Research Article AComparison of Nicotine Biomarkers and Smoking Patterns in Daily and Nondaily Smokers

Background: Nondaily or intermittent smokers (ITS) are increasingly common, but how much nicotine, if any, ITS take in and how quickly they metabolize it has not yet been studied. Methods: We compared carbon monoxide (CO), urinary cotinine, and nicotine metabolism [nicotine metabolite ratio (NMR): 3-hydroxycotinine:cotinine] in 224 ITS and 222 daily smokers (DS). Effects of gender and ethnicity were examined. Results: DS had higher cotinine concentrations than ITS (1,396 69 vs. 478 44 ng/mL), attributable to higher cigarettes per day (CPD). In both groups, cotinine rose more slowly as CPD increased. There were no differences in cotinine betweenWhite (WH) andAfricanAmerican (AA)DS; among ITS, AA cotininewas over twice that of WH. Among DS, CO was significantly higher among WH than AA smokers, but significantly lower amongWH ITS than AA ITS. Although AA ITS smoked more thanWH ITS (CPD: 4.13 0.55 vs. 3.31 0.41), this did not account for the observed cotinine nor CO differences. There were no differences in NMR by group or race, nor any gender effects. Conclusions: At comparable CPD, DS ’ and ITS ’ intake of nicotine per cigarette was similar, as were their rates of nicotinemetabolism.Among ITS,AA smokers smokemore and take inmore nicotine per cigarette than WH ITS, consistent with the view of ITS as a heterogeneous group. Impact: Differences in nicotine intake per cigarette and metabolism likely cannot account for differences in DS and ITS smoking. Future studies should explore ethnic differences in ITS smoking. Cancer Epidemiol Biomarkers Prev; 23(7); 1–9. 2014 AACR