GLOSSARY OF EXPOSURE ASSESSMENT-RELATED TERMS: A COMPILATION Prepared by the Exposure Terminology Subcommittee of the IPCS Exposure Assessment Planning Workgroup for the International Programme on Chemical Safety Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals November 1, 2001 This document is a compilation (a secondary reference). Citations should be made to the original documents, which are referenced herein. This compilation has been developed for the IPCS Exposure Terminology Subcommittee. It does not necessarily represent the views or stated policy of UNEP, ILO or WHO. The International Programme on Chemical Safety (IPCS) Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals GLOSSARY OF EXPOSURE ASSESSMENT-RELATED TERMS: A COMPILATION Preamble This is an unedited selection of exposure assessment related terms taken from a combination of 57 glossaries for exposure and related fields (references below). It has been prepared for the IPCS Exposure Terminology Subcommittee as a research paper for discussion purposes. It makes no pretense at being comprehensive; the 57 glossaries were those that were available to the Subcommittee when the project was in progress. Efforts to obtain several other glossaries were unsuccessful in the period when the work was being done. This compilation is being made available on the IPCS Harmonization website to aid researchers in finding differences in definitions for exposure-related terms, which is part of the original intent of the Exposure Terminology Subcommittee. Selections of terms in this glossary were based on the IPCS Exposure Terminology Subcommittee’s opinion of relevance to exposure assessment. Toxicological terms, risk-related terms, chemical names, procedural terms, and risk management terms were generally excluded from this list, as were terms clearly outside the risk assessment paradigm altogether. The definitions are presented as they were worded in the references, with minor adjustments to reflect agreement among several definitions as to singular vs. plural definitions (e.g., source vs. sources). The order in which the definitions are presented is alphabetical by reference, and should not imply order of importance or “correctness.” Where several references give the same definition, the references are listed in order of dates, with oldest first. The International Programme on Chemical Safety (IPCS) Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals GLOSSARY OF EXPOSURE ASSESSMENT-RELATED TERMS: A COMPILATION Absorbed dose - a. See internal dose. [REAP, Environmental Health Terms]; b. The unitless fraction of the applied dose or as the 1995: Residential Exposure Assessment penetration of a substance through a barrier percent absorbed. [USEPA, 1992a: Dermal Project][USEPA, 1992: GL for Exposure (e.g., the skin, gut, or lungs). [REAP, 1995: Exposure Assessment] Assessment]; b. 1.The energy imparted to a Residential Exposure Assessment Project]; c. unit mass of matter by ionizing radiation. The 1. The penetration of one substance into or Absorption percent - (percent absorbed) The unit of absorbed dose is the rad. One rad through another. 2. Specifically, the relative amount of a substance that penetrates equals 100 ergs per gram. 2.The amount of a penetration of a substance into the body from through a barrier into the body, reported as a substance absorbed into the body, usually per the skin, lungs, or digestive tract. [SRA, 1999: unitless fraction. [USEPA, 1997b: Exposure unit of time. The most common unit of dose is Glossary of Risk Analysis Terms, attributed to Factors Handbook]; mg per kg body weight per day (mg/kg_day). Stephen L. Brown][USDOE, 2000: RAIS [SRA, 1999: Glossary of Risk Analysis Terms, Glossary]; d. The taking in of water and Absorption of radiation - The uptake of attributed to Stephen L. Brown]; c. Energy dissolved minerals and nutrients across cell radiation by a solid body, liquid or gas. The absorbed by matter from ionizing radiation membranes. Contrast with ingestion. [UCMP, absorbed energy may be transferred or per unit mass of irradiated material at the place 1998: Glossary of Ecological Terms]; e. A re_emitted. [USEPA, 2000: Global Warming of interest in that material. The absorbed dose mode of entry of a toxic substance into the Glossary] is expressed in units of rad (or gray) (1 rad = body in which the substance enters through the 0.01 gray). [USDOE, 1998: Radiological unbroken skin. [University of Kentucky, 1999: Acceptable daily intake (ADI) - a. The Control Manual]; d. The energy imparted to a Glossary of Safety Terms]; f. The process by highest daily amount of a substance that may unit mass of matter by ionizing radiation. The which a substance is transported across the be consumed over a lifetime without adverse unit of absorbed dose is the rad or gray. One skin permeability surface barrier and taken up effects. [CARB, 2000: Glossary of Air rad equals 100 ergs per gram. The amount of a into the living tissue of the body; generally Pollution Terms]; b. This is an estimate of