E-cigarettes Contents

2Reducing Harm

E-cigarettes’ comparative lower harm

5.Smoking prevalence amongst young people overall is decreasing in the UK, with almost an 8% decrease amongst 18 to 24-year olds since 2011.10 However, there is great disparity between various groups in society. A quarter of those in manual jobs smoke whilst the same number within managerial jobs is one in ten. Men are more likely to smoke compared to women, and those suffering from poor mental health are over represented in these statistics.11 Public Health England, the NHS, the Department of Health and Social Care and NICE are all encouraging smokers of conventional cigarettes to switch to e-cigarettes.12 Public Health England state that vaping presents a “small fraction of the risks of smoking” and that there are substantial health benefits from swapping permanently.13

6.NHS Scotland recently published a statement on e-cigarettes, co-signed by Action on Smoking & Health Scotland, the Royal College of Physicians of Edinburgh and others, stating that although the safety of e-cigarettes cannot be guaranteed due to lack of high quality and longitudinal research, e-cigarettes are “definitely less harmful” compared to cigarettes.14

7.The UK Centre for Tobacco and Alcohol studies assessed the risks of e-cigarettes in comparison to conventional cigarettes:

Sustained inhalation of the multiple components of [e-cigarette] vapour is likely to cause some harm to health, and potential harms include lung cancer, chronic obstructive pulmonary disease, interstitial lung disease and cardiovascular disease. However the concentrations of toxins and particulates in vapour are generally low, and much lower than in tobacco smoke, so the risk of e-cigarette use is likely to be small in relation to tobacco smoking, and may also be small in absolute terms. Recent evidence indicates that smokers who switch to e-cigarettes experience significant falls in exposure to tobacco carcinogens and other toxicants, consistent with a reduction in health risk.15

8.Public Health England report that e-cigarettes are 95% less harmful than conventional cigarettes, although Professor John Newton, Public Health England’s Director of Health Improvement, explained that the figure was not a precise one:

[The figure] originates from a review of the evidence by independent scientists, who were themselves quoting another figure. Our position on the figure is that it is the best available published estimate. It has value. We are trying to convey the extent to which e-cigarettes are likely to be much less harmful than smoking cigarettes. It is a useful figure, but it is not a precise scientific estimate. As the Committee will know very well, it is not the sort of issue you can put a single number on. We are trying to convey the extent to which e-cigarettes are likely to be much less harmful than smoking cigarettes.16

9.NHS Smokefree’s campaign material highlights that e-cigarette vapour lacks tar and carbon monoxide—two of the most harmful compounds in tobacco smoke—and carries “a small fraction of the risk of smoking, and can help you quit”.17 The Department of Health and Social Care argued that:

The best thing a smoker can do for their health is to quit smoking. However, the evidence is increasingly clear that e-cigarettes are significantly less harmful to health than smoking tobacco. The government will seek to support consumers in stopping smoking and adopting the use of less harmful nicotine products.18

10.The National Institute for Care and Excellence’s (NICE’s) most recent guidance on e-cigarettes similarly states that although not completely risk free, e-cigarettes are comparatively less harmful than conventional cigarettes.19 Our written evidence likewise emphasised the harm-reducing potential of smokers swapping to e-cigarettes. Action on Smoking and Health stated:

E-cigarettes are substantially less harmful than smoking and the regulatory system now in place is likely to reduce the risks still further. E-cigarettes are now the most popular aid for smokers trying to stop smoking, and are proving effective in helping many smokers to stop smoking.20

The Cochrane Tobacco Addiction Review Group summarised the evidence it had reviewed:

Our findings from independently reviewing the best available evidence on the topic suggest that for existing smokers of conventional cigarettes, switching to electronic cigarettes is likely to lead to significant improvements in health. These findings are based in studies of people who smoked conventional cigarettes, but findings are consonant with findings from the Royal College of Physicians which were based on comparisons of the composition of carcinogens and toxicants in tobacco smoke and vapour from electronic cigarettes.21

11.The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment is currently examining e-cigarettes, and has recently finished work on ‘heat-not-burn’ tobacco products (which heat tobacco without combustion (see paragraph 1)). Professor Harrison from the Committee on Toxicity told us that the main health dangers in a conventional cigarette lie in the combustion of the tobacco:

