Glossary


acetylcholinesterase

True cholinesterase (ChE). Acetylcholinesterase hydrolyzes acetylcholine within the central nervous system and peripheral neuro-effector functions.


benchmark dose

A dose with a specified low level of excess health risk, generally in the range of 1% to 10%, that can be estimated from data with little or no extrapolation outside the experimental dose range.


chronic exposure

For laboratory animals, an exposure (usually at low concentrations) of long duration, such as months or years. For human populations, an exposure that lasts at least 7 years and could last as long as a lifetime.

cholinesterase

An enzyme capable of catalyzing the hydrolysis of acetylcholine.



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OCR for page 93
Review of the U.S. Army's Health Risk Assessments for Oral Exposure to Six Chemical-Warfare Agents Glossary acetylcholinesterase True cholinesterase (ChE). Acetylcholinesterase hydrolyzes acetylcholine within the central nervous system and peripheral neuro-effector functions. benchmark dose A dose with a specified low level of excess health risk, generally in the range of 1% to 10%, that can be estimated from data with little or no extrapolation outside the experimental dose range. chronic exposure For laboratory animals, an exposure (usually at low concentrations) of long duration, such as months or years. For human populations, an exposure that lasts at least 7 years and could last as long as a lifetime. cholinesterase An enzyme capable of catalyzing the hydrolysis of acetylcholine.

OCR for page 93
Review of the U.S. Army's Health Risk Assessments for Oral Exposure to Six Chemical-Warfare Agents dose The amount of a substance that enters or interacts with organisms. An administered dose is the amount of substance administered to an animal or human, usually measured in milligrams per kilogram of body weight; milligrams per square meter of body-surface area; or parts per million of the diet, drinking water, or ambient air. An effective dose is the amount of the substance reaching the target organ. epithelial acanthosis An increase in the thickness of the stratum spinosum of the epithelial tissue. LD50 Lethal dose to 50% of test animals. 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 exposure population and its appropriate control group. maximum tolerated dose (MTD) The highest dose that can be administered to animals for two years without causing mortality from causes other than cancer. microgram (µg) One millionth of a gram. milligram (mg) One thousandth of a gram. miosis A decrease in pupil size. modifying factor A factor that is used to account for uncertainties not accounted for by uncertainty factors. nonstockpile chemical materiel (NSCM) NSCM includes a host of lethal wastes from past disposal efforts, unserviceable munitions, chemically contaminated

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Review of the U.S. Army's Health Risk Assessments for Oral Exposure to Six Chemical-Warfare Agents containers, chemical production facilities, newly located chemical munitions, known sites containing significant quantities of buried chemical weapons and wastes, and binary weapons and components. NSCM is not part of the stockpile of lethal chemical agents and munitions kept by the military for retaliatory purposes. no-observed-adverse-effect level (NOAEL) An exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered as adverse, nor precursors to adverse effects. potency The degree to which an agent can cause strong or toxic effects. reference dose As estimate (with uncertainty spanning perhaps on order of magnitude or greater) of a daily dose to the human population (including susceptible subpopulations) that is likely to be without an appreciable risk of deleterious health effects during a lifetime. slope factor The slope of the dose-response curve in the low-dose region. When low-dose linearity cannot be assumed, the slope factor is the slope of the straight line from 0 dose (and 0 excess risk) to the dose at 1% excess risk. An upper bound on this slope is usually used instead of the slope itself. subchronic exposure For laboratory animals, multiple or continuous exposures occurring usually over 3 months. For human populations, exposures that last from 1 to 7 years.

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Review of the U.S. Army's Health Risk Assessments for Oral Exposure to Six Chemical-Warfare Agents threshold The lowest dose of a substance at which a specified measurable effect is observed and below which it is not observed. toxicity The study of adverse effects of chemicals on living organisms. uncertainty factors Factors used to divide a no-observed-adverse-effect level (LOAEL) to obtain a safe exposure level.