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Heat not burn tobacco sticks under fire

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Smokeless tobacco products that 'heat not burn' aren't quite as healthy as they're made out to be, as new research from the US finds that the device heats up much more than claimed, releasing toxic chemicals and increasing the amount of nicotine inhaled. The manufacturers of the iQOS heat stick (Philip Morris International) recommend cleaning the device after every 20 heat sticks but the researchers found that charred tobacco debris builds up after every stick, which shouldn't happen if the device only heated to the temperature claimed. The heat was also sufficient to melt the plastic film (designed to cool the tobacco vapour) even when it wasn't in contact with the heating element, releasing toxic chemicals like formaldehyde cyanohydrin.

Journal/conference: Tobacco Control

Organisation/s: University of California, Riverside, USA

Media Release

From: The BMJ

‘Heat not burn’ smokeless tobacco product may not be as harm free as claimed

iQOS use associated with tobacco plug charring and toxic chemical release

iQOS, one of the first ‘heat not burn’ smokeless tobacco products marketed as a safer alternative to conventional cigarettes, may not be as harm free as its manufacturer claims, suggests research published online in the journal Tobacco Control.

iQOS is a battery-operated electronic device, which mimics the looks, taste, and sensory experience of a cigarette. It contains a specially designed heat stick, which uses a tobacco plug to deliver nicotine. This is heated to temperatures well below those at which conventional cigarettes burn, producing a tobacco-infused vapour for inhalation rather than smoke.

Tobacco smoke is what contains the cocktail of chemicals that is so harmful to health.

The manufacturer, Philip Morris International, has evaluated IQOS in several published studies, but there has been little independent research.

To try and plug this gap, the US researchers set out to assess the performance of iQOS under five different puff conditions, and the impact of two cleaning protocols: a thorough clean after use of each heat stick to remove fluid and debris from the heater; and the manufacturer’s recommendations to clean the device after every 20 heat sticks before using the brush cleaners supplied with the product.

The researchers also wanted to gauge if the plastic polymer film filter, which aims to cool the vapour, might pose a risk to health.

Each iQOS heat stick only lasts for 6 minutes after which it automatically shuts off and requires recharging before use. So to get the most out of each heat stick, real life users would have to shorten the interval between puffs, speeding up their puff rate, and potentially breathing in larger amounts of vapour, say the researchers.

The tobacco plug charred as a result of pyrolysis--thermal decomposition in the absence of oxygen. Charring was more extensive when thorough cleaning was not carried out after use of each heat stick, suggesting that build-up of debris and fluid increases pyrolytic temperatures, say the researchers.

Analysis of the polymer film showed that irrespective of whether cleaning was done or not, the intensity of the heat was sufficient to melt the film even though it was not in direct contact with the heating element.

Following the manufacturer’s recommended cleaning instructions increased both the extent of charring and polymer film melt.

Of further concern was the release of fomaldehyde cyanohydrin by the melting filter at temperatures that all users will easily exceed, say the researchers. This chemical is highly toxic even at very low levels.

“iQOS is not strictly a ‘heat not burn’ tobacco product,” write the researchers, who go on to say: “This study has shown that the iQOS system may not be as harm free as claimed, and also emphasises the urgent need for further safety testing as the popularity and user base of this product is growing rapidly.”


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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Marewa Glover, School of Health Sciences, College of Health, Massey University

"Davis et al (2018) argue that the iQOS 'is not strictly a heat-not-burn tobacco product'. However, they acknowledged that the iQOS did not 'ignite' the tobacco, which is a necessary condition for use of the term burn. To support their argument, the authors instead applied the word 'char' and 'charred' which implies that burning occurred.

"The distinction is important for the Ministry of Health’s legal action against Philip Morris International (PMI). The Ministry of Health have argued that PMI breached Section 29 of the Smoke-Free Environments Act by importing the HEETS sticks used in iQOS devices into New Zealand for sale and distribution. Section 29 of the Act prohibits the import for sale of tobacco products that are not ignited for smoking and are not covered by the Medicines Act, such as nicotine replacement therapies.

"That is, the Ministry of Health are treating iQOS HEETS sticks as an 'oral' tobacco product. Davis et al cast doubt on this classification by saying both that the HEETS stick used in an iQOS is not lit, but it is burned, leaving science or judges to make the final call.

"It’s a war of words that obfuscates the real question. Would switching from smoking tobacco to using an iQOS reduce a person’s risk of developing diseases causing suffering and potentially a shorter life?

"Davis and colleagues do not consider this. Their study was solely concerned with identifying 'limitations' of the iQOS and toxic candidates that could be used to create alarm, fear and distrust of yet another potentially harm-reduced product appealing to smokers.

"This agenda is clear in their conclusion which incorrectly implies that people have been claiming that use of an iQOS is 'harm-free'. No one has claimed that heat-not-burn products providing an alternative to smoking tobacco are harm-free or harmless. The correct word they should have been focused on was 'harm-reduced'. On this point the paper has added nothing."

Last updated: 13 Mar 2018 1:04pm
Associate Professor Natalie Walker from the University of Auckland, National Institute for Health Innovation Programme Leader – Tobacco and Addictions

“As outlined in this paper, 'heat-not-burn' devices are not without harm. However, they are less harmful than smoking cigarettes (which have over 4000 harmful chemicals in the smoke).

"Will this paper have an impact on the current PMI-Ministry of Health court case? Probably not – the court case is about whether PMI purposively broke the law by marketing their 'heat-not-burn' devices in New Zealand. Whether the wording of the specific law that they may/may not have broken is still valid is another issue, and it comes down to whether 'heat-not-burn' devices, and other reduced harm tobacco products, have a role in helping New Zealand reach our Smokefree 2025 goal.

"If you want to quit smoking tobacco and have tried all available quit smoking support and medication, e-cigarettes should be your next ‘port-of-call’, as they don’t contain tobacco and so are safer than 'heat-not-burn' devices.

"However, what do we offer people who’ve tried everything (repeatedly) to quit smoking – even e-cigarettes? We have no other tools in our toolbox to offer. Do reduced harm products like 'heat-not-burn' devices, have a role then? I would argue yes – but in order for this to happen the New Zealand Government would need to consider proportional regulation around tobacco harm.

"With only seven years to reach our smokefree 2025 goal, and no plan to get there, the government urgently needs to do something big and bold with tobacco control. Perhaps this court case will be the trigger."

Last updated: 13 Mar 2018 1:00pm

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