2.1 Are e-cigarettes less harmful than cigarettes?

Yes. Beyond any reasonable doubt, e-cigarettes are much less harmful: one to two orders of magnitude less risky.  Almost all the harm done by cigarettes arises from the smoke, inhaling the products of high-temperature combustion of dried and cured tobacco leaf. The smoke is the sticky smoke particles and hot toxic gases that are drawn into the lung.  E-cigarettes do not produce smoke because there is no combustion and no burning organic material, just heated tiny droplets of nicotine-carrying liquid. Combustion is the key difference and this creates completely different physical, chemical and biological effects.

2.2 Don’t the recent US cases of severe lung injury prove that e-cigarettes are very harmful

As of February 2020, there have been nearly three thousand hospitalisations and over sixty deaths from a severe lung injury condition. This has been given the misleading name EVALI (electronic-cigarette or vaping product use–associated lung injury).  Is this a serious new risk from nicotine vaping?

No, definitely not. These cases have gained worldwide publicity, but they are completely unrelated to normal nicotine e-liquids and e-cigarettes. The cases occurred in users of cannabis vaping products and were caused by the use of a particular additive used for thickening cannabis (THC) oils – Vitamin E Acetate. It is possible other additives were also involved. The additive is used to ‘cut’ (i.e. dilute) expensive THC oils for economic gain, but without losing the viscosity (thickness of the liquid) that consumers use to gauge quality of THC oils. This additive cannot be used in nicotine-based e-liquid and would, in any case, serve no purpose as nicotine liquids are inexpensive and there is no reason to dilute with anything other than PG/VG.

Reasons for doubt 1. There is no credible evidence that links nicotine vaping to these injuries. The primary source of doubt is the inherently unreliable testimony of users, who have incentives not to candidly disclose THC use because of possible legal, employment, education or parental consequences.

A total of 9 of 11 patients who reported no use of THC-containing e-cigarette products in the 90 days before the onset of illness had detectable THC or its metabolites in their BAL [lung] fluid (Blount BC et al. NEJM)

Reasons for doubt 2. As well as unreliable user testimony, a further source of doubt and confusion is that there isn’t a clear definition and diagnosis of the lung injury condition – so several cases may have been included in the diagnosis but actually be a different condition.

Since EVALI is a diagnosis of exclusion for which there is no confirmatory diagnostic test, we could not confirm case status for these three patients. The EVALI case definition is intentionally sensitive, which raises the likelihood that a patient’s illness could be misattributed to EVALI. (Blount BC et al. NEJM)

Reasons to be confident. This is why analysis should focus on the suspect supply chain. Once a cause has been identified in one supply chain (Vitamin E acetate added to illicit THC vapes), there is a vanishingly small chance that a separate independent cause would emerge at the same time and same place with the same symptoms in commercially available e-cigarettes.

The lung injury cases are a tragedy, but they are primarily caused by the illegal supply of cannabis vapes and provide no basis for changing policy on e-cigarettes. They do, however, provide a warning about creating black markets by banning products – and that would be an additional risk of bans on e-cigarettes or flavours: a black market will develop.

Though these cases have nothing to do with regular nicotine liquids or e-cigarettes.  The way key US agencies like CDC and FDA handled the controversy has meant that public opinion falsely attributes the cause to the nicotine products, with over 60% blaming regular nicotine vapes.  No less dangerously, only 28% attribute the cause to adulterated THC vapes.

These misperceptions are potentially deadly:  vapers or dual users may revert to smoking or be put off switching. THC users may continue to use THC vaping products from a compromised supply chain that poses lethal risks. Policymakers may take excessive regulatory action against nicotine products to address risks that do not, in reality, exist.  This is a major public health failure, but no-one is accountable.

