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Waste and Cleanup Risk Assessment Glossary
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Abiotic
Characterized by absence of life; abiotic materials include non-living
environmental media (e.g., water, soils, sediments); abiotic characteristics
include such factors as light, temperature, pH, humidity, and other physical
and chemical influences.
Absorbed Dose
The amount of a substance penetrating the exchange boundaries of an organism
after contact. Absorbed dose for the inhalation and ingestion routes of
exposure is calculated from the intake and the absorption efficiency.
Absorbed dose for dermal contact depends on the surface area exposed and
absorption efficiency.
Absorption
Absorption is the passage of one substance into or through another.
Absorption Efficiency
A measure of the proportion of a substance that a living organism absorbs
across exchange boundaries (e.g., gastrointestinal tract).
Accuracy
The degree to which a measurement reflects the true quantitative value
of a variable.
Acute
Having a sudden onset or lasting a short time. An acute stimulus is severe
enough to induce a response rapidly. The word acute can be used to define
either the exposure or the response to an exposure (effect). The duration
of an acute aquatic toxicity test is generally 4 days or less and mortality
is the response usually measured.
Acute Response
The response of (effect on) an organisms which has a rapid onset. A commonly
measured rapid-onset response in toxicity tests is mortality.
Acute Tests
A toxicity test of short duration, typically 4 days or less (i.e., of
short duration relative to the lifespan of the test organism).
Administered Dose
The mass of a substance given to an organism and in contact with an exchange
boundary (i.e., gastrointestinal tract) per unit wet body weight (BW)
per unit time (e.g., mg/kgBW/day).
Adsorption
Adsorption is the adhesion of molecules of gas, liquid, or dissolved solids
to a surface. The term also refers to a method of treating wastes in which
activated carbon is used to remove organic compounds from wastewater.
See also Carbon Adsorption.
Adverse Ecological Effects
Changes that are considered undesirable because they alter valued structural
or functional characteristics of ecosystems or their components. An evaluation
of adversity may consider the type, intensity, and scale of the effect
as well as the potential for recovery.
Agent
Any physical, chemical, or biological entity that can induce an adverse
response (synonymous with stressor).
American Society for Testing and Materials (ASTM)
The ASTM sets standards for many services, including methods of sampling
and testing of hazardous waste and media contaminated with hazardous waste.
Applicable or Relevant and Appropriate Requirements (ARARs)
"Applicable" requirements are those clean-up standards of control, and
other substantive environmental protection requirements, criteria, or
limitations promulgated under federal or state law that specifically address
a hazardous substance, pollutant, contaminant, response action, location,
or other circumstance at a Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) site. "Relevant and appropriate" requirements
are those clean-up standards which, while not "applicable" at a CERCLA
site, address problems or situations sufficiently similar to those encountered
at the CERCLA site that their use is well-suited to the particular site.
ARARs can be action-specific, location-specific, or chemical-specific.
Aquifer
An aquifer is an underground rock formation composed of such materials
as sand, soil, or gravel that can store ground water and supply it to
wells and springs.
Area Use Factor
The ratio of an organism's home range, breeding range, or feeding/foraging
range to the area of contamination of the site under investigation. (Pertains
to Ecological Risk Assessments)
Aromatics
Aromatics are organic compounds that contain 6-carbon ring structures,
such as creosote, toluene, and phenol, that often are found at dry cleaning
and electronic assembly sites.
Assessment Endpoint
An explicit expression of the environmental value that is to be protected,
operationally defined by an ecological entity and its attributes. For
example, salmon are valued ecological entities; reproduction and age class
structure are some of their important attributes. Together "salmon reproduction
and age class structure" form an assessment endpoint. (Pertains to Ecological
Risk Assessments)
Attribute
A quality or characteristic of an ecological entity. An attribute is one
component of an assessment endpoint.
B
Baseline Risk Assessment
A baseline risk assessment is an assessment conducted before cleanup activities
begin at a site to identify and evaluate the threat to human health and
the environment. After remediation has been completed, the information
obtained during a baseline risk assessment can be used to determine whether
the cleanup levels were reached.
BDAT
Under the RCRA Land Disposal Restrictions Program, EPA establishes treatment
standards governing specific waste codes that are based on the performance
of BDAT. Of the proven, available technologies, EPA designates as BDAT
the technology that best minimizes the mobility or toxicity of the hazardous
waste constituents of a waste.
Bedrock
Bedrock is the rock that underlies the soil; it can be permeable
or non-permeable. See also Confining Layer.
Benthic Community
The community of organisms dwelling at the bottom of a pond, river,
lake, or ocean. (pertains to ecological risk assessments)
Best Demonstrated Available Technology (BDAT)
A BDAT is a technology that has demonstrated the ability to reduce a particular
contaminant to a lower concentration than other currently available technologies.
BDATs can change with time as technologies evolve.
Bioaccumulation
General term describing a process by which chemicals are taken up by an
organism either directly from exposure to a contaminated medium or by
consumption of food containing the chemical.
Bioassessment
A general term referring to environmental evaluations involving living
organisms; can include bioassays, community analyses, etc. (Pertains to
Ecological Risk Assessments)
Bioassay
Test used to evaluate the relative potency of a chemical by comparing
its effect on living organisms with the effect of a standard preparation
on the same type of organism. Bioassay and toxicity tests are not the
same-see toxicity test. Bioassays often are run on a series of dilutions
of whole effluents. (Pertains to Ecological Risk Assessments)
Bioavailability
The degree to which a material in environmental media can be assimilated
by an organism.
Bioccumulation Factor (BAF)
The ratio of the concentration of a contaminant in an organism to the
concentration in the ambient environment at steady state, where the organism
can take in the contaminant through ingestion with its food as well as
through direct contact.
Bioconcentration
A process by which there is a net accumulation of a chemical directly
from an exposure medium into an organism.
Biodegrade
Decompose into more elementary compounds by the action of living organisms,
usually referring to microorganisms such as bacteria.
Biodegradability
Biodegradability is the capability of a substance to break down into simpler
substances, especially into innocuous products, by the actions of living
organisms (that is, microorganisms).
Biomagnification
Result of the process of bioaccumulation and biotransfer by which tissue
concentrations of chemicals in organisms at one trophic level exceed tissue
concentrations in organisms at the next lower trophic level in a food
chain.
Biomarker
Biochemical, physiological, and histological changes in organisms that
can be used to estimate either exposure to chemicals or the effects of
exposure to chemicals.
Biomonitoring
Use of living organisms as "sensors" in environmental quality surveillance
to detect changes in environmental conditions that might threaten living
organisms in the environment.
Body Burden
The concentration or total amount of a substance in a living organism;
implies accumulation of a substance above background levels in exposed
organisms.
Breeding Range
The area utilized by an organism during the reproductive phase of its
life cycle and during the time that young are reared. (Pertains to Ecological
Risk Assessments)
Brownfields
Brownfields sites are abandoned, idled, or under-used industrial and commercial
facilities where expansion or redevelopment is complicated by real or
perceived environmental contamination.
BTEX
BTEX is the term used for benzene, toluene, ethylbenzene, and xylene-volatile
aromatic compounds typically found in petroleum products, such as gasoline
and diesel fuel.
Bulk Sediment
Field collected sediments used to conduct toxicity tests; can contain
multiple contaminants and/or unknown concentrations of contaminants.
C
CERCLIS 3
The newest version of the Comprehensive Environmental Response, Compensation,
and Liability Information System, EPA's primary Superfund database. CERCLIS
3 enables Superfund staff nationwide to share site specific information
and eventually with other federal partners and the public.
Characterization of Ecological Effects
A portion of the analysis phase of ecological risk assessment that evaluates
the ability of a stressor to cause adverse effects under a particular
set of circumstances.
Characterization of Exposure
A portion of the analysis phase of ecological risk assessment that evaluates
the interaction of the stressor with one or more ecological components.
Exposure can be expressed as co-occurrence, or contact depending on the
stressor and ecological component involved.
Contaminants of Potential Concern
Chemicals that are potentially site-related and whose data are of sufficient
quality for use in a quantitative risk assessment.
Chronic
Involving a stimulus that is lingering or continues for a long time; often
signifies periods from several weeks to years, depending on the reproductive
life cycle of the species. Can be used to define either the exposure or
the response to an exposure (effect). Chronic exposures typically induce
a biological response of relatively slow progress and long duration.
Chronic Response
The response of (or effect on) an organism to a chemical that is not immediately
or directly lethal to the organism.
Chronic Tests
A toxicity test used to study the effects of continuous, long-term exposure
of a chemical or other potentially toxic material on an organism.
