(CNN) - Vaping among America's teenagers continues to climb, while the use of other substances -- such as alcohol and opioids -- has declined in recent years, according to a new report.
Monday's report, called Monitoring the Future, comes from the University of Michigan's Institute for Social Research and is based on an annual survey of drug and alcohol use and attitudes among eighth-, 10th- and 12th-graders in the United States. This year's survey included 44,482 students from 392 public and private schools across the country.
Behind drinking alcohol, vaping was the second-most common form of substance use, the study showed, with 17.6% of eighth-graders, 32.3% of 10th-graders and 37.3% of 12th-graders reporting vaping in the past year. Last year, the annual survey found that prevalence of vaping was 13.3% among eighth-graders, 23.9% among 10th-graders and 27.8% among 12th-graders.
Vaping involves using an electronic cigarette, hookah or similar device to inhale certain vapors or aerosols, which could contain substances such as nicotine, marijuana or flavoring.
"What we are seeing is a change in the patterns of drug taking among teenagers in that they are the lowest that we've seen for many years," said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which funded the report.
"So we have very good news," she said, "but at the same time, we have to be vigilant, because of this very high uptake and embracing of vaping by teenagers that could lead them then to the administration of other drugs."
Vaping: 'A real problem'
This year is the second in which the Monitoring the Future survey asked high schoolers about vaping specific substances: nicotine, marijuana or "just flavoring."
Flavoring was the most commonly reported substance among eighth-graders at 15.1%, followed by nicotine at 10.9% and then marijuana at 4.4%.
Tenth-graders reported identical rates for flavoring and nicotine, but 12.4% reported vaping marijuana. Among 12th-graders, 29.7% reported vaping nicotine, 25.7% flavoring and 13.1% marijuana.
"You're seeing right now that 30% of 12th-graders last year were exposed to nicotine," Volkow said.
"Another issue of concern is, these devices are very efficient at delivering drugs rapidly into your brain and, in so doing, deliver the drugs in ways that make them more addictive -- and so it's not just nicotine. Now we also know that they are using it for 9THC," or tetrahydrocannabinol, a cannabinoid chemical in marijuana, she said.
Bonnie Halpern-Felsher, a professor of pediatrics in Stanford University's Division of Adolescent Medicine, called this increase in vaping alarming but not surprising because of new products, such as those from popular e-cigarette maker Juul.
"However, since MTF doesn't appear to separate out vaping vs. Juuling in their survey, it is hard to know what the youth are using," Halpern-Felsher said of the new report.
"The overall decline or stabilization of other drug use is promising, although the increase in vaping marijuana is concerning," she said. "Clearly, youth drug prevention messages needs to go beyond conventional drugs and include all forms of nicotine and vaping."
The overall increase in vaping in the survey appears to be consistent with data from the US Centers for Disease Control and Prevention showing a 78% increase in youth vaping between 2017 and 2018, said Dr. Pamela Ling, a professor of medicine at the University of California, San Francisco, who works with the school's Center for Tobacco Control Research and Education and was not involved with the new report.
The Food and Drug Administration "has also recognized an 'epidemic' of youth vaping. The consistency of these data suggests this is a real problem," Ling said.
"While we see declines in cigarette smoking among youth, the increases in vaping may lead to overall rates of tobacco or nicotine use increasing. We also know from many longitudinal studies of youth that those who use e-cigarettes are about three times more likely to start smoking cigarettes," she said. "The increase in vaping goes against the trends for all other drugs and alcohol, which are declining. That's a problem."
In historical context, "the absolute increases in the prevalence of nicotine vaping among 12th-graders and 10th-graders are the largest ever recorded by Monitoring the Future in the 44 years that it has continuously tracked dozens of substances," the authors of the report wrote in a letter to the editor Monday in the New England Journal of Medicine.
Meanwhile, the traditional use of cigarettes remained at the lowest levels in the survey's history.
Daily cigarette use was reported by 0.8% of eighth-graders, 1.8% of 10th-graders and 3.6% of 12th-graders in 2018, the survey showed. Lifetime cigarette use among 12th-graders went down from 26.6% in 2017 to 23.8% in 2018, and past-month use declined from 9.7% to 7.6%.
In general, substances at historic low levels of use in 2018 were alcohol, cigarettes, heroin, prescription opioids, MDMA (ecstasy or Molly), methamphetamine, amphetamines, sedatives and ketamine, according to the report.
Alcohol and opioid use dropping among teens
Even though alcohol and binge drinking rates appeared to be on the decline, alcohol was still "the most frequently used substance" in the report, Volkow said.
Past-month use of alcohol was reported by 8.2%, 18.6% and 30.2% of eighth-, 10th- and 12th-graders, respectively, according to the survey. Yet the percentage of teenagers who reported ever using alcohol dropped as much as 58% from its peak in 1994.
"Even parents have a tolerance to alcohol, and in many instances, they maybe even provide the alcohol for parties that they are holding in their house, with the sense that, what harm is there to let teenagers drink when they are home?" Volkow said.
"So we have a culture about drinking that is very accepted but that is slowly changing. I think changes in attitudes are in part responsible about why we're seeing the decreases."
The new report also showed a significant drop over the past five years in the percentage of teenagers, particularly 12th-graders, using opioids despite the ongoing epidemic among adults in the United States
"It's fascinating that despite the fact that we have very high rates of opioids and heroin among adults, adolescents have the lowest rates that we have seen since the inception of the survey," Volkow said.
For instance, Vicodin use dropped by 58.4% in eighth-graders, 75.4% in 10th-graders and 67.2% in 12th-graders over the past five years, according to the report.
The survey also showed a shift in how easy teens think opioid drugs are to access.
One in three 12th-graders, or 32.5%, said in this year's report that prescription opioids were easily available, compared with more than 54.2% in 2010.
"Intriguingly, when they go off to college or go to work, you see the highest rates of opioid use among 18 to 24 years of age. So there is a big gap between the patterns of consumptions of opioids in teenagers and then when they go into young adulthood," Volkow said.
She added that the difficulty youths face in accessing opioid drugs could explain this stark difference in use between teenagers and young adults.
"I think many of the campaigns that are trying to make it harder to get access to prescription opioids have had an effect," Volkow said.
"This has been decreasing the number of prescription opioids given in our country, of the number of tablets given, and as a result of that, there are less tablets in parents' cabinets, and they are actually harder to get even in the black market," she said.
"Also, perhaps educational campaigns about the high risk of overdoses that are associated with the use of these substances, and the high risk of addiction to these substances, all of these factors may have had a positive impact (on) teenagers."