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Derivation of an Effective Concentration for 50% of the Population (ECt50) for Whole Blood Acetylcholinesterase Inhibition by VX in the New Zealand White Rabbit

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Technical Report,01 Nov 2017,31 Dec 2017

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U.S. Army Combat Capabilities Development Command Chemical Biological Center Aberdeen Proving Ground United States

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This study established the effective concentration of O-ethyl-S-2-diisopropylaminoethyl methyl phosphonothiolate VX aerosol required to produce mild, moderate, and severe inhibition of whole blood acetylcholinesterase enzyme WB-AChE in the New Zealand white rabbit. A method was established by which an estimate for inhalation toxicity may be derived from known intravenous toxicity data for the rabbit. The calculated effective concentrations for 50 of the population for each severity level were as follows mild 2150 inhibition, 6.6 mg minm3 95 confidence interval CI, 4.310.1 moderate 5180 inhibition, 12.2 mg minm3 95 CI, 8.617.2 and severe 81100 inhibition, 23.2 mg minm3 95 CI, 12.742.3. We estimated that for the moderate severity level, the total VX dose administered was between 1.40 and 2.74 gkg. For comparison, a previous study found an effective dose for 50 of the population that resulted in greater than 50 WB-AChE inhibition after intravenous delivery of VX in rabbits to be 1.37 gkg. This represents a fairly accurate estimation of equipotent dosimetry between two differing routes of exposure.

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  • Chemical, Biological and Radiological Warfare

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