On the news pod, we ask whether an outright ban is the best way to deal with the health and environmental cost of sweet shop style vapes. Also on the programme; a new device for detecting Covid on patients' breath, the search for life elsewhere in the universe intensifies, and we pay tribute to Ian Wilmut, the 'father' of Dolly the sheep
In this episode
UK set to ban disposable vapes
Linda Bauld, University of Edinburgh
Reports this week suggest the UK government is preparing to announce a ban on single use vapes to prevent harmful outcomes on public health and the environment. Refillable vapes, which are less popular among young people, will still be available to buy. The UK has followed the lead of countries like France, where disposable vapes have been banned for some months, rather than take the approach of countries like the US, where regulations on e-cigarettes are less stringent.
Critics of the policy have voiced concern that the illicit market for more dangerous vapes will now grow. To gain a better understanding of the thinking behind the UK’s decision, and to provide some insights on vaping policy in comparable nations, James Tytko spoke with Linda Bauld, Professor of Public Health at the University of Edinburgh…
Linda - So the reasons why this is happening now are actually on two fronts. The first one is a concern about youth vaping. So experimentation with vaping has gone up 50% on the basis of one survey between 2022 and 2023 amongst teenagers. Regular use hasn't risen much, but it's still pretty high. It's about 7.6%. And when you look at why that big rise has happened, you see it's driven by the category of products, disposable vapes. Of all teenagers who vape at all, in 2021, only 7.7% in Great Britain said they used a disposable vape. And that's gone up to 69% in 2023. And these are products that are not legal to be sold to under 18s. And then the second big, and equally important argument is an environmental one. So the lithium polymer batteries that are used in popular disposable e-cigarettes are a risk to the environment if they can't be recharged and reused, which is the case with disposables. There's also emissions from single use vapes and perhaps most importantly for these disposable ones is the packaging and the materials are difficult to recycle and they're also not being recycled correctly, either by users or indeed by the retailers who are not set up to receive them back and get them recycled.
James - The last time you spoke to us on this topic, you outlined some of the policy instruments available to the government to help get vaping, especially among young people, under control. The four P's. You can take action on the product, perhaps by making the vapes weaker. The place, or where kids can access them or buy them. The price, through tax more obviously, or the promotion or marketing. The 'P' you didn't mention is prohibition, which has been what's been settled on. Why an outright ban on disposable vapes rather than a tax or a ban on the colours and flavours that make them attractive to children?
Linda - I think the reason why a ban is being discussed is these environmental issues are really causing a lot of noise, and that's different from the other categories. So, in general, with all vaping products, you could apply the four P's to try and reduce youth use. You could do that on disposables as well. But I think the way that it's being discussed, certainly at England level and indeed elsewhere in the UK, is actually not getting rid of all vaping products. So we know they're very helpful for smokers who are trying to quit. What the government's doing is zooming in on this particular category, which has not exactly emerged from nowhere, but has completely transformed the market within a couple of years. Almost all these products come from China, a small number of companies. The other thing is international. So France is banning disposables, for example, and a number of other countries are just looking at this category of product in particular. So it might be that actually the government just thinks in contrast to the other P's, which are quite complex to legislate on and can be done in stages, they think, well, we'll just deal with this category outright.
James - You mentioned evidence shows vape products can be very effective in helping smokers to quit. It's proven to be less harmful than smoking, although we don't really know the long-term effects. Public health officials must be pretty confident that this ban isn't going to push people who've been using single use vapes to more harmful tobacco products.
Linda - I think they are pretty confident. And the reason for that, again, is backed up by these cross-sectional surveys that we have. So I mentioned that figure of 69% of all teenagers who vape at all vape a disposable. The proportion of adults who vape a disposable has risen a lot. It's about a third, just under a third, 31% in 2023, but it's not the majority. So most adults who vape are ex-smokers or current smokers trying to quit. And about half of them use these refillable tanks. That's the most popular category. So think of the government's thinking as well, if we take action on the product that seems to be particularly a problem for young people, we've still got a bunch of other cartridge refillable tank systems, vaping pipes, which they're not going to remove from the market. And, for adult smokers, it means they still have a choice.
James - There are concerns that I've read doing the rounds that the current black market for vapes, where products currently contain much higher levels of nicotine than are legal, that's set to grow as a result of this ban. Could we be in danger here of exposing people to more harm?
