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On 22 January 2015, the New England Journal of Medicine (NEJM) published a research letter by Jensen et al. on ‘Hidden formaldehyde in e-cigarette aerosols’ [1]. The authors reported laboratory measurements of formaldehyde hemiacetals in e-cigarette vapour and compared these with measurements of formaldehyde emissions present in cigarette smoke from earlier studies. They then calculated a life-time cancer risk for an e-cigarette user (‘vaper’) relative to a cigarette smoker, and report their conclusion as follows:

If we assume that inhaling formaldehyde-releasing agents carries the same risk per unit of formaldehyde as the risk associated with inhaling gaseous formaldehyde, then long-term vaping is associated with an incremental lifetime cancer risk of 4.2×10−3. This risk is 5 times as high (as compared with the risk based on the calculation of Miyake and Shibamoto shown in Figure 1), or even 15 times as high (as compared with the risk based on the calculation of Counts et al. shown in Figure 1) as the risk associated with long-term smoking.

The finding that incremental life-time cancer risk was 5–15 times higher for vaping than for smoking generated world-wide headlines.

Unfortunately, the experiment was fundamentally flawed.

In simple terms, an e-cigarette consists of: a battery to provide power, a liquid containing nicotine, flavours and a diluent that forms aerosol (‘vapour’) when heated and an atomizer, which is a heating element over which the liquid flows and is vaporized when the power is activated.

The authors had constructed a battery and atomizer combination that, when operated at a higher voltage setting, would mean that the atomizer ran extremely hot and constituents in the liquid would create thermal decomposition products, including formaldehyde. The fatal flaw in the experiment is that under these conditions the vapour tastes so acrid and harsh that human users will not inhale it—a widely known phenomenon known as ‘dry puff’ [2]. It means that calculations of human cancer risks are based on conditions that no human user would tolerate even momentarily, let alone over a full life-time. On 16 April NEJM published a critical letter making these points, but the authors' reply did not amount to a convincing defence of their experiment and conclusions [3].

There is a clear risk that extensive and alarming reporting will have persuaded many smokers that there is little to be gained by switching to e-cigarettes, despite the emerging expert consensus that vaping is likely to be at least 20 times lower risk than smoking [4].

We have documented the flaws in the experiment and cancer risk calculations and in the authors' reply to criticisms of their work, and written to the editor of NEJM requesting the retraction of the letter (Supplementary material S1). Many academic journals, including NEJM, participate in the Committee on Publication Ethics and agree to abide its Code of Conduct [5] and Retractions Guidelines [6]. These codes are intended to ‘ensure the integrity of the academic record’ and to initiate a retraction when findings are ‘unreliable’, including through ‘honest error (e.g. miscalculation or experimental error)’. We have written to Addiction to put our complaint on the record (it is included as supplementary material to this letter) and to invite the editor of NEJM to respond through these pages.

Declaration of interests

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  2. Declaration of interests
  3. References
  4. Supporting Information

K.F. reports that some of his studies on electronic cigarettes were performed with unrestricted funds provided to the Onassis Cardiac Surgery Center by FlavourArt and Nobacco. K.F. publishes a blog commenting on research on e-cigarettes and its implications at www.ecigarette-research.org/. C.B. is a long-standing and continuing advocate of ‘harm reduction’ in tobacco and other public health policies and has written extensively on e-cigarettes at www.clivebates.com.

References

  1. Top of page
  2. Declaration of interests
  3. References
  4. Supporting Information

Supporting Information

  1. Top of page
  2. Declaration of interests
  3. References
  4. Supporting Information

Supporting Material S1 Bates CD, Farsalinos KE. Complaint under the Code of Conduct of the Committee on Publication Ethics: Letter in the New England Journal of Medicine Jensen et al (2015), Hidden Formaldehyde in E-cigarette Aerosol, 20 April 2015.

S2 Letter to New England Journal of Medicine, from 40 academics and experts in support of the complaint about the research letter published in the NEJMon Hidden Formaldehyde in E-cigarette Aerosol, 20 April 2015.

FilenameFormatSizeDescription
add13018-sup-0001-Supplementary.pdfPDF document316KSupporting info item
add13018-sup-0002-Supplementary.pdfPDF document137KSupporting info item

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