NEW HAVEN, Conn., Sept. 7 (UPI) -- Research has shown teenagers in the United States are smoking e-cigarettes in increasing numbers. Now, a new study suggests they're also using the compact vaporizers to smoke marijuana.
In a recent survey, one-fifth of teenagers who have smoked e-cigarettes admitted to also using the device for smoking pot. The survey included responses from 3,800 students, from five high schools in Connecticut.
Unlike a cigarette or marijuana joint, which involves actual smoke -- from burned leaves -- a vaporizer turns nicotine, THC or other chemicals into aerosols that can be inhaled by the user.
"To better understand how students were using e-cigarettes or other portable vaporizing devices to vaporize cannabis, we asked students, 'Which of the following have you used to smoke marijuana?'" scientists wrote in their new paper on the subject, published Monday in the journal Pediatrics.
Of the teenagers who admitted to being so-called dual users -- having smoked both e-cigs and marijuana -- 29 percent said they had "vaped" dried pot leaves, while 23 percent used an e-cig to vaporize hash oil.
Hash oil can boast levels of tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana, up to 30 times higher than marijuana leaves. And vaporizing both leaves and hash oil can release THC at higher levels than if the substances were smoked using direct flame. Previous research has shown to disrupt brain development in teens.
Researchers say teens may be using e-cigs to smoke pot for the added potency, or as a way to better conceal the illegal activity.
"It's so much easier to conceal e-cigarette pot use," study co-author Meghan Rabbitt Morean, an assistant professor at Oberlin College, told USA Today. "Everybody knows that characteristic smell of marijuana, but this vapor is different. It's possible that teenagers are using pot in a much less detectable way."
Researchers knew teens were increasingly experimenting with vaporizers. Now they know they're being used to smoke marijuana. But whether or not e-cig use makes it more likely for a teen to try marijuana isn't clear. Neither is what the new data means for the task of preventing tobacco and drug use.
"We now know it's happening, but there are more questions about who is using and how damaging it is," Morean said.
But knowledge, however limited, isn't without value -- acknowledging there is a problem is the first step to recovery, after all.
"I think we need more evidence on this, not just from other high schools in Connecticut," lead study author Suchitra Krishnan-Sarin, a professor of psychiatry at the Yale University School of Medicine, told NBC News.
"We also need evidence, similar evidence from other states in the U.S., especially states in which marijuana is legal," Krishnan-Sarin added. "It would be interesting to see if rates differ in terms of how teens are using this product."