BOX 6 Studies of Lung Cancer Mortality and Exposure to Mustard Gas

In July 1917, in a field outside of Ypres, Belgium, mustard gas was used for the first time in World War I. In total, mustard gas would cause nearly 400,000 casualties during the war, more than any other chemical agent. One of the long-term effects of exposure to mustard gas is chronic bronchitis, but it was unknown whether the long-term risk of lung cancer would be elevated in men who had been exposed. Three samples of World War I veterans totaling 7,151 U.S. white males were followed up for mortality through 1956 and again through 1965 in order to learn whether a single exposure to mustard gas with respiratory injury was associated with increased risk of lung cancer in later life. Men born between 1889 and 1893 who were either (1) exposed to mustard gas as documented by skin burns, or (2) hospitalized with pneumonia in 1918, or (3) hospitalized with wounds of the extremities were traced via the Veterans Administration's death records. Results of both follow-up studies failed to establish a definite carcinogenic effect for mustard gas, although the studies did find a relative risk of 1.3 for lung cancer mortality in exposed as compared to unexposed men. Observed deaths from lung cancer represented 2.5 percent of the mustard gas group, 1.8 percent of the pneumonia group, and 1.9 percent of unexposed men for the period 1919–1965. Even though these results were equivocal, presumably because men in the study received a relatively light dose, the second follow-up did find evidence suggesting a latency period for a carcinogenic effect ranging from 22 to 37 years. Although mustard gas was not used in World War II, both sides produced and stockpiled such weapons and prepared for their possible use. As part of this preparation, roughly 4,000 servicemen participated as experimental subjects in tests of the short-term effects of mustard gas. However, there has been no follow-up assessment of the long-term health effects of mustard gas exposure among these subjects.

Selected References

Beebe, G.W. Lung cancer in World War I veterans: Possible relation to mustard-gas injury and 1918 influenza epidemic. Journal of the National Cancer Institute 25:1231–1251, 1960.

Norman, J.E. Lung cancer mortality in World War I veterans with mustard-gas injury: 1919–1965. Journal of the National Cancer Institute 54:311–317, 1975.

indebtedness to you over so many years and in such a diversity of problems,'' he wrote. Writing to William Stone, then chair of the committee, Cannan noted, "We plan to continue the program of medical follow-up studies and will need the active guidance of a group of medical investigators." He added, however, that he had not decided on the composition or the exact mission of such a group. Esmond Long, a long-time committee member, said that the fact that the follow-up pro-



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