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iQOS: evidence of pyrolysis and release of a toxicant from plastic
  1. Barbara Davis,
  2. Monique Williams,
  3. Prue Talbot
  1. Department of Molecular, Cell and Systems Biology, University of California, Riverside, California, USA
  1. Correspondence to Dr Prue Talbot, Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA 92521, USA; talbot{at}


Objective To evaluate performance of the I quit original smoking (iQOS) heat-not-burn system as a function of cleaning and puffing topography, investigate the validity of manufacturer’s claims that this device does not burn tobacco and determine if the polymer-film filter is potentially harmful.

Methods iQOS performance was evaluated using five running conditions incorporating two different cleaning protocols. Heatsticks were visually and stereomicroscopically inspected preuse and postuse to determine the extent of tobacco plug charring (from pyrolysis) and polymer-film filter melting, and to elucidate the effects of cleaning on charring. Gas chromatography–mass spectrometry headspace analysis was conducted on unused polymer-film filters to determine if potentially toxic chemicals are emitted from the filter during heating.

Results For all testing protocols, pressure drop decreased as puff number increased. Changes in testing protocols did not affect aerosol density. Charring due to pyrolysis (a form of organic matter thermochemical decomposition) was observed in the tobacco plug after use. When the manufacturer’s cleaning instructions were followed, both charring of the tobacco plug and melting of the polymer-film filter increased. Headspace analysis of the polymer-film filter revealed the release of formaldehyde cyanohydrin at 90°C, which is well below the maximum temperature reached during normal usage.

Discussion Device usage limitations may contribute to decreases in interpuff intervals, potentially increasing user’s intake of nicotine and other harmful chemicals. This study found that the tobacco plug does char and that charring increases when the device is not cleaned between heatsticks. Release of formaldehyde cyanohydrin is a concern as it is highly toxic at very low concentrations.

  • new tobacco products
  • heat-not-burn tobacco products
  • electronic nicotine delivery devices
  • ENDS
  • nicotine
  • quality control
  • pyrolysis
  • char

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  • Contributors BD: conceiving and designing experiments, performing experiments, writing and editing manuscript. MW: performing performance experiments and writing part of the Materials and methods section. PT: conceiving and designing experiments, editing manuscript, obtaining funds and overseeing the project.

  • Funding This work was supported by a grant (number 25ST30041) from the Tobacco-Related Disease Research Program (TRDRP) of California.

  • Disclaimer The content is solely the responsibility of the authors and does not necessarily represent the official views of the TRDRP.

  • Competing interests None declared.

  • Patient consent Not required.

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