HEALTH CONSULTATION
Evaluation of Indoor Air Sampling Results
(January 29-30, 2003)
PACIFIC CLEANERS AND RANDY'S NUTRITION
OLYMPIA, THURSTON COUNTY, WASHINGTON
BACKGROUND AND STATEMENT OF ISSUES
The Washington State Department of Health (DOH), in cooperation with the Thurston County Public Health and Social Services Department (TCHD) conducted an exposure investigation to evaluate whether tetrachloroethylene (PCE) and PCE-related chemicals may be present at levels of health concern inside Randy's Nutrition Center (Randy's). Randy's is a health foods store located adjacent to Pacific Cleaners, an active dry-cleaning business that uses PCE. Randy's is located at 3530 Pacific Avenue SE, in Olympia, Washington (Appendix B, Figures 1 and 2). DOH prepares health consultations under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR).
Pacific Cleaners has a history of odor and health complaints. In October 1992, the Olympic Region Clean Air Agency (ORCAA) was contacted by a nearby business about odor and health concerns associated with Pacific Cleaners.1 More recently, in December 2002 and January 2003, the owner of Randy's contacted ORCAA with similar concerns.2 Because of these recent concerns, ORCAA conducted numerous inspections at Randy's and Pacific Cleaners, and confirmed the reported odors. During one of the inspections, using a portable HFC (Halogen Leak Detector), PCE was detected throughout Pacific Cleaners as well as outside the open shop doors. ORCAA also observed vapor leaks, open containers, and possible faulty temperature gauges that resulted in a number of violation notices and at least one fine.2
Because odors continued at Randy's after ORCAA was notified, the owner also contacted TCHD. In January 2003, TCHD sampled Randy's and Pacific Cleaners using a portable photo ionization detector (PID) calibrated for PCE. The PID detected contaminant vapor levels that exceeded health comparison values in both Pacific Cleaners and Randy's.
Following the PID sampling, TCHD collected indoor air samples using 6-liter Summa® canisters with preset flow control devices that allowed time-weighted samples to be collected over a 24-hour period. The samples were collected in the back of Randy's and in a classroom located between Randy's and Pacific Cleaners, from January 29-30, 2003, and were analyzed for volatile organic compounds (VOCs), including PCE. Atmospheric Analysis & Consulting, Inc. analyzed the samples for VOCs using EPA Method TO-15.
The canister sampling indicated that measured levels of PCE, trichloroethylene (TCE), methylene chloride, and numerous other VOCs exceeded corresponding health comparison values. (Table 1).4 Methylene chloride and many of the other VOCs are most likely associated with localized sources, such as office supplies and nearby automobile emissions.
A consultant hired by Pacific Cleaners determined that the source of the PCE was a leak at their dry-cleaning machine. As a result of the leak, ORCAA directed Pacific Cleaners to repair the equipment. In late February, after repairs were made to correct the leak, the Washington Department of Labor and Industries (L&I) inspected Pacific Cleaners, and did not detect any PCE.5
This health consultation evaluates the results of the Summa® canister air samples collected from January 29-30, 2003 by TCHD inside Randy's and the classroom between Randy's and Pacific Cleaners.
Indoor air sampling results from samples obtained in January 2003 from Randy's and the classroom located between Randy's and Pacific Cleaners were screened using ATSDR, U.S. Environmental Protection Agency (EPA), and Washington State Department of Ecology (Ecology) health-based criteria (comparison values). Contaminant concentrations below comparison values are unlikely to pose a health threat, and were not further evaluated. Contaminant concentrations exceeding comparison values and background levels (chemicals of potential concern, or COPCs) do not necessarily pose a health threat, but were further evaluated to determine whether they are at levels that could cause adverse human health effects.
