Chapter Seven - Metabolism and DNA adduct formation of carcinogenic tobacco-specific nitrosamines found in smokeless tobacco products

Abstract

Tobacco-specific nitrosamines are the most abundant strong carcinogens in smokeless tobacco products. This chapter focuses on three of the most important of these compounds: N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). The carcinogenic activities of NNN, NNK, and NNAL are discussed, and the metabolic pathways of these carcinogens are presented. Specific metabolite biomarkers have been developed to assess exposure to tobacco-specific nitrosamines in smokeless tobacco users; these are presented and discussed. DNA and protein adduct formation by tobacco-specific nitrosamines are also summarized, based mainly on studies in laboratory animals.