Induction of local epidermal papillomas and carcinoma by selected nitrosamines

Weekly cutaneous application of N-nitrosobis (2-oxopropyl)amine (BOP) at a dose of 2 mg/application to the neck area resulted in the induction of local papillomas and carcinomas in 80% of Syrian hamsters as early as 19 weeks post-treatment. In addition, a few tumors of internal organs (predominantly in the liver) were also found. N-Nitroso(2-hydroxypropyl) (2-oxopropyl)amine (HPOP), a common metabolite of BOP and BHP, was also found to be an epidermal carcinogen at a dose of 3.8 mg/application. N-Nitrosobis(2-hydroxypropyl)amine (BHP), however, failed to induce any epidermal lesions, when applied similarly at a much higher dose level (%) mg/animal/week). In contrast to BOP and HPOP, BHP induced a high incidence of tumors in internal organs, especially pancreatic cancer, which was the only induced tumor in 5 animals. Skin absorption studies demonstrated that BHP, but not BOP is rapidly absorbed and was detectable in the blood in concentrations of up to 5.5 mug/ml as early as 15 min after carcinogen administration. The possible reasons for the differing effects of BHP and BOP upon hamster skin are discussed.