Talc linked to cancer, and improving yoghurt with ants

0:17Hello, welcome to the Naked Scientist podcast, the programme that brings you the biggest breakthroughs and talks to the major movers and shakers in the worlds of science, technology and medicine. I'm Chris Smith. Coming up, are talc-based products like baby powder linked to cancer? Legal proceedings have launched against one major supplier in the UK. Also, a new ichthyosaur species is discovered from England's Jurassic Coast, which not only looks weird, in the words of the discoverers, but bears the scars of previous battles too. And the double comet and an arriving alien interloper from another star system coming to the night sky near you.

1:03First this week, British consumers have launched a legal action against Johnson & Johnson, claiming that long-term use of its talc-based products, including baby powder, may be linked to ovarian cancer and other health problems. The case is about whether talc, which can sometimes contain traces of the well-known carcinogen asbestos, poses a risk to human health. Here's Sophia Lowes at Cancer Research UK. Talc is a naturally occurring mineral and it's used in lots of industries, so that's including things like making paper, plastic, paint, but also importantly for this story, cosmetics. And what it's used in cosmetics for is to absorb moisture and soften products.

1:46that's things like blush powder foundation eyeshadow but it's very small quantities and so it's that mineral being mined into a powder and being used in those products to help absorb moisture. When you say it's mined you literally mean this this comes out of the ground people dig it up. Exactly it's found naturally in the earth and so it is mined to take it out the earth and then powdered to ground up into a powder to then use in these products. So what are the health claims that have been levelled about it? Talc is also sometimes found naturally near asbestos. And so that means that when talc is mined, when we go and get it, there's a risk that you might get some asbestos with it when you take it out the earth.

2:32And that's a concern because asbestos is a known carcinogen. That's a cancer-causing compound for cancers of things like lung, your larynx in your throat, ovaries, and also mesothelioma, which is the lining of the lungs. And so that's a concern because there's a risk that if that talc gets contaminated and if those asbestos fibres aren't removed, then that could increase the risk of cancer. And it is really important to say that the sale of products containing asbestos is banned in the UK. And it's really important that it's the responsibility of regulators and industry to make sure that those cosmetics products are safety tested before they are sold.

3:14So that's about contaminated talc. But when we're thinking about pure uncontaminated talc, there is still fairly limited research about its effects in humans. And we really need bigger, higher quality studies to confirm if there is any link between uncontaminated talc and cancer. How was a link proposed in the first place? Did someone notice that there were suddenly lots of a particular kind of cancer and then tie that to an exposure to talc then? It's people noticing a link and then saying, OK, this is something we should investigate further. For talcum powder, there are studies that primarily look at the use of talcum powder back in the sort of 70s when it was quite commonly used in kind of larger quantities by people.

4:00And it's that theory that's kind of been proposed and that's been investigated as a potential link to cancer. It must be very tricky, though, because if you've got something which is very ubiquitous and you've got a common condition ovarian cancer is not an uncommon cancer as in we all largely know somebody who's probably been affected by it you've got a commonish condition and a common exposure but there may be loads of other things people have been exposed to as well so how can they possibly tie the two things together absolutely and i think any any research that's trying to really disentangle that correlation from causation for anything it is quite difficult But in general, when you're looking at whether you want to say the evidence is strong enough to say that it causes cancer, there's kind of three broad things that you might need.

4:50One is a kind of good theory about how it might cause cancer, like the mechanism by which it might do that. And you might look at things like exposing cells to your risk factor and then kind of looking at how your cells respond and whether that's indicative of maybe cells potentially turning cancerous. You might also have experimental evidence in animals where you can kind of perform those trials to really kind of remove those other factors that might be influencing any association. But really importantly is that we have good quality evidence in humans that shows that link between your potential risk factor and cancer.

5:29And they need to be big studies, large numbers of people that importantly take into account adjusting for other things that people might be doing that affect their cancer risk. Johnson & Johnson say that there is no or was no asbestos in their talcum powder. and are we not in a dangerous position where if we start saying well there might have been x in substance y 30 years ago because some people have said there was we could start labeling everything as a potential risk for a disease and find fault with everything we were ever exposed to and that wouldn't necessarily mean there was nefarious intent what is important to to kind of keep in perspective and not just health but for lots of other potential exposures as well is the scale of risk as well so for things like smoking things like being overweight or obese as well we're quite clear that they have a big impact particularly on some cancer types but for a lot of other risk factors and for all these kind of potential ones that we're talking about even if there is a risk from talcum powder that kind of is prusen, or if people were potentially exposed to asbestos, contaminated talcum powder, that increase in risk is probably a lot smaller than something like exposure to cigarettes and to smoking.

