title: Lifetime carcinogenicity study of 1- and 2-naphthylamine in dogs.
abstract: Groups of male and female beagle dogs were given daily doses of 400 mg of various mixtures of naphthylamines for up to 109 months. Survivors were killed at 128 months. A variety of pathological conditions was diagnosed, but the only effect related to treatment was the induction of bladder neoplasms. All dogs which received pure 2-naphthylamine developed transitional-cell carcinomas of the bladder within 34 months. Two of 8 dogs receiving 6% 2-naphthylamine in 1-naphthylamine developed early carcinoma and 2/8 dogs receiving 0.5% 2-naphthylamine in 1-naphthylamine developed haemangioma of the bladder. Some of the dogs receiving 1-naphthylamine (total dose 950 g) and the controls had focal cystitis or hyperplasia, but no neoplasia of the bladder. These results confirm the carcinogenicity of 2-naphthylamine to dogs. No carcinogenic effect of 1-naphthylamine was observed, indicating that it is at least 200 times less potent as a carcinogen than 2-naphthylamine. The incidence of bladder cancer in dogs fed mixtures of both naphthylamines explains why previous experimental and epidemiological studies of impure 1-naphthylamine have revealed carcinogenicity.
mesh_terms: D015057:1-Naphthylamine / Q000633:toxicity; D015081:2-Naphthylamine / Q000633:toxicity; D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000139:chemically induced* / Q000473:pathology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D009281:Naphthalenes / Q000633:toxicity*; D001743:Urinary Bladder / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced* / Q000473:pathology
chemical_list: D009281:Naphthalenes; D015057:1-Naphthylamine; D015081:2-Naphthylamine