Effects of relighting cigarettes on biomarkers of carcinogen and toxicant exposures

Some people who relight cigarettes (extinguishing then relighting later) believe they are reducing health harm from smoking, although studies suggest an increase in health risk compared to those who do not relight. Few studies have evaluated differences in biomarkers of exposures to toxicant among those who relight compared to those who do not.

Secondary analyses were conducted on baseline data from two clinical trials. Both studies assessed relighting frequency and collected urine samples. Measures included total nicotine equivalents (TNE), total NNAL (lung carcinogen metabolites for NNK), CEMA (acrylonitrile metabolite), HMPMA (crotonaldehyde metabolite), 3-HPMA (acrolein metabolite), and SPMA (benzene metabolite). Biomarkers were adjusted for creatinine and calculated per cigarette. Wilcoxon rank-sum tests (unadjusted) and multivariable linear regression (adjusting for variables differing between groups) compared participants who reported relighting cigarettes at least half the time and those who did not report relighting.

Relighting participants (N = 94) smoked fewer cigarettes/day than non-relighting participants (N = 181), (13.1 vs. 14.9; p = 0.045) but had higher TNE (p = 0.047). Other biomarkers did not differ (ps > 0.05). In unadjusted analysis most biomarkers per cigarette were higher for relighting participants (ps < 0.021, except total NNAL (p = 0.159). After covariate adjustment, total NNAL was lower for relighting participants (p = 0.019), while no per-cigarette biomarkers were significantly different (ps > 0.05).

People who relight smoke fewer cigarettes but do not reduce exposure to smoke toxicants, possibly due to more intense smoking. However, differences in levels per cigarette observed may primarily reflect individual characteristics, such as age, income, etc., distinguishing relighting from non-relighting participants.