"We now know it’s happening, but there are more questions about who is using and how damaging it is," Morean said.

E-cigarette use among youth increased more than 200% from 2011 to 2013, according to a report in the journal Nicotine and Tobacco Research. Those surveyed had not tried regular cigarettes.

“Unfortunately, there is really no end for what can be vaporized in these devices,” said Erika Sward, a spokeswoman for the American Lung Association.

Supporters of e-cigarettes, who describe them as a healthier alternative to regular cigarettes, found fault with the new survey. The study may not accurately reflect what teens across the country are doing because it surveyed students in only one state, said Phil Daman, president of the Smoke-Free Alternatives Trade Associationand attorney for Daman & Associates.

His group strongly discourages underage use of vapor products.

“While some teens experiment, it's vital that parents and guardians talk to their children about not using any age-restricted products including vapor products," Daman said.

Morean said she and her colleagues plan to conduct additional studies.

She hopes researchers in other states will provide additional data, to provide a clearer picture of national trends.

"This research is so new,” Morean said.

To view the original article on USA Today, click here: http://goo.gl/UeqUbq