Footnotes

• Collaborators CSTP Nicotine Flux Work Group: Andrew J Barnes, Alison Breland, Caroline O Cobb, Joanna E Cohen, Rachel El Hage, Ahmad El Hellani, Alisha Eversole, Jeffrey J Hardesty, Nathalie Hayeck, Cosima Hoetger, Ebrahim Karam, Sarah F Maloney, Alyssa K Rudy, Najat Aoun Saliba, Rola Salman, Soha Talih, Theodore Wagener.

• Contributors The idea for this commentary was developed at a meeting of the CSTP Nicotine Flux Work Group in Lisbon, Portugal, 25–27 October 2019, thus all CSTP Nicotine Flux Work Group members are listed as Collaborators and the work group name is included in the author list. The first draft of the manuscript was prepared by TE, and finalised with input from EKS and AS.

• Funding This work was supported by the National Institute on Drug Abuse of the US National Institutes of Health (NIH) under Award Number U54DA036105 and the Center for Tobacco Products of the U.S. Food and Drug Administration (FDA).

• Competing interests TE and AS are paid consultants in litigation against the tobacco industry and are named on a patent for a device that measures the puffing behavior of electronic cigarette users. In addition, TE is a consultant in litigation against the electronic cigarette industry.

• Patient consent for publication Not required.

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