title: Electronic cigarettes: product characterisation and design considerations.
abstract: OBJECTIVE
  To review the available evidence regarding electronic cigarette (e-cigarette) product characterisation and design features in order to understand their potential impact on individual users and on public health.
  
  
  METHODS
  Systematic literature searches in 10 reference databases were conducted through October 2013. A total of 14 articles and documents and 16 patents were included in this analysis.
  
  
  RESULTS
  Numerous disposable and reusable e-cigarette product options exist, representing wide variation in product configuration and component functionality. Common e-cigarette components include an aerosol generator, a flow sensor, a battery and a nicotine-containing solution storage area. e-cigarettes currently include many interchangeable parts, enabling users to modify the character of the delivered aerosol and, therefore, the product's 'effectiveness' as a nicotine delivery product. Materials in e-cigarettes may include metals, rubber and ceramics. Some materials may be aerosolised and have adverse health effects. Several studies have described significant performance variability across and within e-cigarette brands. Patent applications include novel product features designed to influence aerosol properties and e-cigarette efficiency at delivering nicotine.
  
  
  CONCLUSIONS
  Although e-cigarettes share a basic design, engineering variations and user modifications result in differences in nicotine delivery and potential product risks. e-cigarette aerosols may include harmful and potentially harmful constituents. Battery explosions and the risks of exposure to the e-liquid (especially for children) are also concerns. Additional research will enhance the current understanding of basic e-cigarette design and operation, aerosol production and processing, and functionality. A standardised e-cigarette testing regime should be developed to allow product comparisons.
authors.affiliation: Center for Tobacco Products, U.S. Food and Drug Administration, , Rockville, Maryland, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Brown
authors.forename: James M
authors.initials: JM
authors.lastname: Cheng
mesh_terms: D000336:Aerosols; D066300:Electronic Nicotine Delivery Systems / Q000009:adverse effects; D006801:Humans
chemical_list: D000336:Aerosols
keywords: Electronic nicotine delivery devices; Nicotine; Non-cigarette tobacco products
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