Characterization ofN-Nitrosamino Acids in Tobacco Products and Assessment of Their Carcinogenic Potential

Abstract

Ninety percent of the more than 300 nitrosamines bioassayed are organ-specific carcinogens in animals; some of these compounds are carcinogenic at doses as low as 0.1 mmo1/kg. Several N-nitrosamines are suspected human carcinogens. Recently, our attention has been focused on N-nitrosamino acids (NAA) which occur widely in food products and in other consumer products. N-Nitrosamino acids are also known to be formed by endogenous nitrosation of amino acids. So far 16 nitrosamino acids have been identified in consumer products, 7 have been bioassayed and 3 have been found to be carcinogenic in mice and/or rats: N-nitrososarcosine (NSAR) induces liver carcinoma in male newborn mice and esophageal tumors in BD rats; 3-(methylnitrosamino)propionic acid (MNPA) induces lung tumors in female A/J mice and, 4-(methylnitrosamino)butyric acid (MNBA) causes bladder cancer in F344 rats. The highest levels of carcinogenic N-nitrosamino acids were found in smokeless tobacco products (Table I), MNPA amounting to 70 µg/g