Organophosphates lethality

The Department of Defense Authorization Act of 1986 (Public Law 99-145) directed the Secretary of Defense to destroy all lethal unitary chemical munitions and agents by September 30, 1994, including organophosphate nerve agents such as GB. The act was amended in 1988 (Public Law 100-456) to allow for complete disposal of chemical munitions by April 1997. 

Intermediate-duration inhalation exposures to aerosols of a few organophosphate ester hydraulic fluids (Durad MP280 and "triaryl phosphate ester") produced lethal neurotoxic effects in chickens and rabbits (MacEwen and Vemot 1983 Siegel 1965). Rats and hamsters appear to be less susceptible to the neurotoxic action of organophosphate esters tests of several organophosphate fluids produced no deaths in rats exposed to substantial aerosol concentrations. 

It accounts for the greater span between symptom-producing and lethal doses than most organophosphate compounds. 

A third approach to protection against excessive acetylcholinesterase inhibition is pretreatment with reversible enzyme inhibitors to prevent binding of the irreversible organophosphate inhibitor. This prophylaxis can be achieved with pyridostigmine but is reserved for situations in which possibly lethal poisoning is anticipated, eg, chemical warfare (see Chapter 7). Simultaneous use of atropine is required to control muscarinic excess. 

Evron, T., Geyer, B.C., Chemi, I., Muralidharan, M., Kilboume, J., Fletcher, S.P., Soreq, H., Mor, T.S. (2007a). Plant-derived human acetylcholinesterase-R provides protection from lethal organophosphate poisoning and its chronic aftermath. FASEB J. 21 2961-9. 

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