A review of cancer risk associated with human exposure to hydrazines.

This review assesses the carcinogenic action of five hydrazines: hydrazine, 1-hydrazinophthalazine HCI, isonicotinic acid hydrazide, N-isopropyl-alpha-(2-methyl-hydrazino)-p-toluamide HCI, and beta-phenylethylhydrazine in humans. All five hydrazines are considered as animal carcinogens. Exposure to the base compound hydrazine occurred through occupational settings, while humans were subjected to the other four hydrazine derivatives through drug therapy. Each of the published cases and cohort reports are evaluated by paying particular attention to the number of involved patients, dose and duration of chemical exposure, the extent of the follow-up period and the possible concomitant involvement of other types of chemicals or agents. After the evaluation of each chemical, a conclusion and comments are provided by summarizing the various findings. Even though each report can be criticized for its flaws, nevertheless, a substantial number of reports attributed a positive correlation between hydrazine exposure and cancer development.