Clean Air Act (CAA)
The CAA is a federal law passed in 1970 that requires EPA to establish
regulations to control the release of contaminants to the air to protect
human health and environment.
Cleanup
Cleanup is the term used for actions taken to deal with a release or threat
of release of a hazardous substance that could affect humans and or the
environment. The term sometimes is used interchangeably with the terms
remedial action, removal action, response action, or corrective action.
Clean Water Act (CWA)
CWA is a 1977 amendment to the Federal Water Pollution Control Act of
1972, which set the basic structure for regulating discharges of pollutants
to U.S. waters. This law gave EPA the authority to set wastewater discharge
standards on an industry-by-industry basis and to set water quality standards
for all contaminants in surface waters.
Community
An assemblage of populations of different species within a specified
location and time. (pertains to ecological assessments)
Community Advisory Group (CAG)
A committee, task force, or board comprised of citizens affected by a
hazardous waste site. CAGs provide a public forum for community members
to present and discuss their needs and concerns about the decision-making
process at sites affecting them.
Comparative Risk Assessment
A process that generally uses a professional judgment approach to evaluate
the relative magnitude of effects and set priorities among a wide range
of environmental problems (e.g., U.S. EPA, 1993d). Some applications of
this process are similar to the problem formulation portion of an ecological
risk assessment in that the outcome may help select topics for further
evaluation and help focus limited resources on areas having the greatest
risk reduction potential. In other situations, a comparative risk assessment
is conducted more like a preliminary risk assessment. For example, EPA's
Science Advisory Board used professional judgment and an ecological risk
assessment approach to analyze future ecological risk scenarios and risk
management alternatives (U.S. EPA, 1995e).
Complexation
Formation of a group of compounds in which a part of the molecular bonding
between compounds is of the coordinate type.
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA)
The NCP defines CERCLIS, in part, as "EPA's comprehensive data base and
management system that inventories and tracks released addressed or needing
to be addressed by the Superfund program. CERCLIS contains the official
inventory of CERCLA sites and supports EPA's planning and tracking functions."
See also Superfund.
Comprehensive Environmental Response, Compensation, and Liability
Information System (CERCLIS)
The NCP defines CERCLIS, in part, as "EPA's comprehensive data base and
management system that inventories and tracks released addressed or needing
to be addressed by the Superfund program. CERCLIS contains the official
inventory of of CERCLA sites and supports EPA's planning and tracking
functions.".
Concentration
The relative amount of a substance in an environmental medium, expressed
by relative mass (e.g., mg/kg), volume (ml/L), or number of units (e.g.,
parts per million).
Concentration-Response Curve
A curve describing the relationship between exposure concentration and
percent of the test population responding.
Conceptual Model
Describes a series of working hypotheses of how the stressor might affect
ecological components. Describes ecosystem or ecosystem components potentially
at risk, and the relationships between measurement and assessment endpoints
and exposure scenarios.
Conceptual Site Model (CSM)
A CSM, a key element used in facilitating cleanup decisions during a site
investigation, is a planning tool that organizes information that already
is known about a site and identifies the additional information necessary
to support decisions that will achieve the goals of the project. The project
team then uses the CSM to direct field work that focuses on the information
needed to remove significant unknowns from the model. The CSM serves several
purposes - as a planning instrument; as a modeling and data interpretation
tool; and as a means of communication among members of a project team,
decision makers, stakeholders, and field personnel.
Confining Layer
A "confining layer" is a geological formation characterized by low permeability
that inhibits the flow of water. See also Bedrock and Permeability.
Contaminant
A contaminant is any physical, chemical, biological, or radiological substance
or matter present in any media at concentrations that may pose a threat
to human health or the environment.
Contaminant of (Ecological) Concern
A substance detected at a hazardous waste site that has the potential
to affect ecological receptors adversely due to its concentration, distribution,
and mode of toxicity.
Control
A treatment in a toxicity test that duplicates all the conditions of the
exposure treatments but contains no test material. The control is used
to determine the response rate expected in the test organisms in the absence
of the test material.
Corrective Measure Study (CMS)
If the potential need for corrective measures is verified during a RCRA
Facility Investigation (RFI), the owner or operator of a facility is then
responsible for performing a CMS. A CMS is conducted to identify, evaluate,
and recommend specific corrective measures based on a detailed engineering
evaluation. Using data collected during the RFI, the CMS demonstrates
that proposed measures will be effective in controlling the source of
contamination, as well as problems posed by the migration of substances
from the original source into the environment. The measures also must
be assessed in terms of technical feasibility, ability to meet public
health protection requirements and protect the environment, possible adverse
environmental effects, and institutional constraints. See also RCRA
Facility Investigation.
Correlation
An estimate of the degree to which two sets of variables vary together,
with no distinction between dependent and independent variables.
Corrosivity
Corrosive wastes include those that are acidic and capable of corroding
metal such as tanks, containers, drums, and barrels.
Critical Exposure Pathway
An exposure pathway which either provides the highest exposure levels
or is the primary pathway of exposure to an identified receptor of concern.
Cumulative Distribution Function (CDF)
Cumulative distribution functions are particularly useful for describing
the likelihood that a variable will fall within different ranges
of x. F(x) (i.e., the value of y at x in a CDF plot) is the probability
that a variable will have a value less than or equal to x.
Cumulative Ecological Risk Assessment
A process that involves consideration of the aggregate ecological risk
to the target entity caused by the accumulation of risk from multiple
stressors.
D
Data Quality
The term data quality refers to all features and characteristics of data
that bear on its ability to meet the stated or implied needs and expectations
of the user.
Data Quality Objective (DQO)
RAGS Volume I, Part A, Chapter 4 defines a DQO as "qualitative and quantitative
statements to ensure that data of know and documented quality are obtained
during an RI/FS to support an Agency decision." DQOs are qualitative and
quantitative statements specified to ensure that data of known and appropriate
quality are obtained. The DQO process is a series of planning steps, typically
conducted during site assessment and investigation, that is designed to
ensure that the type, quantity, and quality of environmental data used
in decision making are appropriate. The DQO process involves a logical,
step-by-step procedure for determining which of the complex issues affecting
a site are the most relevant to planning a site investigation before any
data are collected.
Degradation
Conversion of an organic compound to one containing a smaller number of
carbon atoms.
Dense Nonaqueous Phase Liquid (DNAPL)
A DNAPL is one of a group of organic substances that are relatively insoluble
in water and more dense than water. DNAPLs tend to sink vertically through
sand and gravel aquifers to the underlying layer.
Deposition
The lying, placing, or throwing down of any material.
Depuration
A process that results in elimination of toxic substances from an organism.
Depuration Rate
The rate at which a substance is eliminated from an organism.
Detection Limit
The lowest concentration of a chemical that can be distinguished reliably
from a zero concentration.
Deterministic Analysis (as opposed to probabilistic analysis)
Calculation and expression of health risks as single numerical values
or "single point" estimates of risk. In risk assessments, the uncertainty
and variability are discussed in a qualitative manner.
Dietary Accumulation
The net accumulation of a substance by an organism as a result of ingestion
in the diet.
Direct Effect (toxin)
An effect where the stressor itself acts directly on the ecological component
of interest, not through other components of the ecosystem.
Direct Push Sampling
Direct push sampling is a technique in which a sampling tube is hydraulically
pushed or driven into the subsurface, collecting material as it advances.
This technique can be used when sampling for constituents, including VOCs,
SVOCs, PCBs, and PAHs.
Disposal
Disposal is the final placement or destruction of toxic, radioactive or
other wastes; surplus or banned pesticides or other chemicals; polluted
soils; and drums containing hazardous materials from removal actions or
accidental release. Disposal may be accomplished through the use of approved
secure landfills, surface impoundments, land farming, deep well injection,
or ocean dumping.
Disturbance
Any event or series of events that disrupts ecosystem, community, or population
structure and changes resources, substrate availability, or the physical
environment (modified from White and Pickett, 1985).
Dose
A measure of exposure. Examples include (1) the amount of a chemical ingested,
(2) the amount of a chemical absorbed, and (3) the product of ambient
exposure concentration and the duration of exposure.
Dose-Response Curve
Similar to concentration-response curve except that the dose (i.e. the
quantity) of the chemical administered to the organism is known. The curve
is plotted as Dose versus Response.
Duplicate
A sample taken from and representative of the same population as another
sample. Both samples are carried through the steps of sampling, storage,
and analysis in an identical manner.
