Characterizing nicotine exposure among a community sample of non-daily smokers in the United States.

BACKGROUND: Over one-quarter of all smokers in the United States identify as non-daily smokers and this number is projected to rise. Unlike daily smokers who typically maintain consistent levels of nicotine exposure with regular smoking, non-daily smokers have variable patterns of smoking that likely result in high intraindividual variability in nicotine intake. The current study aimed to characterize the weekly intraindividual variability in cotinine and identify smoking-related predictors in nondaily smokers. METHODS: An ecological momentary assessment of 60 non-daily smokers ages 24-57 years was conducted over a consecutive 7-day at-home protocol to log each smoking session, assessments of mood and social activity during smoking, and collection of daily saliva samples in a convenience sample from Pennsylvania, USA. Hierarchical linear regression analyses were conducted to determine the effects of smoking characteristics on total cotinine exposure measured by pharmacokinetic area under the curve and the range, maximum, and minimum cotinine values during the week controlling for demographic variables. RESULTS: The mean daily cotinine level was 119.2 ng/ml (SD = 168.9) with individual values that ranged from nondetectable to 949.6 ng/ml. Menthol predicted increased total cotinine levels (P < 0.05). Shorter time to the first cigarette of the day predicted significantly higher minimum (P < 0.05), maximum (P < 0.05), and total cotinine values (P < 0.05) after controlling for covariates. Negative emotions and social interactions with others were also significantly associated with higher cotinine metrics. There was no significant effect of the nicotine metabolite ratio. CONCLUSIONS: Our findings highlight the variability in nicotine exposure across days among non-daily smokers and point to the role of smoking context in nicotine exposure. The findings suggest the need to develop better assessment methods to determine health and dependence risk and personalized cessation interventions for this heterogeneous and growing group of smokers.

Comparison of Puff Volume With Cigarettes per Day in Predicting Nicotine Uptake Among Daily Smokers.

The role of inhalation behaviors as predictors of nicotine uptake was examined in the Pennsylvania Adult Smoking Study (2012-2014), a study of 332 adults whose cigarette smoking was measured in a naturalistic environment (e.g., at home) with portable handheld topography devices. Piecewise regression analyses showed that levels of salivary cotinine, trans-3'-hydroxycotinine, and total salivary nicotine metabolites (cotinine + trans-3'-hydroxycotinine) increased linearly up to a level of about 1 pack per day (20 cigarettes per day (CPD)) (P < 0.01). Total daily puff volume (TDPV; in mL) (P < 0.05) and total daily number of puffs (P < 0.05), but not other topographical measures, increased linearly with CPD up to a level of about 1 pack per day. The mean level of cotinine per cigarette did not change above 20 CPD and was 36% lower in heavy smokers (≥20 CPD) than in lighter smokers (<20 CPD) (15.6 ng/mL vs. 24.5 ng/mL, respectively; P < 0.01). Mediation models showed that TDPV accounted for 43%-63% of the association between CPD and nicotine metabolites for smokers of <20 CPD. TDPV was the best predictor of nicotine metabolite levels in light-to-moderate smokers (1-19 CPD). In contrast, neither CPD, total daily number of puffs, nor TDPV predicted nicotine metabolite levels above 20 CPD (up to 40 CPD). Finally, although light smokers are traditionally considered less dependent on nicotine, these findings suggest that they are exposed to more nicotine per cigarette than are heavy smokers due to more frequent, intensive puffing.