Linda - Yeah. So this concerns me. That's why I think, if I was legislating, I wouldn't necessarily go for an outright ban. I'd try a slightly more sophisticated approach. First, I'd start with price. Some of these disposables are as cheap as £1.99. So the illicit market is a genuine concern. The first concern is we already have it. We know that trading standards, test purchasing, and also getting devices from a shop and then taking them back to the lab have shown that there are already many products in the market that are not complying with the EU tobacco products directive and the way that was transposed into UK law. So we have consumer standards, they're not being followed. The second reason it concerns me is there's a historical precedent for this. So in the US a number of years ago, we had what was called the EVALI outbreak, which was contraband, illicit vaping products - with mostly cannabis vaping - containing vitamin acetate manufactured by a small number of factories, companies getting around the legal system. And actually there were youth deaths. Young people died in the US as a result of these illicit products. So if we're going to have a ban, the government needs to take equal action to address the illicit trade. Otherwise, I think we're in trouble.
James - Linda, thank you very much.
Linda - Thank you.
07:33 - Device detects drop in Covid in patients' breath
Device detects drop in Covid in patients' breath
Gregory Lane, Northwestern University
Cases of Covid-19 have risen around the country in recent weeks, coinciding with, although not necessarily because of the arrival of a couple of new variants of the virus. At the moment scientists and public health bodies like the World Health Organisation are issuing reassuring messages that the existing immunity among the population seems to be strong enough to keep us safe from severe disease, and that seems to be the experience in most healthcare settings: cases, but not consequences. Nevertheless, the UK at least has brought forward its planned Covid booster vaccine roll out as a precautionary measure, and both Moderna and Pfizer, who manufacture the vaccines we're currently using, have updated the recipes in their shots to keep pace with the evolution of the virus and have said these do appear to confer protection against the latest variants.
But one thing that has remained uncertain is when people really are infectious with the disease, and for how long. One way to find out is to test people regularly across their illness and measure how much virus they are actually shedding in their breath in a standardised way. This might help us to understand better how best to do effective infection control and isolation to keep Covid at Bay. From Northwestern University in Chicago, Greg Lane.
Greg - We were interested in how much virus you are exhaling from the moment you start to feel symptoms until those symptoms abate. So we had to come up with a way to measure people's exhaled breath while they were isolating at home. To do that, we developed this low tech, simple device that people are able to use at home to self collect exhaled breath, condensate samples twice a day over the course of their whole infection, and use those samples to create this map of exhaled virus over the course of their sickness.
Chris - We can get into the nitty gritty in a second of what constitutes infectious particles and so on, but, first and foremost, what did you actually find when you did this? When does a person begin to shed virus and when does their infectivity peak and when does it tail off?
Greg - We worked with people from the day of symptom onset, and what we found is that you exhale a lot of virus for the first eight or nine days of infection, and then there's a steep drop off after that. And it was consistent across all of our participants. There are occasional peaks after day eight in some individuals, but they were never as high as what we saw in those first eight days.
Chris - Now, presumably these are people at home, so these are people who are well enough with SARS-CoV-2 infection not to need hospitalisation. So is this a subgroup then, and is therefore only really representative of people with mild infection?
Greg - I think that's right. These were outpatients, in other words, people who came to Northwestern to get tested for Covid but were well enough, as you say, to go home. But this is an important subgroup. It's perhaps the much larger subgroup of people across the world who are infected with Covid-19.
Chris - Is there a possibility then that if you had a highly symptomatic person and a person with very few symptoms side by side, the more symptomatic person is shedding more virus. Or, if you do stratify like that, do they shed the same amount of virus and it's just the way the body reacts that's different?
Greg - That's a good question. And we looked at this, so we did find people who have more severe symptoms tend to be exhaling more virus. But again, there's a lot of variability there. And we did find people with no symptoms at all, resolved symptoms, who are exhaling very large amounts of virus and people who are experiencing severe symptoms who are exhaling very low amounts of virus. So the takeaway here is that there's a lot of variability in the dynamics of exhaling virus, both over the course of your disease and as it relates to your symptoms. You can't rely on your symptoms to tell you whether you're infectious.
Chris - How did you test how much virus was there and were you measuring just the signature of the virus or were you actually measuring its infectivity, its ability to infect another person?
Greg - We use the same method, I think, a lot of people would be familiar with - the more sensitive test for a nasal swab, which is called PCR. So this is a lab-based test that is highly sensitive and it can detect very small levels of the virus, but it's viral RNA. So this is a signature of the presence of the virus, but it doesn't measure whether that viral copy is viable, whether it could infect somebody. So what we're establishing here is that signatures of the virus are on breath and it would be a next step in our study, it's something we're working on now, to determine what portion of that exhaled viral load is infectious and constitutes a risk to the people around you.
