the nerve agents , ga , gb , and vx are organophosphorus esters that form a major portion of the total agent volume contained in the u.s . 
 stockpile of unitary chemical munitions . 
 congress has mandated the destruction of these agents , which is currently slated for completion in 2004 . 
 the acute , chronic , and delayed toxicity of these agents is reviewed in this analysis . 
 the largely negative results from studies of genotoxicity , carcinogenicity , developmental , and reproductive toxicity are also presented . 
 nerve agents show few or delayed effects . at supralethal doses , gb can cause delayed neuropathy in antidote - protected chickens , but there is no evidence that it causes this syndrome in humans at any dose . 
 agent vx shows no potential for inducing delayed neuropathy in any species . in view of their lack of genotoxcity , 
 the nerve agents are not likely to be carcinogens . 
 the overreaching concern with regard to nerve agent exposure is the extraordinarily high acute toxicity of these substances . 
 furthermore , acute effects of moderate exposure such as nausea , diarrhea , inability to perform simple mental tasks , and respiratory effects may render the public unable to respond adequately to emergency instructions in the unlikely event of agent releaase , making early warning and exposure avoidance important . 
 likewise , exposure or self - contamination of first responders and medical personnel must be avoided . 
 control limits for exposure via surface contact of drinking water are needed , as are detection methods for low levels in water or foodstuffs.imagesfigure 2 .