Doses of nicotine and lung carcinogens delivered to cigarette smokers

Abstract

Background: Cigarette smoke yields of tar and nicotine obtained under the Federal Trade Commission (FTC)-specified machine-smoking protocol (35-mL puff volume drawn for 2 seconds once per minute) may not accurately reflect the delivery of toxins and carcinogens to the smoker. We conducted this study to obtain more realistic estimates of exposure to components of cigarette smoke that affect lung cancer risk.

Methods: We used a pressure transducer system to evaluate puffing characteristics for 133 smokers of cigarettes rated by the FTC at 1.2 mg of nicotine or less (56 smokers of low-yield cigarettes [</=0.8 mg of nicotine per cigarette] and 77 smokers of medium-yield cigarettes [0.9-1.2 mg of nicotine per cigarette]). We programmed measurements from a randomly chosen subset of 72 of these smokers into a piston-type machine to generate smoke from each smoker's usual brand of cigarettes for assays of nicotine, carbon monoxide, tar, and the lung cancer-causing agents 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene. The FTC protocol was also used to assess levels of targeted components in the 11 brands most frequently smoked by study subjects.

Results: Compared with the FTC protocol values, smokers of low- and medium-yield brands took in statistically significantly larger puffs (48.6 and 44.1 mL, respectively) at statistically significantly shorter intervals (21.3 and 18.5 seconds, respectively), and they drew larger total smoke volumes than specified in the FTC parameters. They received, respectively, 2.5 and 2.2 times more nicotine and 2.6 and 1.9 times more tar than FTC-derived amounts, as well as about twofold higher levels of benzo[a]pyrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Smokers of medium-yield cigarettes compared with smokers of low-yield cigarettes received higher doses of all components.

Conclusions: The FTC protocol underestimates nicotine and carcinogen doses to smokers and overestimates the proportional benefit of low-yield cigarettes. Thus, FTC-based nicotine medication doses prescribed/recommended for smoking cessation may need to be reassessed.