, D. A. Reactions of Ozonation Byproducts
With Chlorine and Chloramines. Proc. 1992 AWWA Ann. Conf.,
Vancouver, B.C.
Means, E. G., III, & Krasner, S. W. 1993. D-DBP Regulation:
Issues and Ramifications. Jour. AWWA, 85:2:68.
Meier, J.R. 1985. Evaluation of Chemicals Used for Drinking
Water Disinfection for Production of Chromosomal Damage and SpermHead
Abnormalities in Mice. Environ. Mutagenesis.
Merlet, N., et al. Removal of Organic Matter in BAC
Filters: The Link Between BDOC and Chlorine Demand. Proc. 1991 AWWA
WQTC, pp. 1111-1127, Orlando, Fla.
Metropolitan Water District of Southern California & James
M. Montgomery, Consulting Engineers, Inc. 1991. Pilot-Scale
Evaluation of Ozone and PEROXONE. AWWARF & AWWA, Denver, CO.
Metropolitan Water District of Southern California & James
M. Montgomery, Consulting Engineers, Inc. 1989. Disinfection ByProducts
in United States Drinking Waters. Final Report for United
States Environmental Protection Agency & Association of Metropolitan
Water Agencies. Vol. I.
Miller, R.E.; Randtke, S.J.; Hathaway, L.R.; Denne, J.E.
Organic Carbon and THM Formation Potential in Kansas
Groundwaters; Journal AWWA; March, 1990; pp. 49-62.
Miltner, R., Letter on TOC variability in a series of jar
tests, April 23, 1993.
Miltner, R. J.; Shukairy, H. M.; & Summers, R. S. 1992.
Disinfection By-product Formation and Control by Ozonation and
Biotreatment. Jour. AWWA, 84:11:53.
Miltner, R. J., & Summers, R. S. A Pilot-Scale Study of
Biological Treatment. Proc. 1992 AWWA Ann. Conf. (Water Quality),
pp. 181-198, Vancouver, B.C.
Miltner, R. J. 1993. Personal communication (unpublished
data). USEPA, Drinking Water Research Division, Cincinnati, Ohio
(Jan. 1993).
Mobley, S. A., D.H. Taylor, R.D. Laurie and R.J. Pfohl.
Chlorine dioxide depresses T3 uptake and delays development of
locomotor activity in young rats. In: Water Chlorination: Chemistry,
Environmental Impact and Health Effects. Vol 6. Jolley, Condie,
Johnson, Katz, Minear, Mattice and Jacobs, ed. Lewis Publ., Inc.
Chelsea MI., pp. 347-360.
Morgenstern, H. 1982. Uses of Ecologic Analysis in
Epidemiologic Research. Am. J. Public Health 72: 1336- 1344.
Morris RD, Audet A, Angelillo IO, et al. 1992.
Chlorination, chlorination by-products, and cancer: a metaanalysis.
Am J Public Health 82:955.
Murphy, P.A. and G.F. Craun. 1990. A Review of Previous
Studies Reporting Associations Between Drinking Water Disinfection
and Cancer. Chapter 29 in: Water Chlorination: Chemistry,
Environmental Impact and Health Effects, Vol. 6. R.L. Jolley, L.W.
Condie, J.D. Johnson, S. Katz, R.A. Minear, J.S. Mattice, and V.A.
Jacobs, editors. (Chelsea, MI: Lewis Publishers, Inc.). pp. 361-371.
Murphy PA. 1993. Quantifying chemical risk from
epidemiologic studies: application to the disinfectant byproduct
issue. In: Proceedings: Safety of Water Disinfection: Balancing
Chemical and Microbial Risks. pp. 373-389, International Life
Sciences Institute Press, Washington DC.
Nakano, K.; Okada, S.; Toyokuni, S.; Midorikawa, O. 1989.
Renal changes induced by chronic oral administration of potassium
bromate or ferric nitrilotriacetate in Wistar rats. Jpn. Arch.
Intern. Med. 36:41-47.
National Cancer Institute (NCI). 1976. Report on
carcinogenesis bioassay of chloroform. NTIS PB-264018.
National Academy of Sciences. Drinking Water and Health,
Vol. 1, National Academy Press, Washington DC. pp. 716-717, 1977.
National Academy of Sciences. Drinking Water and Health,
Vol. 7, National Academy Press, Washington DC. 1977.
NTP. 1987. National Toxicology Program. Toxicity and
carcinogenesis studies of bromodichloromethane in F344/N rats and
B6C3F<INF>1 mice (gavage studies). Technical Report Series No. 321.
NTP. 1990. NTP Technical Report on the Toxicology and
Carcinogenesis Studies of Chlorinated and Chloraminated Water in
F344/N rats and B6C3F<INF>1 Mice (Drinking Water Studies). NTP TR
392, National Institutes of Health. 474 pp.
NTP. 1989. National Toxicology Program. Toxicology and
carcinogenesis studies of bromoform in F344/N rats and B6C3F<INF>1
mice (gavage studies). Tech. Rep. Ser. No. 350.
NTP. 1985. National Toxicology Program. Toxicology and
carcinogenesis studies of chlorodibromomethane in F344/N rats and
B6C3F<INF>1 mice (gavage studies). Tech. Rep. Ser. No. 282.
Orme J., D.H. Taylor, R.D. Laurie and R.J. Bull. 1985.
Effects of chlorine dioxide on thyroid function in neonatal rats. J.
Tox. and Environ. Health 15:315-322.
Orme-Zavaleta, J. 1992. Review of Chlorine Dioxide Criteria
Document. Presentation to Science Advisory Board Drinking Water
Committee, USEPA, Office of Science & Technology, Office of Water,
Washington, D.C. (Feb. 10, 1992).
Parnell, M.J., J.H. Exon, and L. Koller. 1988. Assessment
of hepatic initiation-promotion properties of trichloroacetic acid.
Arch. Environ. Contam. Toxicol. 17:429-436.
Paszko-Kolva, C., et al. Impact of Selected Operational
Parameters on AOC Removal Efficiencies Under Pilot Plant Conditions.
Proc. 1992 Pan American Comm. Conf., International Ozone Assn.,
Pasadena, Calif.
Patel, Y. Review of Ozone and By-Products Criteria
Document. Presentation to the Science Advisory Board Drinking Water
Committee by the USEPA, Health and Risk Assessment Branch,
Washington, D.C. (Feb. 11, 1992).
Patterson, K.S., & Lykins, B.W., Jr. The Role of
Mutagenicity in Determining Drinking Water Quality. Proc. 1993 AWWA
Ann. Conf., San Antonio, Tex.
Pellizzari ED, Michael LC, Perritt R, Smith DJ, Hartwell TD
and Sebestik J. 1989. Comparison of indoor and outdoor toxic air
pollutant levels in several southern California communities. Final
Report, EPA Contract # 68-02-4544. USEPA, Research Triangle Park,
NC.
Personal communication. 1993. Novatek, Oxford, Ohio.
Peto, R. 1987. Why do we need systematic overviews of
randomized trials? Stat. Med. 6:233-240.
Pfaff, J.D., & Brockhoff, C.A. 1990. Determining Inorganic
Disinfection By-products by Ion Chromatography. Jour. AWWA,
82:4:192.
Piantiadosi, S., DP Byar, and SB Green. 1988. Am J Epi.
127:893.
Pourmoghaddas, H., & Dressman, R.C. 1992. Determination of
Nine Haloacetic Acids in Finished Drinking Water. Proc. AWWA WQTC,
Toronto, Ontario.
Price, M.L., et al. Evaluation of Ozone-Biological
Treatment for Reduction of Disinfection By-products and Production
of Biologically Stable Water. Presented at 1992 AWWA Ann. Conf.,
Vancouver, B.C.
Private communication. 1993. Chemical Manufacturers
Association, Washington, D.C.
Reckhow, D.A., et al. Control of Disinfection Byproducts
and AOC by Pre-ozonation and Biologically-Active In-line Direct
Filtration. Proc. 1992 AWWA Ann. Conf. (Water Research), pp. 487-
503, Vancouver, B.C.
Reckhow, D.A., & Singer, P.C. 1990. Chlorination Byproducts
in Drinking Waters: From Formation Potentials to Finished
Water Concentrations. Jour. AWWA, 82:4:173.
RESOLVE. 1992a. Negotiated Rulemaking on Disinfectants and
Disinfection By-Products. Public Meeting, September 29-30, 1992.
Meeting Summary. Washington, DC.
Rice, R. G. 1992. U.S. Potable Water Treatment Plants Using
Ozone. RICE, Ashton, Maryland (Aug.-Sept. 1992).
Rijhsinghani, K.S., M.A. Swerdlow, T. Ghose, C. Abrahams
and K.V.N. Rao. 1986. Induction of neoplastic lesions in the liver
of C57BL x C3HFl male in chloral hydrate. Cancer Detection and
Prevention. 9:279-288.
Riley TJ, Cauley JA, Murphy PA, Black D. 1992. The Relation
of Water Chlorination to Serum Lipids in Elderly White Women.
(Abstract). Am J Epidemiol 136:969.
Rook, J.J. 1974. ``Formation of Haloforms During
Chlorination of Natural Water'', Water Treatment and Examination,
23(2):234-243.
Roe, F.J.C. et al. 1979. Safety Evaluation of Toothpaste
Containing Chloroform: Long-term Studies in Mice. Environ. Path.
Toxicol. 2:799-819.
Ruddick, J.A. D.C. Villeneuve, and I. Chu. 1983. A
teratological assessment of four trihalomenthanes in the rat. J.
Environ. Sci. Health. 1318(3):333-349.
Sanders, V.M., B.M. Kauffman, K.L. White, K.A. Douglas,
D.W. Barnes, L.E. Sain, T.J. Bradshaw, J.F. Borzelleca and A.E.
Munson. 1982. Toxicology of chloral hydrate in the mouse. Environ.
Health Perspect. 44:137-146.
Sclimenti, M. J., et al. Ozone Disinfection By-Products:
Optimization of the PFBHA Derivatization Method for the Analysis of
Aldehydes. Proc. 1990 AWWA WQTC, San Diego, Calif., pp. 477-501.
Scully, F. E., & Bempong, M. A. Organic N-Chloramines in
Drinking Water: Chemistry and Toxicology. Environ. Health Persp.,
46:111.
Scully, F. E. 1990. Reaction Chemistry of Inorganic
Monochloramine: Products and Implications for Drinking Water
Disinfection. Paper presented at 200th Amer. Chem. Soc. (ACS) Natl.
Meet., Washington, D.C.
Scully, F.E. and W.N. White. 1991. Reactions of chlorine,
monochloramine in the G.I. tract. Environ. Sci. Technol. 25(5):820-
828.
Shaw, R.W.; Binkowski, F.S.; Courtney, W.J. 1982.
``Aerosols of High Chlorine Concentration Transported Into Central
and Eastern United States,'' Nature, Vol. 296, No. 5854, pp. 229-31.
Shikiya, J.; Tsou, G.; Kowalski, J.; Leh, F. 1984.
``Ambient Monitoring of Selected Halogenated Hydrocarbons and
Benzene in the California South Coast Air Basin,'' Proc-APCA 77th
Annual Mtg, Vol. 1, pp. 84-1.1.
Shy, C. 1985. Chemical Contamination of Water Supplies.
