title: Flavour chemicals in electronic cigarette fluids.
abstract: BACKGROUND
  Most e-cigarette liquids contain flavour chemicals. Flavour chemicals certified as safe for ingestion by the Flavor Extracts Manufacturers Association may not be safe for use in e-cigarettes. This study identified and measured flavour chemicals in 30 e-cigarette fluids.
  
  
  METHODS
  Two brands of single-use e-cigarettes were selected and their fluids in multiple flavour types analysed by gas chromatography/mass spectrometry. For the same flavour types, and for selected confectionary flavours (eg, bubble gum and cotton candy), also analysed were convenience samples of e-cigarette fluids in refill bottles from local 'vape' shops and online retailers.
  
  
  RESULTS
  In many liquids, total flavour chemicals were found to be in the ∼1-4% range (10-40 mg/mL); labelled levels of nicotine were in the range of 0.6-2.4% (6 to 24 mg/mL). A significant number of the flavour chemicals were aldehydes, a compound class recognised as 'primary irritants' of mucosal tissue of the respiratory tract. Many of the products contained the same flavour chemicals: vanillin and/or ethyl vanillin was found in 17 of the liquids as one of the top three flavour chemicals, and/or at ≥0.5 mg/mL.
  
  
  CONCLUSIONS
  The concentrations of some flavour chemicals in e-cigarette fluids are sufficiently high for inhalation exposure by vaping to be of toxicological concern. Regulatory limits should be contemplated for levels of some of the more worrisome chemicals as well as for total flavour chemical levels. Ingredient labeling should also be required.
authors: Department of Civil and Environmental Engineering, Portland State University, Portland, Oregon, USA.
authors: Peyton A
authors: PA
authors: Tierney
authors: Department of Chemistry, Portland State University, Portland, Oregon, USA.
authors: Clarissa D
authors: CD
authors: Karpinski
authors: Department of Civil and Environmental Engineering, Portland State University, Portland, Oregon, USA.
authors: Jessica E
authors: JE
authors: Brown
authors: Department of Chemistry, Portland State University, Portland, Oregon, USA.
authors: Wentai
authors: W
authors: Luo
authors: Department of Civil and Environmental Engineering, Portland State University, Portland, Oregon, USA Department of Chemistry, Portland State University, Portland, Oregon, USA.
authors: James F
authors: JF
authors: Pankow
mesh_terms: D004339:Drug Compounding; D066300:Electronic Nicotine Delivery Systems; D005421:Flavoring Agents / Q000009:adverse effects / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D009538:Nicotine / Q000032:analysis*; D018722:Nicotinic Agonists / Q000032:analysis*; D018570:Risk Assessment; D016540:Smoking Cessation / Q000379:methods*; D000072137:Vaping; D014835:Volatilization
chemical_list: D005421:Flavoring Agents; D018722:Nicotinic Agonists; D009538:Nicotine
keywords: Electronic nicotine delivery devices; Nicotine; Packaging and Labelling; Toxicology