Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents (1997)
Chapter: Glossary
Glossary
A
acetylcholinesterase
True cholinesterase (ChE). Acetylcholinesterase hydrolyzes acetylcholine within the central nervous system and peripheral neuroeffector functions.
acute effect
An effect that results from a brief exposure or shortly after an acute exposure (see below).
acute exposure
A short-term exposure that lasts from minutes to hours (usually 1–24 hr).
aerosol
Liquid or solid particles suspended in air.
C
ChE50
The vapor exposure producing significant cholinesterase (ChE) inhibition in 50% of the given population.
cholinesterase
An enzyme capable of catalyzing the hydrolysis of acetylcholine.
chronic effect
An effect of gradual onset and duration of months and years.
chronic exposure
An exposure (usually at low concentrations) of long duration, such as months or years.
Ct
Concentration × time. Note that Ct is not necessarily a constant. For example, a 2-min exposure to a concentration of 100 mg/m3 (Ct = 200 mg-min/m3) does not necessarily produce the same toxicological effects as a 50-min
exposure to a concentration of 4 mg/m3 (Ct = 200 mg-min/m3).
D
depiliation
Removal of hair.
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.
E
ECt50
The vapor exposure causing a specifically defined effect in 50% of the given population. Within the context of this report, the route of exposure can be either inhalation or percutaneous.
ED50
The dose of liquid agent causing a specifically defined effect in 50% of the given population. In this report, ED50 refers to a percutaneous liquid exposure.
exposure duration
The length of time that a receptor population is exposed to a contaminant.
exposure route
The route by which a contaminant enters the body (dermal, inhalation, or oral).
I
ICt50
The vapor exposure causing incapacitation (see below) in 50% of the given population. Within the context of this report, the route of exposure can be either inhalation or percutaneous.
ID50
The dose of liquid agent causing a defined degree of incapacitation in 50% of the given population. Within this context, ID50 refers to a percutaneous liquid exposure. Unless otherwise specified, all ID50s are for bare skin.
incapacitation
An effect considered moderate to severe, unless otherwise specified. It might include prostration and convulsions.
L
LCt50
The vapor exposure causing lethality in 50% of the given population. Within the context of this report, the route of exposure can be either inhalation or percutaneous.
LD50
The dosage of liquid agent causing lethality in 50% of the given population. Within this context, LD50 refers to a percutaneous liquid exposure. Unless otherwise specified, all LD50s are for percutaneous liquid contamination of bare skin.
M
microgram (µg)
One millionth of a gram.
mild effects
For the organophosphate nerve agents, mild effects are miosis and rhinorrhea. For HD, mild effects are slight ocular irritation.
milligram (mg)
One thousandth of a gram.
minute volume
The volume of air expelled from the lungs in a minute, which is assumed to be 15 liters unless otherwise stated.
miosis
A decrease in pupil size.
N
no-observed-adverse-effect level (NOAEL)
The highest dose of a substance that can be administered without observation of adverse effects in laboratory animals.
P
percutaneous vapor exposure
Percutaneous vapor exposures are defined as vapor exposures to intact bare skin. Vapor inhalation is prevented by use of an appropriate protective mask and does not contribute to overall toxicity. Percutaneous vapor exposures can result from vapor dissemination of chemical agents or from liquid contamination of clothing with subsequent vapor penetration.
potency
The degree to which an agent can cause strong or toxic effects.
R
rhinorrhea
Running nose.
S
severe effects
For the organophosphate nerve agents, severe effects are systemic, such as vomiting, involuntary urination, or defecation, prostration, incapacitation, tremors, collapse, and convulsions. Exposures that produce these effects might not be substantially different from exposures that produce lethality. For HD, severe nonlethal effects consist of skin burns, such as severe redness (erythema) and blistering (vesication).
T
threshold
The lowest dose of a substance at which a specified measurable effect is observed and below which it is not observed. In this report, threshold effects refer to minimal or negligible effects.
toxic
Harmful to living organisms.
toxicity
The adverse effects of chemicals on living organisms.
toxicology
The study of adverse effects of chemicals on living organisms.
toxic substance
A substance that destroys life or injures health when introduced into or absorbed by a living organism.
U
uncertainty factors
Factors used to divide a no-observed-adverse-effect level (NOAEL) or lowest-observed-adverse-effect level (LOAEL) to obtain a safe exposure level.
