June 14 (UPI) -- "Ice"-flavored e-cigarettes may increase the risk for nicotine dependence among young adults who use them, a study published Monday by the journal Tobacco Control found.
Users of these so-called "hybrid" vapes, which combine sweet fruit and cooling mint or menthol flavors, were almost 50% more likely to smoke conventional cigarettes and experience symptoms of nicotine dependence than non-users, the data showed.
Vapers who use the ice flavors were nearly twice as likely as those who preferred fruit flavors to use disposable non-cartridge e-cigarette devices, which are marketed as "tobacco-free nicotine" sources.
Nearly half of the young adults surveyed reported most often using ice-flavored cartridges.
"We have some hypotheses about why use of ice flavors was associated with more frequent use and nicotine dependence symptoms," study co-author Adam Leventhal told UPI in an email.
"We speculate that attractive marketing of ice-flavored products might increase young adult's decisions to try these products [and] the combination ... might be particularly appealing, promote deeper inhalation and encourage continued use," said Leventhal, director of the University of Southern California Institute for Addiction Science in Los Angeles.
Products billed as "ice"-flavored by e-cigarette device manufacturers include "blueberry ice" or "melon ice" and are relatively new to the U.S. market, according to Leventhal.
Earlier studies by Institute for Addiction Science researchers indicate that, at least historically, younger vapers have preferred fruit as well as menthol or mint flavors.
For this study, Leventhal and his colleagues conducted an online survey of 344 young adult e-cigarette users, with an average age of 21 years, in Southern California.
Respondents were asked if they vaped and, if so, which flavor they had used most often in the preceding 30 days.
Among the respondents, 168, or 49%, reported using "ice" flavors most often, while 17% cited menthol or mint and 34% indicated fruit flavors.
Nearly one-third of "ice" users reported also smoking conventional cigarettes during the previous 30 days, compared with 22% of non-users.
Sixty-seven percent of "ice" vapers also said that they had experienced symptoms of vaping dependence, while 43% of fruit-flavor users did so, according to the researchers.
In addition, 65% of "ice" vapers indicated that they used disposable, non-cartridge e-cigarette devices, compared with 35% of fruit vapers, they said.
"Our study found that young adult ice flavored e-cigarette users were more likely to use disposable e-cigarettes, which [are marketed] as containing 'tobacco-free nicotine,'" Leventhal said.
"Whether e-cigarettes with nicotine not derived from tobacco are subject to federal tobacco product regulation is unclear [so] our findings help raise attention toward determining how this newest evolution of e-cigarette products fit into national and local policies," he said.