A study of tobacco carcinogenesis. XIV. Effects of N'-nitrosonornicotine and N'-nitrosonanabasine in rats.

N'-Nitrosonornicotine (NNN) and N'-nitrosoanabasine (NAB) were synthesized and administered in drinking water to male Fischer rats for 30 weeks (total dose, 630 mg). 1,4-Dinitrosopiperazine (DNPI) served as the positive control. By 11 months, all surviving rats given NNN developed esophageal tumors (12/20); 1 had a pharyngeal tumor and 3 had invasive carcinomas originating in the nasal cavity. During the same time, only 1 of 20 rats given NAB developed esophageal tumors. Compared to the strong esophageal carcinogen DNPI, NNN was a moderately active and NAB a weak carcinogen. NNN (0.3-90 parts per million) in chewing tobacco was related to the observation that cancer of the oral cavity and esophagus in man was correlated with the chewing of tobacco.