Risk factors for bladder cancer in a cohort exposed to aromatic amines.

Occupational and nonoccupational risk factors for bladder cancer were analyzed in a cohort of 1385 workers with known exposure to a potent bladder carcinogen, beta-naphthylamine. Bladder cancer was approximately seven times (95% confidence interval [CI] = 3.9, 12.4) more likely in exposed rather than nonexposed individuals, yet, otherwise, the groups were generally similar in other exogenous or hereditary risk factors. A total of 13 cases of bladder cancer were identified. After the first year of a screening program involving 380 members of the cohort, 9 of the 13 cases of bladder cancer and 36 persons with atypical bladder cytology, histology, or pathology were compared with 335 noncases for distributions of different variables. Occupational variables were significant in a multivariate model that controlled for age, cigarette smoking history, and source of drinking water. The estimated odds ratio for the association for bladder cancer and the duration of employment, when controlling of these other variables, is 4.3 (95% CI = 1.8, 10.3). In addition to the occupational factors, age was significant in the multivariate analysis. Other potential risk factors, such as consumption of coffee or artificial sweeteners, use of phenacetin, or decreased use of vitamin A were not found to be significantly different in cases and noncases.