Combustion is extremely important. We reviewed that at length, and we found that, overall, there was a 90% to 95% reduction in cancer-causing chemicals. Some disappeared altogether, and some were reduced by only a half.22

Public Health England and the MHRA23 explained that:

Levels of carcinogenic chemicals (including polycyclic aromatic hydrocarbons, tobacco-specific N-nitrosamines, heavy metals and volatile organic compounds are substantially lower in e-cigarettes’ aerosol compared with tobacco smoke. Biomarkers of carcinogen exposures (chemicals detected in the blood or urine of users) are also substantially decreased in current e-cigarette-only users compared with cigarette smokers, and decrease when smokers switch to e-cigarettes.24

12.Professor Newton from Public Health England told us:

We avoid using the word “safe,” because that is a very difficult word to use, but there is no doubt that using an e-cigarette regularly is much less harmful than smoking cigarettes. It is important to get that message across, particularly to smokers.25

The New Zealand Ministry of Health similarly encourages smokers who want to use e-cigarettes to quit smoking to seek the support of local stop smoking services:

Expert opinion is that e-cigarettes are significantly less harmful than smoking tobacco but not completely harmless. A range of toxicants have been found in e-cigarette vapour including some cancer causing agents but, in general, at levels much lower than found in cigarette smoke or at levels that are unlikely to cause harm. Smokers switching to e-cigarettes are highly likely to reduce their health risks and for those around them.26

In Canada e-cigarettes have been legal since 2016, when the Canadian Government amended the Tobacco Act and the Non-smokers’ Health Act to establish a new legislative framework for regulating vaping products in order to address the risks and potential benefits of these products.27

13.We asked Professor David Harrison from the UK Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment about any ‘second-hand’ harm from vaping: He told us:

With e-cigarettes or with heat-not-burn, there is a similar issue. Everything is reduced compared with cigarette smoke, but bystander effects are something to be aware of. One would expect, however, that the dose would be commensurately less than for cigarettes.28

Professor Aveyard from the Cochrane Tobacco Addiction Group also thought that the harm of second-hand vaping was negligible.29 Professor Ricardo Polosa explained that:

It is very well known historically that combustible cigarette smoke is a big cause of diseases, mainly because of side-stream smoke and the smoke that is generated between puffs. An electronic cigarette does not operate on the same principle. It does not have the deadly side-stream smoke and does not generate any smoke or aerosol between operating cycles. Aerosols are emitted by these products only when you exhale. That sets the principle that, on common sense, you will immediately identify that there is less risk just because of that. If you then consider that, as Public Health England and the Royal College of Physicians have already emphasised in their comprehensive reviews, these aerosols are 95% less harmful than common tobacco, you will immediately realise that, from a percentage point of view, the risks will be minuscule.30

Heat-not-burn tobacco products

14.‘Heat-not-burn’ products contain tobacco which is heated rather than combusted, and is therefore likely to be less harmful compared to conventional cigarettes. The Centre for Tobacco and Alcohol Studies state that the only available data on emissions and safety of heat-not-burn products arises primarily from one of the major tobacco companies, Philip Morris. This research, they argue, therefore needs to be independently validated before it is used to inform policy, but nevertheless pointed to an early evaluation of likely cancer risk which assessed heat-not-burn products to have about 10% of the harm of conventional cigarettes.31

15.The Royal Society for Public Health believed that the lack of independent, high quality research into the “harm profile” of heated tobacco products warrants a regulatory model structured in line with their relative risk as evidence emerges.32 The Department of Health and Social Care similarly stated that there was currently not enough evidence on heat-not-burn products and their relative harmfulness, and that a pragmatic approach to their regulatory framework was appropriate for now.33 Cancer Research UK told us:

Unlike e-cigarettes, [‘heat-not-burn’] tobacco products are a largely unknown entity, and all of these products are owned by the tobacco industry. There is currently no independent evidence of their safety. We need more evidence, independent from tobacco industry funding or involvement, to determine the level of harm these products may cause, as well as the extent of any potential benefits compared to continued use of tobacco cigarettes.34

