Cancer incidence was investigated in a cohort of 700 workers employed at a chemical plant between mid-1965 and 1989. The plant produced a variety of chemicals including arylamines such as dichlorobenzidine, o-dianisidine and o-tolidine; benzidine production ceased prior to mid-1965. The principal finding was a significant increase in the standardized incidence ratio for bladder cancer in men. Based on an exposure classification system, the observed association between bladder cancer cases and exposure to arylamines increased with increasing exposure. Smoking probably contributed to the bladder cancer risk, as all case subjects were known to be current or former cigarette smokers.

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