human
I've been hearing about the dangers of e-cigarettes. What are they?
assistant
E-cigarettes are battery-powered devices that simulate smoking by producing an aerosol, or vapor, from a liquid solution. They typically contain nicotine, which is addictive and can be harmful to health. Some e-cigarettes also may contain other chemicals such as propylene glycol and/or vegetable glycerin, which have not yet been fully studied for safety. The potential risks associated with long-term use of e-cigarettes are unknown.