Cancer incidence in an occupational cohort exposed to bitumen fumes.

This study was conducted to investigate whether bitumen fumes should be considered carcinogenic to human beings. A historical cohort of heavily exposed mastic asphalt workers was followed from 1959 through 1984 (inclusive) with regard to cancer incidence. A total of 679 Danish men were included in the study cohort. Among these, 75 new cases of cancer were observed within the period studied. The cancer incidence observed among the group significantly exceeded that of the total Danish male population, the standardized morbidity ratio (SMR) being 195 (95% confidence interval (95% CI) 153-244). Significant increases were seen for cancer of the mouth (SMR 1111, 95% CI 135-4014), the esophagus (SMR 698, 95% CI 144-2039), the rectum (SMR 318, 95% CI 128-656), and the lung (SMR 344, 95% CI 227-501). It is suggested that exposure to cracking products in the fumes of heated bitumen has contributed to the elevated cancer incidence observed.