Gender differences in tobacco smoking: Higher relative exposure to smoke than nicotine in women

Introduction: Men and women are thought to regulate their smoking differently and to differ in their susceptibility to nicotine addiction. Methods and Materials: Various measures of smoke exposure were compared between 400 current regular tobacco-dependent (DSM-IV) male and female light (1-15 cigarettes per day) and heavy (>15 cigarettes per day) smokers. Between 2 and 8 Pm, blood was collected for nicotine and cotinine analysis, and breath carbon monoxide (CO) was measured. Individuals with genetic variants of the CYP2A6 gene were removed from analysis (n = 25). Results: No significant difference was found in the number of cigarettes per day or CO levels between the sexes. However, females had significantly lower nicotine levels than males (16.9 +/- 0.6 vs. 21.1 +/- 0.07, p < 0.01). This is only partly explained by the fact that females smoked lower nicotine-containing cigarettes. Female heavy smokers demonstrated higher -log nicotine/CO values (a representation of cost of smoking) compared with male heavy smokers (0.1 +/- 0.02 vs. 0.02 +/- 0.01 mg/L ppm, p < 0.05). Conclusions: Thus, gender differences appear to exist in smoking behaviors, nicotine sensitivity, and nicotine requirements. These differences are expected to contribute to gender differences in health risks and cancers associated with smoking.