Evidence about electronic cigarettes: a foundation built on rock or sand?

BMJ 2015; 351 doi: (Published 15 September 2015) Cite this as: BMJ 2015;351:h4863

Evidence about e-cigarettes: They are much safer than cigarettes and do not lure children to smoking.

McKee and Capewell recently criticised Public Health England’s position on e-cigarettes (EC) [1] and our report underlying it [2], in a Lancet letter [3], the media [4], and now again in this BMJ article [5]. Their statement ‘directors of public health and the wider community desperately need advice on EC that is evidence based and free from any suspicion of influence by vested interests’ [5] is offensive.

We have an extensive track record of research dedicated to understanding smoking behaviour and helping smokers stop smoking, published hundreds of primary research articles on smoking, nicotine, and EC and have many years of clinical experience in smoking cessation treatments. During that time we have not taken any funds from the tobacco or EC industry. In contrast, McKee and Capewell are not experts in this field – they have carried out no tobacco dependence, smoking cessation, or EC research - but they have a history of warning smokers and health professionals about EC dangers [6-10]. This may explain their interest in trying to undermine the message that vaping is much safer than smoking and that the public misperception of the relative dangers needs to be corrected.

Several responses to their earlier accusations and inaccuracies have been published [11-14] which were ignored in their latest ‘analysis’. Space constraints allow us to address only a few errors in this latest piece.

1. Defining the role of e-cigarettes.

The analysis states that EC supporters ‘focus narrowly on existing smokers, comparing the device effects with those of smoking conventional cigarettes’ while EC opponents compare vaping with non-smoking and believe that it should be discouraged because of ‘concern about the uptake of EC among people, especially children and adolescents, who would not otherwise smoke and about their long term health effects’.

Comparing vaping with smoking is not a narrow focus. The fundamental task of tobacco control is to reduce death and disease caused by smoking. Switching from smoking to vaping avoids most of the risks of smoking (notwithstanding potential long-term effects) and smokers should be encouraged to do so. The charge that EC should not be promoted because there is no clear evidence that they are more effective than current stop-smoking medications is a non-sequitur. EC currently are much more popular than other treatments and hence have much wider reach and potential for a major public health impact.

We share concerns about uptake of smoking and EC use among children (discussed below). Our report carefully examined the relevant evidence and noted the continuing decline in cigarette smoking, which is the only test of whether EC are ‘renormalising’ smoking that matters.

2. Dual use

McKee and Capewell’s statement that we rarely used this term is inaccurate. We did, additionally making this clear statement ‘As per existing NICE guidance, all smokers should be supported to stop smoking completely, including ‘dual users’ who smoke and use EC’. These ‘dual users’ should not be castigated – most of them are trying to stop smoking and need clear messages about how they can best achieve that goal. In contrast to McKee and Capewell, our report provided some advice about how best to do that.

3. Health effects and quality of evidence

The estimate of relative risk is a matter of logic. Risky chemicals in tobacco smoke are either absent from EC vapour or present at levels much below 5%, and the key chemicals present in EC only are not expected to pose serious health risks. We explained this previously [11] and the accusations about the work of Nutt and colleagues and conflict of interests have been addressed elsewhere [15]. The authors highlight the dangers of formaldehyde - our report covered this false alarm extensively.

4. Gateway effect

The danger of EC luring children to smoking seems to be the core of the authors’ opposition to EC. They present as evidence for this a study suggesting that the same young people who try vaping also try smoking [16]. The authors of this paper acknowledged that their study provided no evidence of causation. EC have not promoted smoking or vaping in children in Great Britain. Daily vaping in non-smokers is extremely rare [17].


We believe that there are much stronger grounds for criticising the stance of McKee and Capewell than for attacking the PHE position. The evidence of relative safety of EC and of the lack of any gateway effect is much stronger than any evidence to the contrary; misinforming smokers and health professionals about the relative risks of smoking and vaping is wrong; and discouraging smokers from using EC is irresponsible, however much the safe-sounding ‘precautionary principle’ is invoked.

Overall however, we agree, as stated clearly in our report, that there remain areas of uncertainty and that ongoing careful monitoring of EC safety and of its population impact is necessary. If problems emerge, regulatory solutions need to be ready.

1 Public Health England: E-cigarettes: a new foundation for evidence-based policy and practice. PHE publications gateway number: 2015260
2. McNeill A, Brose LS, Calder R, Hitchman SC, Hajek P, McRobbie H. E-cigarettes: an evidence update. A report commissioned by Public Health England 2015
3. McKee M, Capewell S. Electronic cigarettes: we need evidence, not opinions. Lancet Lond Engl Published Online First: 4 September 2015. doi:10.1016/S0140-6736(15)00146-4
4. Boseley S. Public Health England under fire for saying e-cigarettes are 95% safer. The Guardian. 2015. (accessed 14 Sep2015).
5 McKee M, Capewell S. Evidence about electronic cigarettes: a foundation built on rock or sand? BMJ Published Online First: 2015. doi:10.1136/bmj.h4863
6 McKee M. E-cigarettes and the marketing push that surprised everyone. BMJ 2013;347:f5780. doi:10.1136/bmj.f5780
7 McKee M. Electronic cigarettes: peering through the smokescreen. Postgrad Med J 2014;90:607–9. doi:10.1136/postgradmedj-2014-133029
8 McKee M. Electronic cigarettes: proceed with great caution. Int J Public Health 2014;59:683–5. doi:10.1007/s00038-014-0589-z
9 Diethelm P, McKee M. Nicotine: not just an unregulated poison but now a potential chemical weapon. Eur J Public Health. 2011 Dec;21(6):681. doi: 10.1093/eurpub/ckr148.
10 BMJ Investigation Examines Bitter Dispute over E-cigarettes in the Public Health Community - ScienceNewsline. (accessed 14 Sep2015).
11 McNeill A, Brose LS, Calder R, et al. E-cigarettes: the need for clear communication on relative risks. Lancet Lond Engl Published Online First: 31 August 2015. doi:10.1016/S0140-6736(15)00079-3
12 O’Connor R, Fenton K. E-cigarettes: spelling out the available evidence for the public. Lancet Lond Engl Published Online First: 2 September 2015. doi:10.1016/S0140-6736(15)00107-5
13 Britton J. E-cigarettes, Public Health England, and common sense. Lancet Lond Engl Published Online First: 4 September 2015. doi:10.1016/S0140-6736(15)00145-2
14 Polosa R. E-cigarettes: Public Health England’s evidence based confusion? Lancet Lond Engl Published Online First: 4 September 2015. doi:10.1016/S0140-6736(15)00133-6
15 Nutt D, Hulbert J. Blinded by smoke? Why do e-cigarettes provoke such irrational reactions? Drug Science, independent committee on drugs. 2015. (accessed 14 Sep2015).
16 Leventhal AM, Strong DR, Kirkpatrick MG, et al. Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence. JAMA 2015;314:700–7. doi:10.1001/jama.2015.8950
17 West R, Brown J. Smoking in England 2007-2014. 2015. (accessed 14 Sep2015).

Competing interests: HM was an investigator on a 2008 study of e-cigarettes sponsored by manufacturer Ruyan Group and conducted independently at University of Auckland. He has no links with any tobacco or e-cigarette manufacturers. The other authors declare no competing interests.

15 September 2015
Ann McNeill
Professor of Tobacco Addiction
Brose LS, Calder R, Hitchman SC (King’s College London) Hajek P, McRobbie H
King's College London
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