Comparative carcinogenicity of the food pyrolysis product, 2-amino-5-phenylpyridine, and the known human carcinogen, 4-aminobiphenyl, in the neonatal B6C3F1 mouse

2-Amino-5-phenylpyridine (2-APP) is a mutagenic heterocyclic aromatic amine that is formed by pyrolysis of phenylalanine in proteins. Since this mutagen is structurally similar to the multipotent carcinogen, 4-aminobiphenyl (4-ABP), we compared their relative tumorigenic activity in the neonatal male B6C3F1 mouse. After determinations of the maximum tolerated dose (MTD), both aromatic amines were administered i.p. at 2 dose levels (MTD and MTD/2) on days 1, 8, 15 and 22 after birth. Groups were killed at 9 and 12 months and examined for histopathologic changes. No treatment-related neoplastic lesions were observed for 2-APP. In contrast, 4-ABP was strongly carcinogenic and induced a high incidence of multiple hepatocellular adenomas and carcinomas.