6:55So when we're thinking about people being worried about using talcum powder now or products containing talc, the amount of talc in these products is very small. And so using them is unlikely to increase your cancer risk because it's about an association that hasn't been fully proven for uncontaminated talc. And the amounts are so small and you're probably using these products not that often and you're not using very much of them. So it's about thinking about the cancer risk in the broader sense and what are the big things that you're doing that could be impacting your cancer risk. And the most important thing that people can do if they are worried about their cancer risk is to stop smoking.

7:33But if people are concerned about calc, then it is possible for people to look for products that don't contain it or just try and use less of them. So keep everything in perspective seems to be the bottom line. That was Sophia Lowe's. She's at Cancer Research UK. We will keep an eye on how that action proceeds. Now, talking of stuff that comes out of the ground, paleontologists have announced a new species of ichthyosaur or marine fish lizard called the sword dragon of dorset that was found on england's jurassic coast as well as being an interesting specimen in its own right with a number of strange adaptations this dolphin-sized creature from over 180 million years ago also shows evidence of old injuries to various parts of its body on what look like signs of a lethal bite to its head, suggesting it was killed possibly by a larger ichthyosaur.

8:23The find, which has been studied and described by Dean Lomax, offers a dramatic glimpse into the deadly life of ancient seas. The specimen was originally found in 2001 by a legendary local fossil collector called Chris Moore. When he found it at a place called Golden Camp, very close by to Charmuth and kind of the stomping grounds of Mary Anning of Lyme Regis. Of course, Mary Anning, living over 200 years ago, finding the very first ichthyosaur was brought to the attention of science. But when Chris spotted this one in 2001, he realized it seemed to show some weird, really weird features. The specimen was sent over to Toronto.

9:02It actually went on display and they never ended up describing the specimen and it was kind of left on display. So obviously people knew it existed. And we said, well, look, why don't we go and visit the Royal Ontario Museum collection. And so we did in 2016. And we went through all of their ichthyosaurs. They've got a great collection of material. And this was one of the focuses. So we had a good look at the specimen. And it was very clear that it was very clearly something weird, and almost certainly something new to science in terms of being a new species. And so we said, we've got lots of other projects going.

9:31And why don't we come back to this in a few years? 2024. So just last year, Judy and I decided to return to the Royal Ontario Museum and actually spend some time to taking the skeleton fully apart and then determine that it was a new genus and species to science and as it stands a one-of-a-kind specimen. For people who haven't seen an ichthyosaur before, can you just paint a picture for us of what one looks like? They kind of look a little bit like dolphins or sharks and yet they're totally unrelated. They are reptiles that were swimming in the seas at the time and the dinosaurs were walking on land.

10:08It's always important to point out as well that ichthyosaurs are not swimming dinosaurs. They're totally unrelated. Very, very, very distant cousins. But they had four flippers. Most of them at least had a chrysantic tail fluke as well, and all of them were predatory. And they've got that long snout, like you say, dolphin-like. So what did they eat? We're very lucky in some respects that some specimens are found with their last meals preserved. So we may have some that have fish remains preserved or squid remains, which you might expect. But then there's others that don't actually have other ichthyosaurs preserved in their gut region.

10:44And we know they're top of the food chain, kind of apex predators that are feasting on other ichthyosaurs. The smallest species that we know of were about a metre, and the largest actually reached upwards of 20 to 25 metres at the very least. Our new ichthyosaur is quite a small one, although it's not fully grown. And we think it's probably somewhere like a sub-adult, maybe a late teenager. It's about three metres long. And what's special about it? So our ichthyosaur has many different features in the skull and in the flippers that we've either never seen before in any other ichthyosaurs, or they have several features in, say, the flipper that match some ichthyosaur family members, or they match a different group of ichthyosaurs.

11:30And so when you're trying to work out where our ichthyosaur sits on the family tree, and you've got all these different features from in the skull and then in the flippers and elsewhere in the skeleton, and you plot them together, it comes out as a member of a family called the Leptonectidae. And the Leptonectidae, they all have what we call Leptonectids. They all have quite long, slender snouts. But what's interesting for ours is the time in which it was alive. So they all come from the early Jurassic, which is where our ichthyosaur comes from. But in particular for our beastie, this individual is roughly 185 million years old from a time in the Jurassic called the Plains Bakian.

