served in other studies adds weight to the evidence of the carcinogenicity of sulfur mustard.

Jackson and Adams (1973) conducted a case control study to explore the causes of aggressive and disfiguring cases of basal cell carcinoma: 33 cases of "horrifying" basal cell carcinoma were compared with 435 other cases of basal carcinoma. Of interest to this discussion, 2 of the 33 cases had histories of mustard vapor burns. One case, reported in some detail, developed a basal cell carcinoma in the scar on his neck left by sulfur mustard in World War I (WWI). This study does not provide an estimate of the risk to veterans with mustard agent burns of subsequently developing dermatologic cancers. The study nevertheless reveals a possible etiologic association between mustard agent burns and aggressive basal cell carcinoma.

Case and Lea (1955) studied a group of 1,267 men who were receiving pensions for the effects of mustard agent poisoning resulting from WWI combat exposures. The mortality experience of this group was compared with expected mortality for males in England and Wales and with the mortality experience of 1,421 other WWI pensioners disabled by bronchitis and another 1,114 pensioners with limb amputations, but without bronchitis, who had not been exposed to sulfur mustard. The results showed that both the cohort exposed to sulfur mustard and the cohort with bronchitis, but not the amputees, had significant excesses of mortality for "all causes" and for "cancer of the lung and pleura." The authors did not feel that these results support the hypothesis that sulfur mustard acts as a direct carcinogen. The major limitation of this study was the lack of information on cigarette smoking. Pension records showed that 81 percent of the exposed cohort were disabled by bronchitis or other pulmonary conditions, but there is no way to determine if their bronchitis is mustard-associated, smoking-associated, or both. It is possible that members of this cohort, like U.S. veterans who were exposed to sulfur mustard (Norman, 1975), smoked less than their peers. Thus, this study provided weak evidence that mustard exposure is not associated with an excess of cancer of the lung.

Beebe (1960) conducted a similar study of U.S. veterans of WWI that was designed to compare the mortality and morbidity of three groups: (1) soldiers hospitalized for exposure to mustard vapor; (2) soldiers with pneumonia; and (3) soldiers requiring amputation. Unlike the British study, all members of the gas cohort had to have had medical evidence of eye or skin burns from mustard agents. Smoking data were also available on a sample of all three cohorts and documented a deficit of smoking in the gas cohort. The sulfur mustard cohort had 1.3 percent