Further reading

  • Blount BC,  et al. Vitamin E Acetate in Bronchoalveolar-Lavage Fluid Associated with EVALI. N Engl J Med. 2019 Dec 20; [link]
  • David Downs, Vape pen lung injury: Here’s what you need to know, Leafly January 2020  [link]
  • Gartner et al. Miscommunication about the causes of the US outbreak of lung diseases in vapers by public health authorities and the media, Drug and Alcohol Review, January 2020 [link]
  • Mike Siegel, Newest CDC Data Confirm that Respiratory Disease Outbreak was Caused by Vitamin E Acetate Oil in THC Vaping Cartridges, The rest of the story, December 2019 [link]
  • Guy Bentley, The CDC Is to Blame For More Americans Than Ever Being Misinformed About Vaping and E-Cigarettes, Reason Foundation, January 2020 [link]
  • CDC. Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products [link].  CDC’s advice has belatedly focused on THC vapes.
  • Michelle Minton, CDC Confirms Black Markets, not “Vaping,” Caused Outbreak, Competitive Enterprise Institute. January 2020. [link]
  • Clive Bates.  Comment to FDA on lung injury outbreak: US vaping lung injury outbreak was a public health fiasco or worse – comment to FDA [link]

2.3 What about long term effects – shouldn’t we take a precautionary approach?

It is true (and a truism) that we cannot have 50-year studies of a product that has only been in use for about 10 years, but that does not mean we have no data. We have extensive data on the toxicants in the vapour and measurements of ‘exposure biomarkers’ in the blood, urine and saliva of users – all suggest very much lower risks than smoking.

One argument is that we should impose very tough regulation by applying the ‘precautionary principle’ until we have certainty about long term risks (by which those supporting the precautionary principle usually mean ‘never’).  This is based on a basic misunderstanding of the precautionary principle. This idea, which is difficult to operationalise in practice, requires an assessment of both the costs of doing nothing but also the possible harms from intervening with excessive regulation, having estimated both the what is known and what risks are less certain. We have no doubt that cigarettes are very harmful, so intervening to discourage switching to vaping on the basis of hypothetical, unknown or trivial risks is likely to be more reckless than it is precautionary.

Further reading

  • The ‘no long term evidence’ gambit [link] and Abusing the Precautionary Principle [link] discussed in the Ten perverse intellectual contortions: a guide to the sophistry of anti-vaping activists [link]

2.4 It took decades for the harmful effects of smoking to emerge, won’t it be the same with vaping?

No. We would know immediately today that smoking is highly harmful.  We would not have to wait five decades for epidemiology to show that smoking was causing cancer, heart disease etc.  This is because the discipline of systems toxicology has hugely advanced since the mid-twentieth century.  We also know a lot more about the risks of particular exposures, for example to heavy metals, without needing data from e-cigarette studies. Instead, we can draw on findings from other disciplines such as occupational health and the limits that are imposed on exposure in the workplace.  These limits provide benchmarks for the tolerability of risk that we can use to benchmark vapour emissions and exposures.

2.5 How much less harmful are e-cigarettes than cigarettes?

The US National Academies of Science Engineering and Mathematics said that compared to cigarettes e-cigarettes are:

“likely to be far less harmful”

The premier British medical organisation, the Royal College of Physicians, said e-cigarettes are

“Although it is not possible to precisely quantify the long-term health risks associated with e-cigarettes, the available data suggest that they are unlikely to exceed 5% of those associated with smoked tobacco products, and may well be substantially lower than this figure.

The main English government public health agency, Public Health England, said that

“…stating that vaping is at least 95% less harmful than smoking remains a good way to communicate the large difference in relative risk.

None of these bodies, or the experts advising them, has any connection to the e-cigarette or tobacco industries. In each case, the experts based their view on a comprehensive published review of the evidence.