The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment highlighted the current uncertainties about any health risks from heat-not-burn products:

The risks associated with use of heat-not-burn tobacco products cannot be quantified due to gaps in the information available and uncertainties in the dose-response relationship of the chemicals and potential adverse health outcomes. In addition, the levels of the different compounds in the aerosol vary compared to the levels in smoke from conventional cigarettes and therefore it is not possible to extrapolate from epidemiological data on smoking risks, particularly given the complexity of the interactions that occur between these compounds in producing adverse health effects.35


16.Some of our evidence expressed a concern about possible risks from e-cigarette liquid flavourings.36 Finland, for example, does not permit flavourings in e-cigarettes at all.37 The British Medical Association believed that flavoured liquids did not cause any acute harm to users, but wanted a long-term assessment to monitor their safety:

Many flavourings used in e-liquid are ‘food safe’, being considered safe when ingested orally, but their safety after heating and inhalation is not established. Given the large numbers of people using flavoured e-liquid without reporting problems, it is unlikely they are having a significant acute impact on the health of users.38

Action on Smoking and Health emphasised the importance of flavourings as part of the appeal of e-cigarettes and possibly also what stopped users from going back to smoking.39 The Cochrane Tobacco Addiction review group called for more research data to be collected from more realistic settings, taking factors such as individual preferences for strength, flavours and devices into account.40

Uncertainty about long-term effects

17.Some have doubts about the long-term safety of e-cigarettes. The US Surgeon General, citing a lack of long-term evidence, could not rule out possible harm from e-cigarette ultra-fine particles, flavourings or heavy metals.41 The US National Academies of Sciences, Engineering, and Medicine explained that in the USA “because the efficacy of e-cigarettes to actually reduce harm remains unclear, some have raised concerns about using e-cigarettes for tobacco harm reduction”.42

18.Australia prohibits the sale of nicotine e-cigarettes unless approved as an aid to help people quit smoking and, so far, no e-cigarette has been approved for this purpose.43 The Australian Health, Sport and Aged Care Committee in the Australian House of Representatives concluded that there were two ways of viewing e-cigarette regulation—to take a precautionary approach or a harm-reducing approach. Those arguing for easier access to e-cigarettes, it said, were following a harm-reducing approach, whereas the Committee favoured a continued ban on the basis of the precautionary approach (like the US Surgeon General) until long-term research is able to rule out any long term health consequences.44

19.The Chair of the Australian Committee dissented from his Committee’s report, however, stating that:

In order to assist the millions of smokers struggling to quit tobacco smoking and improve their quality of life, nicotine e-cigarettes should be made available as consumer products. At the same time, regulatory restrictions should be imposed to limit the appeal of e-cigarettes to young people and non-smokers.45

Professor Newton from Public Health England, when giving evidence to the same Committee, told them:

There is this general problem that many of the people who are opposed to e-cigarettes are starting from a position that any smoking is bad and we need to have a firm line. […] We [in the UK] think that, rather than waiting 20 years to get definitive evidence, we have to make the best decision on the evidence that’s available now, and that points us towards cautious use of e-cigarettes.46

And he explained to us:

The Australian situation was different. They had lower smoking rates to begin with when e-cigarettes first appeared. The feeling there was that they could continue to control and drive down smoking prevalence without using e-cigarettes. Therefore, in the absence of clear evidence of safety, it was wise to ban them.47

20.Some of those who submitted evidence to our inquiry also highlighted a lack of long-term evidence on the potential harm, if any, from e-cigarette use.48 Some noted that there were very few current vapers who had not previously smoked conventional cigarettes, making comparative studies between vapers and non-vapers difficult to assess.49

21.The Tobacco and Alcohol Research Group at University College London argued, on the other hand, that some research reports have “over-claimed” findings on the harmfulness of e-cigarettes because they have “little or no relevance to prediction of serious illnesses in e-cigarette users”.50 Dr Lion Shahab and Dr Jamie Brown from the UCL Research Group explained that:

