No smoke without fire? The science of heated tobacco products

What are heat-not-burn tobacco products, and how are they different to e-cigarettes?

Heat-not-burn, or heated tobacco products were in the news over the weekend, as it emerged that Conservative peer Lord Vaizey put forward an amendment to the tobacco and vapes bill to delay a ban on the products, six weeks after he was a guest of a large tobacco company on a tour of their research facility in Switzerland.

But what are heated tobacco products? We’ve all heard of e-cigarettes – they’re all over the media, where we’re told they are ruining the health of a new generation. And heated tobacco products can look a bit like an e-cigarette – indeed, the Guardian article about Lord Vaizey’s conflict of interest (which to be fair to him he did declare) refers to a device as an electronic cigarette in its picture caption – but they’re a fundamentally different design.

Heated tobacco products, as the name suggest, are filled with tobacco - in many designs you insert a tobacco stick that looks very similar to a cigarette. E-cigarettes are not. They involve a flavoured liquid, often (usually) containing nicotine, but not made of tobacco. And it’s tobacco that contains the harmful compounds – the carcinogens like cadmium and lead, the tar, the formaldehyde, the carbon monoxide.

Well. It’s the tobacco ‘smoke’ anyway. So if these heat-not-burn products don’t burn the tobacco, does that make it safer? Frustratingly, compared to e-cigarettes there has been (comparatively) barely any work done to look at heated tobacco products and their potential risk. A search on the pubmed academic paper library pulls up around 900 papers for these types of products, while I could find over 9000 papers that mention e-cigarettes. Not only that, but the work that has been done has been predominantly conducted by the tobacco companies themselves, at their fancy research facilities like the one Lord Vaizey toured.

One of the key tenets of good quality research is that it’s conducted without prejudice, that is, without expectation or desire for a certain result. Of course researchers will always have a theory as to what to expect, but if an entire business is built on the requirement to sell a product, this can introduce bias, explicit or implicit, in to any research conducted. And it’s well documented that the tobacco industry have form in this regard. If you’ve never seen or read Merchants of Doubt I highly recommend it.

Even Vaizey himself admits this, referring to ‘the sins of …big tobacco’. This is then slightly undone in his next breath where he suggests they have moved on and implies they are now interested in reducing the harm of their products. It’s certainly the case that big tobacco are pushing for this kind of a rebrand. I have been approached several times to attend one of these research facilities and learn about what they describe as their harm reduction programmes. However, as I am a tobacco researcher, accepting any money or hospitality from the tobacco industry would severely limit the journals I could publish my work in, my ability to attend certain conferences, or to apply for certain funding. To put it bluntly, the research community does not believe that they’ve turned over a new (tobacco) leaf.

So. Having said all that. What do we know about the effects of these heat not burn products? Are the harms specific to ‘burning’ tobacco, or does heating it up release them too? After all, we know that the heating process releases nicotine to inhale, otherwise it wouldn’t be marketed as a nicotine delivery device by the tobacco companies that sell it. What else is released in to the aerosol by this process?

One paper that I could find has compiled the primary research that has explored this, to try and tease this out. The researchers, based at the Karolinska Institute in Sweden, who reviewed the literature on heated tobacco products, acknowledge that a lot of these were conducted by tobacco industry funded researchers (they themselves are not). Even so, they found many of the same chemicals in the aerosols from heated tobacco products, albeit sometimes in lower levels (although not always). For example, heated tobacco emissions contain tar, formaldehyde, acetaldehyde and ammonia, and at levels not hugely dissimilar to cigarette smoke.

I’m not going to turn this in to a post about e-cigarettes. I’ve written about them a LOT in the past, and my broad take-away remains the same. If you’re smoking, you’d be better off vaping. If you’re not smoking, don’t start vaping. And don’t use a disposable one. And clean it regularly.

HOWEVER. There is not tar in e-cigarette liquid. There is no carbon monoxide in vape aerosol. A study of actual human people who stopped smoking and started using e-cigarettes found they had lower levels of carcinogens and toxins including volatile organic compounds and tobacco-specific N-nitrosamines. Similar studies haven’t been done for heated tobacco products yet as far as I can see (if you know different, please send them over to me!), but given these devices work by breathing in fumes from a tobacco product, even if they don’t get quite as hot or burnt, I’d be surprised if they were reducing the risk of harm as much as the tobacco industry would like us to believe.

Vaizey was asking the government to exempt heated tobacco products from the upcoming smoking and vapes bill, to allow more research to be conducted. And while I agree that more research would be useful (specifically, independent research), given what we already know about the lethality of tobacco, I can’t see an argument for treating heat not burn devices any different to cigarettes.