Malignant neoplasms among patients with certified chronic arsenic poisoning in Toroku

An epidemiological study has been made to assess the carcinogenic effect of arsenic exposure by analyzing a group of patients with certified chronic arsenic poisoning at “Toroku”, a small mountainous village in Japan. The number of deaths from cancer of the respiratory system and cancer of bladder, kidney and other and unspecified urinary organs showed a significant excess over the expected value, compared with expected number of deaths, based on sex and age-specific mortality of Japanese in 1975, 80 and 85. The number of patients from all cancers, respiratory cancer and urinary tract cancer showed a significant exess of former workers, using data classified by employment history. Classified by employment history and smoking habits, the number of respiratory cancers showed a significant excess only in the cohort of former workers with a smoking history. This finding suggests that there is an interaction between exposure to arsenic and smoking. Eleven of seventeen cancer cases were accompanied by cancer of other organs, including Bowen's disease. These results demonstrated that a follow-up study on these patients should be conducted with a particular emphasis on cancers.