CHEMICAL-ANALYSIS, PREVENTION, AND LOW-LEVEL DOSIMETRY OF HETEROCYCLIC AMINES FROM COOKED FOOD

Potent mutagenic and carcinogenic heterocyclic amines are produced fro m heated food derived from muscle. These compounds are present at part -per-billion levels and consist primarily of the amino-imidazoazaarene class of chemicals. Additional mutagens present in the meat are not a s clearly characterized. Commercial fried-beef patties (hamburgers) ha ve low levels of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 0 .1-0.68 ng/g meat for MeIQx and slightly lower for 4,8-DiMeIQx. The fo rmation of these heterocyclic amines can be reduced by microwave pretr eatment of meat, with the resulting liquid being poured off before fry ing. The Ames/Salmonella mutagenic activity was reduced to 5-10% of th at of non-microwave-treated samples. MeIQx and DiMeIQx concentrations were reduced to 12% and 50% of levels in the non-microwave-treated sam ples, respectively. MeIQx adducts, as measured by accelerator mass spe ctrometry, were found to be linear with doses from 5 mg/kg to 500 ng/k g. Linear DNA binding at low doses is important for assuming linear ri sk estimation from the high animal-feeding doses causing cancer to the low human-dietary exposures. Extrapolating from the rodent TD50 dose to humans gives a maximum credible risk from consumption of heterocycl ic amines of approximately 1/1000 exposed individuals.