Indoor
air sampling results revealed that PCE and TCE levels were much higher than
the concentrations of other detected chemicals, and are considered as chemicals
of potential concern. PID readings revealed contaminant vapor levels from 10,000
parts per billion (ppb) to 2,000,000 ppb in Pacific Cleaners, and from 1,100
ppb to 20,400 ppb in Randy's. The highest levels were measured in and around
the dry-cleaning machine, and at the rear of the dry-cleaning business, near
the ceiling vent.3 It should be noted that a PID is a screening level
instrument designed to provide an estimate of organic vapors present, not to
precisely distinguish one ionizable gas (such as PCE) from another. Therefore,
if there is more than one compound present, the PID will not provide an accurate
concentration of a particular gas, only an approximate reading of total gas
concentration. Results of 24-hour Summa® canister air samples revealed PCE
levels from 4,617 micrograms per cubic meter (µg/m3) to over 8,000
µg/m3, while TCE levels ranged from 397 µg/m3 to 468 µg/m3 (Table 1).4
Methylene chloride and benzene were also detected above their respective health comparison values in both locations tested. However, the levels were low and were at or near background levels of these chemicals commonly present in urban indoor and ambient air (Table 1).6,7 Health risks from exposure to these two chemicals was estimated to be low, and will not be discussed further in the health consultation. A number of other VOCs were also found at low levels in indoor air. Many of these VOCs were expected, since they have many common sources, including cleaning supplies, office equipment, nail polish, paint, and gasoline among others. These other VOCs were either below health comparison values, or at background levels. As a result of these findings, only the potential health hazards posed by PCE and TCE will be discussed further in this health consultation.
Table 1. Pacific Cleaners and Randy's Nutrition
Center.
Chemicals detected in indoor air exceeding health comparison values and background
indoor air values, January 29-30, 2003
(Units are in micrograms per cubic meter)
| Chemical | Location | Comparison Value | Background Indoor Air Literature Values | Cancer Class | ||
| Randy's back room (Summa® canister) | Classroom (Summa® canister) |
Cancer | Noncancer | |||
| methylene chloride | 38.2 | 21.2 | 3 (CREG) | 1,042 (chronic MRL) |
6 | EPA B2 |
| benzene | 3.2 | 4.8 | 0.1 (CREG) | 30 (RfC) | 10 | EPA Group A |
| tetrachloroethylene (PCE) |
8,113 | 4,617 | NA | 271 (chronic MRL) 101,748 (LOAEL) |
5 (Shah & Singh)6 |
NA |
| trichloroethylene (TCE) |
468 | 397 | NA | 40 (NCEA RfC) 37,619 (subchronic LOAEL) |
0.7 (Shah & Singh)6 |
NA |
| toluene | 10.6 | 13.6 | NA | 400 (RfC) | 5.7 (HSDB/indoor air) |
EPA Group D |
Shaded cells = chemicals of potential concern further evaluated
in the health consultation
NA = not available
CREG = ATSDR cancer risk evaluation guide
MRL = ATSDR minimal risk level
EPA = Environmental Protection Agency
RfC = Reference concentration
LOAEL = Lowest Observed Adverse Effect Level
Ppb = parts per billion
NCEA = National Center for Environmental Health
HSDB = Hazardous Substance Data Bank
To estimate the potential for noncancer health effects
from exposure to PCE and TCE,
the concentrations of these two chemicals were
compared to their respective
noncancer comparison value [EPA reference
concentration (RfC) or ATSDR
chronic minimal risk level (MRL)]. RfCs and MRLs
are set well below the actual toxic
effect level (i.e., lowest observed adverse effect level
(LOAEL) or no observed adverse
effect level (NOAEL) determined from those studies
upon which they are based. This
approach provides additional health protection to
account for the uncertainty
associated with setting these "safe" levels of exposure.
As shown in Table 1, PCE and
TCE levels in Randy's and the adjacent classroom
exceed background levels and
their respective MRL or RfC.
