were available for comparison, all the associated confidence intervals included unity, and no adjustment for possible confounders was attempted.
Siemiatycki et al. (1988) addressed the 121 interviewed melanoma cases in the Montreal multicancer case-control study in seeking associations with various exhaust and combustion-product exposures. They reported that melanoma was associated (p<0.05) with propane exhaust (OR 3.3, 90% CI 1.2–9.0) and there were suggestive increases with jet-fuel exhaust (OR 1.8, 90% CI 0.5–6.4) and liquid-fuel combustion (OR 1.8, 90% CI 0.9–3.4). In a more recent publication on this dataset, Fritschi and Siemiatycki (1996a) found no compelling association between any combustion-products exposure and melanoma. For an exposure to be analyzed (with adjustment for age, education, and ethnicity), there had to be at least four exposed cases. Estimates hovering about unity were reported for gasoline-engine emissions, PAHs from petroleum, and carbon monoxide. An appendix listed several additional combustion-products-related exposures for which the lower 95% confidence limit of the estimate of association with melanoma did not exceed 0.9: the air-transport, motor-transport, and railway-transport industries, with six, eight, and five exposed cases, respectively; the occupations of mechanic or motor-transport worker, with five and 10 exposed cases, respectively; and diesel-engine emissions, liquid-fuel combustion products, PAHs from any source, and pyrolysis fumes not classified elsewhere, with 10, six, 57, and 11 exposed cases, respectively. There was no explanation of why the number of interviewed melanoma cases considered had decreased by 18 (15%); only inconsequential perturbations resulted in the statistics for the exposures common to the two publications (assuming that “petrol engine emissions” equates to “gasoline exhaust”).
Nelemans et al. (1993) compared 140 melanoma cases with 181 controls who had other malignancies, all gathered from a cancer registry in the mideastern part of the Netherlands. After adjustment for age, sex, education, pigmentation factors, and exposure to sunlight, those who had ever worked in the “transport and communications” industry had a greater risk of melanoma than those who had not (OR 1.70, 95% CI 0.84–3.46); the difference was intensified by contrasting this group with those who had never worked in any of 10 hypothetically high-risk industries (OR 1.92, 95% CI 0.84–4.35). For the transportation and communications workers, tar products, cutting oils or coolants, and lubricating oils were among the exposures that were self-reported more frequently than by other workers, but no formal analysis was presented, and there was no attempt at a JEM approach to evaluating exposure. This elementary study provides some weak support for the possibility that exposure to combustion products is associated with the occurrence of cutaneous melanoma.
Using the Swedish Cancer Environment Registry database, Linet et al. (1995) identified 3,850 men diagnosed with melanoma in 1961–1979 who had been listed as occupationally active in the 1960 census; this sample would be expected to coincide with the male portion of the set of 5,003 melanoma cases studied in somewhat less detail by Vagero et al. (1990). The global categories for the “transport and communications” industry or occupation showed no indication of a relationship between melanoma and employment that might involve exposure to vehicle exhaust. Occupational subcategories in this sector, however, did show some increases; the risk for “traffic administration” was 1.6 (p<0.05, adjusted for age and region), and the risk for the more specific classification “traffic enforcement or railroad work” even more pronounced (SIR 3.1, p<0.01).