Critical Evaluation of Phosmet's Breast Cancer Risk

Abstract Phosmet is an organophosphate insecticide, widely used on fruit trees in orchards. There is a potential for occupational and para-occupational exposure to this insecticide. While there is some evidence of a carcinogenic effect, phosmet has not been through a complete review for its carcinogenic potential by the International Agency for Research on Cancer (IARC), or the United States Environmental Protection Agency (EPA). Health effects from phosmet are undergoing a review at EPA, as part of the procedure for reassessment of tolerances for OP under the Food Quality and Protection Act of 1996 (FQPA). In this evaluation, we have used a modification of the IARC approach to conduct a detailed evaluation of any direct or related evidence of cancer risk, with a focus on breast cancer risk from phosmet. We have critically evaluated all the available human, experimental animal, and cancer-related molecular and mechanistic studies on phosmet. Chemical and up-to-date regulatory information is included, as well as a discussion of phosmet's environmental fate and potential for human exposure. Evidence available so far does not indicate that phosmet increases breast cancer risk. We propose that phosmet be classified in Group 3 in the Program on Breast Cancer and Environmental Risk Factor's (BCERF) breast cancer risk classification scheme (see Appendix B). This group represents chemicals that are not classifiable for breast cancer risk in humans.