A research team including experts from Johns Hopkins conducted a survey to determine trends in e-cigarette use. Based on more than 400,000 responses from the national telephone survey led by the Centers for Disease Control and Prevention, the researchers estimate that 1.4 percent of the population in the U.S. vapes. Yet these roughly 1.9 million people do not report smoking cigarettes regularly.

E-cigarettes contain the addictive chemical nicotine, and as they are unregulated can contain other harmful chemicals. Although adults report using e-cigarettes to wean themselves off of traditional cigarettes, younger generations are taking up vaping without prior experience smoking.

Their findings in a brief research report, published on Oct. 9 in the Annals of Internal Medicine, suggest that regulating sales and education for vulnerable young people may be needed to prevent more people from getting hooked on nicotine. The researchers found that 60 percent of vapers were younger than 25 years old. Michigan had the highest prevalence of vapers in the population, whereas Alaska had the fewest. People who only smoked e-cigarettes also engaged in more risky behavior, such as binge drinking, risky sex and drug use.