Cytogenetic effects of a food mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine (PhIP), and its metabolite, 2-hydroxyamino-1-methy-6-phenylimidazo[4,5-beta]pyridine (N-OH-PhIP), on human and Chinese hamster cells in vitro.

2-Amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine (PhIP) induced structural chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs) in human lymphocytes and human diploid fibroblasts (TIG-7) at concentrations above 12.5 microgram /ml in the presence of rat S9 mix. PhIP also elevated the frequencies of SCEs in human lymphocytes in the presence of rat S9 at concentrations above 2.0 microgram/ml with dose-dependency. A proximate form of metabolites of PhIP, 2-hydroxy-amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine (N-OH-PhIP), caused CAs in human and Chinese hamster fibroblast cells in the absence of S9 mix at concentrations above 0.75 microgram/ml and 1.25 microgram/ml, respectively, which were 10 times lower than the effective concentration of PhIP. No marked differences were observed in the cytogenetic sensitivity to N-OH-PhIP between human and Chinese hamster cells, except between lymphocytes obtained from different donors.