2016 feels like it went by in a haze and for a considerable number of teens, it literally did. According to a new report from the U.S. Centers for Disease Control and Prevention (CDC), more teens than ever are vaping—and many aren’t using e-cigarettes for nicotine.

According to the study, nearly 38 percent of high school students and 13.5 percent of middle schoolers have reportedly tried e-cigarettes. Nearly one in three of those students who have used an e-cigarette admitted to using it with a substance other than nicotine.

While the data examined by the CDC didn’t specify what other substances were being used by teens, other studies like a 2015 paper published in the journal Pediatrics suggest it is likely to be some form of cannabis.

Most students—53.4 percent—who reported using an e-cigarette used the rechargeable or refillable variety—the increasingly common devices that use liquid cartridges. A smaller number of users—just 14.5 percent—tried a disposable e-cigarette, with 32.1 percent trying both varieties.

Brand recognition hadn’t stuck with the majority of the youth users, with just over half unable to identify the maker of e-cigarette they tried. Of the brands that were named, blu and Vuse were the most popular—both of which are owned by two of the four largest tobacco companies in the world.

The big names and dollars behind blu and Vuse are important, as the brands are heavily promoted and advertised by their parent companies. A CDC study published earlier this year found kids who were exposed to ads for e-cigarettes were more likely to try the devices; in 2014, the center found seven in 10 middle school and high school students had seen an advertisement for e-cigarettes.

Earlier this year, the Surgeon General issued a report on e-cigarette usage among teens which found the rate of use of the devices had tripled among middle and high school students and doubled with young adults ages 18 to 24 since 2011. The Surgeon General described the use of the devices as unsafe for young adults.

It’s still unclear the true affect users, especially in teens, but there is research that indicates kids who use e-cigarettes are considerably more likely to start smoking—which has been proven harmful to their growth and development.