[A cohort study on the cancer experience among workers exposed to benzidine-derived dyes in Shanghai leather-tanning industry].

901 male workers who have ever been exposed to the benzidine-derived dyes for more than 1 year in Shanghai leather-tanning industry, were investigated about their occupational history, smoking and drinking histories, case history of cancer, and the causes of death. The results showed that there was an excess morbidity of bladder cancer in this population, and the SIR was 273 (P = 0.05) compared with the general population of Shanghai urban. It may be noted that the excess of the bladder cancer was presented mainly in those workers whose ages of the first exposure were under 19 years old, and the bladder cancer incidence seemed to be associated positively with the cumulative duration of exposure. The survey about the smoking history did not show any obvious relationship between smoking and the development of the bladder cancer. Moreover, it was seen that a trend of excessive in incidence of the nasopharyngeal cancer and the lymphosarcoma existed in this population.