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Medical Management of Chemical Casualties Handbook Chemical Casualty Care Office Medical Research Institute Of Chemical Defense Aberdeen Proving Ground, MD 21010 September 1995
CLINICAL EFFECTS
The initial effects of exposure to a nerve agent depend on the dose and the route of exposure. The initial effects from a sublethal amount of agent by vapor exposure are different from the initial effects from a similar amount of liquid agent on the skin.
Toxicities:The estimated amounts to cause certain effects in man are shown in Table I and Table II. In Table I, L indicates lethal, I indicates incapacitating (severe), and M indicates miosis. The large amounts of GA and GB required to produce effects after skin application reflect the volatility of these agents. They evaporate rather than penetrate the skin. However, if these agents are occluded and prevented from evaporating, they penetrate the skin very well.
Table I
Vapor toxicity
mg-min/m3
|
Agent |
LCt50 |
ICt50 |
MCt50 |
|
GA |
400 |
300 |
2-3 |
|
GB |
100 |
75 |
3 |
|
GD |
70 |
UNK |
<1 |
|
GF |
UNK |
UNK |
<1 |
|
VX |
50 |
35 |
0.04 |
Table II
LD50 on skin
|
Agent |
Amount |
|
GA |
1000 mg |
|
GB |
1700 mg |
|
GD |
50 mg |
|
GF |
30 mg |
|
VX |
10 mg |
GB, the agent studied most thoroughly in man, will cause miosis, rhinorrhea, and a feeling of tightness in the throat or chest at a Ct of 3 to 5 mg-min/m3.
Effects: Exposure to a small amount of nerve agent vapor causes effects in the eyes, nose, and airways. These effects are from local contact of the vapor with the organ and do not indicate systemic absorption of the agent. In this circumstance, the erythrocyte-ChE may be normal or depressed. A small amount of liquid agent on the skin causes systemic effects initially in the gastrointestinal (GI) tract. Lethal amounts of liquid or vapor cause a rapid cascade of events culminating within a minute or two with loss of consciousness and convulsive activity followed by apnea and muscular flaccidity within several more minutes.
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