PCE is a manufactured compound widely used for dry-cleaning fabrics and as a metal degreaser. It is also used as an intermediate in the manufacturing of other products. It evaporates easily into the air, and has a sharp, sweet odor at high concentrations.8 TCE is primarily used as a metal degreaser, particularly in the automotive and metals industries. It is a breakdown product of PCE and it is also found in some household products, such as typewriter correction fluid, paint removers, adhesives, and spot removers.9
The MRL for PCE is based upon neurobehavioral effects observed during a 10-year occupational study.8 Other systemic health effects associated with exposure to high levels of PCE in air include hepatotoxic (liver) effects, reversible kidney damage, endocrine effects, reproductive, and developmental effects.8, 10 TCE exposure is associated with many of the same health effects as PCE, including neurotoxicity, immunotoxicity, developmental toxicity, liver and kidney toxicity, and endocrine effects.9,10 The RfC for TCE is based on critical effects on the central nervous system, liver, and endocrine system.10
While levels of PCE and TCE in indoor air exceeded their respective MRL or RfC, indicating the possibility of adverse noncancer (i.e., central nervous system, liver, and endocrine) effects from continuous, long-term exposure, it should be noted that the levels were from 10 to 100 times lower than the actual levels that produced these effects in the relevant occupational and laboratory animal studies.8, 9, 10, 11, 12
Table 2. Randy's Nutrition Center and adjacent
classroom.
Noncancer risks (hazard quotients) associated with chronic exposure to the maximum
concentration of PCE and TCE measured in indoor air*
| Chemical | Location | |
| *Hazard Quotient (Randy's back room) |
*Hazard Quotient (Classroom) |
|
| tetrachloroethylene (PCE) | 6** | 3.4** |
| trichloroethylene (TCE) | 2.3** | 2** |
*Correction factor of 0.2 was used in the exposure calculations
to account for the less than 24-hours/day, 7-days/week exposure frequency for
an office worker (see Appendix B).
**Hazard quotient greater than 1 indicates a potential noncancer health risk
(see Appendix B for health risk formulas). Of the detected chemicals, PCE and
TCE accounted for all of the potential noncancer risks (i.e., hazard quotient
greater than 1).
Tetrachloroethylene (PCE)
Although it has not been shown to cause cancer in people, the U.S. Department of Health and Human Services has determined that PCE may reasonably be anticipated to be a carcinogen.8, 10, 12 The International Agency for Research on Cancer (IARC) has determined that it is probably carcinogenic to humans, based on limited human evidence and sufficient evidence in animals. EPA is currently reassessing PCE toxicity, and has not adopted a final position on the weight-of-evidence classification.10, 12
Although a number of human studies (primarily epidemiology studies of dry-cleaning workers) suggest the possibility of increased cancer incidences from exposure to PCE, particularly esophageal and bladder cancers, it has not been shown to definitively cause cancer in humans. Other cancers suspected of being associated with exposures to high levels of PCE include intestinal, pancreatic, lung, kidney, skin, colon, and lymphatic/hematopoietic cancer. PCE increased the incidence of hepatocellular tumors in laboratory mice after oral and inhalation exposure and mononuclear cell leukemia and kidney tumors in rats after inhalation.8, 10, 12
The California Environmental Protection Agency (Cal EPA) recently derived an inhalation unit risk for PCE that can be used to estimate cancer risk.13 Using this value, the estimated increased risk of developing cancer, assuming continuous exposure over a working lifetime to the detected concentrations of PCE in indoor air, is from approximately two to four additional cancers in a population of 1,000 persons exposed (2 x 10-3 to 4 x 10-3) (Table 3). Actual risks are probably much lower than this, as exposure to these levels is more likely to have occurred over a period of days or weeks, not years.
