The heterocyclic aromatic amines (HAAs) 2-amino-l-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP), 2-amino-3, 8-di-methylimidazo[4,5-f)quinoxaline (MelQx), 2-amino-3, 4, 8-tri-methylimidazo[4, 5-f)quinoxaline (4, 8-DiMeIQx) and 2-aminoαcarboline (AαC) were quantitated in grilled bacon and beef. The levels of PhIP in bacon ranged from < 0.1 to 52 p.p.b., MelQx was detected at levels ranging from 0.9 to 18 p.p.b. Both 4, 8-DiMeIQx and AαC were found at <1 p.p.b. In grilled meat patties, MelQx and PhIP were detected at levels ranging from 0.8 to 3.2 p.p.b., while 4, 8-DiMeIQx and AαC were below the limit of detection (∼0.5 p.p.b.). HAAs were below the limit of detection in grilled fish. The bacon fat drippings and the pan scrapings obtained from grilled meat and fish also contained significant amounts of HAAs and indicated that either these carcinogens are released with the fat during grilling or that HAAs are formed directly in the released fat and juices. Several of these carcinogens were detected in the pan scrapings at concentrations 10- to 100-fold higher than in cooked meats. PhIP was detected at 144 p.p.b. in combined grilled meat and fish scrapings, followed by AαC at 77 p.p.b., MelQx at 29 p.p.b. and 4, 8-DiMeIQx at 4 p.p.b. The co-mutagens harman and norharman were also detected in cooked meats and fish at amounts ranging from 5 to 30 p.p.b. Fat drippings and grill residue scrapings are often used as a base for gravies and sauces. Thus, cooking practices and dietary habits have a strong impact on HAA exposure.
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We would like to thank Dr Phaik-Moi Morgenthaler and Mr Olivier Muller for conducting mutagenicity assays, Mr Santo Ali and Miss Janique Richoz for analysis of HAAs, and Dr Cynthia Leaf for her critical review of the manuscript. This work was partially funded (W.G.S., P.L.S. and S.R.T.) by NIH grants ES05622 and ES02109.