Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents (1997)
Chapter: Lethal Effects (LCt50)
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Review of Acute Human-Toxicity Estimates for GB (Sarin)
GB (Sarin or isopropyl methylphosphonofluoridate) is an organophosphate nerve agent. The physical and chemical properties, toxico-kinetics, and toxicity of GB are discussed in detail by CDEPAT (1994), Marrs et al. (1996), and Somani (1994). Only a few toxicity end points were considered (for example, lethality in animals, incapacitation, changes in cholinesterase (ChE) activity, and ocular effects). The subcommittee's assessment of the scientific validity of CDEPAT's proposed human-toxicity estimates for GB is discussed below.
Percutaneous Vapor Exposure
Lethal Effects (LCt50)
After reviewing the available animal lethality data, CDEPAT proposed a human LCt50 estimate of 10,000 mg-min/m3 following percutaneous exposure to GB vapor, assuming light clothing and exposure durations of 30 to 50 min for the soldiers. The existing LCt50 estimate is 15,000 mg-min/m3 (CDEPAT 1994).
The Army's proposed estimate is supported by an LCt50 of 9,700 mg-
