EXPOSURE TO HETEROCYCLIC AMINES

Many mutagenic heterocyclic amines (HAs) have been isolated from cooke d foods and pyrolysates of amino acids and proteins, and the carcinoge nicity of 10 of these HAs in rodents and of 1 in monkeys has been repo rted. Quantification of these carcinogenic HAs in various kinds of coo ked foods indicated that the level of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) was highest (0.56-69.2 ng/g), that of 2-amino-3 ,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was second highest (0.64- 6.44 ng/g), and those of other HAs were 0,03-2.50 ng/g. Heterocyclic a mines were found in urine samples of 10 healthy volunteers consuming a normal diet, but HAs were not detectable in urine samples of three pa tients receiving parenteral alimentation. These results strongly sugge st that humans are continuously exposed to HAs derived from food in th e normal diet. Based on quantitative data on the levels of HAs in cook ed foods and urine samples, the daily exposures to PhIP and MeIQx were estimated to be 0.1-13.8 mug and 0.2-2.6 mug per person, respectively . These levels of carcinogenic HAs are in the same range as those of o ther carcinogens such as N-nitrosodimethylamine and benzo[a]pyrene to which humans are exposed.