Dynamic Work Plan
A dynamic work plan is a work plan that allows project teams to make decisions
in the field about how site activities will progress. Dynamic work plans
provide the strategy for the way in which dynamic field activities will
take place. As such, they document a flexible, adaptive sampling and analytical
strategy. Dynamic work plans are supported by the rapid turnaround of
data collected, analyzed, and interpreted in the field.
E
Easement An easement is a right to use the land of another for a specific purpose, such as a right-of-way or a utility.
EC50
A statistically or graphically estimated concentration that is expected
to cause one or more specified effects in 50% of a group of organisms
under specified conditions. (Pertains to ecological assessments)
Ecological Component
Any part of an ecosystem, including individuals, populations, communities,
and the ecosystem itself.
Ecological Entity
A general term that may refer to a species, a group of species, an ecosystem
function or characteristic, or a specific habitat. An ecological entity
is one component of an assessment endpoint.
Ecological Relevance
One of the three criteria for assessment endpoint selection. Ecologically
relevant endpoints reflect important characteristics of the system and
are functionally related to other endpoints.
Ecological Risk Assessment
The application of a formal framework, analytical process, or model to
estimate the effects of human actions(s) on a natural resource and to
interpret the significance of those effects in light of the uncertainties
identified in each component of the assessment process. Such analysis
includes initial hazard identification, exposure and dose-response assessments,
and risk characterization.
Ecosystem
The biotic community and abiotic environment within a specified location
and time, including the chemical, physical, and biological relationships
among the biotic and abiotic components.
Ecotoxicity
The study of toxic effects on nonhuman organisms, populations, or communities.
Electrochemical Detector Kits
Electrochemical test kits use the electrical charges of ions that make
up the target analyte(s) to identify and quantify the target analyte(s)
in a sample. Typically, the ions are attracted to an anode or a cathode
or both, depending on their charge, resulting in the generation of an
electrical current that is measured and converted into a sample concentration
by the unit's display or electronics. An analyte-specific catalyst can
be used to aid in the reaction. The self-contained kits include all the
equipment and supplies necessary to produce an analytical result.
Electromagnetic (EM) Geophysics
EM geophysics refers to technologies used to detect spatial (horizontal
and vertical) differences in subsurface electromagnetic characteristics.
The data collected provide information about subsurface environments.
Electromagnetic (EM) Induction
EM induction is a geophysical technology used to create a magnetic field
beneath the earth's surface, which in turn causes a secondary magnetic
field to form around nearby objects that have conductive properties, such
as ferrous and nonferrous metals. The secondary magnetic field then is
used to detect and measure buried debris.
Emergency Removal
An emergency removal is an action initiated in response to a release of
a hazardous substance that requires on-site activity within hours of a
determination that action is appropriate.
Emerging Technology
An emerging technology is an innovative technology that currently
is undergoing bench-scale testing. During bench-scale testing, a
small version of the technology is built and tested in a laboratory.
If the technology is successful during bench-scale testing, it is
demonstrated on a small scale at field sites. If the technology
is successful at the field demonstrations, it often will be used
full scale at contaminated waste sites. As the technology is used
and evaluated at different sites, it is improved continually. See
also Established Technology.
Enforcement Action
An enforcement action is an action undertaken by EPA under authority granted
to it under various federal environmental statutes, such as CERCLA, RCRA,
CAA, CWA, TSCA, and others. For example, under CERCLA, EPA may obtain
voluntary settlement or compel potentially responsible parties (PRP) to
implement removal or remedial actions when releases of hazardous substances
have occurred. See also Comprehensive Environmental Response, Compensation,
and Liability Act; Potentially Responsible Party; and Removal Action.
Engineered Control
An engineered control, such as barriers placed between a contaminated
area and the rest of a site, is a method of managing environmental and
health risks. Engineered controls can be used to limit exposure pathways.
Environmental Audit
An environmental audit usually refers to a review or investigation that
determines whether an operating facility is in compliance with relevant
environmental regulations. The audit may include checks for possession
of required permits, operation within permit limits, proper reporting,
and record keeping. The typical result is a corrective action or compliance
plan for the facility.
Environmental Impact Statement (EIS)
Environmental impact statements are prepared under the National Environmental
Policy Act by Federal agencies as they evaluate the environmental consequences
of proposed actions. EISs describe baseline environmental conditions;
the purpose of, need for, and consequences of a proposed action; the no-action
alternative; and the consequences of a reasonable range of alternative
actions. A separate risk assessment could be prepared for each alternative,
or a comparative risk assessment might be developed. However, risk assessment
is not the only approach used in EISs.
Environmental Risk
Environmental risk is the chance that human health or the environment
will suffer harm as the result of the presence of environmental hazards.
Environmental Site Assessment (ESA)
An ESA is the process that determines whether contamination is present
at a site.
EPA Risk Assessor
The risk assessor responsible for reviewing the risk assessment on behalf
of EPA.
Established Technology
An established technology is a technology for which cost and performance
information is readily available. Only after a technology has been
used at many different sites and the results fully documented is
that technology considered established. The most frequently used
established technologies are incineration, solidification and stabilization,
and pump-and-treat technologies for ground water. See also Emerging
Technology.
Ex Situ
The term ex situ or "moved from its original place," means excavated or
removed.
Exposure
The contact or co-occurrence of a stressor with a receptor.
Exposure Medium
The contaminated environmental medium to which an individual is exposed,
such as soil, water, sediment and air.
Exposure Pathway
RAGS Volume I, Part A, Chapter 6 defines exposure pathway as "the course
a chemical or physical agent takes from a source to an exposed organism.
An exposure pathway describes a unique mechanism by which an individual
or population is exposed to chemicals or physical agents at or originating
from a site. Each exposure pathway includes a source or release from a
source, an exposure point, and an exposure route. If the exposure point
differs from the source, a transport/exposure medium (e.g. air) or media
(in cases of intermedia transfer) also is included.
Exposure Pathway Model
A model in which potential pathways of exposure are identified for the
selected receptor species.
Exposure Point
The potential contact between a person and a contaminant within an exposure
medium.
Exposure Point Concentration
The value that represents a conservative estimate of the chemical concentration
available from a particular medium or route of exposure. See definitions
for Medium EPC and Route EPC, which follow.
Exposure Profile
The product of characterizing exposure in the analysis phase of ecological
risk assessment. The exposure profile summarizes the magnitude and spatial
and temporal patterns of exposure for the scenarios described in the conceptual
model.
Exposure Route
The mechanism for which a contaminant comes in contact with a person (e.g.,
by ingestion, inhalation, dermal contact).
Exposure Scenario
A set of assumptions concerning how an exposure takes place, including
assumptions about the exposure setting, stressor characteristics, and
activities of an organism that can lead to exposure.
F
False Negative
The conclusion that an event (e.g., response to a chemical) is negative
when it is in fact positive (see Appendix D).
False Positive
The conclusion that an event is positive when it is in fact negative (see
Appendix D).
Fate
Disposition of a material in various environmental compartments (e.g.
soil or sediment, water, 5 air, biota) as a result of transport, transformation,
and degradation.
Filtration
Filtration is a treatment process that removes solid matter from water
by passing the water through a porous medium, such as sand or a manufactured
filter.
Flame Ionization Detector (FID)
A FID is an instrument often used in conjunction with gas chromatography
to measure the change of signal as analytes are ionized by a hydrogen-air
flame. It also is used to detect phenols, phthalates, PAHs, VOCs,
and petroleum hydrocarbons. See also Gas Chromatography.
Food-Chain Transfer
A process by which substances in the tissues of lower-trophic-level organisms
are transferred to the higher-trophic-level organisms that feed on them.
Forage (feeding) Area
The area utilized by an organism for hunting or gathering food.
Fourier Transform Infrared Spectroscopy
A fourier transform infrared spectroscope is an analytical air monitoring
tool that uses a laser system chemically to identify contaminants.
Fumigant
A fumigant is a pesticide that is vaporized to kill pests. They often
are used in buildings and greenhouses.
G
Gas Chromatography
Gas chromatography is a technology used for investigating and assessing
soil, water, and soil gas contamination at a site. It is used for the
analysis of VOCs and SVOCs. The technique identifies and quantifies organic
compounds on the basis of molecular weight, characteristic fragmentation
patterns, and retention time. Recent advances in gas chromatography that
are considered innovative are portable, weather-proof units that have
self-contained power supplies.
