A study of betel quid carcinogenesis. 3. 3-(Methylnitrosamino)-propionitrile, a powerful carcinogen in F344 rats.
3-(Methylnitrosamino)propionitrile (MNPN) is formed in vitro under mild nitrosation conditions from the major areca alkaloid arecoline. It appears likely that MNPN is generated during betel quid chewing especially when tobacco is added to the quid. Upon subcutaneous injection of 1.1 mmol of MNPN in 60 subdoses, all of the 15 male and of the 15 female F344 rats developed tumors within 24 weeks. Twenty-six of the rats had tumors in two different organs at least. Twenty-seven rats had esophageal tumors, 21 nasal tumors, 11 had tongue tumors and two animals had either pharyngeal carcinomas or papillomas of the forestomach. No tumors were observed in the solvent control group. These data indicate that MNPN is a potent carcinogen.