New research estimates that 4.5% of adults in the US currently use e-cigarettes. That equates to more than 10.8 million e-cigarette users, most of them—51.2%—under the age of 35 and about 60% are men. Those data come from an analysis of national self-reported health behaviors.

Additionally, e-cigarette use was higher among people who were lesbian, gay, bisexual or transgender, as well as in the unemployed and those with cardiovascular disease, asthma, and cancer. It was even higher in those with chronic obstructive pulmonary disease and depression.

The research, appearing in the latest issue of the Annals of Internal Medicine, was conducted by the Tobacco Regulation and Addiction Center of the American Heart Association, the world’s leading voluntary organization dedicated to building healthier lives, free of cardiovascular diseases and stroke.

Researchers looked at data from the Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance System (BRFSS) 2016. This was the first year that e-cigarette use was included in this annual survey of US adults that asks about risk behaviors, use of preventive services, and other chronic health conditions.

About 96% of the 486,303 people surveyed provided answers to questions about whether they had ever used an e-cigarette or other electronic vaping product at any time in their life. Those who had were asked if they were now using the products every day, some days, or not at all, with responses of “every day” or “some days” defining current use.

Among current users, 33.5% said they used e-cigarettes daily, with use highest among those ages 18-24. Within that age group, 44.3% of e-cigarette users reported they had never been regular cigarette smokers.

“It’s particularly disturbing, to see these younger people who have never been regular cigarette smokers, taking up the use of e-cigarettes, perhaps with the assumption that this alternative nicotine delivery system has been proven to be safe,” said Rose Marie Robertson, MD, Chief Science and Medical Officer of the American Heart Association and a director of the Tobacco Regulation and Addiction Center. “But ongoing research shows that not only are there potential health hazards associated with exposure to the volatile organic compounds produced by e-cigarettes, but the nicotine delivered, especially by more recent devices, can produce and maintain strong dependence. This can lead to dual use or even serve as a gateway to other tobacco product use, including smoking combustible cigarettes—a practice that kills more than 480,000 Americans every year.”

Overall, e-cigarette users were more likely to be:

•Younger, average age 40-44, compared to 55-59 for non-users
•Current or former cigarette smokers, 85% compared to 15% never-smokers
•Males, 60% of users

The researchers also report, for the first time, the prevalence of e-cigarette use by state. Oklahoma had the highest use of e-cigarettes, with 7% of the population reporting as current users, compared to South Dakota with the lowest rate at 3.1%.

“We found e-cigarette use was highest in southern and western states, but it varied widely even within particular regions of the country,” said Michael J. Blaha, MD, the study’s lead author and director of clinical research at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins University in Baltimore. “The reasons for this aren’t clear but may include factors, such as socioeconomic status, tobacco laws, or taxation. Further research in this area could better inform our policy and educational initiatives to combat e-cigarette use.”

Dr. Robertson said although there is still much to learn about the dangers of e-cigarettes, insufficient regulation, targeted marketing to youth, and the growing threat to renormalize smoking in society call for interventions to stop this growing public health problem.