Teens who use e-cigarettes are more likely than others to smoke conventional cigarettes and other tobacco products, according to a new study.

Researchers interviewed nearly 2,500 teens at ten Los Angeles area high schools and found that 9 percent of kids had tried e-cigs at least once, but never conventional cigarettes.

Six months later, nearly 30 percent of them said they had tried cigarettes, cigars or water pipes.

"[The study] is the strongest evidence to date that e-cigarettes might pose a health hazard by encouraging adolescents to start smoking conventional tobacco products," said Dr. Nancy Rigotti, director of a tobacco research and treatment center at Massachusetts General Hospital.

Watch the "Shepard Smith Reporting" clip above.

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