Ingested arsenic, keratoses, and bladder cancer.

A cohort of 478 patients treated with Fowler's solution (potassium arsenite) in Lancashire, England, during the period 1945-1969 and previously followed until January 1, 1980, was followed for an additional 11 years. A significant excess of bladder cancer mortality occurred (observed/expected ratio = 5/1.6; p = 0.05). No excess was found for other causes of death. In a subcohort of 142 patients examined for signs of arsenicism around 1970, all 11 subsequent cancer deaths occurred in those with signs of arsenicism (p = 0.0009).