Chris - I ask that because a lot of the studies that were done in other ways looking at when people appeared to be most infectious from swabs and so on during the pandemic seemed to hinge on day five or six. So is that because at day five or six they stopped shedding viable virus that's capable of infecting people, but they still shed the residuum of the infection, a signature that you can pick up with tests like you used, and that could account for that disparity?
Greg - It could. This is a very important question and this is why we are focusing on determining this portion of viable virus in your breath. It could be the case that when you measure the presence of the signature of the virus in an oral swab or a nasal swab, that measure may differ from the amount of virus that appears on breath. And the reason for that is that as you imagine swabbing your own nose, you're taking a sample from a very, very small area, but the virus replicates throughout your respiratory tract. And when we measure breath, we're measuring from all of those areas that contribute to these little aerosols and water droplets on your breath. So that's an open question and it's one we're trying to address now.
14:19 - Closeby water world replete with methane and CO2
Closeby water world replete with methane and CO2
Matt Bothwell, University of Cambridge
Are we alone in the universe? Events this week may have taken us a step closer to answering that question. Observations made with the James Webb Space Telescope on the star behind the stir - K2-18 - found evidence of methane and carbon dioxide in the atmosphere of a watery world in its orbit. These chemicals are thought to be essential for life. The planet in question - K2-18b - also sits in the so-called ‘habitable zone’ temperature wise, and is a mere 120 light years away: in astronomical terms, that’s practically our own backyard! Matt Bothwell is the University of Cambridge’s Public Astronomer, based at the Institute of Astronomy, where the findings were made. I started by asking him how they did it…
Matt - So they used a technique called transmission spectroscopy, which is a very fancy way of saying essentially you look at the starlight passing through the atmosphere of the planet and then the light passing through the atmosphere, all the chemicals in the atmosphere will leave their fingerprints in the light. So when you take a spectrum of the light, the fingerprints of all those chemicals, like methane, like carbon dioxide, will be left in the light for us to discover.
Chris - And when one looks at that spectrum, what is the recipe and the atmosphere they're seeing?
Matt - So this type of planet is something called a hycean world. Hycean being a portmanteau of hydrogen and ocean. But the stuff that's got everyone really excited is the carbon dioxide and methane in the atmosphere. It's been a problem for a few years that whenever we look at gassy planets or planets with thick atmospheres, we don't find methane. And of course here on earth methane is one of the chemicals associated most with life. But now loud and clear, we see plenty of methane in this planet's atmosphere, which is very exciting.
Chris - They're also talking about the chemical dimethyl sulphide, which we used to think when we went to the seaside and smelled this, we were smelling ozone. Now we realise it's this chemical which comes, we are told, exclusively from life. And that's there too.
Matt - You are right. So that was reported in the paper as a tentative finding. I think this one is proving to be a little bit controversial in the field. Like you said, dimethyl sulphide is a pretty slam dunk bio indicator, at least here on Earth. It's only produced by life. There is what the authors report as a tentative detection. So they're not claiming a full detection. They're not saying yes, we've definitely found it. They're saying hopefully if we go back and get more data, we might be able to prove this definitively. Other people in the field are a bit more sceptical. I think it's an ongoing controversy. I think we've all got our fingers crossed and we hope that it turns out to be real.
Chris - It's a fairly big planet. I think the paper suggests it's about nine times bigger than Earth. Is that right?
Matt - Yeah. Just about, yeah. Eight or nine times bigger than Earth, which it really has to be to hold onto hydrogen in its atmosphere. Hydrogen's a very light gas, so the atoms and molecules travel very fast. Unless the planet's very massive, it can't hang onto a hydrogen atmosphere.
Chris - You've been saying ocean. Is that a liquid ocean? And if so, how do we know that?
Matt - So we are pretty sure it's a liquid ocean that's based on the temperature of the planet that we infer. We can see how far the planet is away from the star, and we can, based on the star's temperature, we can work out how much radiation is falling on the planet and how hot it's going to be. So this planet has an equilibrium temperature of somewhere ish, roughly zero, it's very possible that this planet is 10 or 20 degrees Celsius, like a nice warm room temperature. So I think it is very possible that this is liquid.
