Teens who use e-cigarettes more likely to start smoking, study says

(Steven Senne | The Associated Press) In this Wednesday, April 11, 2018 photo, an unidentified 15-year-old high school student displays a vaping device near the school's campus in Cambridge, Mass. Schools and health officials across the U.S. are struggling to curb what they say is an epidemic of underage vaping. Officials say teens and children are getting easy access to e-cigarettes and other vaping devices, which heat liquid into an inhalable vapor that often contains nicotine.

Two new studies of e-cigarettes may bolster the U.S. government’s efforts to stem what it calls a growing epidemic of youth vaping.

Children and teens who had used e-cigarettes were four times more likely to have taken up cigarette smoking than those who didn’t vape, according to a study published Friday in the Journal of the American Medical Association. Almost 179,000 youth who have tried cigarettes and more than 43,000 who are currently smoking would not be if they had never started vaping, the study found.

The link between vaping and cigarette use was particularly pronounced in those thought to be low-risk for smoking given their lack of prior drug and alcohol use, according to the study. That raises the concern "that e-cigarettes may renormalize smoking behaviors and erode decades of progress in reducing smoking among youths," the study's authors wrote.

"These findings strengthen the rationale for aggressive regulation of youth access to and marketing of e-cigarettes to achieve future decreases in the prevalence of cigarette use among youths," they said.

The JAMA study analyzed data on 6,123 youth collected by the National Institutes of Health and the U.S. Food and Drug Administration from 2013 to 2016.

The report was released on the same day as a separate study by the Harvard T.H. Chan School of Public Health that found common e-cigarette flavors may harm users' lungs. The findings may deal a blow to the vaping industry, which has come under fire by the FDA for allegedly marketing to teenagers by using fruit flavors.

Philip Morris International Inc., whose sister company Altria Inc. is seeking FDA approval to sell its "heat-not-burn" IQOS tobacco device, said a balance must be struck between seeking to prevent teens from using nicotine products and helping to move adult smokers away from cigarettes.

"Nicotine is addictive. It is not risk-free, and it poses particular risks for adolescents," said PMI spokesman Corey Henry. He said the company won't offer its smoke-free products to people who have never smoked or those who have quit smoking.

FDA Commissioner Scott Gottlieb proposed measures in November for restricting sales of most flavored e-cigarettes and limiting them to specialized shops and online retailers that can verify a purchaser's age. That was a reversal of a hands-off approach to e-cigarettes Gottlieb took in 2017 that was followed by a 75 percent rise between 2017 and 2018 in use of e-cigarettes by children and teens.

In 2017, more than 2 million middle- and high-school students used e-cigarettes, according to the Centers for Disease Control and Prevention.

The Harvard study published in Scientific Reports determined that two chemicals commonly used to flavor e-cigarettes may be harming the cilia, the antennae-like protrusions that line human airways to help keep them clean.

The study examined diacetyl, which has previously been linked to an illness known as "popcorn lung" in workers in factories that make microwave popcorn, and an alternative called 2,3-pentanedione. Those chemicals haven't been tested for inhalation safety, said senior co-author Joseph Allen, assistant professor of exposure assessment science at Harvard.

"Although some e-cig manufacturers are stating that they do not use diacetyl or 2,3-pentandione, it begs an important question: What chemicals, then, are they using for flavoring?" Allen said in a statement.

Juul Labs Inc., the vaping market leader whose devices are wildly popular with teens, says on its website that "our development and manufacturing process does not add diacetyl and acetylproprionyl (or 2,3-pentanedione) as flavor ingredients."

A study published earlier this week in the New England Journal of Medicine found e-cigarettes are almost twice as effective at helping cigarette smokers quit as other nicotine-replacement therapies. Gottlieb has maintained that e-cigarettes could be a valuable tool to help adult smokers quit, but tweeted Thursday that children and teens are still his priority.

Bloomberg’s Tiffany Kary contributed.