Application of the margin-of-exposure (MoE) approach to substances in food that are genotoxic and carcinogenic e.g.: benzo[a]pyrene and polycyclic aromatic hydrocarbons.

Benzo[a]pyrene (BaP) and a number of other polycyclic aromatic hydrocarbons (PAH) are mutagenic and are also carcinogenic in rodent bioassays. Oral carcinogenicity data are not available for individual PAH other than BaP, and so BaP has been used as a marker of the carcinogenicity of, and exposure to, PAHs. Carcinogenicity studies of coal tar mixtures, considered to be representative of the genotoxic and carcinogenic PAH in food, have been used for dose-response modelling. Modelling the number of tumour-bearing mice resulted in a BMDL(10) of 0.122 mg BaP/kg-bw/day, which was lower than that for any of the individual tumours and was considered to be most appropriate since the different PAH may have different mechanisms of carcinogenicity. An average dietary exposure estimates of 0.008 microg BaP/kg-bw/day was identified from the range of national estimates. The calculated MoE was 15,000.