E-cigarettes: What's known, what's unknown.

Use and awareness of the e-cigarette, also referred to in the literature as an Electronic Nicotine Delivery Device, has dramatically increased since its introduction to the U.S. market in 2007. The regulatory power of the Food and Drug Administration over these devices is restricted to their classification as a tobacco product, as the manufacturers do not claim a therapeutic effect, as is the case with nicotine replacement therapy. The use, safety, chemical content and efficacy of the device for smoking cessation is the subject of considerable debate in the scientific community and poses a challenge to clinicians whose patients have elected to use e-cigarettes as a replacement for (or in addition to) cigarettes, to reduce the number of cigarettes they smoke, or for smoking cessation.