Teenagers who use e-cigarettes frequently are more likely to become regular tobacco cigarette smokers, according to a research letter published Tuesday in JAMA.
Several studies have found an association between young people trying e-cigarettes and tobacco smoking later in life, but this is the first to find that vaping leads to teens becoming frequent or regular smokers, according to Adam Leventhal, the letter's lead author and director of USC's Health, Emotion and Addiction Laboratory.
A spokesman for an e-cigarette advocacy group says the study's findings overlook the fact that e-cigarettes' growth in popularity has coincided with a decline in national teen smoking rates.
Leventhal and his colleagues surveyed more than 3,000 10th graders at 10 Los Angeles County public high schools about their use of e-cigarettes and cigarettes, then followed up with the same students six months later. They found that the more often teenagers reported using e-cigarettes, the more likely they were to report becoming infrequent or frequent smokers.
Of the students who reported frequent use of e-cigarettes, meaning they used them three or more times in the past 30 days, roughly 20 percent were smoking tobacco frequently and more than 11 percent were smoking infrequently (once or twice a month) six months later, the survey found.
Of those who reported infrequent vaping, 9 percent were smoking infrequently and about 5 percent smoked frequently six months later.
Leventhal says it typically takes teens months or years to progress from never smoking to experimentation to more frequent use of tobacco products, but "what we're showing is that the more you vape, the faster it accelerates you on that sequence."
These findings prove that teen e-cigarette use should be considered a top public health concern, he says, because "if a significant portion of them go on to become adult, life-long smokers, then of course they're going to develop smoking related diseases and of course have a dramatic cost to the medical care system."
Gregory Conley, president of the American Vaping Association, argues that e-cigarettes serve a public health benefit by deterring some young people from smoking cigarettes.
"Just like some teens who start off with white wine may later be more likely to drink beer than somebody who had never experimented with alcohol in their life, e-cigarettes are not going to be able to keep every teen at risk of smoking from not doing so," Conley says. He says a majority of teens who vape don't use nicotine in their products.
Leventhal says he and his team will continue periodically surveying the L.A. students through next spring, when they will be graduating from high school. He hopes to acquire funding to follow the students after graduation.