E-cigarettes, promoted as a safer alternative to regular cigarettes, may actually be a new route to conventional smoking and nicotine addiction for teenagers, according to a new study.
In the first analysis of the relationship between e-cigarette use and smoking among US adolescents, researchers found that teens who used the devices were more likely to smoke cigarettes and less likely to quit smoking.
The study by the University of California, San Francisco researchers of nearly 40,000 youth also found that e-cigarette use among middle and high school students in US doubled between 2011 and 2012, from 3.1 per cent to 6.5 per cent.
"Despite claims that e-cigarettes are helping people quit smoking, we found that e-cigarettes were associated with more, not less, cigarette smoking among adolescents," said lead author Lauren Dutra.
"E-cigarettes are likely to be gateway devices for nicotine addiction among youth, opening up a whole new market for tobacco," she said.
E-cigarettes are battery-powered devices that look like cigarettes and deliver an aerosol of nicotine and other chemicals.
Promoted as safer alternatives to cigarettes and smoking cessation aids, the devices are rapidly gaining popularity among adults and youth around the world.
In the study, the researchers examined survey data from middle and high school students who completed the National Youth Tobacco Survey in 2011 and 2012.
They found the devices were associated with higher odds of progression from experimenting with cigarettes to becoming established cigarette smokers.
Additionally, adolescents who smoked both conventional cigarettes and e-cigarettes smoked more cigarettes per day than non-e-cigarette users, researchers found.
Contrary to advertiser claims that e-cigarettes can help consumers stop smoking conventional cigarettes, teenagers who used e-cigarettes and conventional cigarettes were much less likely to have abstained from cigarettes in the past 30 days, 6 months, or year.
At the same time, they were more likely to be planning to quit smoking in the next year than smokers who did not use e-cigarettes, researchers said.
Researchers noted that about 20 per cent of middle school students and about 7 per cent of high school students in US who had ever used e-cigarettes had never smoked regular cigarettes - meaning that some kids are introduced to the addictive drug nicotine through e-cigarettes.
"It looks to me like the wild west marketing of e-cigarettes is not only encouraging youth to smoke them, but also it is promoting regular cigarette smoking among youth," said senior author Stanton A Glantz.
The study was published in the journal JAMA Pediatrics.