Go To Toxicological Acronyms

 

CLEANUP LEVELS ACRONYMS

ASLs - Any-Use Soil Levels, levels used for registry sites in Missouri

ATSDR - Agency for Toxic Substances and Disease Registry. This is the health agency that supports the EPA as well as other agencies and the public.

BTEX - Acronym for the suite of the following chemicals; benzene, toluene, ethylbenzene and xylene

CALM - Cleanup Action Levels for Missouri, the tiered guidance and the levels used for some VCP sites in Missouri.

cleach - Leaching concentration, chemical-specific, a level that addresses the leaching to groundwater pathway when calculating cleanup levels for soils. More info in the EPA Soil Screening Guidance.

csat - Saturation concentration, chemical-specific, a level that addresses the concentration in soils at which a chemical might become saturated and therefore, possibly migrate from the soil particles and pore spaces. More info in the EPA Soil Screening Guidance.

DEP - Usually the Department of Environmental Protection, a state department with environmental oversight

DEQ - Usually the Department of Environmental Quality, a state department with environmental oversight

EPA - United States Environmental Protection Agency

IRIS - Integrated Risk Information System. EPA-supported database of toxicological values used in risk assessments and in calculations of cleanup levels.

koc - Soil organic carbon - water partition coefficient (mouthful). What does it mean? Check the Soil Screening Guidance for info on this variable. You can find some koc values in SSG's Attachment C here.

MCLs - Maximum Contaminant Levels, EPA standards for drinking water. Used as the screening and cleanup levels at many hazardous waste sites. NOTE: Although it is commonly believed, not all MCLs are based on a 1 x 10(-6) target risk. Some MCL levels were set to other risk levels or set to a non-risk-based level to account for sampling technology, aesthetics, etc. Also, many of the that were set to risk levels were for the ingestion pathway only.

MCLGs - Maximum Contaminant Level Goals, EPA levels they would like to see in water. Due to many factors (see MCLs), not all MCLs are as protective as many would like. These levels are usually lower (or the same in some cases) as MCLs.

MCP - Massachusetts Contingency Plan

MEGs - Maximum Exposure Guidelines, Maine levels for drinking water.

MRLs - Minimum Risk Levels, health-based levels published by ATSDR.

MSLs - Medium-specific Screening Levels. risk-based levels published by EPA Region 6.

MTBE - Methyl tertbutyl ether, a gasoline additive that is\was believed to reduce emissions\pollution but is now seeping into many water supplies from leaking gasoline tanks

PCBs - Polychlorinated Biphenyls - For us laypersons, an example is the heavy liquid stuff found in older electrical transformers

PHGs - Public Health Goals, levels used by CalEPA for water

PRGs - Preliminary Removal Goals, Preliminary Remedial Goals, Preliminary Remediation Goals, etc., levels used by EPA and others, for example, the state of Kentucky, for screening, assessment, monitoring and/or cleanup. Usually refers to USEPA Region 9's Preliminary Remediation Goals (GO).

RAGS - Risk Assessment Guidance For Superfund, EPA

RAIS - Risk Assessment Information System, Internet resource for finding cleanup levels

RBCs - Risk-based Concentrations, levels used in EPA Region 3

RBSLs - Risk-based Screening Levels, levels used in the Montana DEQ Program for petroleum releases

RELs - Acute and Chronic Reference Exposure Levels, levels used by CalEPA for air

RCLs - Recommended Soil Cleanup Levels, soil levels used for Utah's UST sites

SQAGs - Numerical Sediment Quality Assessment Guidelines for Florida Coastal Waters

SRLS - Soil Remediation Levels, soil levels for sites in Arizona

SRVS - Draft Soil Reference Values, to be used by Minnesota's VCP Program

SSG - EPA Soil Screening Guidance

SSLs - Soil Screening Levels, term for levels presented in EPA's Soil Screening Guidance. Also, the acronym used by some state programs for their cleanup levels, including New Mexico.

SVOCs - Semi-volatile Organic Compounds

TPH - Total Petroleum Hydrocarbons. Need info on this? Call your state resource\environmental protection program and ask for the Tanks section. Those guys know this stuff backwards and forwards.

