E-cigarettes are being used by more people to smoke marijuana or synthetic drugs, CNN reports.
People use the devices to get high without police, parents or teachers knowing.
E-cigarette devices, known as vape pens, are showing up in a growing number of drug busts, according to CNN. It is almost impossible to tell whether a person is using them to smoke nicotine, marijuana concentrate or synthetic drugs such as K2 or Spice.
"It's the concealment method; we don't know what is in a vape pen until we actually have it tested by a forensic laboratory," said Supervisory Special Agent John Scherbenske of the U.S. Drug Enforcement Administration.
According to Reuters, a new study finds almost 20 percent of high school students who said they used e-cigarettes for nicotine also used them to vaporize marijuana.
The study of almost 4,000 teens appears in the journal Pediatrics.
"Forms of cannabis that can be vaporized, like hash oil, can be many times stronger than marijuana that is smoked," lead researcher Meghan Morean of Oberlin College in Ohio told Reuters. She found that of students who had used e-cigarettes, 18 percent used them to vaporize cannabis in some form, including hash use and wax infused with THC, the main psychoactive ingredient in marijuana.
The study found students were 27 times more likely to use e-cigarettes to vaporize cannabis than adult e-cigarette users.