Toxicity mechanisms, lewisite

The dominant element in the lewisite structure is arsenic, which is able to react with the sulfhydryl groups of various enzymes, disabling the enzyme in the process (Goldman and Dacre, 1989). Figure 50.7 depicts the structure of lewisite and its toxic mechanism. 

Lewisite (15-chlorovinyldichloroarsine) was synthesized in 1918 for use as a weapon, and its clinical effects are similar to those of mustard in many respects, although the cellular mechanisms are believed to differ. However, unlike mustard. Lewisite liquid or vapor produces irritation and pain seconds to minutes after contact. Immediate decontamination may limit damage to skin or eyes, and intramuscular injections of a specific antidote, dimercaprol, or British antiLewisite (BAL) will reduce the severity of systemic effects. BAL has toxic effects of its own, however, and must be used with care. 

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