substance absorbed into the body, usually per synonymous with percutaneous absorption and the amount of a substance in food that can be unit of time. The most common unit of dose is with dermal uptake. [USEPA, 1992a: Dermal ingested daily over a lifetime by humans mg per kg body weight per day (mg/kg_day). Exposure Assessment]; g. The uptake of without appreciable health risk. The concept of [USDOE, 2000: RAIS Glossary]; e. The water , other fluids, or dissolved chemicals by the ADI has been developed principally by amount of a substance penetrating across an a cell or an organism (as tree roots absorb WHO and FAO and is relevant to chemicals absorption barrier (the exchange boundaries) dissolved nutrients in soil.) [USEPA, 1997a: such as additives to foodstuffs, residues of of an organism, via either physical or EPA Terms of Environment] pesticides and veterinary drugs in foods. ADIs biological processes. Sometimes called are derived from laboratory toxicity data, and internal dose. [USEPA, 1992a: Dermal Absorption barrier - a. Any of the exchange from human experiences of such chemicals Exposure Assessment]; f. In exposure barriers of the body that allow differential when this is available, and incorporate a safety assessment, the amount of a substance that diffusion of various substances across a factor. The ADI is thus an estimate of the penetrates an exposed organism's absorption boundary. Examples of absorption barriers are amount of a substance in food that can be barriers (e.g.,, skin, lung tissue, the skin, lung tissue, and gastrointestinal tract ingested over a lifetime by humans without gastrointestinal tract) through physical or wall. [USEPA, 1992: GL for Exposure appreciable health risk (for contaminants in biological processes. The term is synonymous Assessment][USEPA, 1992a: Dermal food and drinking water, Tolerable Intakes _ with internal dose. [USEPA, 1997a: EPA Exposure Assessment]; b. Any of the daily or weekly _ are used). See Tolerable Terms of Environment]; g. The amount of exchange sites of the body that permit uptake Daily Intake. [Duffus, 2000: Univ. Edinburgh pesticide entering systemic circulation after of various substances at different rates (e.g., Med School On-line Chemical Safety crossing a specific absorption barrier (e.g., the skin, lung tissue, and gastrointestinal tract Glossary]; c. The ADI of a chemical is the exchange boundary of the skin, lung, or wall) [USEPA, 1997a: EPA Terms of estimate of the amount of a substance in food digestive tract); normally expressed as mass Environment] and/or drinking water, expressed on a body- per unit body weight per unit time (e.g., weight basis, that can be ingested daily over a mg/kg/day). Internal dose is a more general Absorption cross section - A measurement of lifetime without appreciable health risk to the term denoting the amount absorbed with an atom or molecule's ability to absorb light at consumer on the basis of all the known facts at respect to specific absorption barriers or a specified wavelength, measured in square the time of the evaluation. It is usually exchange boundaries [USEPA, 1998: Postapp. cm/particle. [SHSU, 2000: Atmospheric expressed in milligrams of the chemical per Exposure Test GL., attributed to USEPA, Chemistry Glossary, attributed to Journal of kilogram of body weight. [FAO/WHO, 1997: 1992]; h. Dose resulting from the agent Atmospheric Sciences 50:941-950 (1994) and Food Consumption & Exp. Assessment of crossing the contact boundary and diffusing Journal of Chemical Education 71:105-108 Chemicals]; d. The amount of a chemical a through a resisting boundary layer [Zartarian, (1994)] person can be exposed to on a daily basis over et al., 1997: Quant. Def. of Exp. & Related an extended period of time (usually a lifetime) Concepts] [Cf. internal dose] Absorption factor - The fraction of an agent without suffering deleterious effects. [IRIS, (e.g., a chemical) making contact with an 1999: Glossary of IRIS Terms]; e. Same as Absorption - a. The process of taking in, as organism that is systemically distributed in the "Reference Dose". Estimate of largest amount when a sponge takes up water. Chemicals can organism. [REAP, 1995: Residential Exposure of exposure to an agent on a daily basis not be absorbed through the skin into the Assessment Project] expected to result in adverse effects. [REAP, bloodstream and then transported to other 1995: Residential Exposure Assessment organs. Chemicals can also be absorbed into Project]; f. An estimate of the daily exposure the bloodstream after breathing or swallowing. Absorption fraction - The relative amount of dose that is likely to be without deleterious [ATSDR, 1999: Online Glossary][New York a substance on the skin that penetrates through effect even if continued exposure occurs over Department of Health, 1999: Glossary of the epidermis into the body; reported as the a lifetime. [USDOE, 2000: RAIS Glossary] 3 pollutant concentrations). [SRA, 1999: RAIS Glossary]; c. Adherence of a solid or Glossary of Risk Analysis Terms]; d.