Graphite Furnace Atomic Absorption (GFAA) Spectroscopy
Graphite furnace atomic absorption (GFAA) spectroscopy is a highly sensitive
spectroscopic technique that provides excellent detection limits for measuring
concentrations of metals in liquid sample media. Water samples may be
analyzed directly, while soil samples first must undergo an extraction
process to draw the contaminants into solution for analysis. The sample
is vaporized in the graphite furnace, and light of a specific wavelength
then is passed through the atomic vapor of an element of interest. The
attenuation of the intensity of the light as a result of absorption is
measured, and the amount of attenuation is converted into an estimate
of the contaminant metal's concentration.
Ground Water
CERCLA and the NCP define ground water as "water in a saturated zone or
stratum beneath the surface or land or water".
Ground-Penetrating Radar (GPR)
GPR is a technology that emits pulses of electromagnetic energy into the
ground to measure its reflection and refraction by subsurface layers and
other features, such as buried debris.
H
Habitat
Place where a plant or animal lives, often characterized by a dominant
plant form and physical characteristics. (PERTAINING TO ECOLOGICAL ASSESSMENTS)
Halogenated Organic Compound
A halogenated organic compound is a compound containing molecules of chlorine,
bromine iodine, and fluorine. Halogenated organic compounds were used
in high-voltage electrical transformers because they conducted heat well
while being fire resistant and good electrical insulators. Many herbicides,
pesticides, and degreasing agents are made from halogenated organic compounds.
Hazard
The likelihood that a substance will cause an injury or adverse effect
under specified conditions.
Hazard Assessment
This term has been used to mean either (1) evaluating the intrinsic effects
of a stressor (U.S. EPA, 1979) or (2) defining a margin of safety or quotient
by comparing a toxicologic effects concentration with an exposure estimate
(SETAC, 1987).
Hazard Identification
The process of determining whether exposure to a stressor can cause an
increase in the incidence or severity of a particular adverse effect,
and whether an adverse effect is likely to occur.
Hazard Index
The sum of more than one hazard quotient for multiple substances and/or
multiple exposure pathways. The HI is calculated separately for chronic,
subchronic, and shorter-duration exposures.
Hazard Quotient
The ratio of an exposure level to a substance to a toxicity value selected
for the risk assessment for that substance (e.g., LOAEL or NOAEL).
Hazard Ranking System (HRS)
The NCP defines the HRS as "the method used by EPA to evaluate the relative
potential of hazardous substance releases to cause health or safety problems,
or ecological or environmental damage." The HRS is the primary screening
tool used by EPA to assess the risks posed to human health or the environment
by abandoned or uncontrolled hazardous waste sites. Under the HRS, sites
are assigned scores on the basis of the toxicity of hazardous substances
that are present and the potential that those substances will spread through
the air, surface, water, or ground water, taking into account such factors
as the proximity of the substance to nearby populations. Scores are used
in determining which sites should be placed on the NPL. See also National
Priorities List.
Hazardous and Solid Waste Amendments (HSWA)
HSWA are 1984 amendments to RCRA which required phasing out land disposal
of hazardous waste and added minimum technology requirements. See
also Resource Conservation and Recovery Act.
Hazardous Substance
CERCLA defines a hazardous substance as "(A) any substance designated
pursuant to section 1321(b0(2)(A) of Title 33, (B) any element, compound,
mixture, solution or substance designated pursuant to section 9602 of
this title, (C) any hazardous waste having the characteristics identified
in under or listed pursuant to section 3001 of the Solid Waste Disposal
Act (but not including any waste the regulation of which the Solid Waste
Disposal Act has been suspended by Act or Congress), (D) any toxic pollutant
listed under section 1317(a) of Title 33, (E) any imminently hazardous
chemical substance or mixture with respect to which the (EPA) Administrator
has taken action pursuant to section 2606 of Title 15. The term does not
(within the context of CERCLA) include petroleum, crude oil or any fraction
thereof which is not otherwise specifically listed or designated as a
hazardous substance (by CERCLA)...The term (hazardous substance) does
not include natural gas, natural gas liquids, liquified natural gas, or
synthetic natural gas usable for fuel (or mixtures of natural gas and
such synthetic gas).
Health Assessment
An evaluation of available data on existing or potential risks to human
health posed by a Superfund site. The Agency for Toxic Substances and
Disease Registry (ATSDR) of the Department of Health and Human Services
is required to perform such an assessment at every site on the National
Priorities List.
Heavy Metal
The term heavy metal refers to a group of toxic metals including arsenic,
chromium, copper, lead, mercury, silver, and zinc. Heavy Metals often
are present at industrial sites at which operations have included battery
recycling and metal plating.
Herbicide
A herbicide is a chemical pesticide designed to control or destroy plants,
weeds, or grasses.
High-Frequency Electromagnetic (EM) Sounding
High-frequency EM sounding, the technology used for nonintrusive geophysical
exploration, projects high-frequency electromagnetic radiation into subsurface
layers to detect the reflection and refraction of the radiation by various
layers of soil. Unlike ground-penetrating radar, which uses pulses, the
technology uses continuous waves of radiation. See also Ground-Penetrating
Radar.
Home Range
The area to which an animal confines its activities. (PERTAINING TO ECOLOGICAL
ASSESSMENTS)
Hydrocarbon
A hydrocarbon is an organic compound containing only hydrogen and carbon,
often occurring in petroleum, natural gas, and coal.
Hydrogeology
Hydrogeology is the study of ground water, including its origin, occurrence,
movement, and quality.
Hydrology
Hydrology is the science that deals with the properties, movement, and
effects of water found on the earth's surface, in the soil and rocks beneath
the surface, and in the atmosphere.
Hydrophilic
Denoting the property of attracting or associating with water molecules;
characteristic of polar or charged molecules.
Hydrophobic
With regard to a molecule or side group, tending to dissolve readily in
organic solvents, but not in water, resisting wetting, not containing
polar groups or sub-groups.
Hydrophobic Dye
Hydrophobic dye is added to liquids to assist in the observation of the
presence of items that are colorless.
Hypothesis
A proposition set forth as an explanation for a specified phenomenon or
group of phenomena.
I
Ignitability
Ignitable wastes can create fires under certain conditions. Examples include
liquids, such as solvents that readily catch fire, and friction-sensitive
substances.
Immunoassay
Immunoassay is an innovative technology used to measure compound-specific
reactions (generally colorimetric) to individual compounds or classes
of compounds. The reactions are used to detect and quantify contaminants.
The technology is available in field-portable test kits.
Indirect Effect
An effect where the stressor acts on supporting components of the ecosystem,
which in turn have an effect on the ecological component of interest.
Infill Development
Infill development is new construction on previously developed land in
cities or developed suburbs. The term often refers to redevelopment of
small residential, commercial, or industrial properties. An important
aspect of many infill development projects is the enhancement of the built
environment with open space and parks.
Information Repository
An information repository is a location in a public building that is convenient
for local residents, such as a public school, city hall, or library, that
contains information about a Superfund site, including technical reports
and reference documents.
Infrared Monitor
An infrared monitor is a device used to monitor the heat signature of
an object, as well as to sample air. It may be used to detect buried objects
in soil.
Ingestion Rate
The rate at which an organism consumes food, water, or other materials
(e.g., soil, sediment). Ingestion rate usually is expressed in terms of
unit of mass or volume per unit of time (e.g.,kg/day, L/day).
Insecticide
An insecticide is a pesticide compound specifically used to kill or control
the growth of insects.
In Situ
The term in situ, "in its original place," or "on-site", means unexcavated
and unmoved. In situ soil flushing and natural attenuation are examples
of in situ treatment methods by which contaminated sites are treated without
digging up or removing the contaminants.
Integrated Risk Information System (IRIS)
IRIS is an electronic database that contains EPA's latest descriptive
and quantitative regulatory information about chemical constituents. Files
on chemicals maintained in IRIS contain information related to both noncarcinogenic
and carcinogenic health effects.
Interim Deliverables
A series of Standard Tables, Worksheets, and Supporting Information, identified
in the Workplan for each site, that should be developed by the risk assessment
author, and evaluated by the EPA risk assessor, prior to development of
the Draft Baseline Risk Assessment Report. After review and revision,
as necessary, these documents should be included in the Baseline Risk
Assessment Report. The Standard Tables should be prepared for each site
to achieve standardization in risk assessment reporting. The Worksheets
and Supporting Information should also be prepared to further improve
transparency, clarity, consistency, and reasonableness of risk assessments.
Ionization
The process by which a neutral atom loses or gains electrons, thereby
acquiring a net charge and becoming an ion.
L
LC50
A statistically or graphically estimated concentration that is expected
to be lethal to 50% of a group of organisms under specified conditions.