Chris - And if it is as big as we think it is, does that mean it's sort of all ocean or will there be any rocky stuff there? Do we have any idea of its overall composition?
Matt - Yeah. So based on the density, this is a rocky world, but I think based on the atmospheric composition, I think it's most likely to be almost entirely ocean. Because we can't really see the planet, all of this is based on looking at starlight filtering through the atmosphere. So it's all based on our best guesses. But this is consistent with a world that is completely covered in ocean, but has a rocky core.
Chris - Waterworld. Are these common?
Matt - That's the million dollar question. It's very difficult to talk about how common different types of planets are because the different observational techniques that we used to find planets like the transits I mentioned before, they have these biases built in. It's very easy to find very big planets close to your star. It's hard to find smaller rocky planets far away from your star. We are finding more and more of them as time goes on. And so we think at the very least there are almost certainly hundreds and hundreds of millions of these in the galaxy.
Chris - And will the aim now be to pursue these signals to a check that they're right, but go after this dimethyl sulphide question, this possible hallmark as you dub it, the 'slam dunk' of life. Because if that's there, that's pretty important, isn't it?
Matt -
Absolutely. I think that's the thing that has got everyone very, very excited. If we can confirm the existence of this biosignature, it's gonna be enormous news. So the real aim is to get more time on the James Webb space telescope. Look at this planet for more transit and confirm that line. So far we've only seen this planet going past its star twice. So if we go back, we get more of those transits, get better data and see if this thing is real.
Chris - It does that quite often though, doesn't it? Because you're saying it's quite close in, so it must have quite a fast orbit.
Matt - It does. I think about five or six months. We saw it going past in January and then in June of the same year. So yes. So we shouldn't need much time to confirm this.
Chris - You should have said, watch this space, Matt
Matt - <laugh> watch this space.
20:14 - Ian Wilmut, 'father' of Dolly the sheep, dies
Ian Wilmut, 'father' of Dolly the sheep, dies
This week the scientific community mourned the loss of the British biologist and cloning pioneer, Sir Ian Wilmut, who dubbed himself, "The Father of Dolly the Sheep". She was unveiled to the world via the front cover of the science journal Nature in 1997, and was the first example of anyone cloning - in other words making a genetically identical replica - of an adult mammal. The work was done at Edinburgh's Roslin Institute, where Ian Wilmut led a team that included the cell biologist Keith Campbell whose insights were crucial to making the experiments - that were inspired by science carried out on tadpoles almost a century previously - come to fruition. But the objective, when the work began in the 1980s and early 90s, wasn't simply to clone animals: it was about genetically manipulating them for therapeutic purposes, as Ian Wilmut himself explained back when he talked to the Naked Scientists in an interview marking a decade on from Dolly...
Ian - The ambition was to be able to make genetic changes in farm animals so they would produce proteins needed to treat human disease. That was the aim when we first started.
At the time, they were injecting DNA instructions into eggs to make animals with the ability to produce human gene products; one of their successes was a sheep called "Tracy" that produced in her milk the substance alpha-1-antitrypsin, which is used to treat some forms of emphysema.
Wilmut acknowledged that more valuable animals, like cows, were the ultimate animal goal for the work, but they also had long gestation periods and were expensive. Sheep, on the other hand, reproduced far more rapidly and, as Ian Wilmut put it, "you could buy one for less than the price of a bottle of mineral water at a posh hotel."
After genetically modifying Tracy, Wilmut became interested in the question of whether it might be possible to clone a mammal; presumably the idea was that once you'd made one special animal, you might want more identical ones, so being able to copy them faithfully would be beneficial. Or if you could produce new organs this way, it would be handy to have ones that were genetically identical to the donor to avoid immune rejection later.
The technique that the Roslin team refined and which ultimately resulted in Dolly's creation is called "somatic cell nuclear transfer".
Put simply, the nucleus - containing the DNA - is removed from an adult cell and injected into an unfertilised egg cell that has had its own DNA removed.
Dolly got her name - by Wilmut's own admission - from Dolly Parton because, she was cloned from a cell collected from an adult sheeps' udder. Dolly Parton, in turn upon hearing about her ovine namesake remarked that "no publicity is Baaa'd publicity!"
Crutically, the work - that was painstaking and took hundreds of attempts to perfect - showed that something about the internal environment of an unfertilised egg has the ability to reprogramme donor DNA so that it "forgets" that it was previously in a specialised adult cell and is "rebooted" as an embryo that begins to develop.
