Doctor says device may cause lasting harm to brain development

The findings prompted strong warnings from the head of the Centers for Disease Control and Prevention, Dr. Tom Frieden, about the effects of any form of nicotine on young people.

"We want parents to know that nicotine is dangerous for kids at any age. Adolescence is a critical time for brain development," Frieden says.

He added, "Nicotine exposure at a young age may cause lasting harm to brain development, promote addiction and lead to sustained tobacco use."

The statistical findings, published in this week's issue of Morbidity and Mortality weekly report, come from the CDC's National Youth Tobacco Survey.

The latest survey found that the use of e-cigarettes increased from 1.1 percent in 2013 to 3.9 percent in 2014 among middle school students, and from 4.5 percent to 13.4 percent among high school students.

That translates to a total of 450,000 middle school students now using e-cigarettes, alongside 2 million high school students. The new evidence comes as the Food and Drug Administration is deciding how to regulate e-cigarettes.

The devices heat a nicotine-laced fluid, which then becomes a vapor that users inhale. While many doctors say the vapor of e-cigarettes is likely less damaging than the smoke of burned tobacco leaves, there is intense debate about how safe e-cigarettes are.

Some public health researchers say the electronic devices may be useful for helping some smokers give up traditional cigarettes. But many also fear the devices may hook a new generation on nicotine and lead them to start smoking traditional cigarettes.