Incorporation of the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) into hair of mice

The incorporation of the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP) into hair of newborn mice was investigated in order to co ntribute to the validation of PhIP in hair as a suitable biomarker for huma n dietary exposure. Black mice (C57BL/6J; 7-9 days old) were given graded d oses of [H-3]-PhIP subcutaneously during the start of the hair growth perio d. The distribution of [H-3]-PhIP and incorporation into hair were investig ated by rape-section autoradiography. Almost all the radioactivity in hair represented PhIP as shown by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). A dose-response proportio nality of incorporation into hair was found when incorporation was determin ed by liquid scintillation counting. Autoradiography showed that PhIP was r apidly cleared from the skin, but remained for at least 28 days in the part of the hair shafts which was formed during the exposure period. The presen t results obtained using the mouse as a model, further support the suggesti on that PhIP in hair may be a suitable biomarker for human exposure to diet ary PhIP.