E-cigarettes: what’s the harm?
Are they a legitimate smoking cessation device—or keeping smokers addicted?
The controversy over regulation of e-cigarettes highlights a split in the medical community.
Some doctors believe they could revolutionise public health, saving thousands of lives as smokers switch from tobacco to e-cigarettes. Others, including the World Health Organization (WHO), worry that they are yet another tactic by the tobacco industry to glamorise the act of smoking and keep the world hooked on nicotine. But who is right? Could e-cigarettes be doing more good than harm?
What are e-cigarettes?
The e-cigarette was invented in China in 2003, with the intention of capturing the experience of smoking without the harm. It is a battery powered device that heats a cartridge of nicotine solution, producing an aerosolised vapour that users inhale. An e-cigarette delivers a quick hit of nicotine to the lungs, mimicking the effect of smoking. There are many models of e-cigarettes, from disposables that look like tobacco cigarettes to larger modifiable devices. The use of e-cigarettes has increased rapidly. It is estimated that at least 1.3 million people in the United Kingdom use e-cigarettes. Eleven per cent of tobacco smokers currently also use e-cigarettes—up from 3% of smokers in 2010.  The worldwide value of the market is thought to be at least US$2bn (£1.2bn; €1.5bn).
Are they safer than tobacco?
Few things are worse for health than smoking tobacco. The general consensus is that using e-cigarettes is likely to be safer than smoking. Because e-cigarettes do not burn tobacco, they do not produce the wide range of carcinogenic and toxic substances that cause such harm to human health. But that doesn’t mean they are completely harmless.
The vapour in e-cigarettes is produced from heating nicotine with water and propylene glycol or glycerol, which are chemicals often used to produce smoke effects for the entertainment industry. High levels of exposure over a long period can cause irritation to the airways, but they are classified as “generally safe.” An analysis of the nicotine solution from cartridges found small traces of carcinogenic substances called tobacco-specific nitrosamines, as well as traces of metals that may have come from the heating elements. Nicotine itself is not carcinogenic. But it is highly addictive, constricts blood vessels, and has a short term effect on blood pressure and heart rate. Studies of medicinal nicotine replacement therapy show no increased risk of cardiovascular events but nicotine may be teratogenic in pregnancy.
E-cigarettes are also not subject to the strict manufacturing standards applied to medicinal products given to patients. Studies have shown that despite being labelled the same strength the levels of nicotine in e-cigarettes can vary, and that canisters may leak or be contaminated with other ingredients within the e-cigarette. There have also been reports of lithium batteries in e-cigarettes exploding and causing burns.
Clinical studies of the effects of e-cigarettes on health are sparse. The biggest studies showed no increase in adverse effects for people using e-cigarettes over six months, compared with nicotine patches and non-nicotine e-cigarettes. To get an accurate picture of the harms we need longer term data in many more people to be sure about the potential harms of these devices. However, a recent summary of the evidence in the journal Addiction concluded that “long-term use of e-cigarettes, compared to smoking, is likely to be much less, if at all, harmful to users or bystanders.”
Regulation of e-cigarettes is controversial. In August, WHO recommended that the sale of e-cigarettes to those under 18 years should be prohibited and that use in public confined spaces—such as offices and bars—should also be banned.  However, in an open letter to WHO president Margaret Chan in May, 50 researchers in the field of nicotine addiction wrote: “These products could be among the most significant health innovations of the 21st century, perhaps saving hundreds of millions of lives.” They subsequently criticised the WHO position as “exaggerating the risks” of e-cigarettes. Some countries have opted to ban the sale of e-cigarettes altogether, including Brazil, Singapore, and Canada. Other countries such as the US intend to regulate them as tobacco products. In Europe, e-cigarettes are currently classified under consumer regulation, which means a product must comply with basic safety regulations. But starting from 2017, the European Parliament has amended the Tobacco Product Directive to include e-cigarettes. The directive will allow the sale of e-cigarettes as tobacco products up to a limit of 20 mg/mL and will introduce additional requirements for manufacturers to ensure consistency and openness about ingredients and nicotine strength, and to report any adverse effects. Above 20 mg/mL, e-cigarettes cannot be sold as leisure products but they can be licensed as medicine products, if clinical efficacy for smoking cessation or harm reduction can be proven. The UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) says it encourages manufacturers to apply for licensing under this basis. It’s likely that only a minority of big companies will take up this invitation. With e-cigarettes continuing to be sold as leisure and medicinal products, a two-tier system of regulation further complicates the issue.
Do they help smokers quit?
Surprisingly, there has been only one randomised controlled study looking at whether e-cigarettes are helpful for smokers wanting to quit smoking. The study compared e-cigarettes containing nicotine with nicotine patches and e-cigarettes containing no nicotine (placebo cigarettes). The study found no significant difference in long term tobacco smoking quit rates between the three groups (between 4.1% and 7.3%). At best, the study shows they may work as well as nicotine replacement therapy (NRT) patches. There have been no studies on how they perform compared with other smoking cessation medication, such as bupropion and varenicline. At present, e-cigarettes cannot be prescribed on the NHS but this could change if they were officially regulated as medicinal products.