12:11And the Plains Bakian worldwide is incredibly rare to find any kind of marine reptiles in there. In fact, so much so that our ichthyosaur is the most complete marine reptile ever found in the Plains Bakian. you mentioned this one is pre-adult an adolescent ichthyosaur why is it dead then this is a weird one right so you have to be very careful when you're looking for any features that might be something new because you also have to bear in mind that there could be features there that could be indicative of say predation actually whilst we were looking at the skeleton very carefully we did find evidence of some sort of disease or at least the bite marks or predation marks in the limb bones so in both flippers we also found evidence of really strange um probably diseased teeth as well so some of the teeth were really bulbous and it's not a typical um shape or structure of their teeth that's very different they were very weird so maybe an infection in the teeth but even the flippers showed even potentially some evidence of even the bends which obviously divers get from kind of servicing too quickly so that's another thing but more in particular as to why this specimen was not a fully grown individual as to why it may may have ended up dying.

13:22Bearing in mind, the rest of the skeleton is almost perfectly preserved in three dimensions. The very back of the skull is really weirdly crushed. And there's some weird surface structure there that looks like bite marks. And we think it was probably attacked by a larger predator, almost certainly another ichthyosaur. And the bottom water levels, pretty much there's nothing kind of living there. It's not super anoxic. So there's not like there's a lot severe lack of oxygen, but nothing is living down there. And so there's a good chance that, say potentially our ichthyosaur may have been bitten on the back of the head, managed to escape to some extent, but then died from its injuries and ultimately drifted into the abyss where the predator wouldn't have followed necessarily.

14:02Dean Lomax at the University of Manchester and Dean's also written some terrific books about the dinosaurs and ichthyosaurs that he studies, so do look him up online if you want to hear a bit more.

14:20IP engineering services for UK businesses. Find out how Spitfire can empower your company at spitfire.co.uk. Music in the programme is sponsored by Epidemic Sound. Perfect music for audio and video productions. This is the Naked Scientist podcast with me, Chris Smith, and still to come, the Natural History Museum's Sarah Russell on a dramatic double comet coming to the skies near you this month. But first, you might think your morning yoghurt is made from fairly simple stuff, some milk, some bacteria, and maybe a drizzle of honey. But a new study suggests that ants, of all things, might hold the key to improving it.

15:02Researchers in Denmark have discovered that the microbes carried by certain ant species, as well as the formic acid they make to defend themselves, can clot milk into yoghurt. Now the practice is actually documented in Turkish and Bulgarian folklore and done the traditional way you just add a few wood ants, whole in fact, to the milk and then bury the pot covered with some cheesecloth in the ant nest itself and then you wait for the magic to happen Taking their inspiration from a Michelin star establishment that were also experimenting in the same direction Veronica Sinot and speaking first Leonie Yarn decided to add some science to this recipe For me, this journey started when I was working together with a two-michelle restaurant, The Alchemist in Copenhagen, because they have an R &D team.

15:52And they were doing a lot of fun fermentations and really interesting things. And I got really curious to understand the underlying biology that is giving rise to all these flavors and textures and really interesting foods. So I was working with them on different projects. And then they mentioned that they had experimented with ants and and milk, mainly out of a flavour interest because they thought maybe the ant had some lemon-like flavours. And then they actually noticed that it was coagulating and turning into really delicious yoghurt. And I thought this is really interesting. And I got curious to understand what is the ant doing?

16:29What is it contributing? And Veronica, what do the ants do when you put them into the milk that you're starting with? what role do they play? One of the most important parts is the bacteria that live on and inside of the ant. So some of this bacteria escapes from the ant's body and can proliferate and grow in the milk. And it's things like lactic acid bacteria or acetic acid bacteria. As their names indicate, they produce acid that can give yogurt that tiny fresh flavour. Ants produce formic acid, don't they which is part of their defense mechanism does that select for the right sorts of microbes then which is why they're enriched on the ants and that's why you can get them into the yogurt from the ants yes that was something we found out that certainly the formic acid from the ants was entering into the yogurt and likely made a more favorable environment both in the ants and then in the yogurt for these lactic and acetic acid bacteria to grow so it maybe jump-started that fermentation process.

17:40How did you do this in the lab then? Did you literally just almost like racks of test tubes set it up as a proper experiment adding a certain number of ants, a certain amount of milk, certain conditions? Talk me through actually how you set about investigating this. We got some local ants and then we had essentially test tubes of sterile milk so it was all really clean environment so we would know just what the ants were adding into the milk, what microbes they might have. We fermented it just like you might ferment yogurt at home, kind of on a standard protocol. And then we started to do some more laboratory analysis to see what microorganisms are there, what acids were there, and also what enzymes.

