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

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.