Trichloroethylene (TCE)
The NCEA is currently revising a human health risk assessment for TCE that will present EPA's most current evaluation of the potential health risks from exposure to this chemical. The mechanistic information suggests some risk factors that may make some populations more sensitive, and that TCE could affect children and adults differently.11
Recent and extensive review of available data has led EPA to characterize TCE as "highly likely to produce cancer in humans." These findings are consistent with those of the International Agency on Research of Cancer (IARC, 1995) and the National Toxicology Program (NTP, 2000). This classification is based on sufficient evidence in animals and limited evidence in humans. The strongest evidence that TCE can cause cancer in humans comes from occupational studies that have found increases in lung, liver and kidney cancers in workers exposed over several years.11
In experimental rodent studies, high doses of TCE administered to mice resulted in tumors of the lungs, liver, and testes. Other possible cancers associated with exposure to high levels of TCE include cancer of the bladder, stomach, prostate, kidney, and pulmonary system.9, 11 TCE cancer effects levels (CELs), which were derived from lowest observed adverse effects levels (LOAELs) in chronic-duration studies on rats and mice, ranged from 100,000 ppb to 600,000 ppb.9, 11 TCE levels measured in indoor air in Randy's and the adjacent classroom were thousands of times lower than these CELs.
Although the data obtained from high-dose animal or worker exposure studies is not directly applicable to exposures at these businesses, theoretical cancer risk estimates can be made based on this data. In order to estimate the increased cancer risk for persons assumed to be chronically exposed to the detected levels of TCE in indoor air, the current recommended EPA inhalation slope factor was used.11 The estimated increased cancer risk from TCE exposure in the two locations tested is similar to the risk from exposure to PCE, approximately five additional cancers in a population of 1,000 persons exposed over a working lifetime (5 x 10-3) (Table 3).
Table 3. Randy's Nutrition and adjacent
classroom
Estimated increased cancer risk associated with chronic exposure to the maximum
concentration of PCE and TCE measured in indoor air*
| Chemical | Location | |
| Randy's back room | Classroom | |
| tetrachloroethylene (PCE) | 3.8E-3 | 2.2E-3 |
| trichloroethylene (TCE) | 6E-3 | 5E-3 |
| Total increased cancer risk | 1E-2 | 7E-3 |
*CF = 0.08 correction factor to account for the less than 24-hours/day,
7 days/week exposure frequency for an office worker (see Appendix B).
For this health consultation, a 25-year exposure duration was assumed (EPA Exposure
Factors Handbook, 1997).
It should be noted that the estimated exposures and risks presented above are based on the results of a single sampling event, and therefore may not represent levels under different conditions or times. The suspected source of the PCE and TCE was reportedly eliminated, so current levels are likely much lower, or nonexistent. However, as sampling data does not exist to confirm this conclusion, DOH recommends follow up confirmatory sampling.
It is plausible that trichloroethylene and tetrachloroethylene jointly act in an additive manner to impair nervous system function. There is no evidence to indicate that these chemicals jointly act on the nervous system in a less-than-additive or greater-than-additive mode.14
The effect of tetrachloroethylene on trichloroethylene's liver and kidney toxicity was projected to occur by a less-than-additive joint action based on in vivo evidence that tetrachloroethylene inhibits the metabolism of trichloroethylene in humans under occupational exposure conditions, and evidence that trichloroethylene and tetrachloroethylene act in a less-than-additive manner to cause liver and kidney peroxisomal proliferation. In summary, the available data provide no evidence of greater-than-additive interactions among trichloroethylene or tetrachloroethylene that might cause liver and kidney effects to occur.14
A component-based hazard index approach that assumes additive joint toxic action and uses ATSDR MRLs based on neurological impairment is recommended for exposure-based assessments of possible health hazards from exposure to mixtures of trichloroethylene and tetrachloroethylene. There is no evidence to indicate that greater-than-additive interactions would cause liver and kidney effects to occur at exposure levels lower than those influencing the nervous system.14
Quantitative estimates (total estimated increased cancer and non-cancer risks) from exposure to all of the chemicals listed in Table 1 were also evaluated. TCE and PCE accounted for almost all of the increased risk.
