E-cigarettes: what do(n’t) we know?

E-cigarettes represent perhaps the most polarising issue in contemporary public health. Many have firmly backed them as a mechanism for reducing adult smoking rates. Others have expressed concerns regarding their potential to renormalise smoking, or to act as a pathway into smoking. Some have adopted a middle ground position, arguing that e-cigarettes should be available to support smoking cessation, but that every effort should be made to prevent their use by non-smokers (particularly young people). Of course, given how rapidly their use has grown, there is currently too little evidence to be sure whether the net effects for public health of e-cigarettes will ultimately be beneficial, harmful or neutral.

Findings from CHETS 2, our study on childhood e-cigarette use, are described in a recent peer-reviewed article in Tobacco Control. To date, these findings have been discussed by Welsh Government in the context of current policy concerns regarding the role of e-cigarettes as a gateway into smoking. They have also been cited within Welsh Government policy consultation documents on proposed legislation for e-cigarettes. The findings have also triggered some interest from parts of the media, and the e-cigarette lobby, whose own interests and positions have shaped the manner in which the findings have been presented. In light of these various interpretations of our work, this blog describes some of the key current controversies around e-cigarettes and clarifies what our findings add to this debate.

E-cigarettes as a replacement for tobacco

Many leading public health experts have thrown their weight behind e-cigarettes as a less harmful replacement for tobacco, analogous to major technological shifts such as movement to DVDs from VHS. A recent systematic review failed to reach firm conclusions regarding harms of e-cigarettes; many studies were poor quality, or conducted by e-cigarette manufacturers. However, it seems unlikely that they will prove as harmful as standard cigarettes. Wholesale movement from tobacco to e-cigarettes would probably save many lives.

However, the DVD analogy currently falls down because, despite emerging evidence that e-cigarettes support cessation for some smokers, most adult e-cigarette users continue to smoke tobacco. Few currently make the switch to e-cigarettes and never return to tobacco.

E-cigarettes are changing, and the trends observed to date may also change. Some have argued that early trials of e-cigarettes as cessation devices had disappointing outcomes because early e-cigarettes were not as good at delivering nicotine, and hence not as effective, as newer models. Time and further trials will tell if this is the case.

Ultimately, e-cigarettes may develop to a stage where they become as satisfying as tobacco, without associated harms, and may be embraced by so many smokers that tobacco can be phased out. While this revolution is presented by some as an inevitability, there is currently no evidence to back it up. Further research is needed.

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E-cigarette use as a pathway into smoking

Those who have opposed e-cigarettes, or emphasised a need for caution regarding potential unwanted effects of backing e-cigarettes too uncritically, have advanced arguments around the re-normalisation of smoking, or e-cigarettes acting as a ‘gateway’ to tobacco or other drugs, particularly for young people. As the World Health Organization acknowledges, there is no evidence for these arguments.

But of course there is not; there simply hasn’t been time for the longitudinal studies we would need to definitively answer these questions. E-cigarette enthusiasts, including many respected academics, have made the fundamental logical error of presenting absence of evidence as evidence of absence, dismissing out of hand any concerns that challenge their own hunches.

Among adults, e-cigarettes do not appear to have been widely adopted by non-smokers. Hence, concerns that e-cigarettes will be widely normalised throughout the adult population appear to have little foundation. Among children and adolescents though, there is international evidence of growing experimental use, though regular use remains rare.

However, the landscape in which e-cigarettes are marketed, bought and sold is changing. The tobacco industry has invested widely in e-cigarettes in the last 18 months. Perhaps this is to ensure they have a product to sell after the demise of tobacco. However, ultimately if all smokers switch to e-cigarettes, and no non-smokers take them up, the e-cigarette market will die with the last ex-smoker. Hence, from a business perspective, it will become essential for the manufacturers to create new markets beyond the limited pool of current smokers. The tobacco industry’s track record of aggressively targeting young people with their products should surely cause us some disquiet. Within this changing landscape, it is essential that we continue to investigate possible adverse consequences of e-cigarettes.

Our key findings: childhood e-cigarette use

Our data shows that experimental e-cigarette use is more common than experimental tobacco use among 10-11 year olds in Wales, and that e-cigarette use is more common among children whose parents smoke and use e-cigarettes. This raises a number of questions. Are children mimicking parental smoking or e-cigarette use, or using their parents’ e-cigarettes out of curiosity? Are devices used by adults to reduce their use of tobacco giving their children a first experience of nicotine? Further research is needed to answer these questions.

We also show that children who have used an e-cigarette report weaker anti-smoking intentions than those who have not (after adjustment for demographic differences and normative variables). Of course, data are cross-sectional; we do not know whether children used an e-cigarette because they were more open to the idea of smoking, or vice versa. We do not know the extent to which children follow through with these intentions. So we make no grand claims to have ‘proved’ the gateway hypothesis. But the data are consistent with a hypothesis that e-cigarette use might increase susceptibility to smoking. We should not dismiss these concerns out of hand as many advocates of e-cigarettes would have us do. Longitudinal data are needed to explore these issues more definitively.

Future steps: toward a reasoned debate informed by evidence

The public health community can agree that the ultimate goal is to eliminate tobacco use. There is a substantial need for those interested in public health to move toward a more reasoned debate on the role of e-cigarettes within this endgame. E-cigarettes may play a valid role in reducing adult smoking. The best available evidence indicates that this would be highly beneficial for public health. However, at the same time we need to ensure that we continue to investigate potential side effects of this endeavour, such as use by children and adolescents who would not otherwise be using tobacco. These are complementary, not competing goals.


This piece discusses the following paper:

Moore G, Littlecott H, Moore L, Ahmed N, Holliday J. E-cigarette use and intentions to smoke among 10-11-year-old never-smokers in Wales. Tobacco Control 2014, published online 22 December 2014. doi:10.1136/tobaccocontrol-2014-052011

The full paper is available, open access, here.

About the blog authors: Dr. Graham Moore is a Research Fellow; Hannah Littlecott is undertaking a PhD entitled ‘Understanding perceptions and utilisation of school-level tailored health profiles from a complex systems perspective: a mixed methods evaluation’, and Dr. Jo Holliday is a Research Fellow. All are based at DECIPHer, at Cardiff University.

Image source: Joseph Morris, via Flickr.com.

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