The rate of teens smoking cigarettes has dropped for the past decade. However, according to the CDC, tobacco use among U.S. youth is rising.

More than 1 in 4 high school students said they had used a tobacco product in the past 30 days.

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“E-cigarette use increased from 11.7% to 20.8% among high school students,” the CDC said. “No change was found in the use of other tobacco products, including cigarettes, during this time.”

The CDC said the demographics most likely to use e-cigarettes are males, whites and high-schoolers.

FDA Commissioner Scott Gottlieb has labeled teen e-cigarette use an "epidemic."

"I think people should interpret the fact that I and others have made such a dramatic shift from our prior position with respect to these products as representing the fact that we have seen information that is deeply disturbing and startling in terms of the rapid rise of youth use over a short period of time," Gottlieb told CNBC in September.

E-cigarettes create an aerosol by heating a liquid, usually containing nicotine and flavoring. Inhaling this allows the user to imbibe nicotine.

The CDC warns that while e-cigarette aerosol contains fewer toxic chemicals than those in regular cigarettes, it is not harmless.

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“It can contain harmful and potentially harmful substances, including nicotine, heavy metals like lead, volatile organic compounds, and cancer-causing agents,” their guide says.

The guide also warns that nicotine can harm adolescent brain development, which continues into their 20s.