Influence of Tobacco Variety and Curing on Free Radical Production in Cigarette Smoke

Introduction Cigarette smoke contains highly reactive free radicals thought to play an important role in tobacco smoke-induced harm. Previously, large variations in free radical and toxicant output have been observed in commercial cigarettes. These variations are likely because of cigarette design features (paper, filter, and additives), tobacco variety (burley, bright, oriental, etc.), and tobacco curing methods (air, sun, flue, and fire). Previous reports show that tobacco varieties and curing methods influence the production of tobacco smoke constituents like the tobacco-specific carcinogen nicotine-derived nitrosamine ketone (NNK). Aims and Methods We evaluated free radical, nicotine, and NNK production in cigarette smoke from cigarettes produced with 15 different types of tobacco. Gas-phase free radicals were captured by spin trapping with N-tert-butyl-alpha-phenylnitrone and particulate-phase radicals were captured on a Cambridge Filter pad (CFP). Both types of radicals were analyzed using electron paramagnetic resonance spectroscopy. Nicotine and NNK were extracted from the CFP and analyzed by gas chromatography flame ionization detection and liquid chromatography-mass spectrometry, respectively. Results Gas-phase radicals varied nearly 8-fold among tobacco types with Saint James Perique tobacco producing the highest levels (42 +/- 7 nmol/g) and Canadian Virginia tobacco-producing the lowest levels (5 +/- 2 nmol/g). Nicotine and NNK levels in smoke varied 14-fold and 192-fold, respectively, by type. Gas-phase free radicals were highly correlated with NNK levels (r = 0.92, p < .0001) and appeared to be most impacted by tobacco curing method. Conclusions Altogether, these data suggest that tobacco types used in cigarette production may serve as a target for regulation to reduce harm from cigarette smoking. Implications Variations in cigarette free radical and NNK levels vary based on the tobacco variety and curing method. Reducing the ratio of high-producing free radical and NNK tobacco types offer a potential tool for regulators and producers looking to reduce toxicant output from cigarettes.