 The U.S. Environmental Protection Agency (EPA) grades it as "B2—a probable human carcinogen based on animal study evidence".The International Agency for Research on Cancer (IARC) rates hydrazine as "2A—probably carcinogenic to humans" with a positive association observed between hydrazine exposure and lung cancer.Based on cohort and cross-sectional studies of occupational hydrazine exposure, a committee from the National Academies of Sciences, Engineering and Medicine concluded that there is suggestive evidence of an association between hydrazine exposure and lung cancer, with insufficient evidence of association with cancer at other sites.