The term “electronic cigarette” refers to a battery-powered device that heats a tank or cartridge of liquid usually containing nicotine, flavorings and other chemicals, but not the cancer-causing tar found in tobacco cigarettes. Users inhale and exhale the vapor. The devices come in numerous shapes, including ones that look like pens, flash drives and hookahs. Many consumers are confused about the health implications of e-cigarettes. This is a primer about what research so far shows about these devices.

Are they safer than traditional cigarettes?

Yes. But that does not mean they are safe.

E-cigarettes contain far fewer dangerous chemicals than those released in burning tobacco. Tobacco cigarettes typically contain 7,000 chemicals, including nearly 70 known to be carcinogenic. E-cigarettes also don’t release tar, the tobacco residue that damages lungs but also contributes to the flavor of tobacco products. In the United States, cigarettes are associated with 480,000 deaths a year from coronary heart disease, stroke and numerous cancers, among other illnesses.

The research on e-cigarettes is young because the products have only been around for a little over a decade. Exacerbated by the voltage of a given device, certain e-cigarette flavors can irritate the airways, researchers say: benzaldehyde (added to cherry flavored liquids), cinnamaldehyde (gives cinnamon flavor), and diacetyl (a buttery flavor that can cause lung tissue damage called “popcorn lung.”) Some flavors become irritants when added to vaping liquids. The process of turning liquid chemicals into vapor releases harmful particulates deep into the lungs and atmosphere, including heavy metals.