Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents (1997)
Chapter: Lethal Effects (LCt50)
6—
Review of Acute Human-Toxicity Estimates for VX
VX (O-ethyl-S-[2(diisopropylamino)ethyl]methylphosphonothioate) is an organophosphate nerve agent. It is less volatile than G-nerve agents, a property that might significantly affect its role in chemical warfare. The physical and chemical properties, toxicokinetics, and toxicity of VX are discussed in detail by CDEPAT (1994), Marrs et al. (1996), and Somani (1994). Human-toxicity estimates have been derived for percutaneous vapor exposures, vapor inhalation, and percutaneous liquid exposures. Only a few end points were considered—lethality in animals, changes in cholinesterase (ChE) activity in humans and animals, incapacitation, ocular toxicity, and rhinorrhea. The subcommittee's assessment of the scientific validity of CDEPAT's human-toxicity estimates for VX is discussed below.
Percutaneous Vapor Exposure
Lethal Effects (LCt50)
CDEPAT's proposed LCt50 estimate for percutaneous exposure to VX vapor is 150 mg-min/m3 assuming exposure durations of 30 to 50 min and moderate temperatures. There is no existing LCt50 estimate (CDEPAT 1994).
