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Summary of the Public Health Goal for Benzo(A)Pyrene (BaP)

A Public Health Goal (PHG) of 4 ppt is developed for benzo(a)pyrene (BaP) in drinking water. The PHG is based on carcinogenic effects observed in experimental animals. The 1967 study by Neal and Rigdon cited in the development of the PHG demonstrated gastric tumors in mice administered BaP in the diet. For the calculation of the PHG, cancer potency estimates were made based upon the recommended practices of the U.S. Environmental Protection Agency (U.S. EPA) for cancer risk assessment in which the linearized multistage (LMS) model is fit to the experimental data in order to establish the lower 95% confidence bound on the dose associated with a 10% increased risk of cancer (LED10). An assumption of linearity was made for doses below this and outside of the range of observation in order to generate a cancer slope factor (CSF). Inter-species extrapolation was also done using the guidance provided by U.S. EPA. For the calculation of the PHG, theoretical excess individual cancer risk from exposure to BaP was limited to the de minimis level of 10-6. On the basis of the cancer risk calculations, a PHG of 4 ppt is developed. The PHG is considered to contain an adequate margin of safety for the potential noncarcinogenic adverse effects including adverse effects on the skin, and the hematological, gastrointestinal, immunological and reproductive and developmental systems.