Env. Health Perspect. 62: 399-406.
Siddiqui, M. S., & Amy, G. L. 1993. Factors Affecting DBP
Formation During Ozone-Bromide Reactions. Jour. AWWA, 85:1:63.
Singer, P. C., & Chang, S. D. 1989. Correlations Between
Trihalomethanes and Total Organic Halides Formed During Water
Treatment. Jour. AWWA, 81:8:61.
Singh, H.B.; Salas, L.J.; Smith, A.J.; Shigeishi, H. 1981.
``Measurements of Some Potentially Hazardous Chemicals in Urban
Environments,'' Atmos. Environ. 15(4):601-12.
Singh et al. 1983. Cited in Wallace, 1991.
Sorrell, R.K. & Hautman, D.P. 1992. A Simple Concentration
Technique for the Analysis of Bromate at Low Levels in Drinking
Water. American Water Works Association Water Quality Technology
Conference Proceedings.
Spitzer, W.O. 1991. Editorial. Meta-meta-analysis:
Unanswered questions about aggregating data. J. Clin. Epidemiol.
44:103-107.
Stevens, A.A. 1981. ``Reaction Products of Chlorine
Dioxide''; Env. Health Persp.; Vol. 46; December, pp. 101-110.
Stevens, A. A., et al. 1987. By-Products of Chlorination at
Ten Operating Utilities. In Disinfection By-Products: Current
Perspectives, AWWA, Denver, CO.
Stevens, A. A.; Moore, L. A.; & Miltner, R. J. 1989.
Formation and Control of Non-Trihalomethane Disinfection Byproducts.
Jour. AWWA, 81:8:54.
Summers, R. S., et al. 1993. Effect of Separation Processes
on the Formation of Brominated THMs. Jour. AWWA, 85:1:88.
Symons, J.M.; Bellar, T.A.; Carswell, J.K.; DeMarco, J.;
Kropp, K.L.; Robeck, G.G.; Seeger, D.R.; Slocum, C.J.; Smith, B.L.;
Stevens, A.A. 1975. ``National Organics Reconnaissance Survey for
Halogenated Organics''; Journal AWWA; Vol. 67; No. 11; November, pp.
634-647.
Symons, J.M., et al. 1993. Measurement of THM and Precursor
Concentrations Revisited: The Effect of Bromide Ion. Jour. AWWA,
85:1:51.
Symons, J. M., et al. 1979. Ozone, Chlorine Dioxide and
Chloramines as Alternatives to Chlorine for Disinfection of Drinking
Water. Water Chlorination: Environmental Impact and Health Effects,
Vol. 2 (R. L. Jolley et al, editors). Ann Arbor Sci. Publ., Ann
Arbor, Mich.
Symons, J. M., et al. 1981. Treatment Techniques for
Controlling Trihalomethanes in Drinking Water. EPA-600/2-81-156.
MERL, USEPA, Cincinnati, Ohio.
Tate, C. H. 1991. Survey of Ozone Installations in North
America. Jour. AWWA, 83:5:40.
Taylor D., and R. Pfohl. 1985. Effects of chlorine dioxide
on neurobehavioral development in rats. Water Chlorination. Vol 5,
pp. 355-364.
Tomatis L., ed. 1990. Cancer : Causes, Occurrence and
Control. IARC Scientific Publications No. 100. International Agency
for Research on Cancer, Lyon, France.
Toth G., R. Long, T. Mills and M.K. Smith. 1990. Effects of
chlorine dioxide on developing rat brain. J. Tox. and Environ.
Health. 31:29-44.
Tuthill, R.W. and G.S. Moore. 1980. JAWWA 72:570.
Uden, P.C.; Miller, J.W. 1983. Chlorinated Acids and
Chloral in Drinking Water; J. Amer. Water Works Assoc.; Vol. 75; No.
10; October, pp. 524-527.
Uhler, A.D.; Diachenko, G.W. 1987. Volatile Halocarbons in
Process Water and Processed Foods; Bull. Environ. Cont. Toxic.; Vol.
39; No. 4; October, pp. 601-607.
USEPA. 1978. National Organics Monitoring Survey (NOMS).
Technical Support Division, U.S. Environmental Protection Agency,
Office of Drinking Water, Cincinnati, OH.
USEPA. 1980. Ambient Water Quality Criteria Document for
Halomethanes. Office of Health and Environmental Assessment,
Environmental Criteria Office, Cincinnati, OH; 1980. Cited in USEPA,
(Bromoform).
USEPA. 1985. U.S. Environmental Protection Agency. ``Health
and Environmental Effects Profile for Bromodichloromethanes''.
Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment, Cincinnati, Ohio; June, 1985, p. 25.
(BDCM). 600/x-85/397. NTIS PB88-174610.
USEPA. 1986. Risk Assessment Guidelines of 1986. EPA/600/8-
87/045. NTIS PB88-123997.
USEPA. 1989. U.S. Environmental Protection Agency. Health
and Environmental Effects Document for Bromoform. Criteria and
Assessment Office, Cincinnati, OH; September, 1989. (Bromoform).
600/8-90-025. NTIS PB91-216424.
USEPA. 1991. Status Report on Development of Regulations
for Disinfectants and Disinfection By-Products. USEPA, Office of
Groundwater and Drinking Water, Washington, D.C.
USEPA. 1991. Revised Final Draft for the Drinking Water
Criteria Document on Ozone and Ozonation By-Products. Prepared for
Health and Ecological Criteria Div., Office of Science & Technology,
Office of Water, USEPA, Washington, D.C. (June 1991).
USEPA. 1991a. U.S. Environmental Protection Agency.
Technical Support Division Unregulated Contaminant Database. Office
of Ground Water and Drinking Water.
USEPA. 1991b. U.S. Environmental Protection Agency. Draft
Drinking Water Health Advisory for Brominated Trihalomethanes:
Bromoform, Dibromochloromethane, Bromodichloromethane; Office of
Water; September, 1991. (Bromoform).
USEPA. 1992. Water Treatment Plant User's Manual. Office of
Ground Water and Drinking Water Resource Center. Wash. D.C. EPA-811-
8-B-92-001.
USEPA. 1992a. U.S. Environmental Protection Agency.
Occurrence Assessment for Disinfectants and Disinfection By-Products
(Phase 6a) in Public Drinking Water, August 1992.
USEPA. 1992b. Technical Support Division Disinfection ByProducts
Field Study Data Base. Office of Ground Water and Drinking
Water, Communication with Patricia Fair, TSD, Cincinnati, February
14, 1992.
USEPA. 1992c. U.S. Environmental Protection Agency. Review
of the Drinking Water Criteria Document for Chlorine Dioxide.
Drinking Water Committee, Science Advisory Board. Memorandum from
Ray Loehr and Verne Ray to William K. Reilly. August 12.
USEPA. 1993. U.S. Environmental Protection Agency. Guidance
Manual for Enhanced Coagulation and Enhanced Precipitative
Softening. Washington, DC.
USEPA. 1993a. U.S. Environmental Protection Agency. Report
of the Panel on Reproductive Effects of Disinfection By-Products in
Drinking Water. USEPA and International Life Sciences Institute-Risk
Science Institute. September.
USEPA. 1994. U.S. Environmental Protection Agency.
Regulatory Impact Analysis of Proposed Disinfectant/Disinfection ByProducts
Regulations. Washington, DC.
USEPA (undated). The National Organic Monitoring Survey.
Unpubl., Tech. Support Div., Office of Water Supply.
U.S. Government Printing Office. 1992. Statistical Abstract
of the United States (p370, Table 592). Washington, DC.
U.S. Office of the Federal Register. 1987. Protection of
Environment: Definition and Procedure for the Determination of the
Method Detection Limit. Code of Federal Regulations, 40:136B:510.
Van der Kooij, D.; Visser, A.; & Hijnen, W.A.M. 1982.
Determining the Concentration of Easily Assimilable Organic Carbon
in Drinking Water. Jour. AWWA, 74:10:540.
Von Gunten, U., & Hoigne, J. 1992. Factors Controlling the
Formation of Bromate During Ozonation of Bromide-Containing Waters.
J. Water SRT--Aqua, 41:5:299.
Wallace, L. 1992. Human Exposure, Body Burden, and
Exposure-Body Burden Relationships for Chloroform and Other
Trihalomethanes: U.S. Environmental Protection Agency, Office of
Research and Development, Warrenton, VA; Apr. 14, 1992.
Weinberg, H. S., et al. 1993. Formation and Removal of
Aldehydes in Plants That Use Ozonation. Jour. AWWA, 85:5:72.
Weinberg, H. S.; Glaze, W. H.; & Pullin, J. J. Modification
and Application of Hydrogen Peroxide Analysis in Ozonation Plant
Surveys. Proc. 1991 AWWA WQTC, Orlando, Florida.
Westrick, J.J.; Mello, J.W.; Thomas, R.F. 1983. The Ground
Water Supply Survey Summary of Volatile Organic Contaminant
Occurrence Data. Technical Support Division, Office of Drinking
Water and Office of Water, U.S. Environmental Protection Agency,
Cincinnati, Ohio.
Wie, C.I.; Cook, D.L.; Kirk, J.R. 1985. Use of Chlorine
Compounds in the Food Industry. Food Technology, Vol. 39, No. 1, pp.
107-115.
Wilkins JR, Comstock GW. 1981. Source of Drinking Water at
Home and Site-specific Cancer Incidence in Washington County,
Maryland. Am J Epidemiol 114:178-190.
Wolfe, R. L., et al. 1988. Biological Nitrification in
Covered Reservoirs Containing Chloraminated Water. Jour. AWWA,
80:9:109.
Xie, Y., & Reckhow, D. A. 1993. Identification of
Trihaloacetaldehydes in Ozonated and Chlorinated Fulvic Acid
Solutions. Analyst.
Xie, Y., & Reckhow, D. A. A New Class of Ozonation ByProducts:
The Ketoacids. Proc. 1992 AWWA Ann. Conf. (Water Quality),
Vancouver, B.C., pp. 251-265.
Young, T.B., D.A. Wolfe, and M.S. Kanarek. 1987. CaseControl
Study of Colon Cancer and Drinking Water Trihalomethanes in
Wisconsin. Int. J. Epidemiol. 16: 190-197.
Young TB, Wolf DA, Kanarek MS. 1981. Epidemiologic Study of
Drinking Water Chlorination and Wisconsin Female Cancer Mortality. J
Natl Cancer Inst 67:1191-1198.
Zeighami, E.A., A.P. Watson, and G.F. Craun. 1990.
Chlorination, Water Hardness and Serum Cholesterol in Forty-six
Wisconsin Communities. Int. J. Epidemiol. 19: 49-58.
Zierler, S., L. Feingold, R.A. Danley, and G. Craun. 1988.
Bladder Cancer in Massachusetts Related to Chlorinated and
Chloraminated Drinking Water: A Case-control Study. Arch. Environ.
Health 43: 195-200.
Zierler, S., R.A. Danley, and L. Feingold. 1986. Type of
Disinfectant in Drinking Water and Patterns of Mortality in
Massachusetts. Environ. Health Perspect. 69: 275-279.

