"Electronic nicotine delivery devices such as electronic cigarettes (e-cigarettes) are battery-powered devices that deliver nicotine, flavorings (e.g., fruit, mint, and chocolate), and other chemicals via an inhaled aerosol. E-cigarettes that are marketed without a therapeutic claim by the product manufacturer are currently not regulated by the Food and Drug Administration (FDA) (1).*"

"* Currently, e-cigarettes and their components, such as the nicotine they contain, that are intended for therapeutic purposes (e.g., for smoking cessation) are drug/device combination products. When they are marketed for therapeutic purposes they are regulated by the FDA's Center for Drug Evaluation and Research. FDA’s Center for Tobacco Products currently regulates cigarettes, cigarette tobacco, roll-your-own tobacco, and smokeless tobacco. FDA has stated its intention to issue a proposed rule extending FDA's tobacco product authorities beyond these products to include other products like e-cigarettes not intended for therapeutic purposes."

"Propylene glycol and glycerin are the main base ingredients of the e-liquid. Exposure to propylene glycol can cause eye and respiratory irritation, and prolonged or repeated inhalation in industrial settings may affect the central nervous system, behavior, and the spleen.⁶⁶ In its product safety materials, Dow Chemical Company states that "inhalation exposure to [propylene glycol] mists should be avoided,"⁶⁷ and the American Chemistry Council warns against its use in theater fogs because of the potential for eye and respiratory irritation.68 When heated and vaporized, propylene glycol can form propylene oxide, an International Agency for Research on Cancer class 2B carcinogen,⁶⁹ and glycerol forms acrolein, which can cause upper respiratory tract irritation.^70,71
"Major injuries and illness have resulted from e-cigarette use,⁷² including explosions and fires.^73,74 Less serious adverse events include throat and mouth irritation, cough, nausea, and vomiting.⁷²"