Sulfur mustard acute toxic effects

In addition to the acute toxic effects on the eyes, skin, and respiratory tract, both acute and longer-term neuropsychiatric effects (e.g. depression, anxiety, neurasthenia, insomnia, post-traumatic stress syndrome) have been documented for individuals exposed to sulfur mustard (Romano et al, 2008). Many of these effects have been documented for individuals exposed during noncombat (e.g. munitions plant workers) activities and are not always the result of high-level exposure that result in serious overt effects. Longer-term effects such as chronic bronchitis have been associated with occupational exposures that included episodes of acute toxicity, and delayed or recurrent keratitis may occur 8-40 years after a severe vapor exposure. Sulfur mustard-induced immunosuppression resulting in greater susceptibility to infections has also been reported. 

Sulfur mustard is a known human carcinogen, and some of its degradation products may also be carcinogenic (IOM, 1993). Sulfur mustard acts as a vesicant or blister agent and shows acute systemic toxicity in addition to its effects on skin, eyes, and the respiratory tract. 

Acute lethality data in animals are summarized in Table 8.7. Based upon the animal data, interspecies variability in the lethal response to sulfur mustard vapor is less than an order of magnitude. For nonlethal effects, the animal data suggest that test species exhibit signs of toxicity that are qualitatively similar to humans when acutely exposed to sulfur mustard vapor. Ocular and respiratory tract irritations are clearly evident in studies using dogs, rats, mice, rabbits, and guinea pigs. 

Studies in animals have shown that sulfur mustard may induee developmental and reproductive effects (reviewed in NRC, 1999, 2003). Acute exposures resulting in systemic uptake may have effects on reproductive organs, including inhibition of spermatogenesis. Fetal anomalies were observed in tests with rats given sulfur mustard during gestation but only at maternally toxic doses. 

Studies of occupational exposures to sulfur mustard indicate an elevated risk of respiratory tract and skin tumors following long-term exposure to acutely toxic concentrations. Overall, several factors are important regarding the assessment of the carcinogenicity of sulfur mustard. Increased cancer incidence in humans appears to be associated only with exposures that caused severe acute effects, and occupational exposures tended to involve repeated exposures and repeated injury of the same tissues. Because the therapeutic use of the sulfur mustard analog nitrogen mustard is associated with an increased incidence of CML, the reports of CML in HD-exposed individuals appear to be relevant to the eareinogenicity of sulfur mustard. 

In addressing the ecotoxicological implications of HD dumped in the Baltic Sea, Muribi (1997) reported on the acute toxicity of HD to the invertebrate Daphnia magna in brackish water at 19.5°C. Exposure to 0.5 mg/1 HD (the highest concentration tested) for 48 h did not induce any visible effects. Additional toxicity studies with salt- and freshwater organisms, reviewed by Muribi (1997) and Munro et al. (1999), indicate that dissolved sulfur mustard is generally not acutely toxic at concentrations below 1 mg/1 (close to its water solubility value). For some algae, a concentration of 1 mg/1 may be acutely toxic (Stock, 1996). Thus, the environmental action of HD is limited by its low water solubility. 

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