ATLANTA, Sept. 7 (UPI) -- In 2012, more almost 2 million U.S. middle- and high-school students tried electronic cigarettes, almost double the number in 2011, health officials say.
The findings from the National Youth Tobacco Survey found the percentage of high school students who reported ever using an e-cigarette rose from 4.7 percent in 2011 to 10 percent in 2012.
In the same time period, high school students using e-cigarettes within the past 30 days rose from 1.5 percent to 2.8 percent.
The study, published in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report, found 76.3 percent of middle and high school students who used e-cigarettes within the past 30 days also smoked conventional cigarettes in the same period.
In addition, 1-in-5 middle school students who reported ever using e-cigarettes said they had never tried conventional cigarettes -- raising the concern there might be young people for whom e-cigarettes could be an entry point to use of conventional tobacco products, including cigarettes.
"The increased use of e-cigarettes by teens is deeply troubling," Dr. Tom Frieden, director of the CDC, said in a statement. "Nicotine is a highly addictive drug. Many teens who start with e-cigarettes might be condemned to struggling with a lifelong addiction to nicotine and conventional cigarettes."
E-cigarettes are battery-powered devices that provide doses of nicotine and other additives to the user in an aerosol. E-cigarettes not marketed for therapeutic purposes are currently unregulated by the U.S. Food and Drug Administration.