A new study finds the use of e-cigarettes among teens is associated with heavier use of regular cigarettes. The researchers say their findings suggest that the devices are creating a new pathway for youth to become addicted to nicotine.

Researchers at the University of California, San Francisco, studied 75,000 South Korean teenagers. They found four out of five teens who use e-cigarettes also smoke tobacco cigarettes, according to the San Francisco Chronicle. Young e-cigarette smokers were more likely to have tried to quit smoking, which the researchers say suggests that some teens may be using e-cigarettes to try to quit smoking regular cigarettes.

“Use of e-cigarettes is associated with heavier use of conventional cigarettes, which raises the likelihood that actual use of e-cigarettes may increase harm by creating a new pathway for youth to become addicted to nicotine and by reducing the odds that an adolescent will stop smoking conventional cigarettes,” the researchers wrote in the Journal of Adolescent Health.

“We are witnessing the beginning of a new phase of the nicotine epidemic and a new route to nicotine addiction for kids,” study senior author Stanton A. Glantz, PhD, said in a news release. “Our paper raises serious concern about the effects of the Wild West marketing of e-cigarettes on youth.”