HETEROCYCLIC AROMATIC-AMINES IN HUMAN URINE FOLLOWING A FRIED MEAT MEAL

In a search for suitable biomarkers for human dietary exposure to hete rocyclic aromatic amines (HAAs), we have investigated the concentratio ns of three common fried food mutagens in food and urine after consump tion of a fried meat meal. In this connection we developed a method fo r the determination of HAAs and have investigated the common fried red meat HAAs 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-a mino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-t rimethylimidazo[4,5-f]quinoxaline (DiMeIQx). Eight volunteers particip ated in the study, each consuming a meal of fried minced beef patties (295 g), boiled potatoes, and a green salad. Urine was collected for t wo 12-hr periods prior to and following the meal. HAAs were determined in cooked meat and in untreated and acid hydrolysed urine by a series of liquid/liquid extractions, followed by Blue cotton adsorption and finally by a novel derivatization technique for gas chromatography-mas s spectrometry (GC-MS). The primary amino groups were derivatized by a cylation with heptafluorobutyric acid anhydride, and the resulting ami de methylated using diazomethane. Phenolic hydroxyl groups were also m ethylated by this procedure, making it possible to detect hydroxylated HAAs, possible metabolites or constituents of the fried meat. 4'-Hydr oxy-PhIP -methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine} (4'-OH-PhI P) was indeed found in meat as well as in urine. The contents of PhIP, MeIQx and DiMeIQx in meat were 4.0 +/- 2.6, 3.5 +/- 0.9 and 0.3 +/- 0 .1 ng g(-1) (mean +/- SD, n = 4), from which the mean amounts ingested were calculated to be 1180, 1030 and 90 ng, respectively. Total amoun ts of HAAs in the 0-24-hr post-meal untreated urine (and percent of in gested dose) were 6-23 ng PhIP (0.5-2%) and 10-63 ng MeIQx (1-6%). In hydrolysed urine, the levels of HAAs were higher, totalling 24-100 ng PhIP (2-8.5%) and 133-329 ng of MeIQx (13-32%). DiMeIQx was below dete ction limit in all urine samples. Judged from our study, there were ra ther large inter-individual variations in the amounts of excreted HAAs , possibly caused by variations in the activities of enzymes taking pa rt in HAA metabolism. (C) 1997 Elsevier Science Ltd. All rights reserv ed.