List of Subjects

40 CFR Part 141

Intergovernmental relations, Reporting and recordkeeping
requirements, Water supply.

40 CFR Part 142

Adminstrative practice and procedure, Reporting and recordkeeping
requirements, Water supply.

Dated: June 7, 1994.
Carol M. Browner,
Administrator.

For the reasons set out in the preamble, chapter I of title 40 of
the Code of Federal Regulations is proposed to be amended as follows:

PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS

The authority citation for part 141 continues to read as
follows:

Authority: 42 U.S.C. 300f, 300g-1, 300g-2 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4 and 300j-9.

2. Section 141.2 is amended by adding the following definitions in
alphabetical order to read as follows:

Note: The definition for ``subpart H systems'' has been proposed
(59 FR 6332, February 10, 1994) and is included in this proposal for
the convenience of the reader.

Sec. 141.2 Definitions.

* * * *
Biologically active filtration (BAF) means conventional filtration
treatment or direct filtration preceded by continuous application of
ozone (in possible combination with hydrogen peroxide), but no other
continuous chemical disinfectant, utilizing filtration media and rate
(i.e., empty bed contact time) sufficient to remove substantial levels
of biodegradeable ozone byproducts.
Enhanced coagulation means the addition of excess coagulant for
improved removal of disinfection byproduct precursors by conventional
filtration treatment.
Enhanced softening means the improved removal of disinfection
byproduct precursors by precipitative softening.
* * * *
GAC10 means granular activated carbon filter beds with an empty-bed
contact time of 10 minutes based on average daily flow and a carbon
reactivation frequency of every 180 days.
GAC20 means granular activated carbon filter beds with an empty-bed
contact time of 20 minutes based on average daily flow and a carbon
reactivation frequency of every 60 days.
* * * *
Haloacetic acids (five) (HAA5) mean the sum of the concentrations
in milligrams per liter of the haloacetic acid compounds
(monochloroacetic acid, dichloroacetic acid, trichloroacetic acid,
monobromoacetic acid, and dibromoacetic acid), rounded to two
significant figures after addition.
* * * *
Maximum residual disinfectant level (MRDL) means a level of a
disinfectant added for water treatment that may not be exceeded at the
consumer's tap without an unacceptable possibility of adverse health
effects. For chlorine and chloramines, a PWS is in compliance with the
MRDL when the running annual average of monthly averages of samples
taken in the distribution system, computed quarterly, is less than or
equal to the MRDL. For chlorine dioxide, a PWS is in compliance with
the MRDL when daily samples are taken at the entrance to the
distribution system and no two consecutive daily samples exceed the
MRDL. MRDLs are enforceable in the same manner as maximum contaminant
levels under section 1412 of the Safe Drinking Water Act. There is
convincing evidence that addition of a disinfectant is necessary for
control of waterborne microbial contaminants. Notwithstanding the MRDLs
listed in Sec. 141.65, operators may increase residual disinfectant
levels of chlorine or chloramines (but not chlorine dioxide) in the
distribution system to a level and for a time necessary to protect
public health to address specific microbiological contamination
problems caused by circumstances such as distribution line breaks,
storm run-off events, source water contamination, or cross-connections.
Maximum residual disinfectant level goal (MRDLG) means the maximum
level of a disinfectant added for water treatment at which no known or
anticipated adverse effect on the health of persons would occur, and
which allows an adequate margin of safety. MRDLGs are nonenforceable
health goals and do not reflect the benefit of the addition of the
chemical for control of waterborne microbial contaminants.
* * * *
Subpart H systems means public water systems using surface water or
ground water under the direct influence of surface water as a source
that are subject to the requirements of subpart H of this part.
* * * *
Total Organic Carbon (TOC) means total organic carbon in mg/l
measured by methods specified in subpart L of this part using heat,
oxygen, ultraviolet irradiation, chemical oxidants, or combinations of
these oxidants that convert organic carbon to carbon dioxide, rounded
to two significant figures.
* * * *
Subpart B is amended by revising Sec. 141.12 to read as follows:

Sec. 141.12 Maximum contaminant levels for total trihalomethanes.

The maximum contaminant level of 0.10 mg/l for total
trihalomethanes (the sum of the concentrations of bromodichloromethane,
dibromochloromethane, tribromomethane (bromoform), and trichloromethane
(chloroform)) applies to Subpart H community water systems which serve
a population of 10,000 people or more until [insert date 18 months
after date of publication of the final rule in the Federal Register].
This level applies to community water systems that use only ground
water not under the direct influence of surface water and serve a
population of 10,000 people or more until [insert date 42 months after
date of publication of the final rule in the Federal Register].
Compliance with the maximum contaminant level for total trihalomethanes
is calculated pursuant to Sec. 141.30. After [insert date 42 months
after date of publication of the final rule in the Federal Register],
this section expires.
4. Section 141.30 is amended by adding paragraph (g) to read as
follows:

Sec. 141.30 Total trihalomethanes sampling, analytical and other
requirements.

* * * *
(g) The requirements in paragraphs (a) through (f) of this section
apply to Subpart H community water systems which serve a population of
10,000 or more until [insert date 18 months after date of publication
of the final rule in the Federal Register]. The requirements in
paragraphs (a) through (f) of this section apply to community water
systems which use only ground water not under the direct influence of
surface water that add a disinfectant (oxidant) in any part of the
treatment process and serve a population of 10,000 or more until
[insert date 42 months after date of publication of the final rule in
the Federal Register]. After [insert date 42 months after date of
publication of the final rule in the Federal Register], this section
and Appendix A (Summary of Public Comments and EPA responses on
Proposed Amendments to the National Interim Primary drinking Water
Regulations for Control of Trihalomethanes in Drinking Water), Appendix
B (Summary of Major Comments), and Appendix C (Analysis of
Trihalomethanes) of this part expire.
Section 141.32 is amended by revising paragraph (a) introductory
text; removing the word ``MCLs'' and adding, in its place, the words
``MCLs and MRDL(s)'' in paragraph (a)(1)(iii); removing the words
``maximum contaminant level'' and adding, in its place, the words
``maximum contaminant level and maximum residual disinfectant level''
in paragraph (c); and adding paragraphs (a)(1)(iii)(E) and (e)(83)
through (88) to read as follows:

Subpart D--Reporting, Public Notification and Recordkeeping

Sec. 141.32 Public notification.

* * * *
(a) Maximum Contaminant Levels (MCLs), Maximum Residual
Disinfectant Levels (MRDLs), treatment technique, and variance and
exemption schedule violations. The owner or operator of a public water
system which fails to comply with an applicable MCL, MRDL, or treatment
technique established by this part or which fails to comply with the
requirements of any schedule prescribed pursuant to a variance or
exemption, shall notify persons served by the system as follows:
(1) * * *
(iii) * * *
(E) Violation of the MRDL for chlorine dioxide as defined in
Sec. 141.65 and determined according to Sec. 141.133(b)(2)(iii)(B).
* * * *
(e) * * *
(83) Chlorine. The United States Environmental Protection Agency
(EPA) sets drinking water standards and has determined that chlorine is
a health concern at certain levels of exposure. The Safe Drinking Water
Act requires disinfection for all public water systems. This chemical
is used to disinfect drinking water. Chlorine is added to drinking
water to kill bacteria and other disease-causing microorganisms.
Chlorine is also added to provide continuous disinfection throughout
the distribution system. However, at high doses for extended periods of
time, chlorine has been shown to damage blood in laboratory animals.
EPA has set a drinking water standard for chlorine to protect against
the risk of these adverse effects. Drinking water which meets this EPA
standard is associated with little to none of this risk and should be
considered safe with respect to chlorine.
(84) Chloramines. The United States Environmental Protection Agency
(EPA) sets drinking water standards and has determined that chloramines
are a health concern at certain levels of exposure. The Safe Drinking
Water Act requires disinfection for all public water systems. This
chemical is used to disinfect drinking water. Chloramines are added to
drinking water to kill bacteria and other disease-causing
microorganisms. Chloramines are also added to provide continuous
disinfection throughout the distribution system. However, at high doses
for extended periods of time, chloramines have been shown to damage
blood and the liver in laboratory animals. EPA has set a drinking water
standard for chloramines to protect against the risk of these adverse
effects. Drinking water which meets this EPA standard is associated
with little to none of this risk and should be considered safe with
respect to chloramines.
(85) Chlorine dioxide. The United States Environmental Protection
Agency (EPA) sets drinking water standards and requires disinfection of
drinking water. The Safe Drinking Water Act also requires disinfection
of all public water systems. Chlorine dioxide is used in water
treatment to kill bacteria and other disease-causing microorganisms and
can be used to control tastes and odors. However, at high doses,
chlorine dioxide in drinking water has been shown to damage blood in
laboratory animals. Also, high levels of chlorine dioxide given to
pregnant laboratory animals in drinking water have been shown to cause
delays in development of the nervous system of their offspring. These
effects may occur as a result of a short term exposure to excessive
chlorine dioxide levels. To protect against such potentially harmful
exposures, EPA requires chlorine dioxide monitoring at the treatment
plant, where disinfection occurs, and at representative points in the
distribution system serving water users. EPA has set a drinking water
standard for chlorine dioxide to protect against the risk of these
adverse effects.

Note: In addition to paragraph (e)(85) of this section, systems
must include either paragraph (e)(85)(i) or paragraph (e)(85)(ii) of
this section. Systems with a violation at the treatment plant, but
not in the distribution system, are required to use the language in
paragraph (e)(85)(i) of this section and treat the violation as a
nonacute violation. Systems with a violation at the treatment plant
and in the distribution system are required to use the language in
paragraph (e)(85)(ii) of this section and treat the violation as an
acute violation.

(i) The chlorine dioxide violations reported today are the result
of exceedances at the treatment facility only, and do not include
violations within the distribution system serving users of this water
supply. Continued compliance with chlorine dioxide levels within the
distribution system minimizes the potential risk of these violations to
present consumers or
(ii) The chlorine dioxide violations reported today include
exceedances of the EPA standard within the distribution system serving
water users. Violations of the chlorine dioxide standard within the
distribution system may harm human health based on short-term
exposures. Certain groups, including pregnant women, may be especially
susceptible to adverse effects of excessive chlorine dioxide exposure.
The purpose of this notice is to advise that such persons should
consider reducing their risk of adverse effects from these chlorine
dioxide violations by seeking alternate sources of water for human
consumption until such exceedances are rectified. Local and State
health authorities are the best source for information concerning
alternate drinking water.
(86) Disinfection byproducts and treatment technique for DBPs. The
United States Environmental Protection Agency (EPA) sets drinking water
standards and requires the disinfection of drinking water. The Safe
Drinking Water Act also requires disinfection for all public water
systems. However, when used in the treatment of drinking water,
disinfectants combine with organic and inorganic matter present in
water to form chemicals called disinfection byproducts (DBPS). EPA has
determined that a number of DBPs are a health concern at certain levels
of exposure. Certain DBPs, including some trihalomethanes (THMs) and
some haloacetic acids (HAAs), have been shown to cause cancer in rats.
Other DBPs have been shown to damage the liver and the nervous system,
and cause reproductive or developmental effects in laboratory animals.
There is also some evidence that exposure to certain DBPs may produce
adverse effects in people. EPA has set standards to limit exposure to
THMs, HAAs, and other DBPs.
(87) Bromate. The United States Environmental Protection Agency
(EPA) sets drinking water standards and has determined that bromate is
a health concern at certain levels of exposure. Bromate is formed as a
by-product of ozone disinfection of drinking water. Ozone reacts with
naturally occurring bromide in the water to form bromate. Bromate has
been shown to produce cancer in rats. EPA has set a drinking water
standard to limit exposure to bromate.
(88) Chlorite. The United States Environmental Protection Agency
(EPA) sets drinking water standards and has determined that chlorite is
a health concern at certain levels of exposure. Chlorite is formed from
the breakdown of chlorine dioxide, a drinking water disinfectant.
Chlorite in drinking water has been shown to damage blood cells and the
nervous system. EPA has set a drinking water standard for chlorite to
protect against these effects. Drinking water which meets this standard
is associated with little to none of these risks and should be
considered safe with respect to chlorite.

Subpart F--Maximum Contaminant Level Goals

6. Subpart F is amended by adding new Secs. 141.53 and 141.54 to
read as follows:

Sec. 141.53 Maximum contaminant level goals for disinfection
byproducts.

(a) MCLGs are zero for the following contaminants:
(1) Chloroform;
(2) Bromodichloromethane;
(3) Bromoform;
(4) Bromate; and
(5) Dichloroacetic acid.
(b) MCLGs for the following contaminants are as indicated:

MCLG(mg/l)
Contaminant

Chloral hydrate............................................. 0.04
Chlorite.................................................... 0.08
Dibromochloromethane........................................ 0.06
Trichloroacetic acid........................................ 0.3

Sec. 141.54 Maximum residual disinfectant level goals for
disinfectants.

The MRDLGs for disinfectants are as follows:

Disinfectant residual MRDLG (mg/l)

Chloramines......................................... 4 (as Cl<INF>2)
Chlorine............................................ 4 (as Cl<INF>2)
Chlorine dioxide.................................... 0.3 (as ClO<INF>2)

Subpart G--National Revised Primary Drinking Water Regulations:
Maximum Contaminant Levels

7. Subpart G is amended by adding Secs. 141.64 and 141.65 to read
as follows:

Sec. 141.64 Maximum contaminant levels for disinfection byproducts.

(a) The following Maximum Contaminant Levels (MCLs) for
disinfection byproducts apply to community water systems and
nontransient, noncommunity water systems; compliance dates are
indicated in paragraph (d)(1) of this section:

Contaminant MCL (mg/l)

Bromate................................................... 0.010
Chlorite.................................................. 1.0
Haloacetic acids (five) (HAA5)............................ 0.060
Total trihalomethanes (TTHM).............................. 0.080

(b)(1) For Subpart H systems that serve more than 10,000 people,
the HAA5 and TTHM MCLs (the Stage 1 MCLs) in paragraph (a) of this
section will be superseded by the MCLs (the Stage 2 MCLs) in paragraph
(b) of this section 18 months after publication of the final MCLs in
paragraph (b) of this section in the Federal Register with compliance
as indicated in paragraph (d)(2) of this section. The MCLs in paragraph
(a) of this section continue to apply for all other systems.