A lot of the papers, while written quite correctly, in the press release overstate what has been found. This may be partly because often the papers look at acute and not at chronic effects, and effects that are not very well linked to long-term health outcomes. One of them is arterial stiffness on which a paper was published recently. That was then linked to the fact that ecigarettes cause heart disease. The very same authors also published a paper that showed that, for instance, exercise increased arterial stiffness, so it is very difficult to link that particular marker to long-term health outcomes. That is one of the problems. Another is that often people use unrealistic use conditions. A study looked at the formation of formaldehyde, which is very toxic. […] It is an acrid taste called dry puffing, which is unlikely to occur in real-life conditions. Lastly, often the models used to investigate the effects of ecigarettes are not really relevant to humans—for example, mice models. One big problem is that mice are much more sensitive to nicotine than humans, and often the effects observed in animal studies may just reflect nicotine poisoning rather than the effects of any of the other potentially harmful substances.51

22.Professor Peter Hajek, Professor of Clinical Psychology, Queen Mary University of London, did not believe the uncertainty about any long-term effects would be significant:

We have two ways of looking at it; there is logic and there is data. The logic tells you that most of the chemicals that are dangerous to smokers are absent, or present in very small amounts, in e-cigarettes. As far as we know, none of the chemicals that are specific to e-cigarettes and are not present in smoking poses major health harm. Basically, the data back that up. Recently, there was a detailed paper about kinds of carcinogens, comparing the risk of cancer from smoking and from vaping. That paper took at face value some of the studies on e-cigarettes that actually fry the e-liquid and therefore produce aldehydes, which could be carcinogenic, but even taking into account those studies, which do not reflect what vapers are taking in, the conclusion was that the cancer risk is less than 0.5% of the cancer risk from smoking.52

23.Ultimately, whatever any long-term risks there may be from e-cigarettes, not switching from conventional cigarettes also presents its own (very certain) risks in terms of continued conventional smoking-related diseases. Dr Jamie Brown from UCL was clear about how such a balance of risks should be weighed:

Any perceived risk associated with offering reassurance before we have the long-term data [on e-cigarettes] must be balanced against the risk associated with the opportunity cost of failing to inform the millions of people who are currently smoking uniquely dangerous products that e-cigarettes are safer when they believe they are not.53


24.Although the evidence we received has been overwhelmingly that e-cigarettes are much less harmful than conventional cigarettes, new products are constantly being developed; both e-cigarettes and heat-not-burn devices. Research needs to keep abreast of these developments in order to continue to reassure consumers of their relative safety. The Cochrane Tobacco Addiction Review Group told us that more randomized controlled trials were needed, which would compare electronic cigarettes with “alternative pharmacological and behavioural treatments”.54 They stated:

As electronic cigarettes have been used for only a few years, there is little evidence on their safety when used as a long-term or permanent replacement for smoking. As almost all regular use of electronic cigarettes occurs in former or current smokers, interpreting future epidemiological data will be difficult. In the meantime, findings from short- to medium- term studies, studies of biomarkers, and studies of toxicants all suggest electronic cigarettes are significantly less harmful than conventional cigarettes.55

25.The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment noted that the settings, such as voltage and temperature, on some e-cigarette devices can be modified by the user which, they told us, will result in variations in the composition of the vapour. They explained that the settings on devices used in studies are often not reported in the literature, and that as a result “it will be difficult to establish a worst-case scenario that is representative of human exposure”.56 Professor Aveyard from the Cochrane Review emphasised that “the majority of dangerous compounds present in cigarettes are not there in e-cigarettes”, but:

what we do not have is a cohort of people who have been using ecigarettes for a long time, in order to realise whether there is a true risk in humans. Everything we say is either extrapolation or speculation. There is not a technological fix around that problem; we just do not have people who have used them for 30 or 40 years.57

