Understanding the mediation effects of cigarettes per day on time to first cigarette and carcinogen biomarkers: National Health and Nutrition Examination Survey 2015–2016

Abstract

Introduction: Previous research indicates that cigarette smokers with a time to first cigarette (TTFC) of less than 30 minutes after waking up had significantly higher levels of carcinogen biomarkers compared to those with a TTFC of more than 30 minutes. The mediation (potential mediator: cigarettes smoked per day) between TTFC and carcinogen biomarkers, remains unclear and has yet to be established. Methods: Multivariable linear regression models were used to estimate adjusted geometric means (GMs) and ratios of GMs for urine biomarkers of VOCs by smokers’ TTFC status (≤30 vs >30 min). Further, data from the NHANES 2015–2016 special sample were analyzed to assess the mediation between TTFC (exposure) and carcinogen biomarkers, including urine metabolites of polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and cadmium. Results: Cigarette smokers with a short TTFC (≤30 min) presented significantly higher concentrations in 8 out of 17 urine metabolites of VOCs examined compared to smokers with TTFC >30 min. The association between exposure and carcinogen biomarkers was not mediated by CPD. Conclusions: Cigarette smokers with a short TTFC (≤30 min) had significantly higher levels in VOCs, PAHs, and cadmium, but the association was not mediated by cigarettes smoked per day.