Contaminant MCL (mg/l)

Haloacetic acids (five)................................... 0.030
Total trihalomethanes..................................... 0.040

(2) Prior to the publication of the final MCLs in paragraph (b) of
this section in the Federal Register, the Administrator shall conduct a
second regulatory negotiation or similar proceeding intended to develop
a consensus rulemaking through negotiation to review these levels. The
Administrator shall provide notice to the public of the availability of
the monitoring data collected in accordance with Secs. 141.140 through
141.142 and the results of health effects research relating to
disinfectants and disinfection byproducts completed during the period
1994-1996. Thereafter, the Agency shall initiate the second regulatory
negotiation or similar proceeding to ensure that the affected interests
that participated in the 1993 negotiated rulemaking participate fully
with the Agency in the evaluation of the proposed Stage 2 MCLs in light
of the monitoring data, health effects research, and other information
developed since the proposal of the Stage 2 MCLs. If the second
negotiated rulemaking or similar proceeding produces a consensus among
the affected interests, the Agency will proceed in accordance with that
consensus. The Agency agrees to take action on the proposed Stage 2
MCLs by December 31, 1998, and to publish notice of that action in the
Federal Register. If data prior to this second rulemaking warrants
earlier action on acute health effects, a meeting shall be convened to
review the results of these data and to develop recommendations.
(c)(1) The Administrator, pursuant to Section 1412 of the Act,
hereby identifies the following as the best technology, treatment
techniques, or other means available for achieving compliance with the
maximum contaminant levels for disinfection byproducts identified in
paragraph (a) of this section:

Disinfection byproduct Best available technology (stage 1)

TTHMs............................ Enhanced coagulation or enhanced

softening or GAC10, with chlorine as
the primary and residual
disinfectant.

HAA5............................. Enhanced coagulation or enhanced

softening or GAC10, with chlorine as
the primary and residual
disinfectant.

Bromate.......................... Control of ozone treatment process to

reduce production of bromate.

Chlorite......................... Control of treatment processes to

reduce disinfectant demand and
control of disinfection treatment
processes to reduce disinfectant
levels.

(2) The Administrator, pursuant to Section 1412 of the Act, hereby
identifies the following as the best technology, treatment techniques,
or other means available for achieving compliance with the maximum
contaminant levels for disinfection byproducts identified in paragraph
(b) of this section:

Disinfection byproduct Best available technology (stage 2)

TTHMs............................ Enhanced coagulation or enhanced

softening, and GAC10; or GAC20; with
chlorine as the primary and residual
disinfectant.

HAA5............................. Enhanced coagulation or enhanced

softening, and GAC10; or GAC20; with
chlorine as the primary and residual
disinfectant.

(d) Compliance dates for community water systems and nontransient
noncommunity water systems. (1) Compliance with the MCLs in paragraph
(a) of this section. Subpart H systems serving 10,000 or more persons
must comply with the MCLs contained in paragraph (a) of this section
beginning [insert date 18 months after date of publication of the final
rule in the Federal Register]. Subpart H systems serving fewer than
10,000 persons or systems using only ground water not under the direct
influence of surface water serving 10,000 or more persons must comply
with the MCLs in paragraph (a) of this section beginning [insert date
42 months after date of publication of the final rule in the Federal
Register]. Systems using only ground water not under the direct
influence of surface water serving fewer than 10,000 persons must
comply with paragraph (a) of this section beginning [insert date 60
months after date of publication of the final rule in the Federal
Register].
(2) Compliance with the MCLs in paragraph (b) of this section.
Subpart H systems serving 10,000 or more persons must comply with the
listed MCLs or alternative requirements as developed under the
negotiated rulemaking or similar process contained in paragraph (b) of
this section beginning 18 months after date of publication of the final
MCLs in paragraph (b) of this section in the Federal Register.
(3) A system that is installing GAC or membrane technology to
comply with this section may apply to the State for an extension of up
to 42 months past the dates in paragraphs (d) (1) or (2) of this
section, but not to exceed 60 months from the date of publication of
the final rule in the Federal Register. In granting the extension,
States must set a schedule for compliance and may specify any interim
measures that the system must take. Failure to meet the schedule or
interim treatment requirements constitutes a violation of National
Primary Drinking Water Regulations.

Sec. 141.65 Maximum residual disinfectant levels.

(a) The maximum residual disinfectant levels (MRDLs) are as
follows:

Disinfectant residual MRDL (mg/l)

Chloramines......................................... 4.0 (as Cl<INF>2)
Chlorine............................................ 4.0 (as Cl<INF>2)
Chlorine dioxide.................................... 0.8 (as ClO<INF>2)

(b) The Administrator, pursuant to Section 1412 of the Act, hereby
identifies the following as the best technology, treatment techniques,
or other means available for achieving compliance with the maximum
residual disinfectant levels identified in paragraph (a) of this
section: control of treatment processes to reduce disinfectant demand
and control of disinfection treatment processes to reduce disinfectant
levels.
(c) Compliance dates. (1) CWSs and NTNCWSs. Subpart H systems
serving 10,000 or more persons must comply with this section beginning
[insert date 18 months after date of publication of the final rule in
the Federal Register]. Subpart H systems serving fewer than 10,000
persons or systems using only ground water not under the direct
influence of surface water serving 10,000 or more persons must comply
with this subpart beginning [insert date 42 months after date of
publication of the final rule in the Federal Register]. Systems using
only ground water not under the direct influence of surface water and
serving fewer than 10,000 persons must comply with this subpart
beginning [insert date 60 months after date of publication of the final
rule in the Federal Register].
(2) Transient NCWSs. Subpart H systems serving 10,000 or more
persons and using chlorine dioxide as a disinfectant or oxidant must
comply with the chlorine dioxide MRDL beginning [insert date 18 months
after date of publication of the final rule in the Federal Register].
Subpart H systems serving fewer than 10,000 persons and using chlorine
dioxide as a disinfectant or oxidant or systems using only ground water
not under the direct influence of surface water serving 10,000 or more
persons and using chlorine dioxide as a disinfectant or oxidant must
comply with the chlorine dioxide MRDL beginning [insert date 42 months
after date of publication of the final rule in the Federal Register].
Systems using only ground water not under the direct influence of
surface water and serving fewer than 10,000 persons and using chlorine
dioxide as a disinfectant or oxidant must comply with the chlorine
dioxide MRDL beginning [insert date 60 months after date of publication
of the final rule in the Federal Register].
8. A new Subpart L is proposed to be added to read as follows:

Subpart L--Disinfectant Residuals, Disinfection Byproducts and
Disinfection Byproduct Precursors

Sec.
141.130 General requirements.
141.131-141.132 [Reserved]
141.133 Analytical and monitoring requirements.
141.134 Reporting and recordkeeping requirements.
141.135 Treatment technique for control of Disinfection Byproduct
Precursors (DBP).

Subpart L--Disinfectant Residuals, Disinfection Byproducts and
Disinfection Byproduct Precursors

Sec. 141.130 General requirements.

(a) The requirements of this subpart L constitute national primary
drinking water regulations. Subpart L of this part establishes criteria
under which community water systems (CWSs) and nontransient,
noncommunity water systems (NTNCWSs) which add a chemical disinfectant
to the water in any part of the drinking water treatment process must
modify their practices to meet MCLs and MRDLs in Secs. 141.64 and
141.65 and must meet the treatment technique requirements for
disinfection byproduct precursors in Sec. 141.135. In addition, subpart
L of this part establishes criteria under which transient NCWSs that
use chlorine dioxide as a disinfectant or oxidant must modify their
practices to meet the MRDL for chlorine dioxide in Sec. 141.65. MCLs
for TTHMs and HAA5 and treatment technique requirements for
disinfection byproduct precursors are established to limit the levels
of known and unknown disinfection byproducts which may have adverse
health effects. These disinfection byproducts may include chloroform;
bromodichloromethane; dibromochloromethane; bromoform; dichloroacetic
acid; trichloroacetic acid; and chloral hydrate
(trichloroacetaldehyde).
(b) Compliance dates. (1) CWSs and NTNCWSs. Unless otherwise noted,
compliance with the requirements of this subpart shall begin as
follows: Subpart H systems serving 10,000 or more persons must comply
with this subpart beginning [insert date 18 months after date of
publication of the final rule in the Federal Register]. Subpart H
systems serving fewer than 10,000 persons or systems using only ground
water not under the direct influence of surface water serving 10,000 or
more persons must comply with this subpart beginning [insert date 42
months after date of publication of the final rule in the Federal
Register]. Systems using only ground water not under the direct
influence of surface water serving fewer than 10,000 persons must
comply with this subpart beginning [insert date 60 months after date of
publication of the final rule in the Federal Register].
(2) Transient NCWSs. Subpart H systems serving 10,000 or more
persons and using chlorine dioxide as a disinfectant or oxidant must
comply with any requirements for chlorine dioxide in this subpart
beginning [insert date 18 months after date of publication of the final
rule in the Federal Register]. Subpart H systems serving fewer than
10,000 persons and using chlorine dioxide as a disinfectant or oxidant
or systems using only ground water not under the direct influence of
surface water serving 10,000 or more persons and using chlorine dioxide
as a disinfectant or oxidant must comply with any requirements for
chlorine dioxide in this subpart beginning [insert date 42 months after
date of publication of the final rule in the Federal Register]. Systems
using only ground water not under the direct influence of surface water
and serving fewer than 10,000 persons and using chlorine dioxide as a
disinfectant or oxidant must comply with any requirements for chlorine
dioxide in this subpart beginning [insert date 60 months after date of
publication of the final rule in the Federal Register].
(c) Each CWS and NTNCWS regulated under paragraph (a) of this
section must be operated by qualified personnel who meet the
requirements specified by the State and are included in a State
register of qualified operators.
(d) Control of Disinfection Byproducts. (1) All CWS and NTNCWS must
comply with MCLs in Sec. 141.64.
(2) All CWS and NTNCWS must comply with monitoring requirements in
Sec. 141.133.
(e) Control of Disinfectant Residuals. (1) All CWS and NTNCWS must
comply with MRDLs in Sec. 141.65. All transient NCWSs that use chlorine
dioxide as a disinfectant or oxidant must comply with the chlorine
dioxide MRDL in Sec. 141.65.
(2) All CWS and NTNCWS must comply with monitoring requirements in
Sec. 141.133. All transient NCWSs that use chlorine dioxide as a
disinfectant or oxidant must comply with the chlorine dioxide
monitoring requirements in Sec. 141.133.
(3) Not withstanding the MRDLs in Sec. 141.65, systems may increase
residual disinfectant levels in the distribution system of chlorine or
chloramines (but not chlorine dioxide) to a level and for a time
necessary to protect public health, to address specific microbiological
contamination problems caused by circumstances such as, but not limited
to, distribution line breaks, storm run-off events, source water
contamination, or cross-connections.

Secs. 141.131-141.132 [Reserved]

Sec. 141.133 Analytical and monitoring requirements.

(a) Analytical Requirements. Only the analytical method(s)
specified in this paragraph (a), or otherwise approved by EPA, may be
used to demonstrate compliance with the requirements of this subpart.
These methods are effective for compliance monitoring [insert date 30
days after date of publication of the final rule in the Federal
Register].
(1) Disinfection Byproducts. (i) Disinfection byproducts must be
measured by the methods listed below:

Approved Methods for Disinfection Byproduct Compliance Monitoring

Methodology\2\
-------------------------------------------------------------
Byproduct measured\1\ EPA
method\3\ TTHMs\4\ HAA5\5\ Chlorite Bromate

P&T/GC/ElCD & PID................................. 502.2\6\ X
P&T/GC/MS......................................... 524.2 X
LLE/GC/ECD........................................ 551 X
LLE/GC/ECD........................................ \7\6233 B .......... X
SPE/GC/ECD........................................ 552.1 .......... X

IC................................................ 300.0 .......... .......... X X

\1\X indicates method is approved for measuring specified disinfection byproduct.

