*The following is excerpted from an online article posted on HealthDay.
Teens and young adults who use electronic cigarettes -- also known as vaping -- are almost four times as likely as their non-vaping counterparts to begin smoking traditional cigarettes, a new review suggests.
"E-cigarette use increases the risk of subsequent cigarette smoking, even for teens and young adults who might not be at the highest risk for smoking," said study lead author Samir Soneji.
"This increased risk may counter the successful tobacco control efforts that have produced a steady decline in smoking since 1998," he said.
Soneji is an assistant professor at the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, N.H.
Battery-powered e-cigarettes deliver nicotine through vapor instead of smoke. Their effect on public health is still being debated. Some say they may help adults wean themselves off tobacco cigarettes, while others feel they may introduce kids to smoking, according to background information in the study.
Dr. Michael Siegel, a professor of community health sciences at Boston University School of Public Health, isn't convinced that e-cigarettes are to blame for kids starting to smoke tobacco cigarettes.
"These are kids who likely would have smoked anyway. There is no evidence that the e-cigarette experimentation is contributing towards an increased risk for smoking," said Siegel, who wasn't involved with the review.
The new review looked at the results of nine studies. The studies included more than 17,000 teens and young adults aged 14 to 30 when the studies began. Fifty-six percent of the study volunteers were female.
When the studies were combined, the researchers found that an estimated 30 percent of teens who had ever used an e-cigarette went on to use traditional cigarettes. Only about 8 percent of those who never used e-cigarettes went on to smoke tobacco cigarettes.
When the researchers looked at the past 30 days, 21.5 percent of those who'd smoked e-cigarettes went on to smoke regular cigarettes. Less than 5 percent of those who hadn't smoked e-cigarettes tried regular cigarettes.
The new report didn't observe if people kept smoking over long periods. It also didn't examine whether smoking affected their health.
Soneji pointed to three possible reasons why e-cigarette users may be drawn to smoke traditional cigarettes: They may become addicted to nicotine and seek a greater fix; they may learn to enjoy smoking and spend more time with friends who light up; and e-cigs may make it easier for users to transition to cigarette smoking because they've already learned how to do it.