Dermal toxicity of sulfur mustard

Sulfur mustard [bis(2-chloroethyl)sulfide, CAS 505-60-02] is a potent, delayed contact irritant that has no use other than as a chemical warfare agent. It is commonly classed as a “vesicant agent” by virtue of the extensive skin blisters that arise following dermal exposure. A common synonym is “mustard gas,” said to be derived from the smell following its use in trenches during World War I. However, this is probably misleading for two reasons. Firstly, it is more likely that “mustard” refers to the taste of the chemical, as the odor of weapons-grade material has been described by first-hand accounts as more akin to that of horseradish or garlic (1). When new substances were first synthesized during the 19th century, chemists had a limited range of techniques available to characterize them and so relied heavily on organoleptic means of analysis: One of the chemists credited with the synthesis of sulfur mustard noted that its taste was reminiscent of mustard (2). However, this gustatory effect has not been subsequently confirmed! Secondly, sulfur mustard is not a gas but a liquid (melting point~14°C), which evaporates to form a vapor that can cause ocular, inhalation, and/or dermal injuries. While not generally regarded as a lethal chemical (like the nerve agents VX or sarin), exposure to sulfur mustard may result in long-term debilitation, which would impose both an acute and chronic burden on medical resources.