How worrying is it that more and more teens are using e-cigarettes?

Youth smoking rates have been falling for decades. But now doctors and parents in the US are sounding the alarm over a new teen trend: the fashion for vaping. Between 2010 and 2017, the percentage of US high-school seniors (aged 17 or 18) who had used an electronic cigarette in the past 30 days jumped from 1.5 per cent to 13 per cent. Some reports suggest that the US Food and Drug Administration (FDA) has more recent unpublished data showing an even steeper rise since 2017. “I now have good reason to believe that it’s reached nothing short of an epidemic proportion of growth,” FDA chief Scott Gottlieb wrote in a statement on the agency’s website in September. Cigarette smoke contains at least 70 known carcinogens, mostly produced by burning tobacco. Electronic cigarettes vaporise nicotine without producing smoke, thereby cutting out most of the harmful substances inhaled by smoking. When e-cigarettes first came onto the market in 2004, regulators treated them with a light touch, seeing an opportunity to help addicted smokers switch to a less harmful habit. But the products’ new-found popularity among young people has prompted a change of tack. “The FDA won’t tolerate a whole generation of young people becoming addicted to nicotine as a trade-off for enabling adults to have unfettered access to these same products,” Gottlieb wrote. The surge in vaping among teenagers has been largely driven by one product, Juul, which now accounts for over half of all e-cigarette sales in the US. Juul’s allure may owe something to its sleek design, enticing flavours and social media cachet. That’s not all. Juul uses a different formulation of nicotine to most brands. The liquid comes in pods containing the equivalent of about 20 combustible cigarettes. Each pod is designed to last for 200 puffs, meaning the amount of nicotine per puff is comparable to cigarettes. But because it uses what is known as protonated nicotine, Juul vapour lacks the harshness of tobacco smoke, which means vapers can inhale much more. “Protonated nicotine formulations are problematic because they seemingly allow users to inhale much higher nicotine concentrations that they would otherwise be able to,” says Tory Spindle at Johns Hopkins University School of Medicine, Maryland. That could increase the risk of dependence, he says. Information available so far suggests that young people who try Juul are more likely to become regular users than those who try conventional e-cigarettes. Juul insists that its product isn’t intended for under-18s or marketed to them, but its popularity has attracted the attention of the FDA. In September, the agency conducted a surprise inspection of Juul’s offices, seizing thousands of documents relating to sales and marketing practices. It is illegal to sell tobacco products to minors in the US. If vaping is substantially less harmful than cigarette smoking, as most doctors seem to agree, then what’s the worry? This year, the US National Academies of Sciences, Engineering, and Medicine published a comprehensive report on the health effects of vaping. It concluded that most e-cigarettes emit numerous potentially toxic substances in addition to nicotine. “We really don’t know, if the kids go on and vape for a year, 10 years or 30 years, what the consequences of that will be,” says Michael Cummings at the Medical University of South Carolina. Nicotine itself isn’t completely benign. Animal studies suggest exposure during adolescence could impair brain development, but evidence from humans is lacking. Worryingly, a US survey found that 63 per cent of 15 to 24-year-olds didn’t know that Juul products contain nicotine. However, studies on other forms of non-combustible nicotine, such as nicotine gum and snus suggest there are few serious consequences of long-term use. A bigger concern is that teens will progress from e-cigarettes to combustible cigarettes. The National Academies’ report found “substantial evidence” that e-cigarette use increases the risk of transitioning to smoking conventional cigarettes. However, it isn’t clear-cut, says Linda Bauld at the University of Edinburgh, UK. The evidence comes from surveys showing that teens who vape are more likely to have tried smoking a year later, but this correlation could be explained by the same kids being likely to take up either habit. “One may not lead to the other,” she says. A bigger test is what happens to rates of smoking. “If there was a gateway, we would see those [declining] smoking figures stall or go up,” says Bauld. So far, this doesn’t seem to be happening. The FDA has yet to decide how it will act to stop the surge in teen vaping, but Gottlieb’s statement said the agency might take steps to curtail the marketing and selling of flavoured products, which are thought to drive the youth appeal. One manufacturer, Altria, has already pledged to stop selling all flavours apart from menthol and tobacco. But flavours are part of the appeal for adult smokers too. “I think it’s a phenomenally stupid idea,” says Bauld. “What they should do is ban the marketing.” Under the European Union’s Tobacco Products Directive, which was implemented in 2016, e-cigarette advertisements are prohibited online, on TV and radio, and in print media. The legislation also set a limit for the nicotine concentration in e-cigarette liquid of 20 milligrams per millilitre. In the US, there are no marketing restrictions other than avoiding misleading claims, and no limit on the nicotine levels. Health authorities in the UK seem less worried about vaping teenagers, but perhaps that is because of the stronger regulations. In the UK, 17 per cent of 11 to 16-year-olds have tried e-cigarettes, but only 1 per cent use them regularly (see “Graph”). The regular vapers are almost all teens who already smoke cigarettes.

Not so addictive

Juul launched in the UK in July, but the EU limit means the UK product contains about a third of the nicotine in the US version. We should continue to keep a close eye on the situation, says Bauld. But for the moment, she is not overly concerned. “I think [the UK] got it right in relation to youth. Whether we’ve got it right with the whole regulatory context, I’m not convinced.” Smoking is still a huge cause of disease, resulting in 79,000 deaths a year in England alone. A 2018 review by Public Health England (PHE) found that e-cigarettes were associated with improved success rates in giving up smoking, and could be helping at least 20,000 people a year to quit. But about 40 per cent of smokers still haven’t tried e-cigarettes, and many incorrectly believe they are just as harmful as smoking. “I think more regulation on e-cigarettes is throwing adult smokers under the bus for fears about the next generation,” says Bauld. She supports the conclusions of a recent UK parliamentary Science and Technology Committee report, which recommends relaxing rules against vaping in mental-health units and allowing more freedom to advertise. The mantra of e-cigarettes for harm reduction has been enthusiastically adopted by Scottish prisons, which have offered prisoners free vaping kits as a step towards eliminating smoking. PHE’s review also advocated making it easier for patients to vape in hospitals, pointing out that there is no evidence that passive exposure to vapour is harmful to health. In contrast, the US debate is heavily weighted towards the dangers of e-cigarettes, rather than their potential to help addicted smokers. Getting the balance right will be difficult for the FDA. “I would hope their approach would be one of setting appropriate standards to maximise public-health benefit – not just protecting kids, but also benefiting adult addicted smokers,” says Cummings.

New Scientist, 7 November 2018 ; http://www.newscientist.com/