Licensed NRT products are designed to be non-addictive, by slowly releasing nicotine without the addictive, so called hit that cigarettes provide. The purpose is to dampen nicotine cravings while people quit tobacco and nicotine altogether. E-cigarettes mimic the nicotine hit and people tend to use them long term, sometimes without the intention to stop smoking altogether. Surveys suggest that people using e-cigarettes who intend to quit smoking are actually less likely to give up tobacco than those who don’t use e-cigarettes.
The numbers of teenagers experimenting with e-cigarettes are growing fast, and as many as 20% of teenage users of e-cigarettes have not previously smoked tobacco. It’s unclear whether these are young people who would otherwise have smoked tobacco cigarettes, or people who would not have tried cigarettes at all had e-cigarettes not been available. The public health fear is that e-cigarettes will act as a gateway to tobacco use. These fears have been challenged in a recent review in the British Journal of General Practice, which says there is no evidence of a gateway effect, and no rise in young people smoking. 
The new normal?
Re-normalisation of smoking is a major concern in the public health community. Since smoking bans have been introduced across Europe, it has quickly become unusual to see people smoking indoors in public places. However, the introduction of e-cigarettes has reintroduced this experience. Coupled with this is the effect of advertising. Tobacco advertising is banned in the UK, but e-cigarette advertising is allowed, providing companies do not make explicit health claims or suggest that they can aid smoking cessation.  However, the concern is that advertisements may encourage people to smoke more tobacco because the act of smoking is made visible and unconsciously acceptable. In one US survey, 76% of smokers who viewed a television advertisement for e-cigarettes said it made them think about smoking tobacco, compared with 74% who said it made them think about quitting. The Advertising Standards Authority launched an investigation into the sector in March 2014, and says it will report in the autumn of 2014.
Celebrity endorsement is another issue, with the likes of Leonardo DiCaprio and Lily Allen photographed using the products. E-cigarettes also have a strong online community behind them, with many vapers, as they are known, using social media to discuss and promote the practice.
How should doctors react?
There is little formal advice for doctors about e-cigarettes. The National Institute for Health and Care Excellence (NICE), in its guidance on tobacco harm reduction, says only that licensed NRT products should be recommended to people wishing to cut down or stop smoking. Most doctors agree they would prefer their patients to use e-cigarettes than smoke tobacco, although they would prefer them to quit altogether.
Essex general practitioner Keith Hopcroft says: “I say something like: ‘We don’t really know if they work but it seems pretty unlikely that they could do much harm, and certainly less than smoking. On the other hand, as you’re seriously thinking about quitting, what about trying something we know for sure helps?’”
Tom Fardon, a chest physician in Dundee, adds: “I tell patients that anything that increases the risk of them stopping smoking is ultimately beneficial to them, on an individual basis. But, we don’t know about the safety of any e-cigarette brand, and cannot be certain that we are not swapping one carcinogen for another. I tell my patients that e-cigarettes must be the pathway to complete cessation, with the aim of being off the e-cigarettes within 6 weeks.”
Andrew Bush, consultant paediatric chest physician at Royal Brompton and Harefield NHS Foundation Trust, is more suspicious of the motivations of tobacco companies. “Their history of corruption and data retention and secrecy is second to none. I don’t trust them,” he said. He raised concerns about the glamorisation of e-cigarettes and their potential to attract young people. “It’s like turning the clock back, projecting them as sexy and cool.”
Both Bush and Fardon believe e-cigarettes should be regulated as medicinal products, to ensure we know what is in e-cigarette vapour. “Without regulation we have no idea what else is in there,” said Fardon. “Big tobacco has been quick to buy up e-cigarette manufacturers. They will wish to keep users addicted, and that may mean more chemicals, and those need regulation,” he added.
A recent editorial in Clinical Medicine, the journal of the Royal College of Physicians, concluded: “The RCP supports improved regulation to ensure quality and safety and to protect against unscrupulous marketing, but recognises the important role that such products can play in assisting smokers to give up smoking completely.”
Do electronic cigarettes do more good than harm? For individual smokers who use them to quit smoking tobacco completely, the answer is yes. But the effects of e-cigarettes on the wider population are not yet known. We still need better clinical research about how well they actually work as smoking cessation products, more information about their long term safety, better manufacturing standards and regulation, and a consistent policy on marketing.
What do we know about e-cigarettes?
- Do they help people quit smoking?—We don’t know
- Are they less harmful than smoking tobacco?—Almost certainly yes
- What are the long term health effects?—We don’t know
- Do they encourage young people to smoke?—We don’t know
Correspondence to: firstname.lastname@example.org
Competing interests: None declared.
Provenance and peer review: Commissioned; not externally peer reviewed.
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Cite this as: Student BMJ 2014;22:g5672