mustard gas (Büscher, 1932; Easton et al., 1988; Inada et al., 1978; Klehr, 1984). Pigmentary disorders, skin ulcers, and cutaneous cancers and precancers have been the most common entities described. Klehr described a group of World War II (WWII) German mustard gas workers as having multiple skin tumors, even in unexposed skin, and numerous painful ulcerations that tend to spread. Klehr's report is principally descriptive and is without valid comparative data or control populations, as are most other reports of occupational diseases associated with sulfur mustard exposure. Of 53 workers remaining alive and examined, 34 percent experienced multiple skin tumors, and 45 percent experienced arterial vascular ulcers of the lower extremities. Klehr's clinical description of the kinds of ulcers seen gives the impression that they are not unlike leg ulcers commonly found in individuals with chronic arterial and venous disease. The lack of a control population and the very general descriptive and retrospective nature of this report make it difficult to place value on the content.

Wada and colleagues (1962, 1963) and Inada and colleagues (1978) describe findings in a group of former workers exposed for variable periods to a variety of "war gases" manufactured on Okuno-jima island in Japan (see Chapter 6). Of 488 workers, 115 showed pigmentary skin changes consisting of hyperpigmented and depigmented raindrop spots, mostly on covered skin of the trunk and extremities. Another 22 cases with Bowen's disease, basal cell carcinoma, and other hyperkeratotic skin lesions were described. Of 5 cases extensively described, the average time between initial exposure to sulfur mustard and the development of tumors varied between 31 and 46 years. The number of years worked in the facility varied from 3 to just over 15 years. Most workers in this facility wore protective clothing, which was described as "defective and ill-fitting" most of the time: numerous instance of skin burns, blisters, and other cutaneous injuries were reported. Although an adequate control population was not simultaneously studied, 77 workers who were engaged in clerical and guard duty at the same facility, did not develop evidence of long- or short-term defects.

The principal drawback to assigning a cause and effect relationship solely to sulfur mustard exposure at this facility may be found in the background comments: before 1937, workers whose tasks were limited to the production of "war gases" worked in the manufacture of gases of all types, including mustard gas and Lewisite (Wada et al., 1962). Also missing from these studies is a statistical comparison of the number of cases of Bowen's disease one could expect to find in a comparable population of nonexposed Japanese. In a nationwide 5-year study of skin cancer, the overall incidence of skin cancer among 851,685 new patient visits to dermatologic clinics at major Japanese universities was