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expert reaction to report on nicotine and toxicant exposure in vapers and smokers

Research published in JAMA Network Open demonstrates that exclusive use of e-cigarettes results in less exposure to tobacco-related toxicants than cigarette smoking. There is evidence that using regular tobacco cigarettes alone or with e-cigarettes is associated with higher concentrations of potentially harmful tobacco constituents.


Dr Ed Stephens, Senior Research Fellow, University of St Andrews, said:

“This JAMA Network Open paper is important, being the most comprehensive study of its type yet published (more subjects tested, more biomarkers measured and an impressive collection of world class expertise among the authors). The study confirms the findings of some smaller studies that have appeared recently.

“The paper shows that e-cigarette users are exposed to some harmful chemical compounds but mostly at much lower levels than smokers. Smokers who take up vaping for health reasons but continue to smoke some cigarettes will be disappointed to learn from this study that, unless they quit smoking entirely, vaping will not significantly reduce their level of exposure to harmful toxic compounds.

“These findings are not unexpected. The vapours emitted by e-cigarettes can pick up metallic components of the device along with chemicals from the breakdown of nicotine, solvents as well as flavourings. The absence of tobacco and combustion products generally means that the levels of most harmful chemicals is much lower in e-cigarette vapour than in tobacco smoke as long as vapers don’t exceed the manufacturer’s recommended power settings.

“The paper’s findings reinforce some simple messages based on a growing body of evidence. For smokers who switch to vaping in order to reduce their exposure to harmful chemicals while continuing to satisfy their need for nicotine: quit smoking entirely otherwise your exposure will remain at high levels.  For those who neither vape nor smoke: don’t be tempted to start vaping as the “safer” option or you may be exposed to low but significant levels of toxic compounds, and nicotine is addictive. Nothing matches fresh air for long term health.”


Prof Nick Plant FRSB, Professor of Systems Biology at the University of Leeds, said: 

“This study is one of a number that have looked at the level of toxicants that electronic cigarettes users may be exposed to, and compared these levels to those associated with traditional cigarette use.

“The study is reasonably large in number, but there are a number of design issues that make it more difficult to robustly interpret the results. For example, there are significant differences in the number of individuals within each group (e.g. ten times as many cigarette smokers compared to e-cigarette users), and the make-up of each group varies (i.e. sex, age, race, education level). Finally, the level of cigarette or e-cigarette use was based upon a recall questionnaire, which may not represent the true level of use for an individual, nor can we be certain if levels of any particular chemical are due to smoking, or from another source.

“Both e-cigarettes and traditional cigarettes use a heat source to generate the inhaled product, and this means that hazardous pyrolysis products such acrolein will be produced in both cases. However, many previous studies have shown the levels generated in e-cigarettes are significantly lower than in traditional cigarettes, meaning that the risk of harm is also significantly lower: this paper confirms these findings. Likewise, tobacco-specific nitrosamines (e.g. NNK) have been previously detected in e-cigarette liquids and vapour, but these levels are very low and comparable to those seen in pharmaceutical nicotine products.

“In summary, this study confirms the large existing body of work that shows that e-cigarette use is associated with exposure to some of the hazardous chemicals associated with traditional cigarettes, but at much lower levels. This means that the risk of adverse health impacts from e-cigarettes is not zero, but is many times lower than from traditional cigarette use. If smokers are using e-cigarettes as an alternative to traditional cigarettes then they are almost certainly reducing their risk of the known long-term health issues associated with traditional cigarettes.”


‘Comparison of Nicotine and Toxicant Exposure in Users of Electronic Cigarettes and Combustible Cigarettes’ by Maciej Goniewicz et al. was published in JAMA Network Open at 4pm UK time on Friday 14 December.


 Declared interests

Prof Plant: I was a member of the MHRA Nicotine Containing Products Working Group (2011-2016)

Prof Stephens: I have no interests to declare.

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