Biomarkers of Nicotine and Toxicant Exposure by E-liquid Nicotine Concentration Level among U.S. Adult Exclusive E-cigarette Users.

Background: The current e-cigarette market has been rapidly evolving with an increase in the share of high nicotine concentration vaping products. This study examined urinary biomarkers of exposure (BOEs) by nicotine concentration level among exclusive e-cigarette users.

Methods: Data were drawn from Wave 5 (December 2018-November 2019) of the Population Assessment of Tobacco and Health (PATH) Study. Between-subject differences in BOEs of nicotine, metal, tobacco-specific nitrosamine (TSNA), and volatile organic compounds (VOC) were examined across e-cigarettes containing nicotine or not (yes [n=300] vs. no [n=31] vs. non-tobacco use [n=3021]) and different nicotine concentration levels (0.1-1.7%, 1.8-4.9%, and 5.0%+).

Results: Among 3353 participants, exclusive e-cigarette users exhibited higher mean concentrations of nicotine metabolites than non-tobacco users. Nicotine e-cigarette users had higher concentrations of TNE2 (mean [95% CI]=21.8 [15.2-31.2] vs. 0.2 [0.1-0.6] nmol/mg creatinine, p<.0001) and cotinine (1418.2 [998.0-2015.4] vs. 12.2 [0.1-0.6], p<.0001) ng/mg creatinine, p<.0001) than non-nicotine e-cigarette users. Users of e-cigarette products with nicotine levels of 1.8-4.9% had higher TNE2 and cotinine levels than those using 0.1-1.7%, though differences were insignificant after adjusting for covariates. As compared to non-tobacco users, nicotine vapers had higher concentrations of lead (adjusted p=0.01).

Conclusions: Nicotine containing e-cigarette users exhibited elevated levels of nicotine metabolites than non-nicotine containing vapers and non-tobacco users. Future research needs to investigate health effects of e-cigarette use across different nicotine levels Impact: Regulating the nicotine content in e-cigarettes could be crucial in managing nicotine exposure and potentially mitigating associated health risks.