title: Electronic cigarettes: human health effects.
abstract: OBJECTIVE
  With the rapid increase in use of electronic nicotine delivery systems (ENDS), such as electronic cigarettes (e-cigarettes), users and non-users are exposed to the aerosol and product constituents. This is a review of published data on the human health effects of exposure to e-cigarettes and their components.
  
  
  METHODS
  Literature searches were conducted through September 2013 using multiple electronic databases.
  
  
  RESULTS
  Forty-four articles are included in this analysis. E-cigarette aerosols may contain propylene glycol, glycerol, flavourings, other chemicals and, usually, nicotine. Aerosolised propylene glycol and glycerol produce mouth and throat irritation and dry cough. No data on the effects of flavouring inhalation were identified. Data on short-term health effects are limited and there are no adequate data on long-term effects. Aerosol exposure may be associated with respiratory function impairment, and serum cotinine levels are similar to those in traditional cigarette smokers. The high nicotine concentrations of some products increase exposure risks for non-users, particularly children. The dangers of secondhand and thirdhand aerosol exposure have not been thoroughly evaluated.
  
  
  CONCLUSIONS
  Scientific evidence regarding the human health effects of e-cigarettes is limited. While e-cigarette aerosol may contain fewer toxicants than cigarette smoke, studies evaluating whether e-cigarettes are less harmful than cigarettes are inconclusive. Some evidence suggests that e-cigarette use may facilitate smoking cessation, but definitive data are lacking. No e-cigarette has been approved by FDA as a cessation aid. Environmental concerns and issues regarding non-user exposure exist. The health impact of e-cigarettes, for users and the public, cannot be determined with currently available data.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Callahan-Lyon
mesh_terms: D000336:Aerosols / Q000009:adverse effects; D003367:Cotinine / Q000097:blood; D066300:Electronic Nicotine Delivery Systems / Q000009:adverse effects*; D004781:Environmental Exposure; D005990:Glycerol / Q000009:adverse effects; D006801:Humans; D009538:Nicotine / Q000009:adverse effects
chemical_list: D000336:Aerosols; D009538:Nicotine; D003367:Cotinine; D005990:Glycerol
keywords: adverse event; aerosol; e-cigarettes; second-hand exposure; toxicity
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