Leachate
A leachate is a contaminated liquid that results when water collects contaminants
as it trickles through wastes, agricultural pesticides, or fertilizers.
Leaching may occur in farming areas and landfills and may be a means of
the entry of hazardous substances into soil, surface water, or ground
water.
Lethal
Causing death by direct action.
Light Nonaqueous Phase Liquid (LNAPL)
An LNAPL is one of a group of organic substances that are relatively insoluble
in water and are less dense than water. LNAPLs, such as oil, tend to spread
across the surface of the water table and form a layer on top of the water
table.
Long-Term Monitoring
Long-term monitoring of a site typically is performed to verify that contaminants
pose no risk to human health or the environment and that natural processes
are reducing contaminant levels and risk as predicted.
Lines of Evidence
Information derived from different sources or by different techniques
that can be used to describe and interpret risk estimates. Unlike the
term "weight of evidence," it does not necessarily imply assignment of
quantitative weightings to information.
Lipid
One of a variety of organic substances that are insoluble in polar solvents,
such as water, but that dissolve readily in non-polar organic solvents.
Includes fats, oils, waxes, steroids, phospholipids, and carotenes.
Lowest-Observable-Adverse-Effect Level (LOAEL)
The lowest level of a stressor evaluated in a toxicity test or biological
field survey that has a statistically significant adverse effect on the
exposed organisms compared with unexposed organisms in a control or reference
site.
M
Magnetrometry
Magnetrometry is a geophysical technology used to detect disruptions that
metal objects cause in the earth's localized magnetic field.
Mass Spectrometry
Mass spectrometry is a method of chemical analysis in which the substance
to be analyzed is heated and placed in a vacuum. The resulting vapor is
exposed to a beam of electrons that causes ionization to occur, either
of the molecules or their fragments. The ionized atoms are separated according
to their mass and can be identified on that basis.
Matrix
The substance in which an analyte is embedded or contained; the properties
of a matrix depend on its constituents and form.
Maximum Acceptable Toxic Concentration (MATC)
For a particular ecological effects test, this term is used to mean either
the range between the NOAEL and the LOAEL or the geometric mean of the
NOAEL and the LOAEL. The geometric mean is also known as the chronic value.
Measure of Ecosystem and Receptor Characteristics
Measures that influence the behavior and location of ecological entities
of the assessment endpoint, the distribution of a stressor, and lifehistory
characteristics of the assessment endpoint or its surrogate that may affect
exposure or response to the stressor.
Measure of Effect
A change in an attribute of an assessment endpoint or its surrogate in
response to a stressor to which it is exposed.
Measure of Exposure
A measure of stressor existence and movement in the environment and its
contact or co-occurrence with the assessment endpoint.
Measurement Endpoint
A measurable ecological characteristic that is related to the valued
characteristic chosen as the assessment endpoint. Measurement endpoints
often are expressed as the statistical or arithmetic summaries of
the observations that make up the measurement. As used in this guidance
document, measurement endpoints can include measures of effect and
measures of exposure, which is a departure from U.S. EPA's (1992a)
definition which includes only measures of effect. (pertains to
ecological assessments)
Media
Specific environmental compartments-air, water, soil-which are the subject
of regulatory concern and activities.
Median Effective Concentration (EC50)
The concentration of a substance to which test organisms are exposed that
is estimated to be effective in producing some sublethal response in 50
percent of the test population. The EC50 usually is expressed
as a time-dependent value (e.g., 24-hour EC50). The sublethal
response elicited from the test organisms as a result of exposure must
be clearly defined.
Median Lethal Concentration (LC50)
A statistically or graphically estimated concentration that is expected
to be lethal to 50 percent of a group of organisms under specified conditions.
Medium
The environmental substance (e.g, air, water, soil) originally contaminated.
Medium EPC
The EPC, based on either a statistical derivation of measured data or
modeled data. The Medium EPC differs from the Route EPC in that the Medium
EPC does not consider the transfer of contaminants from one medium to
another.
Metallophytes
Metallophytes are plants that preferentially colonize in metal-rich soils.
Metric
Relating to measurement; a type of measurement-for example a measurement
of one of various components of community structure (e.g., species richness,
% similarity).
Migration Pathway
A migration pathway is a potential path or route of contaminants from
the source of contamination to contact with human populations or the environment.
Migration pathways include air, surface water, ground water, and land
surface. The existence and identification of all potential migration pathways
must be considered during assessment and characterization of a waste site.
Monitored Natural Attenuation
The term monitored natural attenuation refers to the remedial approach
that allows natural processes to reduce concentrations of contaminants
to acceptable levels. Monitored natural attenuation involves physical,
chemical, and biological processes that act to reduce the mass, toxicity,
and mobility of subsurface contamination. Physical, chemical, and biological
processes involved in monitored natural attenuation include biodegradation,
chemical stabilization, dispersion, sorption, and volatilization.
Monitoring Well
A monitoring well is a well drilled at a specific location on or off a
hazardous waste site at which ground water can be sampled at selected
depths and studied to determine the direction of ground water flow and
the types and quantities of contaminants present in the ground water.
Mortality
Death rate or proportion of deaths in a population.
N
National Contingency Plan (NCP)
The NCP is formally known as the "National Oil and Hazardous Substances
Pollution Contingency Plan, and is promulgated under 40 CFR Part 300.
RAGS Volume I, Part A defines the NCP as "the regulation that implements
CERCLA. Among other things, the NCP establishes the overall approach for
determining appropriate remedial actions at Superfund sites." See
also Superfund.
National Pollutant Discharge Elimination System (NPDES)
NPDES is the primary permitting program under the Clean Water Act, which
regulates all discharges to surface water. It prohibits discharge of pollutants
into waters of the United States unless EPA, a state, or a tribal government
issues a special permit to do so.
National Priorities List (NPL)
The NCP defines the NPL as "the list compiled by EPA pursuant to CERCLA
section 105, of uncontrolled hazardous substance releases in the United
States that are priorities for long-term evaluation and response.
Nonaqueous Phase Liquid (NAPL)
NAPLs are organic substances that are relatively insoluble in water and
are less dense than water. See also Dense Nonaqueous Phase Liquid
and Light Nonaqueous Phase Liquid.
National Response Center (NRC)
The NRC, staffed by the U.S. Coast Guard, is a communications center that
receives reports of discharges or releases of hazardous substances into
the environment. The U.S. Coast Guard in turn, relays information about
such releases to the appropriate federal agency.
Nonparametric
Statistical methods that make no assumptions regarding the distribution
of the data.
Non-Point Source
The term non-point source is used to identify sources of pollution that
are diffuse and do not have a point of origin or that are not introduced
into a receiving stream from a specific outlet. Common non-point sources
are rain water, runoff from agricultural lands, industrial sites, parking
lots, and timber operations, as well as escaping gases from pipes and
fittings.
No-Observed-Adverse-Effect Level (NOAEL)
The highest level of a stressor evaluated in a toxicity test or biological
field survey that causes no statistically significant difference in effect
compared with the controls or a reference site.
O
Organic Chemical or Compound
An organic chemical or compound is a substance produced by animals or
plants that contains mainly carbon, hydrogen, and oxygen.
Oxygenate
Oxygenates are hydrocarbons added to fuels to increase the oxygen
content of those fuels to improve combustion, thereby reducing emissions,
such as carbon monoxide and other pollutants. Examples of oxygenates
include methyl tertiary butyl ether (MTBE), ethyl tertiary butyl
ether (ETBE), tertiary amyl methyl ether (TAME), ethanol, and other
ethers and alcohols.
P
Parameter
Constants applied to a model that are obtained by theoretical calculation
or measurements taken at another time and/or place, and are assumed to
be appropriate for the place and time being studied.
Parametric
Statistical methods used when the distribution of the data is known.
Permeability
Permeability is a characteristic that represents a qualitative description
of the relative ease with which rock, soil, or sediment will transmit
a fluid (liquid or gas).
Pesticide
A pesticide is a substance or mixture of substances intended to prevent
or mitigate infestation by, or destroy or repel, any pest. Pesticides
can accumulate in the food chain and or contaminate the environment if
misused.
Phase I Environmental Assessment
A Phase I environmental assessment is an initial environmental investigation
that is limited to a historical records search to determine ownership
of a site and to identify the kinds of chemical processes that were carried
out at the site. A Phase I assessment includes a site visit, but does
not include any sampling. If such an assessment identifies no significant
concerns, Phase II and III audits are not necessary. Phase I assessments
also are commonly referred to as site assessments.
