For the first time, more teens are smoking e-cigarettes than tobacco cigarettes, according to a new survey of 40,000 to 50,000 students in the 8th, 10th and 12th grades.
The annual University of Michigan "Monitoring the Future" report found that both alcohol and cigarette use in 2014 were at their lowest points since the study began in 1975. But they were most concerned about the rise of e-cigarettes, which are not regulated and whose formulas are undisclosed.
"As one of the newest smoking-type products in recent years, e-cigarettes have made rapid inroads into the lives of American adolescents," Richard Miech, a senior investigator of the study, said in a statement. "Part of the reason for the popularity of e-cigarettes is the perception among teens that they do not harm health."
The survey found that in the past 30 days, more than twice as many 8th- and 10th-graders reported using e-cigarettes versus tobacco cigarettes. Among 12th-graders, 17 percent reported e-cigarette use and 14 percent reported use of a tobacco cigarette. But 16 percent of 10th graders surveyed reported using an e-cigarette, while 7 percent reported using a tobacco cigarette.
"This could be a result of e-cigarettes being relatively new," Lloyd Johnston, principal investigator of the project, said in a statement. "So today's 12th-graders may not have had the opportunity to begin using them when they were younger. Future surveys should be able to tell us if that is the case."
E-cigarettes are battery-powered devices with a heating element that typically produces a nicotine-infused aerosol, or vapor, that users inhale. The products come in hundreds of flavors including bubble gum and milk chocolate cream.
The researchers did not determine whether those who used e-cigarettes were likely to go on to use tobacco products. But use of tobacco among high schoolers continued a decades-long decline.
In 2014, the use of tobacco cigarettes declined to 8 percent from 10 percent in 2013. The figure in 1998 was 28 percent.
Some 15 percent of 8th-graders said there's a great risk of harm with regular use of e-cigarettes, compared with 62 percent who said there's a great risk from tobacco cigarettes.
British researchers say electronic cigarettes could save 6,000 lives per year for every million smokers, a claim that has reignited the debate over the health impact of vaping.
In September, in an editorial published British Journal of General Practice, a research team from University London College argued that the public health community was jumping the gun in their rush to regulate e-cigarettes the same as tobacco products.
"Given that smokers smoke primarily for the nicotine but die primarily from the tar, one might imagine that e-cigarettes would be welcomed as a means to prevent much of the death and suffering caused by cigarettes," they wrote.
The science on e-cigs as a smoking cessation tool is mixed. Earlier this year, the University London College team found that smokers were about 60 percent more likely to quit if they used e-cigarettes. But other studies have found that smokers who switched to e-cigarettes were less likely or no more likely to quit than if they used a patch or gum.
A recent study from the U.S. Centers for Disease Control and Prevention found e-cigarette use among school-age children has tripled in the last three years, with half of kids who report vaping stating that they intended to smoke conventional cigarettes within the next year.
With reporting by ABC News' Liz Neporent.