PARIS--The rapid spread of e-cigarette use among young teenagers has not slowed the decline in smoking in the same age group, much less reversed it, according to a new study.
Nor has vaping caused 13-to-15 year olds canvassed in Britain to see tobacco use in a more positive light, researchers reported Tuesday.
The findings, published in the BMJ journal Thorax, are the latest to conclude that nicotine-delivering electronic cigarettes are not, as once feared, a gateway drug for tobacco.
"Our research does not support the hypothesis that e-cigarettes 'renormalized' youth smoking during a period of growing but largely unregulated use in the UK," the study concluded.
But neither did it alleviate growing concern about the health consequences of vaping, which remain largely unknown in part because the practice is so new.
It took decades, experts point out, to determine that smoking tobacco -- which accounts for more than 7 million premature deaths worldwide every year -- is truly dangerous.
Research on nearly 100,000 adults in the United States -- presented at a major conference last month there -- showed that e-cigarette use increases the likelihood of heart attacks, coronary artery disease and depression by 34, 25 and 55 percent respectively.
Rates of these conditions were far higher among smokers.
Another study from February, published in the Nature Journal Scientific Reports, linked chemicals used in 90 percent of vaping systems to impaired lung function.
"We must take aggressive steps to protect our children from these highly potent products," the US Surgeon General said in a rare public advisory in December, warning of the harmful impact of nicotine on still-developing brains.
The new findings looked at changes in behavior and attitude among a quarter of a million young teens in Britain from 1998 to 2015.
During that period, they found, the percentage of 13-to-15 years olds who had smoked at least once fell from 70 to 27, and the share of regular smokers dropped from 19 to 5 percent.
SMOKING NOT 'RENORMALIZED'
Perceptions changed as well. Only 27 percent of young teens in 2015 said it was "OK to try a cigarette", compared with 70 percent 15 years earlier.
Crucially, the rate at which these shifts took place barely slowed, if at all, from 2011 to 2015, the period when e-cigarettes were taking off.
"Favorable perceptions of regular smoking among this age group also fell at a faster rate after the proliferation of e-cigarettes, which would not be expected if smoking was in the process of being 'renormalized'," the authors concluded.
Figures from the rest of Europe and North America suggest similar trends.
The use of e-cigarettes in the United States jumped by more than 75 percent in 2018 compared with the year before, prompting the US Food and Drug Administration to call last fall tighter regulations.
Teens in every age bracket are today more likely to vape than to smoke cigarettes, according to the US National Institute on Drug Abuse (NIDA).
Nearly 10 percent of 13-to-14 year olds said they had vaped within the last month, but less than four percent had lit up a cigarette, the NIDA reported in November.
For 17-to-18 year olds, the gap closed, but the number of smokers was still 50 percent lower than users of e-cigarettes.
In the United States today, one in 20 adults -- or more than 10 million people -- use e-cigarettes, while 3 times as many are smokers.