Nearly one quarter of teens are using marijuana, according to a new survey.
Of eighth, 10th and 12th graders surveyed, 24 percent said they've used the drug in the past year, according to research from the University of Michigan. The 1.3 percent increase is the first significant rise in seven years.
The increase in teens using marijuana comes as more states legalize pot for medical and recreational use.
This year, 14.1 percent of high school seniors said they see "great risk" in smoking marijuana occasionally, down from 17.1 percent last year. Also, 64.7 percent said they disapprove of using the drug regularly, down from 68.5 percent last year.
Those statistics indicate marijuana use among teens could continue to grow, the study's principal investigator Richard Miech said.
"It should raise eyebrows," Miech said. "And people should be alert to the possibility that marijuana is about to launch."
Marijuana's popularity has flipped with cigarettes', the survey found. The percent of seniors smoking cigarettes daily has plummeted to 4.2 percent from 24.7 percent at its peak in 1997. Meanwhile, marijuana use has increased to 5.9 percent from its lowest point in 1992.
Vaping has become a popular mechanism for using marijuana and nicotine. Within the past year, 1 in 10 high school seniors reported vaping marijuana, and 19 percent of them said they vaped nicotine, according to the survey.
"We're certainly surprised by (the number of seniors vaping nicotine), and it speaks to how popular these devices have become and how this represents a new concern for public health officials, parents and others that take care of or care about teens," said Wilson Compton, deputy director of the National Institute on Drug Abuse, part of the National Institutes of Health, which funded the survey.
The findings are likely to give ammunition to public health advocates who have argued sleek devices and unique flavors are appealing to kids. The already fiery debate over e-cigarettes received even more fuel this summer when the Food and Drug Administration delayed impending regulations on the products until 2022.
Anti-smoking advocates like the Campaign for Tobacco-Free Kids argue flavors entice adolescents. The 2009 Family Smoking Prevention and Tobacco Control Act prohibited cigarettes from containing characterizing flavors, excluding menthol. Yet they're pervasive in vaping products.
Critics warn it's not just the flavors but the sleek and discreet design of some e-cigarette brands, such as market leader JUUL, that attract kids.
Senate Minority Leader Chuck Schumer pointed to the devices when he called for the FDA reverse its decision.
"We're very concerned about anecdotal reports that JUUL has become a trendy popular new product with kids and young adults, and that's the kind of product the FDA ought to be reviewing now to see if it is attracting kids. Waiting four years to do that will likely be too late if these products do grow in popularity," said the Campaign for Tobacco-Free Kids' vice president of communications Vince Willmore.
Like other e-cigarette makers, JUUL says its products are meant for adult smokers who are looking to switch from conventional products. In response to reports of adolescents using its products, the company has invested in education and prevention efforts such as "secret shoppers" who test to make sure retailers are not selling to minors.
"It's a really, really important issue," said JUUL Labs' chief administration officer Ashley Gould. "We don't want kids using our products."