18:26When people do this not in the lab, Leonie, how do they do it? Well, the traditional practice was involving not only the ants, but also ant nests, where the milk was actually buried inside the ant nest. The ants crawled over the ferment, which was only covered with a cheesecloth, which means that the acidity and also the microbes can actually move into the milk. But also the ant nest is warm, so it's actually like an incubator in the lab, almost where you can keep the fermentation at the right temperature. I've got to ask you at this stage, because everyone's going to be dying to hear you say, does it taste any good?

19:04What does it taste like? They were good. They were yogurt-like. The lab versions, they were a bit more acidic than conventional yogurt, a little bit more lemony. Yeah, the Bulgarian yogurts I haven't tried, so maybe Veronica is the better person to ask. Yeah, they were delicious. The yogurts we made in Bulgaria had that fresh, milky, fatty flavours, and they had kind of herbaceousness to them. Will you be taking your learning back to the Michelin-starred restaurant, Leonie? Yes, so we worked with them in different phases of the project, I would say, and they inspired us to set out to the study.

19:41But then we also came back with results, and we were also testing different things that they were very interested in. For example, in the restaurant, they were first very interested in using frozen or dehydrated ants because it's not easy to have fresh ants around all the time. And we were assessing these different storage conditions and actually found that that makes a huge difference in terms of food safety and resulting flavours and textures. So we could actually give them hands-on advice on how to create those yogurts so that they are safe and delicious. Can we use ants for anything else though?

20:16Can you go beyond yoghurt and extend the food spectrum a bit and use them for other things? Because I'm familiar with a gentleman who works in Cambridge who's actually made gin from ants. He extracts various things that they produce and turns it into a very delicious gin. So could we go a stage further with this than just yogurt? For sure. So the alchemists themselves also experimented with the ants in many different ways. And for example, in the paper, we're also highlighting not only the yogurt they made and the ice cream that was derived from that yogurt, but also panna cotta and also a cocktail that they created based on an ant-derived washing technique, basically, for milk wash.

20:58And what we think is also quite interesting is that the specific lactic acid bacteria that we found in the ant that was growing in the yogurt is actually today only found in sourdough bread or in sourdough starters and in ants. We hypothesize that it's likely that they originally came from the ants into our food system anyway. So it might be that we can experiment then not only with yogurt and dairy products, but also with other plant-based substrates like bread and maybe also other sustainable alternatives like plant-based yogurts or plant-based cheeses, for example. What a great story. Veronica Sinnott and Leonie Jarn there.

21:39They've just published their study in iScience. Now this month, a rare celestial pairing might be visible across our skies when two comets called Swan and Lemon are expected to appear at the same time. Astronomers say conditions could allow them both to be seen on a single evening. That's not all, though. There's also an interstellar interloper arriving called Atlas, coming from outside our own solar system. Some have speculated it may even be an alien spacecraft. Now, that's probably not true, but it is only the third time that we've observed an object like this. So we put in a call to the Natural History Museum's resident space scientist, Sarah Russell, to tell us all about it.

22:21These are what's called long period comets that we think come from the outer reaches of our solar system, beyond the Kalpa Belt where Pluto lives. And like all comets, they've got what we call an eccentric orbit. So their orbit is not circular, but it is sometimes very, very far away from the sun and then sweeps in closer to the sun and that's when we get to see it here on Earth. When are they appearing or have they already? Yeah, so they are around at the moment and so you should be able to see them but they should get even more visible over the next few days and in particular the beginning of next week, Monday, Tuesday would be a good time to have a look because the moon is waning at the moment, it's getting smaller and smaller every day and there'll be a new moon next week, so we won't have the moonlight to compete with the other lights in the sky.

23:13What are they actually made of, these comets? Do we know? We know a bit because there have been a couple of missions to visit comets, including the ESA mission called Rosetta that went to see a comet called 67P. Comets are fantastic things because they're visitors through time and space, so they come from the outer reaches of our solar system. They can tell us what that part of our solar system's made of And they also formed very, very early in our solar system's history. So they can give us an insight into what the planets were formed of. And they're basically bodies of rock and ices, not just water ice, but also things like CO2 ice and ammonia.

23:52And a very rich blend of organic material as well. They're all formed either in the very earliest times of the solar system or even pre-solar before our solar system started to collapse and form. When they come in this close into the inner solar system, very different conditions compared to where they normally live out there towards the Kuiper Belt, as you're saying. Do they change or does the fact that it's a lot warmer around here make a difference to them? Absolutely. It makes a massive difference to them. So a comet in its natural environment in the outer solar system is actually very, very dark because of all the carbon it contains.

