THE BRONX - A new study has found that more and more teenagers are lighting up e-cigarettes.

According to the Centers for Disease Control, usage of electronic cigarettes has doubled among middle and high schoolers from just 4.7 percent in 2011 to 10 percent in 2012.

E-cigarettes are battery-powered devices that allow smokers to inhale nicotine and exhale vapor. They come in a variety of flavors, including chocolate, mint and even milkshake.

Experts say very little research has been conducted, so it's unclear just how how harmful they are compared with other nicotine products.