Significant numbers of high school students are using e-cigarettes to vaporize cannabis, new data suggest.

An anonymous survey of 3,847 Connecticut high school students found that, overall, 5.4% of the total sample reported using e-cigarettes or vaporizers to vaporize cannabis, either in the form of hash oil, THC-infused wax, or dried leaves.

Among students who had ever used an e-cigarette, 18% said that they had used it for cannabis, while 18.4% of cannabis users reported using e-cigarettes for cannabis.

More than one-quarter of students who reported using both cannabis and e-cigarettes said they had used e-cigarettes as a delivery mechanism for cannabis, according to a study published online Sept. 7 in Pediatrics.

Males and younger students were significantly more likely than females or older students to use e-cigarettes for cannabis, and the researchers found that the students’ socioeconomic status (SES) was not related to their tendency to use e-cigarettes to vaporize cannabis. The study did find significantly different rates of cannabis e-cigarette use between the five schools included in the study.

“These results indicate that factors such as the acceptability of cannabis use within a school (i.e., ‘cannabis culture’) or the extent to which a school has explicit policies prohibiting e-cigarette use may play a more important role in encouraging or deterring vaporizing cannabis than students’ SES,” wrote Meghan E. Morean, Ph.D., of Oberlin College, Ohio, and her coauthors.

Dried cannabis leaves were the most popular form of cannabis used in portable vaporizers, and hash oil was more commonly used with e-cigarettes than THC-infused wax (Pediatrics. 2015 Sept. 7. doi: 10.1542/peds.2015-1727).

While acknowledging that the results might be an underestimation of true figures because of the limitations of self-reporting, the authors said that further research is needed to determine whether e-cigarette use might serve as a gateway to cannabis use and the health impact of vaporized cannabis.

“At this time, the relative safety of using e-cigarettes for vaping cannabis versus smoking combustible cannabis is not well established,” Dr. Morean and her coauthors wrote. “However, a recent study indicated that adults who vaporize hash oil experience greater subjective tolerance and evidence of dependence compared with those smoking combustible cannabis.”

Cannabis consumed through e-cigarettes is particularly challenging for parents, teachers, and police to detect because the device does not produce the characteristic pungent aroma of smoked cannabis, the researchers reported.

“As e-cigarettes and related devices continue to gain popularity among youth, it will be important to monitor rates of using these products to vaporize cannabis.”

When asked about the findings, Dr. Robert L. DuPont said in an interview that American drug markets are changing rapidly, making more drugs available through highly potent routes of administration such as vaporization.

“This effective and convenient way of delivering THC has much appeal, especially to youth, being new, cool, and smoke-free as the rate of cannabis passes cigarettes for youth,” said Dr. DuPont, president of the Institute for Behavior and Health in Rockville, Md., and the first director of the National Institute on Drug Abuse.

The study was funded by the National Institutes of Health. No conflicts of interest were declared.