Further reading

  • National Academies of Science, Engineering and Medicine NASEM (US).  The Public Health Consequences of E-cigarettes. Washington DC. January 2018. [link]  Launch presentation summary (slide 44)  [link][link]
  • Tobacco Advisory Group of the Royal College of Physicians (London), Nicotine without smoke: tobacco harm reduction. 28 April 2016 [link]
  • McNeill A, Brose LS, Calder R, Bauld L & Robson D. Evidence review of e-cigarettes and heated tobacco products 2018. A report commissioned by Public Health England. London: Public Health England. 6 February 2018 [link] [Press release]

2.6 Is it fair to say e-cigarettes are likely to be at least 95% lower risk than smoking?

Yes, the statements above are reasonable expert estimates of the relative long-term risks based on what we know of the respective toxicology of cigarette smoke and vape aerosol and also what we know of the exposure to toxicants in the body as measured in blood, saliva and urine. Based on the available evidence on relative toxicity and human exposures to toxicants, independent experts making assessments for PHE in 2015 and the RCP in 2016 concluded that it is reasonable to work on the basis that e-cigarettes are likely to be at least 95% lower risk than cigarette smoking and potentially substantially lower than that. In the short to medium term, there does not appear to be any significant risks given the experience of tens of millions of users over 10 or more years.

At present, there is no new evidence that would challenge that assessment and much that would reinforce it.   While it is possible that some risks will emerge it is also quite possible that long term effects will be negligible or that technology improvements or regulation will allow us to tackle any risks that do emerge. In practice, we will not be able to directly determine the actual health effect of vaping for many decades, if ever (given that most vapers have also been smokers).  But knowledge of systems toxicology is far advanced from the early days of smoking and health research and we do not need to wait many decades to understand risk.

It is important to be clear what these communications are.

  • These communications are designed to address a widespread problem – the misperception of relative risk among the public (see below) whereby many people believe the products are as harmful or more harmful, and if there is a difference, the risk is only a little less.
  • Perceptions inform behaviours, and in this case, we expect false perceptions to be causing more cigarette smoking and dual-use than would otherwise be the case – therefore causing material physical harm.
  • It is what is known as a heuristic (a rule of thumb), that aims to guide people in making good, well-informed decisions, that are less vulnerable to biases induced by the way that messages are communicated.
  • Figures of this nature are widely used in health and risk communication to help the public understand what otherwise confusing and complex data really mean for them using the best judgement of experts.
  • The alternative is to leave those at risk to form their views from the media based on many misleading communications from academics, activists and billionaire funders and their proxies.
  • The format “likely to be at least 95% lower” is not a point estimate based on deterministic calculations, but expressed as a rough guide to where the risks are likely to come out based on expert judgement
  • It is based on what is currently known, but by definition, it cannot assess ‘unknown-unknowns’ – however, after 10 years of widespread use there are no signs of surprises and it is important to assess the likelihood of something novel emerging.

Why the hostility to these claims? These basic risk communications have been the subject of sustained attacks from tobacco control activists. I do not believe this is because those involved are concerned about misleading smokers or vapers (few complain when academics mislead smokers by falsely claiming that smoking and vaping are of equivalent risk).  It is more because they just do not like this approach, which is based on empowered consumers interacting with innovative businesses in a lightly regulated market.  This is antithetical to the tobacco control playbook, which tends to favour punitive, coercive and stigmatising measures.

Further reading

  • Clive Bates. Vaping is still at least 95% lower risk than smoking – debunking a feeble and empty critique, January 2020 [link]
  • Clive Bates. Public Health England says truthful realistic things about e-cigarettes, August 2015 [link]
  • Clive Bates.  Smears or science? The BMJ attack on Public Health England and its e-cigarettes evidence review, November 2015 [link]

2.7 Do people understand the risks of vaping?

No, most people greatly over-estimate the risks compared to smoking.  The chart below from ASH (UK) is the position in Britain – only 15% accurately identify e-cigarettes as a lot less harmful than smoking.  But 26% think they are more or equally harmful.  Because behaviour is informed by perceptions, it means that many people may be still smoking because they do not understand the benefits of switching.

