Electronic cigarettes, touted as potentially game-changing harm-reduction devices by longtime nicotine addicts and some health experts, are surprisingly popular among American teenagers, according to new survey results.

In fact, more students reported using an e-cigarette in the past month than admitted to past-month use of traditional cigarettes in the 2014 Monitoring the Future survey, which gathers information on eighth-, 10th- and 12th-grade students.

Survey results released Tuesday show more than 17.1 percent of high school seniors said they used an e-cigarette in the past month, while just 13.6 percent said they used a traditional cigarette in the previous 30 days.

The gap was wider among younger students. About 16.2 percent of high school sophomores used an e-cigarette in the past month, whereas 7.2 percent used a conventional cigarette. For eighth-grade students, self-reported e-cigarette use was also more than double the conventional use rate, at 8.7 and 4 percent, respectively.

A significant number of past-month e-cigarette users said they had never tried a conventional cigarette or varieties of smokeless tobacco.

About 36 percent of eighth-grade students who used an e-cigarette in the past month said they never used traditional tobacco products, which was also the case for 30 percent of 10th-grade and 21 percent of 12th-grade students who had used e-cigarettes.

This was the first year the survey asked about e-cigarettes. The survey did not ask about daily, annual or lifetime use of the vapor-producing devices.

The findings “surprised all of us, because [the rates are] much higher than the rates we’ve seen in surveys from the past couple of years from other sources,” says Dr. Wilson Compton, deputy director of the National Institute on Drug Abuse, which funds the annual University of Michigan-led survey.

Lindsey Cook/USN&WR

Results from the Centers for Disease Control and Prevention's 2013 National Youth Tobacco Survey, for example, put past-month e-cigarette use at 4.5 percent among high school students, lower than conventional cigarette use. Nearly all of the e-cigarette users in that survey used multiple nicotine products (only 0.6 percent reported exclusive e-cigarette use).

The new Monitoring the Future results are in line, however, with two state-level studies published this week in academic journals. Researchers, using 2013 data, found 29 percent of ninth- and 10th-grade Hawaii students and 25 percent of Connecticut high school students had ever used an e-cigarette, with past-month use at 18 and 12 percent, respectively.

Despite the apparent jump in students sampling e-cigarettes, the national 2014 survey results show past-month and daily use of conventional cigarettes dropped to all-time lows for each age group. For high school seniors, the daily use rate dropped from 8.5 percent in 2013 to 6.7 percent in 2014.

E-cigarettes are generally considered less harmful to users’ health, though long-term studies have not been conducted.

Some health regulators and politicians allege e-cigarette flavor options may appeal to youth, and that high rates of teen use could reverse years of progress toward reducing nicotine addiction. Compton, however, isn’t willing to describe the devices as gateways to lifelong addiction or to conventional cigarette use, citing a need for more research.

“It is absolutely true that I don’t have information or data about whether they are gateway, introductory products,” he says. “But that, of course, would be our biggest fear.”

Gregory Conley, president of the American Vaping Association trade group, says more research is needed on teen use of e-cigarettes.

“Our understanding of youth e-cigarette use is constrained by the fact that the survey only looked at past 30-day use, which prevents researchers from distinguishing between regular users and experimenters," he says.

Conley also points out that past-month use of alcohol and marijuana are higher than past-month e-cigarette use.

“Alcohol and marijuana use clearly present more significant health risks to teens than vaping, but it is doubtful that the loudest voices against vaping will pause to consider whether some of their resources may be better utilized combating youth usage of these products," he says. “No use of vapor products by youth is obviously the ideal, but we do not live in a perfect world.”

Another nicotine delivery device – hookahs – were used by about 22 percent of high school seniors in the last year, continuing a multiyear uptick.

Most states ban sales of e-cigarettes to people under age 18, and pending Food and Drug Administration regulations would impose the age limit on the handful of states that do not.