UST - Underground Storage Tanks

VCP - Voluntary Cleanup Program, state programs that are designed to allow more remedial flexibility

VRP - Voluntary Remediation Program, state programs that are designed to allow more remedial flexibility

VOCs - Volatile Organic Compounds

 

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Toxicological Terms

BORROWED (AND MODIFIED) FROM THOSE WONDERFUL FOLKS AT IRIS. Go to IRIS Glossary.

 
 
Acceptable Daily Intake (ADI): The amount of a chemical a person can be exposed to on a daily basis over an extended period of time (usually a lifetime) without suffering deleterious effects.
 
Acute Exposure: One dose or multiple doses of short duration spanning less than or equal to 24 hours.
 
Acute Toxicity: Any poisonous effect produced within a short period of time following an exposure, usually 24 to 96 hours.
 
Adverse Effect: A biochemical change, functional impairment, or pathologic lesion that affects the performance of the whole organism, or reduces an organism's ability to respond to an additional environmental challenge.
 
Average Daily Dose (ADD) : Dose rate averaged over a pathway-specific period of exposure expressed as a daily dose on a per-unit-body-weight basis. The ADD is usually expressed in terms of mg/kg-day or other mass-time units.
 
Background Levels: Two types of background levels may exist for chemical substances:. (a) Naturally occurring levels: Ambient concentrations of substances present in the environment, without human influence; (b) Anthropogenic levels: Concentrations of substances present in the environment due to human-made, non-site sources (e.g., automobiles, industries).
 
Benchmark Dose (BMD) or Concentration (BMC): A statistical lower confidence limit on the dose that produces a predetermined change in response rate of an adverse effect (called the benchmark response or BMR) compared to background.
 
Benchmark Response (BMR): An adverse effect, used to define a benchmark dose from which an RfD (or RfC) can be developed. The change in response rate over background of the BMR is usually in the range of 5-10%, which is the limit of responses typically observed in well-conducted animal experiments.
 
Bioavailability: The degree to which a substance becomes available to the target tissue after administration or exposure.
 
Carcinogen: An agent capable of inducing cancer.
 
Chronic Effect: An effect which occurs as a result of repeated or long term (chronic) exposures.
 
Chronic Exposure: Multiple exposures occurring over an extended period of time, or a significant fraction of the animal's or the individual's lifetime.
 
Chronic Toxicity: The capacity of a substance to cause adverse human health effects as a result of chronic exposure.
 
Co-carcinogen: An agent, when administered with a carcinogen, enhances the activity of the carcinogen.
 
Critical Concentration: An ambient chemical concentration expressed in units of µg/m3 and used in the operational derivation of the inhalation RfC. This concentration will be the NOAEL Human Equivalent Concentration (HEC) adjusted from principal study data.
 
Critical Effect: The first adverse effect, or its known precursor, that occurs to the most sensitive species as the dose rate of an agent increases.
 
Developmental Toxicity: Adverse effects on the developing organism that may result from exposure prior to conception (either parent), during prenatal development, or postnatally until the time of sexual maturation.
 
Dose-Response Assessment: A determination of the relationship between the magnitude of an administered, applied, or internal dose and a specific biological response. Response can be expressed as measured or observed incidence, percent response in groups of subjects (or populations), or as the probability of occurrence within a population.
 
Dose-Response Relationship: The relationship between a quantified exposure (dose), and the proportion of subjects demonstrating specific, biological changes (response).
 
Endpoint: An observable or measurable biological event or chemical concentration (e.g., metabolite concentration in a target tissue) used as an index of an effect of a chemical exposure.
 
Estimated Exposure Dose (EED): The measured or calculated dose to which humans are likely to be exposed considering all sources and routes of exposure.
 
Excess Lifetime Risk: The additional or extra risk of developing cancer due to exposure to a toxic substance incurred over the lifetime of an individual.
 
Exposure: Contact made between a chemical, physical, or biological agent and the outer boundary of an organism. Exposure is quantified as the amount of an agent available at the exchange boundaries of the organism (e.g., skin, lungs, gut).
 
Exposure Assessment: An identification and evaluation of the human population exposed to a toxic agent, describing its composition and size, as well as the type, magnitude, frequency, route and duration of exposure.
 
Hazard: A potential source of harm.
 
Hazard Assessment: The process of determining whether exposure to an agent can cause an increase in the incidence of a particular adverse health effect (e.g., cancer, birth defect) and whether the adverse health effect is likely to occur in humans.
 