This is not confined to the UK, in fact, it is worse in the United States – only 3.6% correctly recognise e-cigarettes are much less harmful than smoking, 45% wrongly believe e-cigarettes are very harmful, 56.5% incorrectly believe that nicotine is the substance that causes most of the cancer caused by smoking, and only less one in seven (13.4%) correctly understand that smokeless tobacco is less risky than cigarettes (and ‘much less risky’ – the real answer is not an option in this survey).

Further reading

  • National Cancer Institute, Health Information National Trends Survey (HINTS) 2018. E-cigarettes compared to cigarettes [link]; E-cigarettes harm to health [link];  Smokeless tobacco compared to cigarettes  [link]; Nicotine as a cause of cancer [link]
  • Huang J, et al. Changing Perceptions of Harm of e-Cigarette vs Cigarette Use Among Adults in 2 US National Surveys From 2012 to 2017. JAMA Netw Open.March 2019[link]

2.8 Isn’t this just the ‘light cigarette’ tobacco industry scam all over again?

No.  Light cigarettes work by diluting the smoke with air drawn in through holes in the filter.  This fools machines into measuring less tar and nicotine or a given puffing regime But humans compensate for this dilution by consuming more smoke or by instinctively blocking the ventilation holes and/or taking more and deeper puffs.  They aim to ‘compensate’ to absorb the same nicotine they want, but that means they also get all the tar that comes with it. The non-combustible products do not produce the toxicants in the first place, so for a given dose of nicotine, the toxic exposure is much lower.  The fact that people were fooled by light cigarettes does not mean a false analogy (used by some unscrupulous tobacco control activists) should be used to fool them and harm them again by exaggerating the risks of e-cigarettes.

+++ See section 6 for questions on secondhand vape aerosol exposure +++  

2.9 What does the novel coronavirus pandemic mean for smoking and vaping? (27 June 2020)

The virus is too new to know very much with any confidence.  There are several types of question that can be asked, and answers could be different for smoking and vaping – it is possible that different effects will push in opposite directions:

  1. Does smoking or vaping change the risk of contracting the COVID-19 disease caused by the virus – does it make it more likely, less likely (i.e. protective) or is it neutral?
  2. Does smoking or vaping create underlying vulnerabilities (e.g. pre-existing lung conditions) or resilience that make the disease more serious or lethal or less serious for those who do contract it?
  3. Does smoking or vaping change the way the disease is transmitted from person to person – does smoking or vaping make people more or less infectious?
  4. Does switching from smoking to vaping, or quitting completely, change the profile of the risks to the individual?
  5. What should smokers and vapers do, especially given the uncertainties?

I cannot address these questions with great confidence now but will leave this as a way of thinking about the problem.  The problem we face is that many sources delivering opinions on this are not trustworthy and some may be cynical and opportunistic in pursuing their ‘tobacco control’ agenda (as we saw with vaping and lung injury).

Instead, for now, I will refer you to further reading from what I consider trustworthy sources (that doesn’t mean they are right):