Phase II Environmental Assessment
A Phase II environmental assessment is an investigation that includes
tests performed at the site to confirm the location and identity of environmental
hazards. The assessment includes preparation of a report that includes
recommendations for cleanup alternatives. Phase II assessments also are
commonly referred to as site investigations.
Phytotoxic
The term phytotoxic is used to describe a substance that is harmful to
plants.
Plume
A plume is a visible or measurable emission or discharge of a contaminant
from a given point of origin into any medium. The term also is used to
refer to measurable and potentially harmful radiation leaking from a damaged
reactor.
Point Source
A point source is a stationary location or fixed facility from which pollutants
are discharged or emitted or any single, identifiable discharge point
of pollution, such as a pipe, ditch, or smokestack.
Population
An aggregate of individuals of a species within a specified location in
space and time.
Potentially Responsible Party (PRP)
A PRP is an individual or company (such as owners, operators, transporters,
or generators of hazardous waste) that is potentially responsible for,
or contributing to, the contamination problems at a Superfund site. Whenever
possible, EPA requires PRPs, through administrative and legal actions,
to clean up hazardous waste sites they have contaminated. See also
Comprehensive Environmental Response, Compensation, and Liability Act
and Superfund.
Power
The power of a statistical test indicates the probability of rejecting
the null hypothesis when it should be rejected (i.e., the null hypothesis
is false). Can be considered the sensitivity of a statistical test.
Precipitation
In analytic chemistry, the process of producing a separable solid phase
within a liquid medium.
Precision
A measure of the closeness of agreement among individual measurements.
Preliminary Assessment and Site Inspection (PA/SI)
A PA/SI is the process of collecting and reviewing available information
about a known or suspected hazardous waste site or release. The PA/SI
usually includes a visit to the site.
Preliminary Remediation Goals
Initial clean-up goals developed early in the remedy selection process
based on readily available information and are modified to reflect results
of the baseline risk assessment. They also are used during analysis of
remedial alternatives in the remedial investigation/feasibility study
(RI/FS).
Presumptive Remedies
Presumptive remedies are preferred technologies for common categories
of CERCLA sites that have been identified through historical patterns
of remedy selection and EPA's scientific and engineering evaluation of
performance data on technology implementation.
Primary Effect
An effect where the stressor acts on the ecological component of interest
itself, not through effects on other components of the ecosystem (synonymous
with direct effect; compare with definition for secondary effect).
Probabilistic Analysis (as opposed to deterministic analysis)
Calculation and expression of health risks using multiple risk descriptors
to provide the likelihood of various risk levels. Probabilistic risk results
approximate a full range of possible outcomes and the likelihood of each,
which often is presented as a frequency distribution graph, thus allowing
uncertainty or variability to be expressed quantitatively.
Probability Density Function (PDF)
Probability density functions are particularly useful in describing
the relative likelihood that a variable will have different particular
values of x. The probability that a variable will have a value within
a small interval around x can be approximated by multiplying f(x)
(i.e., the value of y at x in a PDF plot) by the width of the interval.
Prospective Risk Assessment
An evaluation of the future risks of a stressor(s) not yet released into
the environment or of future conditions resulting from an existing stressor(s).
Q
Quality Assurance (QA)
QA is a system of management activities that ensure that a process, item,
or service is of the type and quality needed by the user. QA deals with
setting policy and implementing an administrative system of management
controls that cover planning, implementation, and review of data collection
activities. QA is an important element of a quality system that ensures
that all research design and performance, environmental monitoring and
sampling, and other technical and reporting activities conducted by EPA
are of the highest possible quality.
Quality Control (QC)
QC refers to scientific precautions, such as calibrations and duplications,
that are necessary if data of known and adequate quality are to be acquired.
QC is technical in nature and is implemented at the project level. Like
QA, QC is an important element of a quality system that ensures that all
research design and performance, environmental monitoring and sampling,
and other technical and reporting activities conducted by EPA are of the
highest possible quality.
R
Radioactive Waste
Radioactive waste is any waste that emits energy as rays, waves, or streams
of energetic particles. Sources of such wastes include nuclear reactors,
research institutions, and hospitals.
Radionuclide
A radionuclide is a radioactive element characterized according
to its atomic mass and atomic number, which can be artificial or
naturally occurring. Radionuclides have a long life as soil or water
pollutants. Radionuclides cannot be destroyed or degraded; therefore,
applicable technologies involve separation, concentration and volume
reduction, immobilization, or vitrification.
RCRA Facility Assessment (RFA)
A RFA is performed at a facility to determine the existence of any continuous
or non-continuous releases of wastes. During the RFA, EPA or state regulators
gather information on solid waste management units and other areas of
concern at RCRA facilities, evaluate this information to determine whether
there are releases that warrant further investigation and action, and
determine the need to proceed to a RCRA Facility Investigation. See
also Resource Conservation and Recovery Act.
RCRA Facility Investigation (RFI)
The purpose of a RFI is to gather sufficient data at a facility to fully
characterize the nature, extent, and rate of migration of contaminant
releases identified in the RCRA Facility Assessment. The data generated
during the RFI is used to determine the potential need for corrective
measures and to aid in the selection and implementation of these measures.
See also Corrective Measure Study and Resource Conservation and Recovery
Act.
Reactivity
Reactive wastes are unstable under normal conditions. They can create
explosions and or toxic fumes, gases, and vapors when mixed with water.
Receptor
The ecological entity exposed to the stressor.
Receptor Age
The description of the exposed individual as defined by the EPA region
or dictated by the site.
Receptor Population
The exposed individual relative to the exposure pathway considered.
Record of Decision (ROD)
A ROD is a legal, technical, and public document that explains which cleanup
alternative will be used at a Superfund NPL site. The ROD is based on
information and technical analysis generated during the remedial investigation
and feasibility study (RI/FS) and consideration of public comments and
community concerns. See also Preliminary Assessment and Site Investigation
and Remedial Investigation and Feasibility Study.
Recovery
The rate and extent of return of a population or community to some aspect(s)
of its previous condition. Because of the dynamic nature of ecological
systems, the attributes of a "recovered" system should be carefully defined.
Reference Site
A relatively uncontaminated site used for comparison to contaminated sites
in environmental monitoring studies, often incorrectly referred to as
a control.
Regression Analysis
Analysis of the functional relationship between two variables; the independent
variable is described on the X axis and the dependent variable is described
on the Y axis (i.e. the change in Y is a function of a change in X).
Relative Risk Assessment
A process similar to comparative risk assessment. It involves estimating
the risks associated with different stressors or management actions. To
some, relative risk connotes the use of quantitative risk techniques,
while comparative risk approaches more often rely on professional judgment.
Others do not make this distinction.
Release
A "release" is defined by CERCLA as "any spilling, leaking, pumping, pouring,
emitting, emptying, discharging, injecting, escaping, leaching, dumping,
or disposing into the environment (including the abandonment or discarding
of barrels, containers and other closed receptacles containing any hazardous
substance or pollutant or contaminant". See also Resource Conservation
and Recovery Act.
Remedial Design and Remedial Action (RD/RA)
Remedial Design is defined in the NCP as "the technical analysis and procedures
which follow the selection of (a) remedy for a site and result in a detailed
set of plans and specifications for implementation of the remedial action.
See also Remedial Investigation and Feasibility Study. "Remedial
Action" is defined in the NCP in part as "those actions consistent with
(a) permanent remedy taken instead of, or in addition to, (a) removal
action(s) in the event of a release or threatened release of a hazardous
substance into the envrionment, to prevent or minimize the release of
hazardous substances so that they do not migrate or cause substantial
danger to present or future public health or welfare, or the environment."
CERCLA defines a removal action in part as "the cleanup or removal of
hazardous substances from the environment, which may be taken in the event
of the threat of release of hazardous substances into the environment."
Remedial Investigation and Feasibility Study (RI/FS) The RI/FS is the step in the Superfund cleanup process that is conducted to gather sufficient information to support the selection of a site remedy that will reduce or eliminate the risks associated with contamination at the site. The RI involves site characterization -- collection of data and information necessary to characterize the nature and extent of contamination at the site. The RI also determines whether the contamination presents a significant risk to human health or the environment. The FS focuses on the development of specific response alternatives for addressing contamination at a site.
Removal Action
CERCLA defines a removal action in part as "the cleanup or removal of
hazardous substances from the environment...which may be taken in the
event of the threat of release of hazardous substances into the environment."
See also Comprehensive Environmental Response, Compensation, and Liability
Act.
Replicate
Duplicate analysis of an individual sample. Replicate analyses are used
for quality control.