Human Equivalent Concentration (HEC) or Dose (HED): The human concentration (for inhalation exposure) or dose (for other routes of exposure) of an agent that is believed to induce the same magnitude of toxic effect as the experimental animal species concentration or dose.
Individual Risk: The probability that an individual will experience an adverse effect.
 
Interspecies Dose Conversion: The process of extrapolating from animal doses to human equivalent doses.
 
Latency Period: The time between first exposure to an agent and manifestation or detection of a health effect of interest.
 
Limited Evidence: A term used in evaluating study data for the classification of a carcinogen by the 1986 U.S. EPA guidelines for carcinogen risk assessment. This classification indicates that a causal interpretation is credible but that alternative explanations such as chance, bias, and confounding variables could not be completely excluded.
 
Linear dose response: A pattern of frequency or severity of biological response that varies proportionately with the amount of dose of an agent.
 
Linearized Multistage Procedure: A modification of the multistage model, used for estimating carcinogenic risk, that incorporates a linear upper bound on extra risk for exposures below the experimental range.
 
Lower limit on Effective Dose 10 (LED10): The 95% lower confidence limit of the dose of a chemical needed to produce an adverse effect in 10 percent of those exposed to the chemical, relative to control.
 
Lowest-Observed-Adverse-Effect Level (LOAEL): The lowest exposure level at which there are statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control group. Also referred to as lowest-effect level (LEL).
 
Lowest-Observed Effect Level (LOEL or LEL): In a study, the lowest dose or exposure level at which a statistically or biologically significant effect is observed in the exposed population compared with an appropriate unexposed control group.
 
Margin of Exposure (MOE): The LED10 or other point of departure divided by the actual or projected environmental exposure of interest.
 
Maximum Likelihood (ML) method, Maximum Likelihood Estimate (MLE): Statistical method for estimating model parameters. Generally provides a mean or central tendency estimate, as opposed to a confidence limit on the estimate.
 
Model: A mathematical function with parameters that can be adjusted so the function closely describes a set of empirical data. A mechanistic model usually reflects observed or hypothesized biological or physical mechanisms, and has model parameters with real world interpretation. In contrast, statistical or empirical models selected for particular numerical properties are fitted to data; model parameters may or may not have real world interpretation. When data quality is otherwise equivalent, extrapolation from mechanistic models (e.g., biologically based dose-response models) often carries higher confidence than extrapolation using empirical models (e.g., logistic model).
 
Modifying Factor (MF): A factor used in the derivation of a reference dose or reference concentration. The magnitude of the MF reflects the scientific uncertainties of the study and database not explicitly treated with standard uncertainty factors (e.g., the completeness of the overall database). A MF is greater than zero and less than or equal to 10, and the default value for the MF is 1.
 
Monte Carlo Technique: A repeated random sampling from the distribution of values for each of the parameters in a calculation (e.g., lifetime average daily exposure), to derive a distribution of estimates (of exposures) in the population.
 
Mutagen: A substance that can induce an alteration in the structure of DNA.
 
No-Observed-Adverse-Effect Level (NOAEL): An highest exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effect between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered adverse, nor precursors to adverse effects.
 
No-Observed-Effect Level (NOEL): An exposure level at which there are no statistically or biologically significant increases in the frequency or severity of any effect between the exposed population and its appropriate control.
 
Oncogenic: Resulting from a gene which can induce neoplastic transformations in the cell in which it occurs or into which it is introduced.
 
ppb: A unit of measure expressed as parts per billion. Equivalent to 1 x 10-9
 
ppm: A unit of measure expressed as parts per million. Equivalent to 1 x 10-6
 
Prevalence: The proportion of disease cases that exist within a population at a specific point in time, relative to the number of individuals within that population at the same point in time.
 
Promoter: An agent that is not carcinogenic itself, but when administered after an initiator of carcinogenesis, stimulates the clonal expansion of the initiated cell to produce a neoplasm.
 
Reference Concentration (RfC): An estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark concentration, with uncertainty factors generally applied to reflect limitations of the data used. Generally used in EPA's noncancer health assessments.
 
Reference Dose (RfD): An estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark dose, with uncertainty factors generally applied to reflect limitations of the data used. Generally used in EPA's noncancer health assessments.
 
