Environmental temperature and the percutaneous absorption of a cholinesterase inhibitor, VX

S-(2-diisoproplaminoethyl) 0-ethyl methylphosphonothioate (VX), an anticholinesterase liquid of low volatility, was applied to the skin of 139 men at environmental temperatures of -18 degrees, 2 degrees, 18 degrees, or 46 degrees C. The skin was decontaminated after 3 hr and the men spent the next 21 hr at about 27 degrees C. The amount of VX penetrating the skin was estimated from the inhibition of red blood cell cholinesterase. The decimal fraction of the dose that penetrated in 3 hr ranged from 0.04 at -18 degrees C to 0.32 at 46 degrees C for the cheek and from 0.004 at +18 degrees C to 0.029 at 46 degrees C for the forearm. Further increase in cholinesterase inhibition after decontamination was evidence of a deposit of VX in the skin. The amount of VX remaining in the skin after decontamination was greater in the forearm and less in the cheek at higher temperatures.