26.The Department of Health and Social Care told us that to support further independent research and collaboration, the UK E-Cigarette Research Forum, an initiative developed by Cancer Research UK in partnership with PHE and the UK Centre for Tobacco and Alcohol Studies, is “bringing together policy-makers, researchers, practitioners and the NGO community to discuss the emerging evidence and knowledge gaps about e-cigarettes”. The Department pointed out that the group has asked it “to contribute suggestions for further areas of e-cigarette research to help develop improvements in policy to achieve the Tobacco Control Plan aims”.58 The Department is also running an annual evidence review on e-cigarettes, through Public Health England, which will look at the latest evidence on “adult and youth prevalence, safety, effectiveness for quitting and perceptions of harmfulness, addictiveness of nicotine and a section on heat-not-burn tobacco products”.59

27.There is clear evidence that e-cigarettes are substantially less harmful than conventional cigarettes. Public Health England estimate e-cigarettes as 95% less harmful, although the evidence available does not currently allow a precise figure to be determined. E-cigarettes lack the tar and carbon monoxide of conventional cigarettes—the most dangerous components of conventional cigarettes—which are produced by combustion. Some potentially harmful components are present in both products, such as heavy metals, but at substantially lower levels in e-cigarettes. Researchers have found it almost impossible to measure the risks from ‘second-hand’ e-cigarette vapour because any potentially harmful compounds released into the surrounding area are so negligible.

28.More recently introduced ‘heat-not-burn’ products—producing nicotine from tobacco but without the combustion—have been estimated to be around 90% less harmful than conventional cigarettes, although there is a lack of independent research to validate this claim.

29.There are uncertainties, nevertheless, especially about any long-term health effects of e-cigarettes, because the products have not yet had a history of long use. The studies needed to guarantee the safety of e-cigarettes are inevitably frustrated by the absence of a population of e-cigarette users who have never smoked conventional cigarettes before taking up vaping. Ultimately, however, any judgement of risks has to take account of the risk of not adopting e-cigarettes—that is, continuing to smoke conventional cigarettes, which are substantially more harmful than e-cigarettes. Existing smokers should always be encouraged to give up all types of smoking, but if that is not possible they should switch to e-cigarettes as a considerably less harmful alternative.

30.To help fill remaining gaps in the evidence on the relative risks of e-cigarettes and heat-not-burn products, the Government should maintain its planned annual ‘evidence review’ on e-cigarettes and extend it to also cover heat-not-burn products. It should support a long-term research programme, to be overseen by Public Health England and the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, to ensure that health-related evidence is not dependent solely on the tobacco industry or the manufacturers of e-cigarettes. That PHE/COT research should include examining health risks arising from the flavourings added to e-cigarettes. The Government should report each year on the state of research in its Tobacco Control Plan, and establish an online hub for making the detailed evidence readily available to the public and to health professionals.

10 Adult smoking habits in Great Britain, The Office for National Statistics, July 2018

11 Adult smoking habits in Great Britain, The Office for National Statistics, July 2018

12 The National Institute for Health and Care Excellence

13 E-cigarettes and heated tobacco products: evidence review, Public Health England, February 2018

19 Stop smoking interventions and services, NICE guideline [NG92], March 2018

23 Medicines and Healthcare Products Regulatory Agency

26 Vaping, smokeless, including heated tobacco, New Zeeland Ministry of Health, October 2017

41 E-cigarette Use Among Youth and Young People, United States Surgeon General, U.S. Department of Health and Human Services

42 Consensus Study Report: Public Health Consequences of E-cigarettes, The National Academies of Sciences, Engineering and Medicine, 2018

43 Report on the Inquiry into the Use and Marketing of Electronic Cigarettes and Personal Vaporisers in Australia, The Standing Committee on Health, Aged Care and Sport, The Australian House of Representatives, March 2018

44 Report on the Inquiry into the Use and Marketing of Electronic Cigarettes and Personal Vaporisers in Australia, The Standing Committee on Health, Aged Care and Sport, The Australian House of Representatives, March 2018

45 Chair’s Foreword, Report on the Inquiry into the Use and Marketing of Electronic Cigarettes and Personal Vaporisers in Australia, The Standing Committee on Health, Aged Care and Sport, The Australian House of Representatives, March 2018

46 Oral Evidence taken 18 October 2017, The Standing Committee on Health, Aged Care and Sport, The Australian House of Representatives, Inquiry into the Use and Marketing of Electronic Cigarettes and Personal Vaporisers in Australia

Published: 17 August 2018