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First burn the barrel, then scrape it - commentary on a letter published in the NEJM

First burn the barrel, then scrape it - commentary on a letter published in the NEJM

21, Jan, 2015

By Tom Pruen

A major talking point today is some new research into the release of formaldehyde from electronic cigarettes. The actual 'publication' is embargoed, so it isn't as yet clear what view the world’s press will make of it, but it's safe to assume that a large majority will blithely accept it, and publish scare stories about the newly discovered dangers of electronic cigarettes.

There are, however, a significant number of problems with this research. First of all, this is not a peer-reviewed scientific publication in the New England Journal of Medicine; it's a letter to the editor. The discussions of methods are sparse, and many of its assumptions are unexplained (and to some extent inexplicable). Its publication as a letter suggests that it might not have survived the rigours of peer review (and indeed the NEJM clearly wanted to publish it, since they did so even though it breaks more than one of their instructions for letter submissions, despite the statement that “Letters that do not adhere to these instructions will not be considered”).

The test conditions and exact nature of the product tested are unclear, however most tank atomisers are not designed to operate with 5 Volts supplied to them. Operating a system at beyond its intended range may yield dangerous levels of formaldehyde, however this is unlikely to represent actual consumer exposure. Consumers are extremely unlikely to voluntarily inhale high concentrations of formaldehyde; formaldehyde is characterized by its unpleasant smell, and at concentrations of as little as 5 parts per million causes burning sensations in the respiratory tract, and breathing difficultyi. No attempt was made to measure the concentration of formaldehyde present during this testing.

In fact, given that the primary source of formaldehyde is combustion, it is surprising that levels from a non-combustion source such as e-cigs can exceed that from a combustive product such as cigarettes. While thermal degradation of propylene glycol to produce formaldehyde is known to occur, it is highly temperature dependent, and other components of the mix also thermally degrade at high temperature (280ºC), notably producing acroleinii, another unpleasant and unpalatable irritant. The emissions of this test are not likely to be what a user would recognise as vapour, but instead a completely unpalatable, burnt, choking mess.

The reference for the release of formaldehyde from biocides does not relate to the specific hemiacetals measured (i.e. those formed from formaldehyde and propylene glycol or glycerol) but instead deals with biocides that are specifically formulated to release formaldehyde and used in metal working solutions (and indeed some of them have other uses; one is notably used as a medicineiii). It is, therefore, speculative to suggest that the availability of formaldehyde from these is 100%. Nor is it clear, given that the main risks associated with formaldehyde are concentration rather than dose dependent (“It has been shown experimentally that effects on organisms (e.g. mammals) are more closely related to concentration than to the accumulated total dose”)iv, how quickly (or indeed, if at all) these hemiacetals are converted back to formaldehyde. Furthermore, this completely invalidates the dose risk calculation used to state that the use of electronic cigarettes is more dangerous than smoking, which already appears to have little basis in toxicological effect.

Indeed, given that formaldehyde is one of at least fifty five carcinogens present in cigarette smokev, all of which are at lower levels or entirely absent from electronic cigarette vapour, alarmist suggestions such as these are likely to have a detrimental effect on public health, by scaring smokers who might be considering switching into continuing to smoke.

The importance of evidence-based statements – without prejudicial scaremongering – was highlighted by Anne McNeill (and others) from the UK Centre for Tobacco and Alcohol Studies (UKCTAS)vi:

“We believe that statements from the research community need to be evidence-based. While lively debates help to advance science and policy, adherence to good scientific practice is paramount. We need more rigour and over-sight to ensure that interpretation of evidence is guided by data, not emotions, and that strong statements based on weak evidence are avoided. We need those reviewing grants and research papers, and also those publishing such papers, to be accountable.” [Emphasis mine]

Unfortunately, this letter to the editor presented as research could be held up as a superb example of how not to do it.

 

 

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