E-cigarettes, promoted as a less harmful alternative for tobacco smokers who can’t quit, produce nicotine-infused vapor, and are thus potentially addictive. Using e-cigarettes, or vaping, is rising among teens, fueled by a perception that they are relatively harmless. Nearly 9% of 8th graders said they’d used an e-cigarette in the previous month, compared to 4% for regular cigarettes. Lloyd Johnston says: “I worry that the tremendous progress that we’ve made over the last almost two decades in smoking could be reversed on us by the introduction of e-cigarettes.”

More about Johnston concerned declines in teen smoking threatened by e-cigarettes >