2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) in human hair as biomarker for dietary exposure

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Abstract
Heterocyclic aromatic amines (HAAs), formed during cooking of meat, are multipotent rodent carcinogens and are suspected to cause cancer in humans. In a search for suitable biomarkers for human dietary exposure to HAAs, we have investigated the concentration of a common fried food mutagen, 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP), in human hair. Fourteen volunteers participated in the study, each contributing hair from a regular haircut, and completing a questionnaire about consumption of fried/grilled meat and smoking habits. Hair samples were treated with 1 N NaOH at 100 C, and the HAAs extracted under alkaline and acidic conditions, derivatized and analysed by gas chromatography-mass spectrometry. PhIP was found in 12 out of 14 hair samples, in amounts from approx. 50 to 5000 pg g-1 hair, while two samples were below the detection limit (-1 hair). Grey/white hair straws from subjects with a mixture of coloured and grey/white hair had about a 50% reduction in PhIP concentration as compared with the natural hair mixture from the same person. This demonstrates that melanin, responsible for hair colour and spectrophotometrically characterized in the samples, participates in PhIP binding. Thus, when HAA binding components of the hair are taken into account, hair seems like an interesting object of further investigation as a biomarker for human exposure to dietary PhIP.