Chemical analysis and significance of heterocyclic aromatic amines

Levels of known heterocyclic amines vary from undetectable in many meats so ld in fast food restaurants, to over 10 ng/g for meats prepared in restaura nts that cook food to order, to hundreds of nanograms per gram for some mea ts cooked under certain home or laboratory conditions. To simulate the dry reactions that seem to occur at the meat surface we developed a model syste m to mimic these processes. Mixtures of free amino acids, creatinine and gl ucose, simulating the composition of beef or chicken, heated at 200 degrees C, form eight heterocyclic amines. Besides the commonly found 2-amino-3,8- dimethylimidazo[4,5-f]quinoxaline, 2-amino-3-methylimidazo [4,5-f]quinoline , 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,4,8-trimethylimida zo [4,5-f]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-1,6-dimethylimidazo[4,5-b]pyridine, 2-amino-1,5,6-trimethylimidazo[ 4,5-b]pyridine and 2-amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b]pyridine we re also found. The calculated risk of consumption of heterocyclic amines is determined by the dietary dose, the extrapolation of carcinogenic potencie s from rodents to humans, and the extrapolation of high rodent doses to low human exposures. Results suggest that DNA binding is linear with dose, but that the human DNA forms more adducts per unit dose than that of the rat. Altogether, the risk appears to be equivalent to that for many carcinogens that are regulated.