\2\P&T=purge and trap; GC=gas chromatography; ElCD=electrolytic conductivity detector; PID=photoionization
detector; MS=mass spectrometer; LLE=liquid/liquid extraction; ECD=electron capture detector; SPE=solid phase

extractor; IC=ion chromatography

\3\As set forth in Methods for the Determination of Organic Compounds in Drinking Water, USEPA, 1988 (revised
July 1991) (available through National Technical Information Service (NTIS), EPA/600/4-88/039, PB91-231480)
for Method 502.2; Methods for the Determination of Organic Compounds in Drinking Water-Supplement II, USEPA,
1992, (available through NTIS, EPA/600/R-92/129, PB92-207703), for Methods 524.2 and 552.1; Methods for the
Determination of Organic Compounds in Drinking Water-Supplement I, USEPA, July 1990 (available through
National Technical Information Service (NTIS), EPA/600/4-90/020, PB91-146027) for Method 551; and Methods for
the Determination of Inorganic Substances in Environmental Samples, EPA/600/R/93/100--August 1993 for Method

300.0.
\4\Total trihalomethanes.
\5\Total haloacetic acids.
\6\If TTHMs are the only analytes being measured in the sample, then a PID is not required.

\7\Method 6233 B, as set forth in Standard Methods for the Examination of Water and Wastewater, 1992 (18th Ed.),

American Public Health Association et al.

(ii) Analysis under this section for disinfection byproducts shall
be conducted by laboratories that have received certification by EPA or
the State after meeting the following conditions. To receive
certification to conduct analyses for the contaminants in
Sec. 141.64(a) (1) through (4), the laboratory must: annually analyze
performance evaluation (PE) samples provided by EPA Environmental
Monitoring Systems Laboratory or equivalent State samples, and achieve
quantitative results on a minimum of 80% of the analytes included in
each PE sample. The acceptance limit is defined as the 95% confidence
interval calculated around the mean of the PE study data between a
maximum and minimum acceptance limit of +/-50% and +/-15% of the study
mean.
(2)(i) Disinfectant Residuals. Residual disinfectant concentrations
for free chlorine, combined chlorine (chloramines), and chlorine
dioxide must be measured by the methods listed below:

Approved Methods for Disinfectant Residual Compliance Monitoring

Residual measured\1\
-------------------------------------------------------------------------
Methodology Standard Free Combined Total Chlorine
method\2\ chlorine chlorine chlorine dioxide

Amperometric Titration................ 4500-Cl D X X X ............
Amperometric Titration................ 4500-Cl E ............ ............ X ............
DPD Ferrous Titrimetric............... 4500-Cl F X X X ............
DPD Colorimetric...................... 4500-Cl G X X X ............
Syringaldazine (FACTS)................ 4500-Cl H X ............ ............ ............
Iodometric Electrode.................. 4500-Cl I ............ ............ X ............
Amperometric Titration................ 4500-ClO<INF>2 C ........<INF>.... ........<INF>.... ........<INF>.... X
DPD Method............................ 4500-ClO<INF>2 D ........<INF>.... ........<INF>.... ........<INF>.... X
Amperometric Titration (proposed)..... 4500-ClO<INF>2 E ........<INF>.... ........<INF>.... ........<INF>.... X

\1\X indicates method is approved for measuring specified disinfectant residual.

\2\As set forth in Standard Methods for the Examination of Water and Wastewater, 1992 (18th Ed.), American

Public Health Association et al.

