Risk assessment of a cohort exposed to aromatic amines: Initial results

A cohort of 1,385 workers potentially exposed to carcinogenic amines was evaluated to determine the extent of its risk for bladder cancer. The cumulative incidence of bladder cancer was determined from death certificates, from interviews with community urologists, and from a screening program. A total of 13 confirmed cases of bladder cancer were identified at the conclusion of the first year of study. The entire cohort has approximately a fourfold excess risk of bladder cancer; however, black workers with more than 10 years of employment had a risk ratio of 111 (based on three cases). The onset of disease occurred, on the average, 15 years earlier in these black workers than in the general U.S. population. The cumulative incidence of bladder cancer increased with the duration of employment, ranging from 0.4% for workers with five or fewer years of employment to 36% for those with greater than 20 years. No significant differences were found between cases and noncases for cigarette smoking, coffee drinking, use of artificial sweeteners, or prior employment in highrisk occupations. More cases of bladder cancer are expected in this cohort because many members have not yet achieved the average latency found for the confirmed cases.