ATSDR recognizes that infants and children may be more vulnerable to exposures than adults when faced with contamination of air, water, soil, or food.15 This vulnerability is a result of the following factors:
Laboratory animal studies involving high dose exposures to the chemicals of concern (PCE and TCE) detected in indoor air in Randy's, the adjacent classroom, and Pacific Cleaners may result in reproductive and/or developmental effects. For example, studies of animals exposed in utero (via oral exposure of mothers) indicate that PCE can adversely influence the developing nervous system, but studies to examine possible associations between occupational exposure of humans to PCE and increased risks for birth defects in offspring or reproductive effects such as menstrual disorders and spontaneous abortions provide only suggestive evidence that these types of effects may occur in humans (ATSDR 1997).
Since direct or indirect exposures to the unborn, infants and young children inside these businesses are expected to be infrequent, DOH considers the risks to be minimal. In addition, the levels of PCE and TCE that produced developmental and reproductive effects in the relevant toxicity studies were considerably higher than the levels detected inside the businesses.
A previous, short-term drycleaning machine leak inside Pacific Cleaners is the likely source of measured levels of PCE and TCE in Randy's Nutrition Center and a classroom situated between Pacific Cleaners and Randy's. A consultant hired by Pacific Cleaners evaluated the leak, which appears to have been mitigated. As a result, current levels are likely much lower, or nonexistent.
Estimated exposures and health risks discussed in the health consultation are based on the results of a single sampling event, and therefore may not represent levels under different conditions or times. Based on the results of this single sampling event, an elevated health risk could have existed in the past, assuming a twenty-five year working lifetime exposure to the measured levels of PCE and TCE. Pending the results of follow up, confirmatory sampling, the businesses tested (Pacific Cleaners, Randy's, and the classroom) are categorized as an indeterminate public health hazard.
RECOMMENDATIONS/PUBLIC HEALTH ACTION PLAN
Action Proposed
Action Proposed
Action Proposed
Paul Marchant
Washington State Department of Health
Office of Environmental Health Assessments
Site Assessment Section
Designated Reviewer
Robert Duff, Manager
Site Assessment Section
Office of Environmental Health Assessments
Washington State Department of Health
ATSDR Technical Project Officer
Debra Gable
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
APPENDIX B: HEALTH RISK FORMULAS AND EXPOSURE ASSUMPTIONS
The formulas and parameters provided below were used to conservatively estimate cancer and noncancer health risks. It is important to note that EPA RfC and IUR values, and ATSDR MRLs assume continuous exposure.
Hazard Quotient using RfCs and MRLs
HQ = Ca/(RfC or MRL) x CF
HQ = hazard quotient (unitless)
Ca = indoor air concentration (ug/m3)
RfC = Reference concentration (ug/m3)
MRL = Minimal Risk Level (ug/m3)
CF = correction factor of 0.2 (8/24 x 5/7 x 50/52) to account for the less than continuous (i.e., 8 hours/day, 5 days/week, 50 weeks/year) exposure scenario assumed for a worker.
Cancer risk using unit risk factors
Cancer risk = Ca x IUR x CF
Ca = indoor air concentration (ug/m3)
IUR = inhalation unit risk (per ug/m3)
CF = correction factor of 0.08 (8/24 x 5/7 x 50/52 x 25/75) to account for the less than continuous (i.e., 8 hours/day, 5 days/week, 50 weeks/year, 25 years) exposure scenario assumed for a worker.
Cancer risk using slope factors
Cancer risk = ((Ca /1000) x IR x EF x ED/(BW x AT)) x CSF
Ca = indoor air concentration in micrograms/m3
IR = inhalation rate (adult worker - 10.4 m3/day)
EF = exposure frequency (250 days/year)
ED = exposure duration (25 years)
BW = body weight (72 kg)
AT = averaging time (27,375 days)
CSF = chemical-specific cancer slope factor
This Health Consultation was prepared by the Washington State Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.
Debra Gable
Technical Project Officer,
SPS, SSAB, DHAC
ATSDR
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Sven E. Rodenbeck
for Roberta Erlwein
Chief, SPS, SSAB, DHAC
ATSDR