(ii) Residual disinfectant concentrations for chlorine and
chloramines may also be measured by using DPD colorimetric test kits if
approved by the State. Measurement for residual disinfectant
concentration must be conducted by a party approved by EPA or the
State.
(3) Additional Analytical Methods. Systems required to analyze
parameters not included in paragraphs (a)(1) and (2) of this section
shall use the following methods. Measurement for these parameters must
be conducted by a party approved by EPA or the State.
(i) Alkalinity. All methods allowed in Sec. 141.89(a) for measuring
alkalinity.
(ii) Bromide. EPA method 300.0.
(iii) Total Organic Carbon-Method 5310 C (Persulfate-ultraviolet
Oxidation Method) or Method 5310 D (Wet-oxidation Method) as set forth
in Standard Methods for the Examination of Water and Wastewater, 1992
(18th Ed.), American Public Health Association et al. Samples shall not
be filtered prior to this analysis. For compliance monitoring, TOC and
not dissolved organic carbon (DOC) data are required.
(b) Routine monitoring requirements for disinfection byproducts,
disinfectant residuals, and total organic carbon. All samples must be
taken during normal operating conditions. Failure to monitor in
accordance with the monitoring plan required under the provisions of
Sec. 141.133(d) is a monitoring violation. Where compliance is based on
a running annual average of monthly or quarterly samples or averages
and the system's failure to monitor makes it impossible to determine
compliance with MCLs or MRDLs, this failure to monitor will be treated
as a violation for the entire period covered by the annual average.
(1) Disinfection byproducts. (i) TTHMs and HAA5. (A) Subpart H
systems serving 10,000 or more persons shall take four water samples
each quarter for each treatment plant in the system. At least 25
percent of all samples collected each quarter, including those samples
taken in excess of the required frequency, shall be taken at locations
within the distribution system that represent the maximum residence
time of the water in the system. The remaining samples shall be taken
at locations within the distribution system that represent the entire
system, taking into account the number of persons served, different
sources of water, and different treatment methods employed.
(B) Systems using only ground water sources not under the direct
influence of surface water that use a chemical disinfectant and serve
10,000 or more persons shall take one water sample each quarter for
each treatment plant in the system. Samples shall be taken at locations
within the distribution system that represent the maximum residence
time of the water in the system. At least 25 percent of all samples
collected each quarter, if samples are taken in excess of the required
frequency, shall be taken at locations within the distribution system
that represent the maximum residence time of the water in the system.
The remaining samples must be taken at locations representative of at
least average residence time in the distribution system. Multiple wells
within a system drawing water from a single aquifer shall, with State
approval in accordance with criteria developed under Sec. 142.16(f)(6),
be considered one treatment plant for determining the minimum number of
samples required.
(C) Subpart H systems serving from 500 to 9,999 persons shall take
one water sample each quarter for each treatment plant in the system.
Samples shall be taken at a point in the distribution system that
represents the maximum residence time in the distribution system. At
least 25 percent of all samples collected each quarter, if samples are
taken in excess of the required frequency, shall be taken at locations
within the distribution system that represent the maximum residence
time of the water in the system. The remaining samples must be taken at
locations representative of at least average residence time in the
distribution system.
(D) Subpart H systems serving fewer than 500 persons shall take one
sample per year for each treatment plant in the system. Samples shall
be taken at a point in the distribution system reflecting the maximum
residence time in the distribution system and during the month of
warmest water temperature. If the sample (or average of the annual
samples, if more than one sample is taken) exceeds the MCL, the system
must increase monitoring to one sample per treatment plant per quarter,
taken at a point in the distribution system reflecting the maximum
residence time in the distribution system, until the system meets
criteria in paragraph (c) of this section for reduced monitoring.
(E) Systems using only ground water sources not under the direct
influence of surface water that use a chemical disinfectant and serve
less than 10,000 persons shall sample once per year for each treatment
plant in the system. Samples shall be taken at a point in the
distribution system reflecting the maximum residence time in the
distribution system and during the month of warmest water temperature.
If the sample (or the average of the annual samples, when more than one
sample is taken) exceeds the MCL, the system must increase monitoring
to one sample per treatment plant per quarter, taken at a point in the
distribution system reflecting the maximum residence time in the
distribution system, until the system meets criteria in paragraph (c)
of this section for reduced sampling. Multiple wells drawing water from
a single aquifer shall, with State approval in accordance with criteria
developed under Sec. 142.16(f)(6), be considered one treatment plant
for determining the minimum number of samples required.
(ii) Chlorite. Community and nontransient noncommunity water
systems using chlorine dioxide, for disinfection or oxidation, shall
take three samples each month in the distribution system. One sample
must be taken at each of the following locations: near the first
customer, in a location representative of average residence time, and
near the end of the distribution system (reflecting maximum residence
time in the distribution system). Any additional sampling must be
conducted in the same manner (i.e., three-sample sets, at the specified
locations).
(iii) Bromate. Community and nontransient noncommunity systems
using ozone, for disinfection or oxidation, shall take one sample per
month for each treatment plant in the system using ozone. Samples must
be taken monthly at the entrance to the distribution system while the
ozonation system is operating under normal conditions.
(iv) Compliance. (A) TTHMs and HAA5. For systems monitoring
quarterly, compliance with MCLs in Sec. 141.64 shall be based on a
running annual arithmetic average, computed quarterly, of quarterly
arithmetic averages of all samples collected by the system as
prescribed by this section under paragraphs (b)(1)(i)(A), (B), and (C)
of this section. If the arithmetic average of quarterly averages
covering any consecutive four-quarter period exceeds the MCL, the
supplier of water shall report to the State pursuant to Sec. 141.134
and notify the public pursuant to Sec. 141.32. Systems on a reduced
monitoring schedule whose annual average exceeds the MCL will revert to
routine monitoring immediately. For systems monitoring less frequently
than quarterly, compliance shall be based on an average of samples
taken that year under the provisions of Sec. 141.133(b)(1)(i)(D)
through (E) or Sec. 141.133(c)(1)(iii)(C). If the average of these
samples exceeds the MCL, the system must increase monitoring to once
per quarter per treatment plant. All samples taken and analyzed under
the provisions of this section must be included in determining
compliance, even if that number is greater than the minimum required.
If, during the first year following the effective date, any individual
quarter's average will cause the running annual average of that system
to exceed the MCL, the system is out of compliance at the end of that
quarter.
(B) Bromate. Compliance shall be based on a running annual
arithmetic average, computed quarterly, of monthly samples (or, for
months in which the system takes more than one sample, the average of
all samples taken during the month) collected by the system as
prescribed by paragraph (b)(1)(iii) of this section. If the average of
samples covering any consecutive four-quarter period exceeds the MCL,
the system shall report to the State pursuant to Sec. 141.134 and
notify the public pursuant to Sec. 141.32. If a PWS fails to complete
12 consecutive months' monitoring, compliance with the MCL for the last
four-quarter compliance period shall be based on an average of the
available data.
(C) Chlorite. Compliance shall be based on a monthly arithmetic
average of samples as prescribed by paragraph (b)(1)(ii) of this
section. If the arithmetic average of samples covering any month
exceeds the MCL, the system shall report to the State pursuant to
Sec. 141.134 and notify the public pursuant to Sec. 141.32.
(2) Disinfectant residuals. (i) Chlorine and chloramines. (A)
Subpart H systems must measure the residual disinfectant level at the
same points in the distribution system and at the same time as total
coliforms are sampled, as specified in Sec. 141.21. Systems may use the
results of residual disinfectant concentration sampling conducted under
Sec. 141.74(b)(6)(i) for unfiltered systems or Sec. 141.74(c)(3)(i) for
systems which filter, in lieu of taking separate samples.
(B) Community and nontransient noncommunity systems using only
ground water not under the direct influence of surface water must
measure the residual disinfectant level at the same points in the
distribution system and at the same time as total coliforms are
sampled, as specified in Sec. 141.21.
(ii) Chlorine Dioxide. (A) Routine Monitoring. Community,
nontransient noncommunity, and transient noncommunity water systems
must monitor for chlorine dioxide only if chlorine dioxide is used by
the system for disinfection or oxidation. If monitoring is required,
systems shall take daily samples at the entrance to the distribution
system. For any daily sample that exceeds the MRDL, the system is
required to take samples in the distribution system the following day
at the locations required by paragraph (b)(2)(ii)(B) of this section,
in addition to the sample required at the entrance to the distribution
system.
(B) Additional Distribution System Monitoring. On each day
following a routine sample monitoring result that exceeds the MRDL, the
system is required to take three chlorine dioxide distribution system
samples.
(1) If chlorine dioxide or chloramines are used to maintain a
disinfectant residual in the distribution system, or if chlorine is
used to maintain a disinfectant residual in the distribution system and
there are no disinfection addition points after the entrance to the
distribution system (i.e., no booster chlorination), three samples
shall be taken as close to the first customer as possible at intervals
of at least six hours.
(2) If chlorine is used to maintain a disinfectant residual in the
distribution system and there are one or more disinfection addition
points after the entrance to the distribution system (i.e., booster
chlorination), one sample shall be taken at each of the following
locations: as close to the first customer as possible, in a location
representative of average residence time, and as close to the end of
the distribution system as possible (reflecting maximum residence time
in the distribution system).
(C) CT credit prior to enhanced coagulation or enhanced softening.
Subpart H systems required to operate enhanced coagulation or enhanced
softening under the provisions of Sec. 141.135 may receive credit for
compliance with CT requirements specified by the State if the following
monitoring is completed and the criteria in Sec. 141.135(a)(2)(i)(B)(3)
are met.
(1) For each chlorine dioxide generator, the system must
demonstrate that the generator is achieving at least 95 percent
chlorine dioxide yield and producing no more than five percent chlorine
by measuring a minimum of once per week. Measurements shall be
conducted by using Standard Method 4500-ClO<INF>22 E. Chlorine dioxide
yield and chlorine presence shall be measured as described in Aieta et
al, Journal AWWA, 76:1, pp.66 and 67, respectively. Guidance on
generator effluent sampling, safety, dilutions, replication, and the
measurement of these and related species may be found in [cite Hoehn's
upcoming AWWARF report] and in Aieta et al, Journal AWWA, 76:1, pp.64
through 70, as noted.
(2) On any day that a generator fails to achieve at least 95
percent chlorine dioxide yield and no more than five percent chlorine,
and on subsequent days until these conditions are achieved, the system
may not receive credit for compliance with CT requirements in subpart H
of this part.
(3) On any day that a generator fails to achieve at least 95
percent chlorine dioxide yield but achieves at least 90 percent
conversion efficiency and/or produces more than five percent chlorine
but less than 10 percent, the system may take immediate corrective
action to achieve a minimum of 95 percent chlorine yield and a maximum
of five percent chlorine. If subsequent measurements conducted on the
same day demonstrate at least 95 percent chlorine dioxide yield and no
more than five percent chlorine, the system may receive credit for
compliance with CT requirements in subpart H of this part on that day.
If the generator continues to fail to demonstrate at least 95 percent
chlorine dioxide yield and no more than five percent chlorine, the
system may not receive credit for compliance with CT requirements in
subpart H of this part on that day.
(4) After achieving the conditions in paragraph (b)(2)(ii)(C)(1) of
this section, the system may operate no more than one week without
measurement. If however, in the interim, the system changes generator
operating conditions (e.g., changes chlorine dioxide dose, changes
conditions to match changing plant flow rate) or generator conditions
(e.g., a new batch of sodium chlorite or a different ratio of chlorite
to chlorine or acid is used), the system shall remeasure for chlorine
dioxide yield and chlorine presence and meet the conditions in
paragraphs (b)(2)(ii)(C)(1) or (3) of this section to receive CT
credit.
(iii) Compliance. (A) Chlorine and chloramines. (1) Compliance
shall be based on a running annual arithmetic average, computed
quarterly, of quarterly averages of all samples collected by the system
as prescribed in this section. If the average of quarterly averages
covering any consecutive four-quarter period exceeds the MRDL, the
system shall report to the State pursuant to Sec. 141.134 and notify
the public pursuant to Sec. 141.32.
(2) In cases where systems switch between the use of chlorine and
chloramines for residual disinfection during the year, compliance shall
be determined by including together all monitoring results of both
chlorine and chloramines in calculating compliance pursuant to
paragraph (b)(2)(iii)(C)(1) of this section. Reports submitted pursuant
to Sec. 141.134 will clearly indicate which residual disinfectant was
analyzed for each sample.
(B) Chlorine dioxide. (1) Acute violations. Compliance shall be
based on consecutive daily samples collected by the system as
prescribed in this section. If any daily sample taken at the entrance
to the distribution system exceeds the MRDL, and on the following day
one (or more) of the three samples taken in the distribution system
exceed the MRDL, the system will be in violation of the MRDL and shall
take immediate corrective action to lower the level of chlorine dioxide
below the MRDL and will notify the public pursuant to the procedures
for acute health risks in Sec. 141.32(a)(1)(iii)(E). Failure to take
samples in the distribution system the day following an exceedance of
the chlorine dioxide MRDL at the entrance to the distribution system
shall also be considered an MRDL violation and the system shall notify
the public of the violation in accordance with the provisions for acute
violations under Sec. 141.32(a)(1)(iii)(E).
(2) Nonacute violations. Compliance shall be based on consecutive
daily samples collected by the system as prescribed in this section. If
any two consecutive daily samples taken at the entrance to the
distribution system exceed the MRDL and all distribution system samples
taken are below the MRDL, the system will be in violation of an MRDL
and shall take corrective action to lower the level of chlorine dioxide
below the MRDL at the point of sampling and will notify the public
pursuant to the procedures for nonacute health risks in Sec. 141.32.
Failure to monitor at the entrance to the distribution system the day
following an exceedance of the chlorine dioxide MRDL at the entrance to
the distribution system shall also be considered an MRDL violation and
the system shall notify the public of the violation in accordance with
the provisions for nonacute violations under Sec. 141.32.
(3) Disinfection Byproduct Precursors (DBPP). (i) Subpart H
systems. Community and nontransient noncommunity systems which use
conventional filtration treatment (as defined in Sec. 141.2) must
monitor each treatment plant water source for TOC prior to any
continuous disinfection treatment; except that systems using ozone
followed by biologically active filtration (as defined in Sec. 141.2)
may measure TOC in the treated water following biological filtration
but before the addition of a residual disinfectant and systems using
chlorine dioxide that meet the standards for including CT credit for
its use prior to enhanced coagulation or enhanced softening contained
in Sec. 141.135(a)(2)(i)(B)(3) or Sec. 141.135(a)(2)(ii)(B)(3) may
measure TOC in the treated water at any point prior to the continuous
addition of any other disinfectant. All systems required to monitor
under paragraph (b)(3) of this section must also monitor for TOC in the
source water prior to any treatment at the same time as monitoring for
TOC in the treated water. These samples (source water and treated
water, prior to disinfection) are referred to as paired samples. At the
same time as the source water sample is taken, all systems must monitor
for alkalinity in the source water prior to any treatment.
(ii) Frequency. All systems required to monitor under paragraph
(b)(3)(i) of this section must take one paired sample per month per
plant at a time representative of normal operating conditions and
influent water quality. At the same time, the system must take a source
water alkalinity sample in order to make the appropriate calculations
required to comply with Sec. 141.135.
(iii) Compliance. Compliance shall be determined as specified by
Sec. 141.135(b). Systems may begin monitoring to determine whether Step
1 TOC removals can be met 12 months prior to the compliance date for
the system. This monitoring is not required and failure to monitor
during this period is not a violation. However, any system that: Does
not monitor during this period, and then determines in the first 12
months after the compliance date that it is not able to meet the Step 1
requirements in Sec. 141.135(a)(2) and must therefore apply for
alternate performance criteria, is not eligible for retroactive
approval of alternate performance criteria as allowed pursuant to
Sec. 141.135(a)(3). Systems may apply for alternate performance
criteria any time after the compliance date.
(c) Reduced monitoring requirements for disinfection byproducts,
disinfectant residuals, and total organic carbon. Systems may reduce
monitoring, except as otherwise provided, in accordance with the
following.
(1) Disinfection byproducts. (i) Chlorite. Systems required to
analyze for chlorite may not reduce monitoring.
(ii) Bromate. Systems required to analyze for bromate may reduce
monitoring from monthly to once per quarter, if the system demonstrates
that the average raw water bromide concentration is less than 0.05 mg/l
based upon representative monthly measurements for one year.
(iii) TTHMs and HAA5. (A) Any Subpart H system which has a source
water TOC level, before any treatment, of greater than 4.0 mg/l may not
reduce its monitoring.
(B) Systems may reduce monitoring if they have a running annual
average for TTHMs and HAA5 that is no more than 0.040 mg/l and 0.030
mg/l, respectively, with the following exceptions. Systems using ground
water not under the direct influence of surface water that serve fewer
than 10,000 persons and are required to take only one sample per year
may reduce monitoring if either: the average of two consecutive
representative annual samples is no more than 0.040 mg/l and 0.030 mg/l
for TTHMs and HAA5, respectively, or any representative annual sample
is less than 0.020 mg/l and 0.015 mg/l for TTHMs and HAA5,
respectively. Systems using surface water or ground water under the
direct influence of surface water in whole or in part that serve fewer
than 500 persons may not reduce their monitoring to less than one
sample per year. Systems must meet the requirements for reduction of
monitoring for both TTHMs and HAA5 to qualify for reduced monitoring.
The system may reduce monitoring only after the system has completed at
least one year of monitoring in accordance with paragraph (b)(1)(i) of
this section.
(C) Reduced monitoring frequency. (1) Subpart H systems serving
10,000 persons or more that are eligible for reduced monitoring in
paragraph (c)(1)(iii)(B) of this section may reduce the monitoring
frequency for TTHMs and HAA5 to one sample per quarter per treatment
plant. Samples shall be taken at a point in the distribution system
reflecting the maximum residence time in the distribution system.
(2) Systems using only ground water not under the direct influence
of surface water and serving 10,000 persons or more that are eligible
for reduced monitoring in paragraph (c)(1)(iii)(B) of this section may
reduce the monitoring frequency for TTHMs and HAA5 to one sample per
year per treatment plant. Samples shall be taken at a point in the
distribution system reflecting the maximum residence time in the
distribution system and during the month of warmest water temperature.
(3) Subpart H systems serving between 500 to 9,999 persons that are
eligible for reduced monitoring may reduce the monitoring frequency for
TTHMs and HAA5 to one sample per year per treatment plant. Samples
shall be taken at a point in the distribution system reflecting the
maximum residence time in the distribution system and during the month
of warmest water temperature.
(4) Systems using only ground water sources not under the direct
influence of surface water and serving fewer than 10,000 persons, may
reduce the monitoring frequency for TTHMs and HAA5 to one sample per
three year monitoring cycle, with this three-year cycle beginning on
the January 1 following the quarter in which the system qualifies for
reduced monitoring. Samples shall be taken at a point in the
distribution system reflecting the maximum residence time in the
distribution system and during the month of warmest water temperature.
(D) Systems on a reduced monitoring schedule may remain on that
reduced schedule as long as the average of all samples taken in the
year (for systems which must monitor quarterly) or the result of the
sample (for systems which must monitor no more frequently than
annually) is no more than 0.060 mg/l and 0.045 mg/l for TTHMs and HAA5,
respectively. Systems that do not meet these levels must resume
monitoring at the frequency identified in Sec. 141.133(b)(1) in the
quarter immediately following the quarter in which the system exceeded
75 percent of either MCL.
(E) The State may return a system to routine monitoring at the
State's discretion.
(2) Disinfectant residuals. Monitoring for disinfectant residuals
may not be reduced.
(3) TOC. Subpart H systems with a treated water TOC of less than
2.0 mg/l for two consecutive years, or less than 1.0 mg/l for one year,
may reduce monitoring for both TOC and alkalinity to one paired sample
per plant per quarter.
(d) Monitoring plans. (1) Each system required to monitor under
this subpart must develop and implement a monitoring plan. The system
shall maintain the plan and make it available for inspection by the
State and the general public no later than 30 days following the
applicable effective dates in Sec. 141.130(b). All Subpart H systems
serving more than 3300 people shall submit a copy of the monitoring
plan to the State no later than the date of the first report required
under Sec. 141.134. The State may also require the plan to be submitted
by any other system. The plan must include at least the following
elements.
(i) Locations for collecting samples for any parameters included in
this subpart.
(ii) How the system will calculate compliance with MCLs and MRDLs.
(2) After review, the State may require changes in any plan
elements.

Sec. 141.134 Reporting and recordkeeping requirements.

