Why it’s wrong to say vaping is as bad for you as smoking

BBC Sounds Music Radio Podcasts Hello and thanks for downloading the More or Less Podcast. With a programme that looks at the numbers in the news, and in life, and in nicotine. I'm Charlotte McDonald. According to the World Health Organisation, smoking kills some 7 million people every year. It's one of the world's leading causes of preventable death. With smoking causes lung cancer and other awful health conditions, many smokers switched to vaping, using nicotine-based e-cigarettes. But the World Health Organisation is also concerned about vaping. Last year, they said 100 million people around the world are now using e-cigarettes, including millions of children, and warned that they were fuelling a new wave of nicotine addiction. But how do the health risks of these two means of getting nicotine into your bloodstream compare? According to a recent article in the Daily Mail, they're basically the same. Here's the headline. Vaping is linked to lung and mouth cancer in major study, as experts warn it is not safer than smoking. But is that true? Is vaping just as bad for you as smoking? Tom Coles has been taking a look at this. Hi Tom. Hello Charlotte. So, we know, or more or less, that smoking is one of the clearest examples of something that is unambiguously bad for you. We know that it causes cancer, heart disease, strokes, you name it. Right, and we know why that is, because you're setting chemically treated tobacco on fire and inhaling the smoke, coating your lungs with toxic tar in the process. At the same time, we also know that vaping does not involve those things. E-cigarettes work by heating a liquid containing nicotine and flavourings with an electric coil to produce an aerosol or mist that you inhale. Filling the street with a sickly sweet smell. Indeed. Here's Professor Leon Shahab, co-director of the UCL Tobacco and Alcohol Research Group at University College London. So based on that very simple description of the process in which nicotine gets into the body, it's quite clear that e-cigarettes are not as harmful because there's no combustion going on and there's no tobacco involved. Now, the headline in the mail seems to be saying two things. First, that a major new study has found that vaping is linked to cancer. And second, that this means that it's not safer than smoking. Is that right? Not really and no. Let's start with the first part. The study in question comes from researchers in Australia who did something called a qualitative risk assessment on the carcinogenicity, that is the cancer-causing potential of vaping, by looking at existing research. As Leon says, it's very important to make clear that this is not presenting any new information. So this is a review. The authors of this study didn't undertake any new research themselves. It wasn't a systematic review where you have clear selection criteria and a method for establishing how to weigh different studies. They just looked at recent research on e-cigarettes in general and identified aspects of vaping that had cancer-causing potential. At this point, we don't know whether those potential risks are actual risks. Why not? Because cancer takes a long time to develop, years or even decades. Vapes have only been in widespread use since the 2010s and not enough time has passed to get a clear statistical idea of the cancer risk from actual cancer cases, if there is a risk. So what evidence did they look at in the paper? All kinds of stuff. They looked at biological mechanisms that have a potential cancer risk, things like DNA damage, inflammation and oxidative stress. All of these are potentially linked with cancer but are also potentially not. E-cigarettes increase oxidative stress. That is true. However, oxidative stress is also increased when you exercise or is part of normal ageing. All of these things, individually, aren't a smoking gun that suggests they cause cancer. They also looked at evidence from animal studies, one of which is the topic of considerable scientific debate. This study put mice in vape-filled cages for four hours a day, five days a week, for about a year. The level of nicotine they were exposed to was massively higher than for human vapors, once you take their size into account. And they were exposed over their whole body, which, being furry animals, they constantly lick. Vapors don't tend to do that. Nine out of the 40 mice in the E-cig group developed lung cancer compared to one out of 40 in the control groups. But the scientists who did the research specifically state that, despite the results, electronic cigarettes may or may not pose a danger to humans. That doesn't sound very convincing. No, but the authors of the Australian paper told me that these kind of experiments have helped to identify carcinogens in the past. Okay, but just because you've identified a chemical that can potentially cause cancer in mice under extreme conditions, that doesn't mean that it'll do the same in people who vape, does it? No, and that's exactly Leon's argument. The term I would use there is that the dose makes the poison. We are exposed to things that are considerably carcinogenic in every day, for instance, you have low levels of benzene in soft drinks or if you eat rice, they can contain an organic arsenic. But because of the levels being very, very low, it is unlikely that it will actually, these trace amounts would actually lead to cancer in any large number later in life. In terms of the actual dose, the paper in question includes a table that lists the quantities of known carcinogens that vapors are exposed to, compared to smokers and people who do neither. For most of them, smokers are exposed to much higher quantities than vapors. For one well-known carcinogen known as NNK, the levels were up by 400% in vapors compared to people who don't vape or smoke, but by 22,000% in smokers. But even this question is really difficult to pin down. Another risk assessment this time from New Zealand argued that people who vape were potentially exposed to another carcinogen, formaldehyde, at slightly higher levels than smokers. But when you look at the underlying research, you find that the formaldehyde levels are massively dependent on the voltage of your vape and how hot it makes the liquid, with hugely variable levels and some producing none at all. That paper found that the overall amount of carcinogens inhaled by e-cig users was much lower than for smokers, and they didn't even include some of the worst carcinogens from smoking in their assessment. Which brings us to the second part of the headline. The idea that vaping is not safer than smoking. From what you've said, I'm not clear how you draw that conclusion if we're talking about the cancer risk. Me neither. And if we're talking about cancer, they don't actually say that in the Australian paper. All they say is that nicotine e-cigarettes are likely to be carcinogenic. They don't talk about the size of the potential risk nor the amount of vaping you would have to do in order to be exposed to it. That means they can't actually say how it compares to the massive and known cancer risk from smoking. The New Zealand researchers I just mentioned agreed that there are potential carcinogens in e-cigarette vapour, but they were explicit that the cancer risk from vaping is likely lower than the cancer risk from smoking. Okay, so why do they say that vaping is not safer than smoking? Yeah, it's an odd one. They throw that in as the final line of the Australian paper, and it's talking about the non-cancer risks. It cites a meta-analysis from 2024, which found sizable health risks from vaping around things like strokes, cardiovascular disease and asthma. Although the risks appear to be lower than for smokers, the difference wasn't statistically significant for some of them. Okay, but if we're not including cancer risk, doesn't that make the overall comparison meaningless? Well, that is how it looks to me. It also looks to me like smoking is almost certainly worse for you than vaping. Just how much worse is still up for debate, but if you're a smoker, it seems to make sense to switch if you can't stop by other means. To repeat, vaping has to be really bad to get anywhere near the dangers of smoking. But if you don't smoke or vape and you want to live a healthy life, then probably don't start vaping. It's not good for you and nicotine is highly addictive. Got it. Thanks, Tom. And thanks to Professor Leon Shahab. If you've seen the number or stat in the news you think we should take a look at, email more or less at bbc.co.uk. That's it for this week. Goodbye.