Research based on teenagers in California tentatively proposes link but experts say it does not prove that one leads to the other

A study of teenagers in California has tentatively suggested a link between vaping and starting to smoke cigarettes, although experts say it does not prove that one leads to the other.

About 37% of teens in the US have tried vaping, and there is widespread anxiety that young people who use e-cigarettes may be more likely to start smoking as a result.

The study, published in the Journal of the American Medical Association (JAMA), looked at vaping and smoking in more than 3,000 teenagers, aged about 15, in the 10th grade of 10 public high schools in Los Angeles county, California.



The numbers who vaped or smoked at all were small – only 26 who had never smoked at the beginning of the study said at the end of the follow-up period, six months later, that they had used e-cigarettes and also smoked in the previous month. Others had previously smoked infrequently or frequently.



But the researchers did find a trend. The more the teenagers said they had vaped, the more likely they were to smoke cigarettes. The more frequent vapers were also likely to smoke more heavily.

The public health community is divided over the pros and cons of e-cigarettes. Some doctors believe they may be the best tool yet for helping established smokers quit the habit, but others are less convinced and warn they could be a means of hooking non-smokers into a tobacco habit.

The authors of the study – Adam Leventhal, of the University of Southern California Keck School of Medicine, and colleagues – acknowledge there are many unknowns but conclude that: “The transition from vaping to smoking may warrant particular attention in tobacco control policy.”

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Other experts said although the study was well conducted, it could not explain the link. “This study could not tell us if it is something about the young people that vape that predisposes them to smoking or that vaping itself makes smoking more likely,” said Paul Aveyard, professor of behavioural medicine at the University of Oxford. It was well known that teenagers who tried one risky behaviour were more likely to be willing to try another.

“Smoking in young people has fallen in the UK and the US to record lows in the past few years, despite the rise in prevalence of young people experimenting with e-cigarettes,” he said.

“Very few young people who do not smoke cigarettes become regular users of e-cigarettes. In this context, we should not worry unduly about this study’s findings, but it is important to monitor smoking in young people and its relationship with e-cigarette use.”

Prof John Britton, director of the UK centre for tobacco and alcohol studies at the University of Nottingham, said the study “doesn’t tell us whether vaping caused these young people to start smoking, or whether they would have started smoking anyway; or whether vaping prevented some young people who would otherwise have become smokers from progressing to tobacco smoking.”

Children whose parents were smokers and trying to give up would be more likely to have access to e-cigarettes – and also more at risk of starting to smoke in the first place. “The key question is whether vaping is increasing smoking uptake, over and above that underlying risk,” said Britton. “This study doesn’t answer that question; but it does show that if it does, the proportions of children affected are very small.”