US EPA

In 1992, the U.S. Environmental Protection Agency's (EPA's) Office of Mobile Sources (OMS) requested the National Center for Environmental Assessment (NCEA) to provide an updated characterization of the cancer risk of benzene to humans. The previous characterization of the carcinogenic risk of exposure to benzene was done in 1985 by the Office of Health and Environmental Assessment (the predecessor organization to NCEA). Additional scientific data relevant to the carcinogenicity of benzene have been published in the literature since that time. This has brought into question the relevancy of the earlier quantitative cancer risk estimates. The 1985 cancer unit risk estimates were based on assumptions about the effects of low-level benzene exposure on humans derived from occupational health studies.

The regulatory authority (Clean Air Act Amendments, 1990) for controlling fuel emissions in vehicles resides in OMS. Before OMS exercises its regulatory authority, OMS has asked NCEA for scientific supporting documents based on health implications of continued exposure to benzene.

The scope of this report is limited to issues related to the carcinogenicity of benzene. Specifically, this report evaluates and discusses studies published since 1985 to ascertain if there has been sufficient new scientific information that would significantly alter the 1985 interim benzene unit cancer risk estimate.

Bayliss, D., C. Chen, B. Sonawane, AND L. Valcovic. Carcinogenic Effects of Benzene: An Update (1997 External Review Draft). U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washington Office, Washington, DC, EPA/600/P-97/001A, 1997.