The US surgeon general had described e-cigarettes as an emerging public health threat to the nation's youth.
In a report released yesterday, surgeon general Vivek Murthy acknowledged a need for more research into the health effects of "vaping," but added that e-cigarettes were not harmless and too many teens were using them.
"My concern is e-cigarettes have the potential to create a whole new generation of kids who are addicted to nicotine," Murthy told The Associated Press. "If that leads to the use of other tobacco-related products, then we are going to be moving backward instead of forward."
Battery-powered e-cigarettes turn liquid nicotine into an inhalable vapour that did not contain the harmful tar generated by regular cigarettes. Vaping had been earlier pushed as safer for current smokers, but there was no scientific consensus on the risks or advantages of vaping, including how it affected the likelihood of someone either picking up regular tobacco products or kicking the habit.
According to federal figures from last year, 16 per cent of high school students reported at least some use of e-cigarettes - even some who said they had never smoked a conventional cigarette. While not all contained nicotine, Murthy's report said e-cigarettes were the most commonly used tobacco-related product among youth.
Nicotine is bad for a developing brain no matter how it was exposed, Murthy said.
"Your kids are not an experiment," he said in a public service announcement that would be released with the report.
The report focused on Americans under the age of 25, the cohort that had embraced e-cigarettes with the most enthusiasm. Teens and young adults were more likely to be using the vaping devices than people in any other age group, and among middle and high school students, e-cigarettes had become more popular than traditional cigarettes.
Mounting scientific evidence suggested the adolescent brain was uniquely vulnerable to the harmful effects of nicotine and among other problems, nicotine exposure could lead to ''reduced impulse control, deficits in attention and cognition, and mood disorders,'' Murthy wrote in a preface to the report.