24:28It's this very, very dark, dark lump. But as soon as it comes into the innermost part of the solar system, it starts to warm up and that means that gases start to come off it and then these gases get ionized by the radiation of the sun which forms what's called a coma around the core of the comet it starts to glow it also forms this tail of dust and ions coming up behind it as well so it completely changes its appearance as it comes into the innermost part of the solar system where should people actually look where should i turn my gaze in the night sky to have the best chance of seeing them because they are sunward compared to us so look at just after the sun has set when it starts to get dark look over to the west where the sun has been and you'll find uh comet lemon is actually in the northwest and uh if you see the the big dipper which is quite easy to recognise in the sky.

25:27It's in that sort of neighbourhood. It's just underneath the Big Dipper. And then Comet Swan is actually going to be harder to see. It's going to be more visible in the southern hemisphere. So I know you have lots of listeners from all over the world. If you look more towards the southwest, and if you're lucky enough to be in a dark sky where you can see the Milky Way, this band of stars across the sky, look where the Milky Way hits the horizon. It's around that sort of area but it's going to be very close to the horizon so that will make it difficult to see people in the northern hemisphere you'll need a dark sky to see them and a clear night and very good eyes or a pair of binoculars well i'll be certainly be out there looking the other thing is that i've i've heard there's actually a third body as well it's a bit like buses isn't it you wait hundreds of years for all these comets to come along and then three come along all at once.

26:20What is Comet Atlas? Absolutely. Yeah, so this is everyone's favourite comet at the moment. So this is Comet 3I Atlas and it is an interstellar comet. These have only been discovered fairly recently and Atlas is only the third one. So that's why it's called 3I for third interstellar. So we can tell the interstellar comets because when we look at their trajectory around the sun, they're not actually in orbit around the sun at all, like everything else in our solar system is. But instead, they're basically just passing straight through our solar system. And so these are really, really intriguing for comet scientists, all scientists, because they can potentially give us a glimpse into, you know, what's out there beyond our solar system, they can help us answer questions like whether our solar system is unusual or not.

27:13So they're really exciting. But the trouble with these objects is that we don't get much warning until they're actually in the solar system itself so and then we just have a few months maybe if we're lucky to be able to look at it before it disappears forever and flies off beyond our solar system. But what would make that happen? Why would a huge object or even a modest-sized object leave its own system and end up in ours? So it could have been that it was involved in a collision in its own planetary system that ejected it and we think that happened actually in our solar system as well. When our solar system was first forming the whole system was much less stable than it is now so we think the planets themselves were moving inwards and outwards and there were loads of collisions that that inspired and a lot of these collisions would have kicked out bodies from the entire system.

28:07Given the vast distances though it must have been out there in space for billions of years. Yeah, we don't know. We don't know, Chris. So that's really exciting. And there's a new space mission called Comet Interceptor that should launch in a few years' time. It's a European mission. And the aim of that is that it's going to go and sort of lie in wait so that when a comet, either an interstellar one or a really good solar one, comes along, it can go and take a closer look because we really want to know more about what these objects are we we currently don't know the very brilliant sarah russell at the natural history museum there and if anyone out there does manage to catch a glimpse of any of those three comets swan lemon or atlas that sarah was telling us about do please drop us a line because it will be terrific to hear what you saw well back down here on earth it is time for question of the week and james titko has been trying not to get burnt by this question from listener christoph voiced by our own Will Tingle.

29:05How does the UV filter in sun cream actually work? Thanks, Christoph. UV radiation emitted by the sun, which you can think of as an invisible form of light, is capable of penetrating Earth's atmosphere and causing us harm. It does this by damaging DNA, the genetic material which facilitates all life, compromising its functionality. This can cause sunburn in the short term and in the long term, the most serious effect of UV exposure is skin cancer. Here to explain more is Anthony Young, Professor of Experimental Photobiology at King's College London. Essentially they work by absorbing ultraviolet radiation.

29:46We break sunscreen types into two broad classes. One is organic and these are basically carbon-based molecules. You put them on the skin, they absorb the UV and less UV goes into the skin. And that energy is theoretically converted to heat. They have to be photostable. A sunscreen that's not photostable would not be much use because it would simply break down in the presence of ultraviolet radiation. The other type are called inorganic and they are essentially metal-based. Zinc oxide is one example. And these are tiny particles. And they also mostly work by absorption. They do scatter a little bit, but the vast majority of their effect is based on absorption.