Comparison of Nicotine and Toxicant Exposure in Users of E-Cigarettes and Combustible Cigarettes
Bottom Line: Exclusive use of e-cigarettes appears to result in measurable exposure to known tobacco-related toxicants, but at much lower levels than cigarette smokers. Toxicant exposure is greatest among dual users, and frequency of combustible cigarette use is positively correlated with tobacco toxicant concentration.
Cigarettes are harmful nicotine delivery products, exposing smokers to more than 6,000 chemicals, many of which are toxic to human health. Reducing smoking-related health risks requires complete cessation. Yet, among continuing smokers who cannot or will not quit, questions remain about the potential harm of alternative tobacco products, such as e-cigarettes.
This population-based cohort study of 5105 participants estimated concentrations of tobacco-related toxicants among e-cigarette users and compared these biomarker concentrations with those observed in combustible cigarette users, dual users, and never tobacco users. It found current exclusive e-cigarette users had greater concentrations of biomarkers of nicotine, tobacco-specific nitrosamines, volatile organic compounds, and metals compared with never tobacco users. However, these concentrations were lower than those observed in current exclusive cigarette smokers and dual users of both products.
Compared with exclusive e-cigarette users, never users had 19% to 81% significantly lower concentrations of biomarkers of exposure to nicotine, TSNAs, some metals (eg, cadmium and lead), and some VOCs (including acrylonitrile). Exclusive e-cigarette users showed 10% to 98% significantly lower concentrations of biomarkers of exposure, including TSNAs, PAHs, most VOCs, and nicotine, compared with exclusive cigarette smokers; concentrations were comparable for metals and 3 VOCs. Exclusive cigarette users showed 10% to 36% lower concentrations of several biomarkers than dual users. Frequency of cigarette use among dual users was positively correlated with nicotine and toxicant exposure.
The frequency of e-cigarette use influenced the differences in observed urinary concentrations of several biomarkers among daily vs some-days e-cigarette users: everyday e-cigarette–only users had higher concentrations of all major nicotine metabolites, TSNAs, 2 metals (lead and strontium) and 1 marker for acrylonitrile than some-days e-cigarette–only users.
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• E-cigarette users have greater concentrations of biomarkers of nicotine, tobacco-specific nitrosamines, volatile organic compounds, and metals compared with never tobacco users.
• E-cigarette users' concentration of tobacco toxins is much lower than those observed in current exclusive cigarette smokers.
• Toxicant exposure is greatest among dual users, and frequency of combustible cigarette use is positively correlated with tobacco toxicant concentration.