(a) Systems required to sample quarterly or more frequently must
report to the State within 10 days after the end of each quarter in
which samples were collected. Systems required to sample less
frequently than quarterly must report to the State within 10 days after
the end of each monitoring period in which samples were collected.
(b) Systems required to monitor for the following compounds must
report the following information.
(1) TTHMs and HAA5.
(i) Systems monitoring for TTHMs and HAA5 under the requirements of
Secs. 141.133(b) or (c) on a quarterly or more frequent basis must
report at least the following information. The State may choose to
perform paragraphs (b)(1)(i)(C) through (E) of this section in lieu of
having the system report that information.
(A) the number of samples taken during the last quarter,
(B) the location, date, and result of each sample taken during the
last quarter,
(C) the arithmetic average of all samples taken in the last
quarter,
(D) the arithmetic average of the arithmetic averages reported
under paragraph (b)(1)(i)(C) of this section for the last four
quarters, and
(E) whether the MCL was exceeded.
(ii) Systems monitoring for TTHMs and HAA5 under the requirements
of Sec. 141.133(b) or (c) less frequently than quarterly (but at least
annually) must report at least the following information. The State may
choose to perform paragraphs (b)(1)(ii)(C) through (D) of this section
in lieu of having the system report that information.
(A) the number of samples taken during the last year,
(B) the location, date, and result of each sample taken during the
last quarter,
(C) the arithmetic average of all samples taken over the last year,
and
(D) whether the MCL was exceeded.
(iii) Systems monitoring for TTHMs and HAA5 under the requirements
of Sec. 141.133(c) less frequently than annually must report at least
the following information:
(A) the location, date, and result of the last sample taken, and
(B) whether the MCL was exceeded.
(2) Systems monitoring for chlorite under the requirements of
Sec. 141.133(b) must report at least the following information. The
State may choose to perform paragraphs (b)(2)(iii) through (iv) of this
section in lieu of having the system report that information.
(i) the number of samples taken each month for the last 3 months,
(ii) the location, date, and result of each sample taken during the
last quarter,
(iii) for each month in the reporting period, the arithmetic
average of all samples taken in the month, and
(iv) whether the MCL was exceeded, and which month it was exceeded.
(3) Systems monitoring for bromate under the requirements of
Sec. 141.133(b) or (c) must report at least the following information.
The State may choose to perform paragraphs (b)(3)(iii) through (iv) of
this section in lieu of having the system report that information.
(i) the number of samples taken during the last quarter,
(ii) the location, date, and result of each sample taken during the
last quarter,
(iii) the arithmetic average of the monthly arithmetic averages of
all samples taken in the last year, and
(iv) whether the MCL was exceeded.
(4) Systems monitoring for chlorine or chloramines under the
requirements of Sec. 141.133(b) must report at least the following
information:
(i) the number of samples taken during each month of the last
quarter,
(ii) the monthly arithmetic average of all samples taken in each
month for the last 12 months, and
(iii) the arithmetic average of all monthly averages for the last
12 months, and
(iv) whether the MRDL was exceeded.
(5) Systems monitoring for chlorine dioxide under the requirements
of Sec. 141.133(b) must report at least the following information:
(i) the dates, results, and locations of samples taken during the
last quarter,
(ii) whether the MRDL was exceeded, and
(iii) whether the MRDL was exceeded in any two consecutive daily
samples and whether the resulting violation was acute or nonacute.
(6) Disinfection Byproduct Precursors and enhanced coagulation or
enhanced softening.
(i) Reports from systems monitoring monthly or quarterly for TOC
under the requirements of Sec. 141.133(b)(3) and required to meet the
enhanced coagulation or enhanced softening requirements in Sec. 141.135
(a)(2) or (a)(3) must include at least the following information. The
State may choose to perform paragraphs (b)(6)(i) (C) through (E) of
this section in lieu of having the system report that information.
(A) the number of paired (raw water and treated water, prior to
continuous disinfection) samples taken during the last quarter,
(B) the location, date, and result of each paired sample taken
during the last quarter and the associated source water alkalinity,
(C) for each month in the reporting period that paired samples were
taken, the arithmetic average of the percent reduction of TOC for each
paired sample and the required TOC percent removal,
(D) calculations for determining compliance with the TOC percent
removal requirements, as provided in Sec. 141.135(b)(1), and
(E) whether the system is in compliance with the enhanced
coagulation or enhanced softening percent removal requirements in
Sec. 141.135(a) for the last four quarters.
(ii) Systems monitoring monthly or quarterly for TOC under the
requirements of Sec. 141.133(b) and meeting one or more of the criteria
in Sec. 141.135(a)(1) for avoiding the requirement for enhanced
coagulation and enhanced softening must report at least the following
information. The State may choose to perform paragraphs (b)(6)(ii) (D)
through (I) of this section in lieu of having the system report that
information.
(A) the criterion that the system is using to avoid enhanced
coagulation or enhanced softening,
(B) the number of paired samples taken during the last quarter,
(C) the location, date and result of each sample (identified as
either source water or treated water) taken during the last quarter,
(D) the monthly arithmetic average (or quarterly sample result) of
all treated water samples taken in the quarter and the running annual
arithmetic average based on monthly averages (or quarterly samples)
(for systems meeting the criterion in Sec. 141.135(a)(1)(i) for
avoiding enhanced coagulation or enhanced softening),
(E) the monthly arithmetic average of all treated water samples
taken for each month of the quarter, the quarterly average of the
monthly averages, and the running annual average of the quarterly
averages (for systems meeting the criterion in Sec. 141.135(a)(1)(ii)
for avoiding enhanced coagulation or enhanced softening),
(F) the running annual average of alkalinity of the source water
(for systems meeting the criterion in Sec. 141.135(a)(1)(ii) for
avoiding enhanced coagulation or enhanced softening),
(G) the running annual average for both TTHMs and THAAs (for
systems meeting the criterion in Sec. 141.135(a)(1) (ii) or (iii) for
avoiding enhanced coagulation or enhanced softening),
(H) the running annual average of the amount of magnesium hardness
removal (in mg/l) (for systems meeting the criterion in
Sec. 141.135(a)(1)(iv) for avoiding enhanced coagulation or enhanced
softening),
(I) whether the system is in compliance with the particular
criterion in Sec. 141.135(a)(1) (i) through (iv) that the system is
using to avoid enhanced coagulation or enhanced softening.

Sec. 141.135 Treatment technique for control of Disinfection Byproduct
Precursors (DBP).

(a)(1) Subpart H systems using conventional filtration treatment
(as defined in Sec. 141.2) must operate with enhanced coagulation or
enhanced softening to achieve the TOC percent removal levels specified
in this section unless the system meets at least one of the criteria
listed in paragraphs (a)(1)(i) through (iv) of this section:
(i) The system's treated TOC level, measured according to
Sec. 141.133(b)(3), is less than 2.0 mg/l, calculated quarterly as a
running annual average.
(ii) The system's source water TOC level, measured as required by
Sec. 141.133(b)(3), is less than 4.0 mg/l, calculated quarterly as a
running annual average; the source water alkalinity, measured according
to Sec. 141.133(a)(4), is greater than 60 mg/l, calculated quarterly as
a running annual average; and, prior to the effective date for
compliance in Sec. 141.130, either the TTHM and HAA5 running annual
averages are no greater than 0.040 mg/l and 0.030 mg/l, respectively,
or the system has made a clear and irrevocable financial commitment not
later than the effective date for compliance in Sec. 141.30(b) to use
of technologies that will limit the levels of TTHMs and HAA5 to no more
than 0.040 mg/l and 0.030 mg/l, respectively. Systems must submit
evidence of a clear and irrevocable financial commitment, in addition
to a schedule containing milestones and periodic progress reports for
installation and operation of appropriate technologies, to the State
for approval not later than the effective date for compliance in
Sec. 141.30(b) of this part. These technologies must be installed and
operating not later than the effective date for Stage 2 of the
Disinfectant/Disinfection Byproduct Rule. Violation of the approved
schedule will constitute a violation of the National Primary Drinking
Water Regulation.
(iii) The TTHM and HAA5 running annual averages are no greater than
0.040 mg/l and 0.030 mg/l, respectively, and the system uses only
chlorine for disinfection.
(iv) Systems practicing softening and removing at least 10 mg/l of
magnesium hardness (as CaCO<INF>3), calculated quarterly as a running
annual average, except those that use ion exchange, are not subject to
performance criteria for the removal of TOC.
(2) Enhanced coagulation performance requirements.
(i) Systems not practicing softening. (A) Systems (except those
noted in paragraph (a)(2)(i)(D) of this section) must achieve the
percent reduction of TOC specified in paragraph (a)(2)(i)(E) of this
section between the raw water source and the treated water prior to
continuous disinfection, unless the State approves a system's request
for alternative performance standards under paragraph (a)(3) of this
section. Continuous disinfection is defined as the continuous addition
of a chemical disinfectant for the purposes of achieving a level of
inactivation credit to meet the minimum inactivation/removal treatment
requirements of subpart H of this part.
(B) Continuous disinfection does not include: the addition of a
chemical disinfectant for filter maintenance (when applied
intermittently), or the use of a disinfectant (other than provided for
in paragraph (a)(2)(i)(C) of this section) as an oxidant for the
purposes of controlling water quality problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams, taste, and odor. In determining
compliance with the CT requirements specified by the State, the system
shall not include any credit for disinfectants used either for filter
maintenance or for controlling water quality problems except as allowed
below in paragraphs (a)(2)(i)(B)(1) through (4) of this section.
(1) Systems may include CT credit during periods when the water
temperature is below 5 deg.C and the TTHM and HAA5 quarterly averages
are no greater than 0.040 mg/l and 0.030
mg/l, respectively.
(2) Systems receiving disinfected water from a separate entity as
their source water shall be allowed to include credit for this
disinfectant in determining compliance with the CT requirements. If the
TTHM and HAA5 quarterly averages are no greater than 0.040 mg/l and
0.030 mg/l, respectively, systems may use the measured ``C'' (residual
disinfectant concentration) and the actual contact time (as T<INF>10).
If either the TTHM or HAA5 quarterly average is greater than 0.040 mg/l
or 0.030 mg/l, respectively, systems must use a ``C'' (residual
disinfectant concentration) of 0.2 mg/l or the measured value,
whichever is lower; and the actual contact time (as T<INF>10). This
credit shall be allowed from the disinfection feedpoint, through a
closed conduit only, and ending at the delivery point to the treatment
plant.
(3) Systems using chlorine dioxide as an oxidant or disinfectant
may include CT credit for its use prior to enhanced coagulation or
enhanced softening if the following standards are met: the chlorine
dioxide generator must generate chlorine dioxide on-site and minimize
the production of chlorine as shown by complying with monitoring and
performance standards in Sec. 141.133(b)(2)(ii)(C).
(4) Systems using ozone and biologically active filtration may
include CT credit for its use prior to enhanced coagulation or enhanced
softening.
(C) Systems not required to operate with enhanced coagulation may
continue to include, in compliance calculations, continuous addition of
a chemical disinfectant for the purposes of achieving a level of
inactivation credit to meet the minimum inactivation/removal treatment
requirements of subpart H of this part, even when such addition is also
made for the purpose of controlling water quality problems.
(D) Systems using ozone and biologically active filtration must
achieve the TOC percent reduction specified in paragraph (a)(2)(i)(E)
of this section before the addition of a residual disinfectant. Systems
using chlorine dioxide that meet the requirements for including CT
credit specified in paragraph (a)(2)(i)(B)(3) of this section must
achieve the TOC percent reduction specified in paragraph (a)(2)(i)(E)
of this section before the addition of a residual disinfectant.
(E) Required TOC reductions, indicated in the table below, are
based upon specified source water parameters measured in accordance
with Sec. 141.133(b)(3).

Required Removal of TOC by Enhanced Coagulation for Subpart H Systems

Using Conventional Treatment\2\

Source water alkalinity (mg/l)
--------------------------------
Source water total organic carbon (mg/ >120\1\
l) 0-60 >60-120 (percent)
(percent) (percent)

>2.0-4.0............................... 40.0 30.0 20.0
>4.0-8.0............................... 45.0 35.0 25.0
>8.0................................... 50.0 40.0 30.0

\1\Systems practicing softening must meet the TOC removal requirements

in this column.

\2\Systems meeting at least one of the conditions in Sec. 141.135(a)(1)
(i) through (iv) are not required to operate with enhanced

coagulation.

