Researchers find most teens use e-cigarettes for the flavor of the vapor, rather than for the nicotine.
E-cigarettes (electronic cigarettes) are battery-powered devices that heat up liquids, emitting a vapor that the user inhales, or "vapes." Such liquids come in various flavors, and many contain nicotine and other chemicals.
According to a report published by the Centers for Disease Control and Prevention (CDC) last year, current use of e-cigarettes among middle and high school students tripled between 2013-2014.
The number of middle school students using e-cigarettes increased from 1.1 percent to 3.9 percent during this period, while use of the devices among high school students rose from 4.5 percent to 13.4 percent.
Dr. Richard Miech, of the Institute for Social Research at the University of Michigan and co-author of the new study, and colleagues note that there is a common assumption among researchers and policymakers that all youths who use e-cigarettes are inhaling nicotine.
The authors say this is reflected in the commonly used term "electronic nicotine delivery systems" (ENDS), which implies the devices are always used to inhale nicotine.
However, the researchers say there is limited data on the extent to which adolescents use e-cigarettes to vape nicotine.
With this in mind, Dr. Miech and team set out to determine precisely what substances youths are inhaling when they use e-cigarettes.
Two thirds of students vaping for the flavoring
For their study - published in the journal Tobacco Control - the researchers drew data from the 2015 Monitoring the Future Survey - an annual, nationally representative survey that includes students from 8th, 10th, and 12th grades.
As part of the survey, almost 14,983 students were asked about their e-cigarette use, including whether they had ever used the devices, the last time they had used an e-cigarette, how often they use the devices, and what substances were in the vapor they inhaled at last use.
A total of 3,837 students reported having ever used an e-cigarette, of whom 1,701 reported vaping in the past month. Of the students, 1,085 reported having used an e-cigarette up to five times, while 616 reported using the devices six times or more.
On looking at what substances e-cigarette users reported vaping, the team found "just flavoring" was the most common, with around 65-66 percent of students across all three grades reporting flavoring as the substance they inhaled at last use.
Vaping nicotine at last e-cigarette use was reported by 22 percent of 12th graders, the researchers found, as well as 20 percent of 10th graders and 13 percent of 8th graders.
Around 6-7 percent of students across all grades reported vaping marijuana, while around 6-14 percent could not recall what they last vaped, and 1 percent reported vaping some other substance.
These results, the researchers say, suggest attempts by policymakers to ban the sale of e-cigarettes to youths based on the assumption that they are always used to inhale nicotine may not be supported by evidence.
What is more, the team says the findings question the term "ENDS" to describe e-cigarettes, since the devices are not always used to inhale nicotine.
"The term stands for 'electronic nicotine delivery system,' which seems inaccurate for the description of a device that the majority of youth do not use to vape nicotine," the authors note.
'Vaping could still predict smoking initiation'
Talking to Medical News Today, Dr. Miech says the findings suggest there is not a nicotine epidemic among adolescents, though he says that does not mean e-cigarette use cannot act as a gateway to conventional smoking.
"Even if kids are not vaping nicotine, vaping could still predict smoking initiation to the extent that vaping teaches kids to smoke and gets them used to the behavior.
Regardless of the substance vaped, vaping removes the substantial psychological barriers involved in the inhalation of smoke into the lungs. And vaping any substance could desensitize youth to the dangers of smoking; that is, after vaping flavoring and not seeing any immediate health detriment, some vapers may conclude the dangers of smoking/vaping are exaggerated."
Dr. Richard Miech
Dr. Miech told MNT that he hopes his findings demonstrate the different patterns of e-cigarette use between youths and adults.
"While vaping may serve as a smoking cessation tool for adults, it seems to be used very differently among adolescents," he said. "Taking into account these different use patterns will likely help future intervention to curb nicotine addiction be more effective."