The number of kids vaping nicotine has doubled in the past two years, according to research published Wednesday in the New England Journal of Medicine.

Experts in substance abuse say the new statistics make it clear that vaping is a public health crisis.

"These products introduce the highly addictive chemical nicotine to these young people and their developing brains, and I fear we are only beginning to learn the possible health risks and outcomes for youth," Dr. Nora Volkow, director of the National Institute on Drug Abuse, said in a statement.

The new study looked at data from the 2019 Monitoring the Future Survey of 42,531 students in 8th, 10th and 12th grade. It's an annual report conducted by the University of Michigan on NIDA's behalf.

Researchers found "significant increases" in the numbers of young people using e-cigarettes. Between 2017 and 2019, rates of vaping more than doubled in each of the three grade levels surveyed.

More than 25 percent of high school seniors and more than 20 percent of high school sophomores said they'd vaped within the past month. And one in 11 kids in the 8th grade admitted to vaping as well.

"Parents with school-aged children should begin paying close attention to these devices, which can look like simple flash drives, and frequently come in flavors that are appealing to youth," lead study author Richard Miech, a research professor at the University of Michigan, said in a statement.

The data come amid a growing national epidemic of vaping-related respiratory illnesses. The Centers for Disease Control has reported 380 cases in 36 states, plus the U.S. Virgin Islands. There may be more cases across the country, but the CDC is counting only those that have been confirmed or are highly probable because all other causes of the lung infection have been ruled out by physicians.

Forty-five state health departments overall have reported investigations into more than 500 possible cases, illustrating the broader scope of the problem. On Wednesday, the Mississippi State Department of Health reported its first case. Seven people in six states have died.

Public health investigators have been unable to identify a cause of the illnesses, or any single device linking the cases. However, the Food and Drug Administration has said many of those sickened reported vaping THC, the ingredient in marijuana that gives users a high.

The new research from NIDA focuses on teenagers vaping nicotine. Addiction experts say the nicotine found in e-cigarettes is extremely concentrated, which means it can get into the body much faster and at higher doses compared to traditional cigarettes.

Experts also say that the sweet and minty flavors of e-cigarettes attract youth.

A week ago, the Trump administration announced plans to ban flavored e-cigarettes. It's unclear how or when that ban would take effect.

Some states are not waiting to find out. On Wednesday, the Michigan Department of Health and Human Services announced a ban on flavored e-cigarettes — including menthol and mint flavors — was effective immediately. Retailers will have two weeks to comply.

A similar immediate ban was announced Tuesday in New York. That ban does not include menthol, however, health officials in the state said that they will consider adding it.

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