The Independent “reports”: “Vaping e-cigarette liquids with certain ingredients can cause cardiac arrhythmias that could increase the risk of heart attacks, a new study has suggested.”
The study in question, titled “E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice,” was published in Nature Communications on 25th October 2022 and proves just one thing: that pet owners shouldn’t allow their mice to vape.
The researchers used mouse-specific electrocardiograms (ECGs) to measure the mice’s heart activity following acute inhalation of vapour from an e-cigarette. The researchers claim: “Our study indicates that chemical constituents of e-cigarettes could contribute to cardiac risk by provoking pro-arrhythmic changes and stimulating autonomic reflexes.”
Yet experts in the field of tobacco harm reduction and vaping research were swift to comment.
What do experts say about the mice study’s findings?
Professor Jacob George, Chair of Cardiovascular Medicine and Therapeutics at University of Dundee Medical School, said: “The metabolism of mice is very different from humans and any extrapolation to overall, long-term human health is, frankly, guesswork at best.
“If this was indeed true, given the significant numbers of vapers worldwide, we would have expected to see an explosion in cardiac arrhythmia cases which we are not seeing in clinical practice, at all.
“The science is preliminary, the extrapolation is speculative and the relevance to human health, including around the nicotine effects on blood vessels, is highly questionable.”
Well said, doc.
The science is preliminary, the extrapolation is speculative and the relevance to human health [...] is highly questionable.
Consider the size and beat of a mouse’s heart compared to a human’s. A mouse’s heart is, on average, between 5mm to 8mm long, and beats an average of 400 to 650 times per minute. In contrast, a human’s heart is roughly the size of a fist—an average of 12cm long, beating anywhere from 60 to 100 times per minute at rest.
In truth, a mouse’s heart, metabolism, and anatomy are simply not comparable to a human.
Continuing on, Prof. Jacob George iterates, “Large human observational studies in nicotine replacement therapy users have shown that they do not increase cardiac event rates. The results of this study should not put off anyone wishing to quit tobacco smoking from trying e-cigarettes or nicotine replacement therapy.”
But what do other experts have to say?
Professor Peter Hajek, Director of the Tobacco Dependence Research Unit, Queen Mary University of London, makes an interesting note about the chemicals used in the study. “In this study,” he says, “mice were exposed to aerosol from e-cigarette solvents with […] acrolein, a chemical that can arise from overheated e-liquid. The exposures were accompanied by short-term changes in mice electrocardiograms and increased heart rate.”
He continues, “There are several problems with generalising the findings to humans. Vapers are not exposed to any significant levels of acrolein because overheated e-liquid has an unpleasant taste and so this is avoided.”
This is something that we’ve seen in other studies: exposure to a toxicant that only arises from a burnt coil or from improperly used hardware. As we know, this taste is wildly unpleasant, and vapers know to stop using the vape when this taste occurs. In this study, and many others, researchers expose the subjects to higher levels of this chemical, which does not reflect real-world human usage.
Continuing on, Professor Hajek says, “The study used exposure levels of the other chemicals that are tolerated by humans, but the same doses can be distressing to much smaller mammals with much more sensitive sense of smell and very different tolerance of drug effects. It would be odd if animals exposed to aversive stimulation did not show a cardiovascular response!”
Lastly, Professor Hajek adds, “The reason for conducting the study in mice is unclear. Animal models are used when the experiment cannot be conducted in humans, but there are no barriers to comparing heart rate and ECG responses to e-cigarette components and to smoking in humans.”
So, what did we learn from the mice study?
Quite aptly, Dr Adam Jacobs, Senior Director of Biostatistics at Premier Research, says: “This paper shows that mice exposed to e-cigarette aerosol in enclosed spaces for 90 minutes experienced short-term changes in cardiac rhythm.
“Although the long-term effects of these changes are not known, it seems prudent that owners of pet mice should not allow their mice to use e-cigarettes.”
[I]t seems prudent that owners of pet mice should not allow their mice to use e-cigarettes.
It’s as simple as that. None of the results of the study can be effectively translated to humans, from the conditions of the study to the subjects used and beyond.
Maybe it’s just because I personally love mice—I’ve had many pet mice in my lifetime—but maybe we should leave the mice alone when it comes to vape research and focus on human trials.
Looking for more misinformed “studies” shredded by experts? Check out our other article: 2 Misinformed “Popcorn Lung” News Articles Attack Vaping in the UK.
Sources:
- Independent: Vaping e-liquids can disrupt heart’s rhythm, ‘highly concerning’ study suggests – https://www.independent.co.uk/independentpremium/uk-news/ecigarettes-heart-beat-rhythm-vaping-b2210247.html
- Nature Communications: E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice – https://www.nature.com/articles/s41467-022-33203-1
- Science Media Centre: expert reaction to study of the effects of e-cigarette vapour on mice – https://www.sciencemediacentre.org/expert-reaction-to-study-of-the-effects-of-e-cigarette-vapour-on-mice/