Arguably, it was this discovery - that the clock can be wound back and adult cells can be "unspecialised" - that was one of the most important to emerge from the creation of Dolly the Sheep...
Ian - We all came from a single cell of an embryo, which is smaller than a grain of salt, and almost all of our cells have exactly the same genetic information in them. The way in which the many different tissues that we have are formed is because the functioning of the gentic information is changed systematically to produce muscle, skin, bone, in them and all of the different tissues that we have. We used to believe that the mechanisms that bring that about are so complex and so rigidly fixed that it would not be possible to reverse them. The most important thing to come form the Dolly experiment was to show that's not true...
Indeed, it was this discovery - that adults cells can be reprogrammed to become stem cells again - that opened the door to the creation of what are now called iPS - induced pluripotent stem cells. These are stem cells but made from adult cells.
And this had led to work such as the announcement by scientists in Israel last week that they can now even make artificial human embryos this way.
It also means that we are a step closer to the goal of using embryology and cell biology to produce tailor-made cells to repair diseased human organs.
Equal powerfully, you can also use the technique to reproduce some aspects of a disease in the laboratory dish and test new treatments, although the pace of progress is slow, something Ian Wilmut himself reflected on ruefully towards the end of his life...
Ian - I personally have Parkinson's disease so there is a chance of the same thing happening for that disease and I think that unexpectedly the Dolly experiment has revolutionized the approach to these diseases. I really do genuinely believe that treatments will come along but it may very well be 50 years before the treatment becomes routinely available. So people like me will probably have died of Parkinson's disease before the new treatments become available which is a frustrating thing to think.
Ian Wilmut, who led the team that successfully cloned the first mammal - Dolly the Sheep - and died this week aged 79.
25:42 - Does hot water freeze faster than cold water?
Does hot water freeze faster than cold water?
Will - In 1963, 13 year old Tanzanian Erasto Mpemba was making ice cream at school due to time constraints. He decided not to let the mixture cool down and instead put it straight in the freezer, and found to his surprise that the mixture had frozen faster than everyone else's. So was born, the Mpemba effect, the theory that hot water freezes faster than cool water. But what does the science say? I asked an expert in fluid mechanics at Imperial College, Henry Burridge. Fortunately for us, Henry has spent a lot of time studying this theory.
Henry - Well, we started out really trying to prove why this would happen in the hope that it really did happen and looked very much at the cooling process, the idea being that if water cooled in such a way that it gained a lot of momentum, this could potentially cause warmer water to cool at a greater rate than colder water. We did definitely observe that, but we never observed that that greater rate of cooling carried through into lower temperature states. So the hotter samples that we cooled, they could never overtake the cooling process of the colder samples.
Will - So, no, the purely scientific conclusion states that if you change nothing in either experiment other than water temperature, hot water cannot cool or freeze quicker than cold water. So why has it been observed so many times? Well, the answer might be to do with the conditions that the water is frozen in.
Henry - We did some work where we either sandpapered the inside of a beaker or the outside of the beaker so that heat transfer properties were the same in both cases. But in one case, the water was in a relatively smooth container, and in the other case, there were lots of these minute imperfections.
Will - These imperfections create nucleation sites. It sounds complex, but all you need to know is that a rough edge or a dust molecule or something similar makes water molecules align more often. This makes it favourable for the molecules to shift phases, which is to say, turn from water to ice.
Henry - By biassing whether the water was in a container with a smooth inside or a container with a roughened inside, then we were able to get hot water to freeze in less time than cold water.
Will - So a rough container with hot water will freeze faster than a smooth container with cold water. It should be stated, however, that cold water in a rough container will still freeze faster than hot water in a rough container. So perhaps Mr. Mpemba had a rougher ice tray than everyone else.
Henry - I think it comes down to this lovely nuance that it sounds like a really simple question, but you have to very precisely define what you mean. And if you mean that aspects will be identical except for the initial temperature from which you cool the water, then the answer is no, it cannot be done. But if you allow really subtle changes like allowing your hot water samples to be cooled in a container which is only changed by sandpaper on the inside of it, then you can get your hot water samples to freeze in less time than your cold water samples.
Will - Thank you very much to Tony for the question, and Henry Burridge for the answer. Next time we're answering this question from listener Cecilio,
Cecilio - I want to know how the Sun's impact changes on tattooed skin? Could tattoos protect us from getting burned? Thank you.
Will - And if you have a question of your own, please do send it in via our website nakedscientists.com, or email us at chris@nakedscientists.com.
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