Reportable Quantity (RQ)
The RQ is the quantity of hazardous substances that, when released into
the environment, can cause substantial endangerment to public health or
the environment. Under CERCLA, the federal government must be notified
when quantities equaling or exceeding RQs specified in regulations are
released.
Representative Samples
Serving as a typical or characteristic sample; should provide analytical
results that correspond with actual environmental quality or the condition
experienced by the contaminant receptor.
Resource Conservation and Recovery Act (RCRA)
RCRA is a federal law enacted in 1976 that established a regulatory system
to track hazardous substances from their generation to their disposal.
The law requires the use of safe and secure procedures in treating, transporting,
storing, and disposing of hazardous substances. RCRA is designed to prevent
the creation of new, uncontrolled hazardous waste sites.
Response Action
A response action is a short-term removal action or a long-term remedial
response, authorized under CERCLA that is taken at a site to address releases
of hazardous substances.
Retrospective Risk Assessment
An evaluation of the causal linkages between observed ecological effects
and stressor(s) in the environment.
Reuse Assessment
A reuse assessment involves the collection and evaluation of information
to develop assumptions about reasonably anticipated future land use(s)
at Superfund sites. It provides a tool for implementing the Superfund
land use directive and can involve a review of available records, visual
inspections of the site, and discussions with local government officials,
property owners, and community members about potential future land uses.
Risk
The expected frequency or probability of undesirable effects resulting
from exposure to known or expected stressors.
Risk Assessment
Qualitative or quantitative evaluation of the risk posed to human health
and/or the environment by the actual or potential presence or release
of hazardous substances, pollutants or contaminants.
Risk-Based Corrective Action (RBCA)
As defined by EPA, RBCA is a streamlined approach through which exposure
and risk assessment practices are integrated with traditional components
of the corrective action process to ensure that appropriate and cost-effective
remedies are selected and that limited resources are allocated properly.
RBCA refers specifically to the standard Guide for Risk-Based Corrective
Action Applied At Petroleum Release Sites, published by ASTM. The RBCA
process can be tailored to applicable state and local laws and regulatory
practices. See also American Society for Testing and Materials.
Risk-Based Decision-Making (RBDM)
The term RBDM refers to a process through which decisions are made about
contaminated sites according to the risk each site poses to human health
and the environment. RBDM is a mechanism for identifying necessary and
appropriate action at any phase of the corrective action process. Depending
on known or anticipated risks to human health and the environment, appropriate
action can include site closure, monitoring and data collection, active
or passive remediation, containment, or imposition of institutional controls.
Risk Characterization
A phase of risk assessment that integrates the results of the exposure
and effects analyses to evaluate the likelihood of adverse effects associated
with exposure to the stressor. The ecological significance of the adverse
effects is discussed, including consideration of the types and magnitudes
of the effects, their spatial and temporal patterns, and the likelihood
of recovery.
Risk Communication
Risk communication, the exchange of information about health or environmental
risks among risk assessors, risk managers, the local community, news media
and interest groups, is the process of informing members of the local
community about environmental risks associated with a site and the steps
that are being taken to manage those risks.
Route EPC
The EPC, based on either a statistical derivation of measured data or
based on modeled data, that was selected to represent the route-specific
concentration for the exposure calculations. The Route EPC differs from
the Medium EPC in that the Route EPC may consider the transfer of contaminants
from one medium to another, where applicable for a particular exposure
route.
S
Safe Drinking Water Act
The Safe Drinking Water Act (SDWA) of 1974 was established to protect
the quality of drinking water in the United States. The act focuses on
all waters actually or potentially designed for use as drinking water,
whether from aboveground or underground sources. The Act authorized EPA
to establish safe standards of purity and requires all owners or operators
of public water systems to comply with primary (health-related) standards.
State governments that assume that authority from EPA also encourage attainment
of secondary (nuisance-related) standards.
Sample (Environmental)
Fraction of a material tested or analyzed; a selection or collection from
a larger collection.
Sampling and Analysis Plan A sampling and analysis plan (SAP) documents the procedural and analytical requirements for a one-time or time-limited project that involves the collection of samples of water, soil, sediment, or other media to characterize areas of potential environmental contamination. A SAP contains all the elements of a quality assurance project plan (QAPP) and a field sampling plan (FSP) that must be provided to meet the requirements for any project funded by the EPA under which environmental measurements are to be taken.
Sanborn Map
A Sanborn map is a record kept for insurance purposes that shows,
for a specific property, the locations of such items as USTs, buildings,
and areas where chemicals have been used for certain industrial
processes. A Phase I environmental assessment includes a review
of Sanborn maps. See also Phase I Environmental Assessment.
Saturated Zone
The saturated zone is the area beneath the surface of the land in which
all openings are filled with water.
Scenario Timeframe
The time period (current and/or future) being considered for the exposure
pathway.
Scientific/Management Decision Point (SMDP)
A point during the risk assessment process when the risk assessor communicates
results of the assessment at that stage to a risk manager. At this point
the risk manager determines whether the information is sufficient to arrive
at a decision regarding risk management strategies and/or the need for
additional information to characterize risk.
Secondary Effect
An effect where the stressor acts on supporting components of the ecosystem,
which in turn have an effect on the ecological component of interest (synonymous
with indirect effects; compare with definition for primary effect).
Sediment
Particulate material lying below water.
Semi-Volatile Organic Compound (SVOC)
SVOCs, composed primarily of carbon and hydrogen atoms, have boiling
points greater than 200°C. Common SVOCs include phenols and phthalates.
Sensitivity
In relation to toxic substances, organisms that are more sensitive exhibit
adverse (toxic) effects at lower exposure levels than organisms that are
less sensitive.
Sensitive Life Stage
The life stage (i.e., juvenile, adult, etc.) that exhibits the highest
degree of sensitivity (i.e., effects are evident at a lower exposure concentration)
to a contaminant in toxicity tests.
Sludge
Sludge is a semisolid residue from air or water treatment processes. Residues
from treatment of metal wastes and the mixture of waste and soil at the
bottom of a waste lagoon are examples of sludge, which can be a hazardous
waste.
Solubility
Solubility is a measure of the amount of solute that will dissolve in
a solution. It is the ability or tendency of one substance to dissolve
into another at a given temperature and pressure and is generally expressed
in terms of the amount of solute that will dissolve in a given amount
of solvent to produce a saturated solution.
Source
An entity or action that releases to the environment or imposes on the
environment a chemical, physical, or biological stressor or stressors.
Source Term
As applied to chemical stressors, the type, magnitude, and patterns of
chemical(s) released.
Species
A group of organisms that actually or potentially interbreed and are reproductively
isolated from all other such groups; a taxonomic grouping of morphologically
similar individuals; the category below genus.
Standard Operating Procedure
A standard operating procedure (SOP) is a step-by-step procedure that
promotes uniformity in operations to help clarify and augment such operations.
SOPs document the way activities are to be performed to facilitate consistent
conformance to technical and quality system requirements and to support
data quality. The use of SOPs is an integral part of a successful quality
system because SOPs provide individuals with the information needed to
perform a job properly and facilitate consistency in the quality and integrity
of a product or end result. SOPs also provide guidance in areas in which
the exercise of professional judgment is necessary and specify procedures
that are unique to each task.
Standard Tables
One of the Standard Tools under the RAGS Part D approach. The Standard
Tables have been developed to clearly and consistently document important
parameters, data, calculations, and conclusions from all stages of human
health risk assessment development. Electronic templates for the Standard
Tables have been developed in LOTUS and EXCEL for ease of use by risk
assessors. For each site-specific risk assessment, the Standard Tables,
related Worksheets, and Supporting Information should first be prepared
as Interim Deliverables for EPA risk assessor review, and should later
be included in the Draft and Final Baseline Risk Assessment Reports. The
Standard Tables may be found in Appendix A and on the electronic media
provided with this guidance document. Use of the Standard Tables will
standardize the reporting of human health risk assessments. The Standard
Table formats can not be altered (i.e., columns can not be added, deleted,
or changed); however, rows and footnotes can be added as appropriate.
Standardization of the Tables is needed to achieve Superfund program-wide
reporting consistency and to accomplish electronic data transfer to the
Superfund database.
Standard Tools
A basic element of the RAGS Part D approach. The Standard Tools have been
developed to standardize the planning, reporting, and review of Superfund
risk assessments. The three Standard Tools contained in the Part D approach
include the Technical Approach for Risk Assessment (TARA), the Standard
Tables, and Instructions for the Standard Tables.
