Epidemiological studies of medically used drugs.

In a recent review of chemicals associated with cancer production in man from U.S. National Cancer Institute and two Federal Agencies, seven drugs were listed. The evidence for the carcinogenicity of chlornaphazine will be reviewed and the results of long-term epidemiological studies, which show that phenobarbitone and isoniazid should not be suspected of carcinogenicity, will be discussed.