Heterocyclic amines formed by cooking food: comparison of bioassay results with other chemicals in the Carcinogenic Potency Database.

Results in the Carcinogenic Potency Database (CPDB) on 11 mutagenic heterocyclic amines (HA) tested for carcinogenicity in rats, mice and cynomolgus monkeys are compared to results for other chemicals. An analysis of strength of evidence of carcinogenicity for HA vs. other mutagenic carcinogens and vs. all rodent carcinogens, indicates strong carcinogenicity of HA in terms of positivity rates and multiplicity of target sites. The liver is the most frequent target site in each species. Despite several target sites in each species, concordance in target sites between rats and mice is restricted to the liver for each HA except one. In cynomolgus monkeys, liver tumors have been induced rapidly by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Human exposures to HA in cooked animal foods are small, in the low ppb range. A comparison of possible carcinogenic hazards from a variety of exposures to rodent carcinogens in the American diet is presented, using an index (Human Exposure/Rodent Potency, HERP) that relates human exposure to carcinogenic potency in rodents. Results indicate that there is a large background of exposures to naturally-occurring rodent carcinogens in typical portions of common foods, and that possible hazards from HA rank below those of most natural pesticides and products of cooking or food preparation; synthetic pesticide residues also rank low.