Will the debate over e-cigarettes start cooling down?

The cost-benefit of electronic cigarettes (e-cigarettes) continues to be debated in the public health literature. The most recent estimates indicate that 10.8 million US adults (4.5%) have used an e-cigarette in the past 30 days.1 Among high school students and young adults (aged 18-24 years), these rates are even higher, at 1.73 million (11.7%) and 2.8 million (9.2%), respectively.2 However, cigarette smoking rates continue to decline, and this may be due, at least in part, to smokers switching from smoking cigarettes to using e-cigarettes (ie, vaping). Indeed, most e-cigarette users are current or former smokers. The potential promise of e-cigarettes as a public health benefit lies in their ability to serve as a sufficient replacement for smoking while also reducing users’ exposure to harmful toxicants, rendering them significantly less harmful than cigarettes. While few randomized clinical trials have examined the efficacy of e-cigarettes as a replacement for combustible cigarettes,3 with less-than-encouraging outcomes, studies examining changes in smokers’ exposure to tobacco toxicants on switching to e-cigarette have shown more promise but have often been limited in scope. More comprehensive studies examining e-cigarette users’ exposure to harmful toxicants, especially compared with smokers and nontobacco users, is needed. Goniewicz and colleagues4 begin to address this need, conducting what appears to be to date the most comprehensive study in terms of the range and number of tobacco-related biomarkers examined among e-cigarette users. Specifically, using data collected from Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health Study, a nationally representative, longitudinal cohort study designed to assess tobacco use and health, the authors examined and compared the levels of tobacco toxicant exposure among a sample of never tobacco users, exclusive users of e-cigarettes, exclusive users of cigarettes, and users of both cigarettes and e-cigarettes (dual users). Largely consistent with findings from previous smaller, less-comprehensive studies, Goniewicz et al4 showed that, although exclusive e-cigarette users had significantly higher levels of exposure to nicotine and other tobacco-related toxicants than never users, they had significantly lower levels of exposure compared with exclusive smokers. Dual users evidenced the highest levels of tobacco toxicant exposure, even more than exclusive smokers. While likely influenced by smoking frequency, this finding has also been consistent in the literature and is cause for concern as most e-cigarette users are dual users.1 Although some dual users may be on the path to completely switching, it is also likely that some may be failed switchers or long-term dual users who use e-cigarettes when they cannot smoke. If long-term dual use is more common than complete switching and exposes users to even greater amounts of tobacco toxicants, what may be the downstream health consequences of this type of use? Clear health messages must be delivered to smokers that completely switching from smoking to e-cigarette use is necessary to confer a significant reduction in exposure to cardiovascular, respiratory, reproductive, and development toxicants, as well as carcinogens. While touched on briefly by Goniewicz and colleagues,4 another point of consideration is that, given the timeframe of data collection for this study (2013-2014), it is likely that many of the e-cigarettes being used were early-generation devices, which have been shown to have inefficient nicotine delivery. Since that time, e-cigarettes have continued to evolve, with newer-generation products demonstrating significantly improved nicotine delivery, and maybe addiction potential, often due to increased power (ie, wattage).5 However, with increased power comes increased heating of the e-liquid and the potential for greater thermal degradation of nonnicotine compounds, which are largely responsible for e-cigarette–produced toxicants. Increased power has been directly implicated in raising the production of carbonyl compounds, such as formaldehyde,6 a toxicant not examined in the present study. Moreover, increased power also leads to significantly greater production and consumption of e-cigarette aerosol (vapor) among users,5 likely increasing users’ exposure to toxicants. With continuous e-cigarette product evolution, it remains to be seen how the toxicant exposure presented in this study will compare with future examinations of exclusive e-cigarette users in the next wave of Population Assessment of Tobacco and Health data.

JAMA Network Open 2018

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