Are Electronic Cigarettes harmful to your health? 1,2 Propylene Glycol: A Biomarker of Exposure Specific to e Cigarette Consumption E cigarettes gain attention in schools amid rise in popularity The Washington Post E cigarettes aren't harmless, and combining them with cigarettes makes them even worse Study Summary Read "Public Health Consequences of E Cigarettes" at NAP.edu Oral health may be at risk if you vape Chicago Sun Times