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Differences in flavourant levels and synthetic coolant use between USA, EU and Canadian Juul products
  1. Hanno C Erythropel1,2,
  2. Paul T Anastas3,
  3. Suchitra Krishnan-Sarin2,
  4. Stephanie S O'Malley2,
  5. Sven Eric Jordt2,4,
  6. Julie B Zimmerman1,2
  1. 1Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, USA
  2. 2Center for the Study of Tobacco Products Use and Addiction: Flavors, Nicotine, and Other Constituents, Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
  3. 3School of Public Health, Yale School of Medicine, New Haven, Connecticut, USA
  4. 4Department of Anesthesiology, Duke University School of Medicine, Durham, North Carolina, USA
  1. Correspondence to Professor Julie B Zimmerman, Dept. of Chemical & Environmental Engineering, Yale University, New Haven, Connecticut, USA; julie.zimmerman{at}


Background ‘Juul’ is the dominant US e-cigarette brand and was recently introduced to Canada, UK, France, Germany and Italy, with several flavours available across countries. US/Canadian products are sold with 5%, 3% and 1.5% (Canada only) nicotine content, whereas European Union (EU) regulation limits nicotine content to 1.7%. The differential nicotine content raises the question if flavour profiles and Juul device power output differ between countries.

Methods ‘Mint’, ‘Vanilla’ and ‘Mango’ e-liquids from all six countries were purchased in 2019 and analysed by GC/MS for their principal flavourant and nicotine content. In addition, device power specifications were compared for devices purchased from the respective countries.

Results Compositions of Juul e-liquids from the USA and Canada were identical and differed from the EU-marketed liquids, in which principal flavourant concentrations were significantly lower. EU Juul ‘Mint’ e-liquids contained a synthetic coolant, N-ethyl-p-menthane-3-carboxamide (WS-3), absent in US/Canadian products. US/Canadian ‘Mango’ e-liquid contained triethyl-citrate, an emulsifier. Nicotine contents matched label information, and devices had identical power specifications.

Conclusions Tested US/Canadian Juul e-liquids contained higher flavour concentrations than EU products, likely reflecting adaptation to user preferences. In EU, ‘Mint’ e-liquid, menthol is partially substituted with the synthetic coolant WS-3 that elicits a cooling effect like menthol but lacks its distinct ‘minty’ odour. The inhalational safety of WS-3 is unknown. The use of an emulsifier in US/Canadian ‘Mango’ Juul e-liquid may be necessary to keep the product homogeneous. Similar power specifications of devices between countries suggest that nicotine aerosol delivery is likely proportional to the e-liquid nicotine content.

  • electronic nicotine delivery devices
  • nicotine
  • non-cigarette tobacco products
  • public policy

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  • Contributors HCE and JBZ designed the study. HCE collected and analysed the data, and drafted the manuscript with input from PTA, SEJ and JBZ. All authors critically reviewed, edited and approved the final manuscript. JBZ is the guarantor of the paper. JBZ attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding This work was supported by grants P50DA036151 and U54DA036151 (Yale Centre for the Study of Tobacco Product Use and Addiction: Flavors, Nicotine and Other Constituents) from the National Institute on Drug Abuse and FDA CenterCentre for Tobacco Products (CTP), and grant R01ES029435 from the National Institute of Environmental Health Sciences (NIEHS) of the National Institutes of Health (NIH).

  • Disclaimer The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. The content is solely the responsibility of the authors and does not necessarily represent the views of the NIH or the FDA.

  • Competing interests Unrelated to the current work, over the past 3 years SO reports: having been a consultant or an advisory board member for Alkermes, Amygdala, Indivior, Mitsubishi Tanabe and Opiant; an NIDA Clinical Trials Network DSMB member with honorarium from the Emmes Corporation; having received donated study medications from Astra Zeneca, Pfizer and Novartis; and being a member of the American Society of Clinical Psychopharmacology’s Alcohol Clinical Trials Initiative (ACTIVE Group) supported in the past 3 years by Alkermes, Amygdala Neurosciences, Ethypharm, Indivior, Lundbeck, Mitsubishi, and Otsuka; Unrelated to the current research, SEJ reports receiving personal fees and nonfinancial support from Hydra Biosciences and Sanofi and nonfinancial support from GlaxoSmithKline Pharmaceuticals; Unrelated to the current research, SK-S reports receiving donated study medications from Novartis, Astra-Zeneca and Pfizer.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article.

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