HD (β-β'-dichloroethyl sulfide or bis(2-chloroethyl)sulfide), also known as sulfur mustard, is a vesicant (blistering agent). The physical and chemical properties, toxicokinetics, and toxicity of sulfur mustard 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 exposures, and for percutaneous liquid exposures. Only a few toxicity end points were considered. End points of toxicity that were considered are lethality, vesication, erythema, burns on the skin, and ocular and pulmonary effects. The subcommittee's assessment of the scientific validity of CDEPAT's human-toxicity estimates for HD is discussed below.
CDEPAT's proposed LCt50 estimate for percutaneous exposure to HD vapor is 5,000 mg-min/m3, assuming exposure durations of 30 to 50 min. The existing estimate is 10,000 mg-min/m3 (CDEPAT 1994).