STUDY OF TOBACCO CARCINOGENESIS .19. COMPARATIVE CARCINOGENICITY IN F344 RATS OF THE TOBACCO-SPECIFIC NITROSAMINES, N'-NITROSONORNICOTINE AND 4-(N-METHYL-N-NITROSAMINO)-1-(3-PYRIDYL)-1-BUTANONE

Abstract

The tobacco-specific carcinogens N''-nitrosonornicotine (NNN) and 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were tested for carcinogenicity in F344 rats. Each nitrosamine in trioctanoin was administered by s.c. injection to 12 male and 12 female rats over 20 wk. The total dose of each nitrosamine was 3.4 mmol. The experiment was terminated after 12 mo. NNK induced nasal cavity tumors in 83% of the males and in 83% of the females, liver tumors in 83% of the males and in 100% of the females, and lung tumors in 67% of the males and in 67% of the females. NNN induced nasal cavity tumors in 92% of the males and in 75% of the females. Only 1 liver tumor and no lung tumors were observed in the NNN-treated rats. In the F344 rat NNK apparently is a more powerful carcinogen than is NNN.