4.6 Nerve Gases
Without doubt, the most significant development of lethal agents was the synthesis of organophosphate compounds and other nerve gases. Research in Germany in the 1930s to find organophosphate compounds that could be used as insecticides resulted in the first nerve agent being identified. Known as Tabun, some 12,000 tonnes of the agent had been produced by 1945, and much of it filled into munitions.
Nerve gases or nerve agents are organophosphate compounds that inhibit the enzymes known as cholinesterases and disrupt nerve function. Nerve gases may be absorbed through any body surface, and when dispersed as a vapour, aerosol or in dust, they are rapidly absorbed through the lungs. Effects on individuals are rapid. Exposure to doses above 3 mg-min/m3 will affect vision. The inhibitory effects of the gases on acetylcholinesterase in the nervous system causes a wide range of symptoms at higher concentrations, including severe headache, eye pain, runny nose, tightness in the chest, wheezing, pronounced tiredness and weakness, rapid changes in mood, and nightmares.
Lethal doses of nerve agents are estimated to be about 150 mg-min/m3 per minute for Tabun, 70-100 mg-min/m3 for Sarin, and 35-50mg-min/m3 for VX.
Nerve agents are the only chemical warfare agents for which there are specific antidotes. Following severe poisoning, there is no guarantee of full recovery.