Further reading

  • Konstantinos Farsalinos: Smoking, vaping and the coronavirus (COVID-19) epidemic: rumors vs. evidence, E-cigarette Research blog  [link]
  • Sharon Cox: Risky smoking practices and the coronavirus: A deadly mix for our most vulnerable smokers, BMJ 20 March 2020 [link]
  • Simons D, Perski O. Brown J, Covid-19: The role of smoking cessation during respiratory virus epidemics, BMJ. 20 March 2020 [link]
  • Annie Kleykamp, Being a Smoker or Vaper in the Time of COVID-19, 1 April 2020. [link]
  • Farsalinos K, Barbouni A, Niaura R. Smoking, vaping and hospitalization for COVID-19. Qeios. 2020 3 April – version 12; [link] Check for later versions.
  • Roberto Sussman, Carmen Escrig, Vaping and SARS-CoV-2 and COVID-19: Technical Information for vapers, updated 2 April 2020  [PDF][Google Drive folder for latest versions and Spanish language]
  • Expert reaction: expert reaction to questions about smoking and COVID-19, Science Media Centre, 28 March 2020.  [link]
  • Letter from the Attorney General of Iowa and 12 others to the Food and Drug Administration on its statements on vaping and COVID-19, 31 March 2020 [link] – and change of FDA position: FDA Shifts Its Covid-19 Stance on Vaping, Smoking Impact, Bloomberg, 16 April 2020.
  • Simons D, Shahab L, Brown J, Perski O. The association of smoking status with SARS-CoV-2 infection, hospitalisation and mortality from COVID-19: A living rapid evidence review. Qeios. 2020 June 11; [link]
  • Israel A, Feldhamer I, Lahad A, Levin-Zamir D, Lavie G. Smoking and the risk of COVID-19 in a large observational population study. medRxiv. 2020 Jun 5;2020.06.01.20118877. [link] “The risk of infection by COVID-19 appears to be reduced by half among current smokers.”
  • Chris Snowdon,  Smoking and COVID-19 update, plus a thought for future research, Velvet Glove, Iron Fist [link] – an updated collection of studies.
  • Phil – a Twitter user – produces an epic thread on COVID-19 and smoking studies. Useful for accessing studies,  not really intended for interpretation.
  • Farsalinos K, Barbouni A, Poulas K, Polosa R, Caponnetto P, Niaura R. Current smoking, former smoking, and adverse outcome among hospitalized COVID-19 patients: a systematic review and meta-analysis. Ther Adv Chronic Dis. 2020 Jun 25;11:204062232093576. [link]

Does nicotine have a protective effect against the progression of COVID-19 to more severe symptoms?

Two strands of evidence point to a possible protective effect for nicotine – (1) the striking under-representation of smokers COVID-19 cases and hospitalisations; (2) the physiological basis for a protective mechanism.   The hypothesis is explained in the greatest detail here.

Farsalinos K, Niaura R, Le Houezec J, Barbouni A, Tsatsakis A, Kouretas D, Vantarakis A, Poulas K. Editorial: Nicotine and SARS-CoV-2: COVID-19 may be a disease of the nicotinic cholinergic system. Toxicol Reports. 2020 Apr 30; [link]

Essentially, it sets out the argument that COVID-19 is a disease that causes harm by triggering an immune system overreaction, “a cytokine storm”, the mechanisms in the body that control that response, and the role that nicotine could play in suppressing this extreme inflammatory response.  Similar hypotheses have been published by French Changeux et al and Spanish experts Gonzalez-Rubio et al as well as by Farsalinos et al as pre-prints. The paper in Toxicology Reports by Farsalinos et al. is a far more detailed account with a more in-depth articulation of a possible mechanism.  The cytokine storm problem is well known: see this 2013 paper by the UK bioweapons defence lab – Targeting the Cytokine Storm for therapeutic benefit – for an introduction and role of nicotine as a modulator.

It is a theory, but it is consistent with observations that smokers are surprisingly under-represented in the cases of severe COVID-19 cases – though it is acknowledged that this data is poor quality and could be explained by various biases or measurement problems.  However, a plausible explanatory theory means that what the data actually shows (however shaky) should be taken more seriously than if there was no explanatory theory (i.e. it was a complete mystery).

Other interesting (and accessible) reporting follows:

  • Clive Bates, The unlikely saviour? Smoking, nicotine and Covid-19: What is going on? Tobacco Reporter, June 2020. [link]
  • Sally Satel (30 April): What We Know—and Still Need to Learn—About Coronavirus and Nicotine (The Dispatch).  This inverse relationship between smoking and COVID is striking and unexpected [link]
  • Alex Norcia (28 April): Why Are Smokers Being Hospitalized Less Often From Coronavirus? (Vice)A Greek cardiologist and French neuroscientist are trying to find out. [link]
  • The Economist (2 May edition): Smokers seem less likely than non-smokers to fall ill with covid-19 That may point towards a way of treating it [link]
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