Published online by Cambridge University Press: 01 January 2021
E-cigarettes, sometimes referred to as ENDS (Electronic Nicotine Delivery Systems), include a broad range of products that deliver nicotine via heating and aerosolization of the drug. ENDS come in a variety of forms, but regardless of form generally consist of a solution containing humectant (e.g., propylene glycol or glycerol), flavorings, and usually nicotine (some solutions do not contain nicotine); a battery-powered coil that heats the solution into an aerosol (usually referred to as vapor) in an atomizing chamber; and a mouthpiece through which the user draws the vapor into the mouth and lungs. The devices may be closed systems containing prefilled cartridges, or open systems, where the user manually refills a 1-2 ml. tank with solution. What started as closed-system cigarette-shaped devices marketed as an adjunct for smoking cessation, has transitioned rapidly to literally thousands of hip and funky-designed open-system hookah pens, vape pens, and modifiable devices. For younger people, these forms are the “in” thing, while traditional cigarette-shaped devices are “out.”