(ii) Systems practicing softening. (A) Systems (except those noted
in paragraph (a)(2)(ii)(D) of this section) must achieve the percent
reduction of TOC specified in paragraph (a)(2)(ii)(E) of this section
between the raw water source and treated water prior to continuous
disinfection. Continuous disinfection is defined as the continuous
addition of a chemical disinfectant for the purposes of achieving a
level of inactivation credit to meet the minimum inactivation/removal
treatment requirements of subpart H of this section.
(B) Continuous disinfection does not include: the addition of a
chemical disinfectant for filter maintenance (when applied
intermittently), or the use of a disinfectant (other than provided for
in paragraph (a)(2)(ii)(C) of this section) as an oxidant for the
purposes of controlling water quality problems such as iron, manganese,
sulfides, zebra mussels, Asiatic clams, taste, and odor. In determining
compliance with the CT requirements in subpart H of this part, the
system shall not include any credit for disinfectants used either for
filter maintenance or for controlling water quality problems except as
allowed by paragraphs (a)(2)(ii)(B) (1) through (4) of this section.
(1) Systems may include CT credit during periods when the water
temperature is below 5 deg.C and the TTHM and HAA5 quarterly averages
are no greater than 0.040 mg/l and 0.030 mg/l, respectively.
(2) Systems receiving disinfected water from a separate entity as
their source water shall be allowed to include credit for this
disinfectant in determining compliance with the CT requirements. If the
TTHM and HAA5 quarterly averages are no greater than 0.040 mg/l and
0.030 mg/l, respectively, systems may use the measured ``C'' (residual
disinfectant concentration) and the actual contact time (as T<INF>10).
If either the TTHM or HAA5 quarterly average is greater than 0.040 mg/l
or 0.030 mg/l, respectively, systems must use a ``C'' (residual
disinfectant concentration) of 0.2 mg/l or the measured value,
whichever is lower; and the actual contact time (as T<INF>10). This
credit shall be allowed from the disinfection feed point, through a
closed conduit only, and ending at the delivery point to the treatment
plant.
(3) Systems using chlorine dioxide as an oxidant or disinfectant
may include CT credit for its use prior to enhanced coagulation or
enhanced softening if the following standards are met: the chlorine
dioxide generator must generate chlorine dioxide on-site and minimize
the production of chlorine as shown by complying with monitoring and
performance standards in Sec. 141.133(b)(2)(ii)(C).
(4) Systems using ozone and biologically active filtration may
include CT credit for its use prior to enhanced coagulation or enhanced
softening.
(C) Systems not required to operate with enhanced softening may
continue to include, in compliance calculations, continuous addition of
a chemical disinfectant for the purposes of achieving a level of
inactivation credit to meet the minimum inactivation/ removal treatment
requirements of subpart H of this part, even when such addition is also
made for the purpose of controlling water quality problems.
(D) Systems using ozone and biologically active filtration must
achieve the TOC percent reduction specified in paragraph (a)(2)(ii)(E)
of this section before the addition of a residual disinfectant. Systems
using chlorine dioxide that meet the requirements for including CT
credit specified in paragraph (a)(2)(ii)(B)(3) of this section must
achieve the TOC percent reduction specified in paragraph (a)(2)(ii)(E)
of this section before the addition of a residual disinfectant.
(E) Required TOC reductions are indicated in the table in paragraph
(a)(2)(i)(E) of this section. Systems practicing softening are required
to meet the percent reductions in the far-right column (Source water
alkalinity >120 mg/l) for the specified source water TOC.
(3) Non-softening Subpart H conventional treatment systems that
cannot achieve the TOC removals required by paragraph (a)(2) of this
section due to water quality parameters or operating conditions must
apply to the State, within three months of failure to achieve the TOC
removals required by paragraph (a)(2) of this section, for alternative
performance criteria. If the State approves the alternate performance
criteria, the State may make those criteria retroactive for the
purposes of determining compliance. If the State does not approve the
alternate performance criteria, the system must meet the TOC removals
contained in paragraph (a)(2)(i)(E) of this section.
(i) Such application must include, as a minimum, results of benchor
pilot-scale testing for alternate enhanced coagulation level.
``Alternate enhanced coagulation level'' is defined as coagulation at a
coagulant dose and pH as determined by the method outlined in paragraph
(a)(3)(ii) of this section such that an incremental addition of 10 mg/l
of alum (or equivalent amount of ferric salt) results in a TOC removal
of 0.3 mg/l. The percent removal of TOC at this point on the
``coagulant dose versus TOC removal'' curve is then defined as the
minimum TOC removal required for the system. Once approved by the
State, this minimum requirement supersedes the minimum TOC removal
required by the table in paragraph (a)(2)(i)(E) of this section. This
requirement will be effective until such time as the State approves a
new value based on the results of a new bench- and pilot-scale test
triggered by changes in source water quality. Failure to achieve Stateset
alternative minimum TOC removal levels is a violation of paragraph
(a)(3) of this section.
(ii)(A) Bench- or pilot-scale testing of enhanced coagulation shall
be conducted by using representative water samples and adding 10 mg/l
increments of alum (or equivalent amounts of ferric salt) until the pH
is reduced to a level less than or equal to the enhanced coagulation
maximum pH shown in the table below.

Enhanced Coagulation Maximum pH

Maximum
Alkalinity (mg/l as CaCO<INF>3) pH

0-60........................................................... 5.5
>60-120........................................................ 6.3
>120-240....................................................... 7.0
>240........................................................... 7.5

(B) For waters with alkalinities of less than 60 mg/l for which
addition of small amounts of alum or equivalant addition of iron
coagulant drives the pH below 5.5 before significant TOC removal
occurs, the system must add necessary chemicals to maintain the pH
between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/l per 10
mg/l alum added or equivalant addition of iron coagulant is reached.
(iii) The system may operate at any coagulant dose or pH necessary
(consistent with other NPDWRs) to achieve the minimum TOC percent
removal determined under paragraph (a)(3)(i) of this section.
(iv) If the TOC removal is consistently less than 0.3 mg/l of TOC
per 10 mg/l of incremental alum dose at all dosages of alum or
equivalant addition of iron coagulant, the water is deemed to contain
TOC not amenable to enhanced coagulation. The system may then apply to
the State for a waiver of enhanced coagulation requirements.
(b) Compliance calculations. (1) Subpart H systems other than those
identified in paragraph (b)(2) of this section shall comply with the
TOC compliance requirements contained in paragraph (a) of this section.
Systems shall calculate compliance quarterly by the following method:
(i) Determine actual monthly TOC percent removal, equal to: (1-
(treated water TOC/source water TOC)) x 100.
(ii) Determine the required monthly TOC percent removal (from
either the table in paragraph (a)(2)(i)(E) of this section or from
paragraph (a)(3) of this section).
(iii) Divide paragraph (b)(1)(i) of this section by paragraph
(b)(2)(ii) of this section.
(iv) Add together the results of paragraph (b)(1)(iii) of this
section for the last 12 months and divide by 12.
(v) If paragraph (b)(1)(iv) of this section <1.00, the system is
not in compliance with the TOC percent removal requirements.
(2) Subpart H systems using conventional treatment but not
operating enhanced coagulation must comply with the DBP precursor
treatment technique identified in paragraphs (a)(1) (i) through (iv) of
this section.
(c) Treatment technique requirements for Disinfection Byproduct
Precursors. The Administrator identifies the following as treatment
techniques to control the level of disinfection byproduct precursors in
drinking water treatment and distribution systems: For Subpart H
systems using conventional treatment, enhanced coagulation or enhanced
softening.
PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS
IMPLEMENTATION

The authority citation for Part 141 continues to read as
follows:

Authority: 42 U.S.C. 300g, 300g-1, 300g-2 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4 and 300j-9.
2. Section 142.14 is amended by adding paragraphs (d)(12) and
(d)(13) to read as follows:
Sec. 142.14 Records kept by states.

* * * *
(d) * * *
(12) Records of the currently applicable or most recent State
determinations, including all supporting information and an explanation
of the technical basis for each decision, made under the following
provisions of 40 CFR part 141, subpart L for the control of
disinfectants and disinfection byproducts. These records must also
include interim measures toward installation.
(i) States must keep records of systems that are installing GAC or
membrane technology in accordance with Sec. 141.64(d)(3). These records
must include the date by which the system is required to have completed
installation.
(ii) States must keep records of systems that are required, by the
State, to meet alternative minimum TOC removal requirements in
accordance with Sec. 141.135(a)(3). Records must include the
alternative limits and rationale for establishing such limits.
(iii) States must keep records of Subpart H systems using
conventional treatment meeting any of the enhanced coagulation or
enhanced softening exemption criteria in Sec. 141.135(a)(1).
(iv) States must keep a register of qualified operators that have
met the State requirements developed under Sec. 142.16(f)(2).
(13) Records of systems with multiple wells considered to be one
treatment plant in accordance with Sec. 141.133(b)(1).
* * * *
Section 142.15 is amended by adding paragraphs (c)(5) through
(c)(8) to read as follows:

Sec. 142.15 Reports by states.

* * * *
(c) * * *
(5) Reports of systems that must meet alternative minimum TOC
removal levels and the alternate performance criteria specified in
Sec. 141.135(a)(3).
(6) Any extensions granted for compliance with MCLs in Sec. 141.64
as allowed by Sec. 141.64(c)(3) and the date by which compliance must
be achieved.
(7) A list of systems required to monitor for various disinfectants
and disinfection byproducts.
(8) A list of all systems using multiple ground water wells which
draw from the same aquifer and are considered a single source for
monitoring purposes.
* * * *
Section 142.16 is amended by adding paragraph (f) to read as
follows:

Sec. 142.16 Special primacy requirements.

* * * *
(f) Requirements for States to adopt 40 CFR part 141, subpart L. In
addition to the general primacy requirements elsewhere in this part,
including the requirement that State regulations be at least as
stringent as federal requirements, an application for approval of a
State program revision that adopts 40 CFR part 141, subpart L, must
contain a description of how the State will accomplish the following
program requirements:
(1) Section 141.64(d)(3) (interim treatment requirements).
Determine the interim treatment requirements for those systems electing
to install GAC or membrane filtration and granted additional time to
comply with Sec. 141.64(a).
(2) Section 141.130(c) (qualification of operators). Qualify
operators of community and nontransient-noncommunity public water
systems subject to this regulation. Qualification requirements
established for operators of systems subject to 40 CFR part 141,
Subpart H--Filtration and Disinfection, may be used in whole or in part
to establish operator qualification requirements for meeting
requirements of subpart L of this part if the State determines that the
requirements of subpart H of this part are appropriate and applicable
for meeting requirements of subpart L of this part.
(3) Approve alternative TOC removal levels, as allowed under the
provisions of Sec. 141.135(a).
(4) Section 141.133(a)(2) (State approval of parties to conduct
analyses). Approve parties to conduct pH, alkalinity, temperature, and
residual disinfectant concentration measurements. The State's process
for approving parties performing water quality measurements for systems
subject to requirements of subpart H of this part may be used for
approving parties measuring water quality parameters for systems
subject to requirements of subpart L of this part, if the State
determines the process is appropriate and applicable.
(5) Section 144.133(a)(2) (DPD colorimetric test kits). Approve DPD
colorimetric test kits for free and total chlorine measurements.
Approval granted under Sec. 141.74(a)(5) for the use of such test kits
for free chlorine testing would be considered acceptable approval for
the use of DPD test kits in measuring free chlorine residuals as
required in subpart L of this part.
(6) Section 141.133(b)(3)(ii)(C) (multiple wells as a single
source). Define the criteria to determine if multiple wells are being
drawn from a single aquifer and therefore be considered a single source
for compliance with monitoring requirements.

[FR Doc. 94-17651 Filed 7-28-94; 8:45 am]
BILLING CODE 6560-50-P

Notices For
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

National Primary Drinking Water Regulations; Disinfectants and Disinfection Byproducts; Proposed Rule

Bromate........................................... 0 0.010

ALL.......... 57 897 ND 15.00 ND 0.84 1.88

ALL.......... 100 854 ND 30.00 2.55 4.00 5.95

Total trihalomethanes (TTHM).............................. 0.080

Total trihalomethanes..................................... 0.040

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