A new colon and mammary carcinogen in cooked food, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which is produced during cooking and is mutagenic to bacteria and cultured mammalian cells, was found to induce high incidences of colon and mammary carcinomas in F344 rats when administered at a concentration of 400 p.p.m. in the diet for 52 weeks. Since PhIP is the most abundant of the mutagenic heterocyclic amines in cooked meat and fish, the compound might be related to malignancies of the colon and breast in humans.