Risk (in the context of human health): The probability of injury, disease, or death from exposure to a chemical agent or a mixture of chemicals. In quantitative terms, risk is expressed in values ranging from zero (representing the certainty that harm will not occur) to one (representing the certainty that harm will occur). The following are examples of how risk is expressed within IRIS: E-4 or 10-4 = a risk of 1/10,000; E-5 or 10-5 = 1/100,000; E-6 or 10-6 = 1/1,000,000. Similarly, 1.3 E-3 or 1.3 x 10-3 = a risk of 1.3/1,000=1/770; 8 E-3 or 8 x 10-3 = a risk of 1/125 and 1.2 E-5 or 1.2 x 10-5 = a risk of 1/83,000.
 
Risk Assessment (in the context of human health): The determination of potential adverse health effects from exposure to chemicals, including both quantitative and qualitative expressions of risk. The process of risk assessment involves four major steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization.
 
Risk Management (in the context of human health): A decision making process that accounts for political, social, economic and engineering implications together with risk-related information in order to develop, analyze and compare management options and select the appropriate managerial response to a potential chronic health hazard.
Short-Term Exposure: Multiple or continuous exposure to an agent for a short period of time, usually one week.
 
Slope Factor: An upper bound, approximating a 95% confidence limit, on the increased cancer risk from a lifetime exposure to an agent. This estimate, usually expressed in units of proportion (of a population) affected per mg/kg/day, is generally reserved for use in the low-dose region of the dose-response relationship, that is, for exposures corresponding to risks less than 1 in 100.
 
Subchronic Exposure: Exposure to a substance spanning approximately 10% of the lifetime of an organism.
 
Sufficient Evidence: A term used in evaluating study data for the classification of a carcinogen under the 1986 U.S. EPA guidelines for carcinogen risk assessment. This classification indicates that there is a causal relationship between the agent or agents and human cancer.
 
Systemic Effects or Systemic Toxicity: Toxic effects as a result of absorption and distribution of a toxicant to a site distant from its entry point, at which point effects are produced. Not all chemicals that produce systemic effects cause the same degree of toxicity in all organs.
 
Teratogenic: Structural developmental defects due to exposure to a chemical agent during formation of individual organs.
 
Threshold: The dose or exposure below which no deleterious effect is expected to occur.
 
Toxicity: The degree to which a chemical substance elicits a deleterious or adverse effect upon the biological system of an organism exposed to the substance over a designated time period.
 
Threshold Limit Value (TLV): Recommended guidelines for occupational exposure to airborne contaminants published by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs represent the average concentration in mg/m3 for an 8-hour workday and a 40-hour work week to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.
 
Uncertainty Factor (UF): One of several, generally 10-fold factors, used in operationally deriving the RfD and RfC from experimental data. UFs are intended to account for (1) the variation in sensitivity among the members of the human population, i.e., interhuman or intraspecies variability; (2) the uncertainty in extrapolating animal data to humans, i.e., interspecies variability; (3) the uncertainty in extrapolating from data obtained in a study with less-than-lifetime exposure to lifetime exposure, i.e., extrapolating from subchronic to chronic exposure; (4) the uncertainty in extrapolating from a LOAEL rather than from a NOAEL; and (5) the uncertainty associated with extrapolation from animal data when the data base is incomplete.
 
Unit Risk: The upper-bound excess lifetime cancer risk estimated to result from continuous exposure to an agent at a concentration of 1 µg/L in water, or 1 µg/m3 in air. The interpretation of unit risk would be as follows: if unit risk = 1.5 x 10-6 µg/L, 1.5 excess tumors are expected to develop per 1,000,000 people if exposed daily for a lifetime to 1 µg of the chemical in 1 liter of drinking water.
 
Weight-of-Evidence (WOE) for Carcinogenicity: A system used by the U.S. EPA for characterizing the extent to which the available data support the hypothesis that an agent causes cancer in humans. Under EPA's 1986 risk assessment guidelines, the WOE was described by categories "A through E", Group A for known human carcinogens through Group E for agents with evidence of noncarcinogenicity. The approach outlined in EPA's proposed guidelines for carcinogen risk assessment (1996) considers all scientific information in determining whether and under what conditions an agent may cause cancer in humans, and provides a narrative approach to characterize carcinogenicity rather than categories.

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Updated May 5, 2001