The surgeon general takes a hard line on e-cigarettes among teens
Teen Smoking Electronic Cigarette (Shutterstock)

E-cigarettes have become the most commonly used tobacco products among teens and young adults in the US, the US surgeon general said Thursday, as he called for prevention efforts to "protect our nation's young people from being harmed by these products." The safety of e-cigarettes, which contain nicotine and may contain other chemicals, has been a…