Statistic
A computed or estimated statistical quantity such as the mean, the standard
deviation, or the correlation coefficient.
Stratigraphy
Stratigraphy is the study of the formation, composition, and sequence
of sediments, whether consolidated or not.
Stress Regime
The term "stress regime" has been used in at least three distinct ways:
(1) to characterize exposure to multiple chemicals or to both chemical
and nonchemical stressors (more clearly described as multiple exposure,
complex exposure, or exposure to mixtures), (2) as a synonym for exposure
that is intended to avoid overemphasis on chemical exposures, and (3)
to describe the series of interactions of exposures and effects resulting
in secondary exposures, secondary effects and, finally, ultimate effects
(also known as risk cascade [Lipton et al., 1993]), or causal chain, pathway,
or network (Andrewartha and Birch, 1984).
Stressor
Any physical, chemical, or biological entity that can induce an adverse
response.
Stressor-Response Profile
The product of characterization of ecological effects in the analysis
phase of ecological risk assessment. The stressor-response profile summarizes
the data on the effects of a stressor and the relationship of the data
to the assessment endpoint.
Sublethal
Below the concentration that directly causes death. Exposure to sublethal
concentrations of a substance can produce less obvious effects on behavior,
biochemical and/or physiological functions, and the structure of cells
and tissues in organisms.
Supporting Information
Information submissions that substantiate or summarize detailed data analysis,
calculations, or modeling and associated parameters and assumptions. Examples
of recommended Supporting Information include: derivations of background
values, exposure point concentrations, modeled intakes, and chemical-specific
parameters. Supporting Information should be provided as Interim Deliverables
for EPA risk assessor review prior to the development of the Draft Baseline
Risk Assessment Report.
Surface Water
Surface water is all water naturally open to the atmosphere, such as rivers,
lakes, reservoirs, streams, and seas.
Superfund
Superfund is the trust fund that provides for the cleanup of hazardous
substances released into the environment, regardless of fault. The Superfund
was established under CERCLA and subsequent amendments to CERCLA. The
term Superfund also is used to refer to cleanup programs designed and
conducted under CERCLA and its subsequent amendments. See also Comprehensive
Environmental Response, Compensation, and Liability Act.
Superfund Amendment and Reauthorization Act (SARA)
SARA is the 1986 act amending CERCLA that increased the size of the Superfund
trust fund and established a preference for the development and use of
permanent remedies, and provided new enforcement and settlement tools.
See also Comprehensive Environmental Response, Compensation, and Liability
Act.
Systematic Planning
Systematic planning is a planning process that is based on the scientific
method. It is a common-sense approach designed to ensure that the level
of detail in planning is commensurate with the importance and intended
use of the data, as well as the available resources. Systematic planning
is important to the successful execution of all activities at hazardous
waste sites, but it is particularly important to dynamic field activities
because those activities rely on rapid decision-making. The data quality
objective (DQO) process is one formalized process of systematic planning.
All dynamic field activities must be designed through the use of systematic
planning, whether using DQO steps or some other system. See also Data
Quality Objective.
T
Technical Approach for Risk Assessment (TARA)
One of the Standard Tools under the RAGS Part D approach. The TARA is
a road map for incorporating continuous involvement of the EPA risk assessor
throughout the CERCLA remedial process. Risk-related activities, beginning
with scoping and problem formulation, extending through collection and
analysis of risk-related data, and supporting risk management decision
making and remedial design/remedial action issues are addressed. The TARA
should be customized for each site and the requirements identified should
be included in project workplans so that risk assessment requirements
and approaches are clearly defined. Chapters 2 through 5 of Part D present
the TARA. Worksheets Formats for documenting assumptions, input parameters,
and conclusions regarding complex risk assessment issues. The Data Useability
Worksheet (found in Exhibit 3-3) should be an Interim Deliverable for
all sites. Worksheets addressing Lead and Radionuclides are under development
and will be provided in a revision to RAGS Part D.
Technical Assistance Grant (TAG)
An EPA grant awarded to eligible community groups for the purpose of hiring
an independent technical advisor, enabling community members to participate
more effectively in the decision-making process at Superfund sites.
Threshold Concentration
A concentration above which some effect (or response) will be produced
and below which it will not.
Total Petroleum Hydrocarbon (TPH)
TPH refers to a measure of concentration or mass of petroleum hydrocarbon
constituents present in a given amount of air, soil, or water.
Toxic Mechanism of Action
The mechanism by which chemicals produce their toxic effects, i.e., the
mechanism by which a chemical alters normal cellular biochemistry and
physiology. Mechanisms can include; interference with normal receptor-ligand
interactions, interference with membrane functions, interference with
cellular energy production, and binding to biomolecules.
Toxicant
A poisonous substance.
Toxicity
EPA's Integrated Risk Information System (IRIS) defines toxicity as "The
degree to which a chemical substance (or physical agent) elicits a deleterious
or adverse effect upon the biological system of an organism exposed to
the substance over a designated time period."
Toxicity Assessment
Review of literature, results in toxicity tests, and data from field surveys
regarding the toxicity of any given material to an appropriate receptor.
Toxicity Characteristic Leaching Procedure (TCLP)
The TCLP is a testing procedure used to identify the toxicity of
wastes and is the most commonly used test for degree of mobilization
offered by a solidification and stabilization process. Under this
procedure, a waste is subjected to a process designed to model the
leaching effects that would occur if the waste was disposed of in
a RCRA Subtitle D municipal landfill.
Toxic Substance
A toxic substance is a chemical or mixture that may present an unreasonable
risk of injury to health or the environment. Toxic Substances Control
Act (TSCA) TSCA was enacted in 1976 to test, regulate, and screen all
chemicals produced or imported into the U.S. TSCA requires that any chemical
that reaches the consumer marketplace be tested for possible toxic effects
prior to commercial manufacture. Any existing chemical that poses health
and environmental hazards is tracked and reported under TSCA.
Toxicity Test
The means by which the toxicity of a chemical or other test material is
determined. A toxicity test is used to measure the degree of response
produced by exposure to a specific level of stimulus (or concentration
of chemical) compared with an unexposed control.
Toxicity Value
A numerical expression of a substance's exposure-response relationship
that is used in risk assessments.
Trophic Level
A functional classification of taxa within a community that is based on
feeding relationships (e.g., aquatic and terrestrial plants make up the
first trophic level, and herbivores make up the second).
Type I Error
Rejection of a true null hypothesis.
Type II Error
Acceptance of a false null hypothesis.
U
Uncertainty
Imperfect knowledge concerning the present or future state of the system
under consideration; a component of risk resulting from imperfect knowledge
of the degree of hazard or of its spatial and temporal distribution.
Underground Storage Tank (UST)
A UST is a tank and any underground piping connected to the tank that
is used to contain gasoline or other petroleum products or chemical solutions
and that is placed in such a manner that at least 10 percent of its combined
volume is underground.
Unexploded Ordnance
The term exploded ordnance refers to any munition, weapon delivery system,
or ordnance item that contains explosives, propellants, and chemical agents.
Unexploded ordnance (UXO) consists of the same items after they: (1) have
been armed or otherwise prepared for action; (2) have been launched, placed,
fired, or released in such a manner as to constitute a hazard to operations,
installations, personnel, or material; and (3) remain unexploded either
by design or by malfunction, or for any other reason.
Uptake
A process by which materials are transferred into or onto an organism.
V
Vadose Zone
The vadose zone is the area between the surface of the land and the surface
of the water table in which the moisture content is less than the saturation
point and the pressure is less than atmospheric. The openings (pore spaces)
also typically contain air or other gases.
Vapor
Vapor is the gaseous phase of any substance that is liquid or solid at
atmospheric temperatures and pressures. Steam is an example of a vapor.
Volatile Organic Compound (VOC)
A VOC is one of a group of carbon-containing compounds that evaporate
readily at room temperature. Examples of VOCs include trichloroethane;
trichloroethylene; and BTEX. These contaminants typically are generated
from metal degreasing, printed circuit board cleaning, gasoline, and wood
preserving processes.
Volatilization
The conversion of a chemical substance from a liquid or solid state to
a gaseous vapor state.
W
Wastewater
Wastewater is spent or used water from an individual home, a community,
a farm, or an industry that contains dissolved or suspended matter.
X
Xenobiotic
A chemical or other stressor that does not occur naturally in the environment.
Xenobiotics occur as a result of anthropogenic activities such as the
application of pesticides and the discharge of industrial chemicals to
air, land, or water.
Z
Zoning
Zoning is the exercise of the civil authority of a municipality to regulate
and control the character and use of property.