The big smoke: e-cigarette debate a red herring

The jury is still out on the dangers of e-cigarettes, but Kelly Burrowes says we must start regulating e-cigarettes before it is too late

Not so long ago e-cigarettes were regarded as a smoking-cessation tool and not a particularly cool one, but the vape market has grown exponentially and is particularly popular among young people.

E-cigarettes have only been available since around 2006 and nicotine-containing e-liquids have only legally been available in New Zealand since 2016, so the increasing uptake is concerning. The medical consensus is that e-cigarettes are less harmful than conventional tobacco-based cigarettes and can, when used as an alternative to conventional cigarettes by smokers, save or extend lives. Yet there is increasing evidence that e-cigarettes aren’t safe, and could be considerably more harmful than anticipated. The real story is that no one yet knows the long-term health impacts of e-cigarettes; the jury is very much out.

Electronic cigarettes work by vaporising an e-liquid - typically containing propylene glycol, glycerine, nicotine and flavourings - using a high temperature heating coil. While the range of chemicals found within e-liquids are generally considered to be safe for ingestion (that is, oral consumption) the effect of inhaling these chemicals repeatedly over many years is not known.

In New Zealand, the most popular type of vapes are tank-based devices, followed by replaceable pre-filled pod-type vapes. But, there is a large range of different devices and components so there is a myriad of different materials - more potential chemicals - within these devices. The heating coil is made of various metals and soldering material holds things together and we’ve found, as have other studies, that some of that metal leeches out into a liquid and is contained within the aerosol. That means that you could be inhaling lead, copper, nickel, and zinc, to name a few heavy metals.

Moreover, many e-cigarettes now have adaptable power temperature capabilities, and some studies have shown that higher temperatures induce pyrolysis (which is the decomposition of chemicals into different chemicals due to high temperatures). This can result in the creation of new, potentially harmful chemicals including formaldehyde, acetaldehyde and acrolein, which are the main toxic aldehydes also present in cigarette smoke.

The lungs are a delicate organ that consist of networks of airways and blood vessels, similar to upside-down trees. These networks branch into smaller and smaller tubes until they form a huge surface area - consisting of just a few cells in thickness - where gas exchange takes place. Any chemicals, when inhaled, penetrate deep into the gas exchange surface of the lungs, which is equal to the size of around 20 king-sized beds. The exchange surface is constantly exposed to the external environment via the air that we breathe. When our lungs inhale foreign particles such as pollutants, cigarette smoke or e-cigarette aerosol, the body’s natural inflammatory response is triggered.

The inflammatory response is designed to protect our body to remove unwanted materials, but acute inflammation can cause permanent damage to the cells lining the gas exchange surface, which can result in respiratory disease. Some studies have already shown a link between e-cigarette aerosol and changes in how the lungs work.  One study has also shown a link between nicotine in e-liquids and the incidence of cancer in mice.

You may have seen recent headlines about the lung injuries caused by e-cigarettes in the US. These cases, now called ‘electronic-cigarette or vaping associated lung injury’ or EVALI, show patterns of acute lung injury including various types of pneumonitis. (This refers to lung inflammation caused by inhaling irritants, which is distinct from pneumonia caused by an infection.)

Vitamin E acetate has been identified as a possible culprit in the US cases of EVALI, a synthetic form of Vitamin E often used in supplements and skincare products to stop them from going rancid. It’s not clear why Vitamin E acetate was added to some vaping devices but it was thought to have been added as a thickener in THC-containing vape products, and hasn’t been found in vaping products in New Zealand. However, that doesn’t mean that those without Vitamin E acetate are safe.

One of the big issues is that there is currently no meaningful regulation on these products. For example, e-liquids do not have to specify what chemicals they contain. So, the difficultly in identifying health risks associated with vaping is that there is no standard construction or approval of the e-cigarettes and/or the substances being aerosolised. As described, they use a huge range of flavouring chemicals, with more than 15,000 flavoured e-liquids available, some of which are known to irritate the lungs. Others might have unknown impacts.

My team at the Auckland Bioengineering Institute are concerned that, just as it took decades before we truly understood (and acknowledged) the dangers of tobacco, we’re only beginning to understand the health consequences of vaping.

Our aim is to develop a novel, world-first, multi-scale approach to integrate newly-acquired data on the chemical composition of e-cigarettes, and the impact it can have on our lung cells and whole human lung function. To do this, we have developed a vaping robot to create e-cigarette aerosol. We have begun testing of the chemicals within these aerosols and have initiated experiments to expose lung cells to different aerosols.

We hypothesise that, like conventional cigarettes, e-cigarettes can cause an inflammatory response in the lungs that alters lung function and density, and prolonged use could permanently affect lung function. To test this, we are recruiting healthy volunteers who are either non-smokers/non-vapers, vapers, or smokers for a study in which we’ll use Magnetic Resonance Imaging (MRI) to take pictures inside people’s lungs.

Occasional exposure to some of the chemicals in e-cigarettes might not be dangerous, but if you’re exposed to them 10 times a day, every day, the effect that builds up can prompt an inflammatory response in your lung, and could cause changes in your lungs.

While they might present an alternative to tobacco-smoking, the big worry is people who are non-smokers start to use e-cigarettes, which could lead to new diseases we aren’t yet aware of. People who are dual users - smoking and vaping - could be most at risk and potentially increase the chance of respiratory changes.

Debate about whether e-cigarettes are more or less harmful than conventional cigarettes is, I believe, a red herring, and delaying the urgent need for the understanding of the health consequences of vaping, and the regulation of e-cigarettes, before it is too late.

Dr Kelly Burrowes is a Senior Research Fellow at the Auckland Bioengineering Institute, University of Auckland. Her research is aimed at developing computational and imaging techniques to provide an increased understanding of the pathophysiological mechanisms occurring in obstructive lung and pulmonary vascular diseases. The work on vaping is in collaboration with Dr Vinod Suresh also at Auckland Bioengineering Institute.

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