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.


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.


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

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement