Dr Rupy: Should we all start thinking about reducing our plastic exposure?
Dr Stephanie: Yes.
Dr Rupy: Are there microplastics in the air that we breathe?
Dr Stephanie: Yes.
Dr Rupy: Can we remove plastics in our body naturally through our own detoxification systems?
Dr Stephanie: Yes.
Dr Rupy: Can we actually reduce our exposure in the environment when we're outside?
Dr Stephanie: Yes.
Dr Rupy: Could microplastics drive chronic inflammation?
Dr Stephanie: Yes.
Dr Rupy: Is there plastic in my tap water?
Dr Stephanie: Possibly.
Dr Rupy: And does my tea bag really shed plastic when I dunk it into hot water?
Dr Stephanie: Possibly.
Dr Rupy: How much plastic are we actually exposed to, absorbing, and what is it actually doing to our health? Well, in this eye-opening episode where I learned a ton, I'm joined by Dr Stephanie Wright. She's one of the UK's leading scientists in microplastic research. And we explore what happens when plastic pollution doesn't just affect our environment, but our bodies as well. We're going to dive into the differences between micro and nanoplastics, the types of plastics that we are exposed to, how they're getting into our body via our lungs, our digestive tract, and eventually into the blood. The biggest sources of exposure in modern life from tyres to tap water, food packaging to clothes, as well as the air, particularly in cities where I'm living and actually am right now that I'm breathing in. How plastic particles could be contributing to chronic inflammation, hormone disruption, and affecting fertility, some pretty scary topics. And whether we can actually detox or eliminate plastics from our body naturally and how the liver, fibre in our food, and exercise may play a role. We're also going to talk about a bit about what we know about plastics and brain health and cancer, immunity, dementia, and a ton more as well. Dr Stephanie, honestly, is just an incredible source of knowledge. There are going to be simple science-backed strategies to help reduce your exposure from filters to cooking swaps and smarter shopping and clothing choices as well. If you don't know Dr Stephanie, she's an associate professor in environmental toxicology in the Environmental Research Group at Imperial College London. She received a PhD in biosciences at the University of Exeter and then completed two fellowships at King's College London. She's got 15 years experience in microplastic research and led the microplastics team. She's also participated in microplastic working groups for the World Health Organization and the European Commission. Honestly, her achievements are incredible. She's a wonderful communicator and I'm really excited to share this conversation with our community. For now, this is my conversation with the wonderful Dr Stephanie Wright, who's also an associate professor.
Dr Rupy: We've got a lot to unpack. I thought we could start by just determining what we mean by plastics. And I hear a lot of terms like plastics, macro, microplastics, nanoplastics. Can you give us a sort of like a broad overview of all those different terms for our audience?
Dr Stephanie: Sure. So plastic is obviously plastic materials. We typically make them from petrochemicals, so from oil and gas. That's the source of carbon within the plastic. And it always, almost always contains chemicals as well. So plastic-associated chemicals, and these give it certain properties like flexibility, flame retardants, antimicrobial properties. However, there are other forms of plastic. So I guess we've designed it to do certain jobs, never with the anticipation it would get in our bodies.
Dr Rupy: Right.
Dr Stephanie: But now we know it does break down. So we have microplastics. You would expect a microplastic to be on the micron scale, but actually an arbitrary definition came about. It's anything below 5 millimetres in size.
Dr Rupy: 5 millimetres? That's pretty big.
Dr Stephanie: So you could even see microplastics. Yeah. This was from the National Oceanic and Atmospheric Administration, the NOAA, which is an American institute. And I don't know where it came from to be honest. Maybe practical, how do you separate them from sediments and water and things where they were first being found. Nanoplastic is anything on a nano scale, so measuring below one micron, and one micron is one thousandth of a millimetre.
Dr Rupy: Okay. And when we talk about the plastics that are potentially causing issues in our environment and our bodies, are we referring to a particular type of one of those plastics in terms of size, or across the board are they causing these issues?
Dr Stephanie: So, I would say laboratory studies, experiments which focus on cells or mouse models, rats, things like that, they typically observe toxicological effects with very small microplastics and nanoplastics. But the particles that we measure in the environment are, you know, typically larger. And it's just this misalignment, right? It's really difficult and challenging to analyse microplastic in samples. Some techniques that are used have restrictions on the sizes or limitations on the size that they could actually measure. And so there's a bit of a bias towards larger particles being detected and reported in the literature. Whereas the toxicology focuses on the smaller stuff that's really hard to measure. And so to draw a line between one or the other is quite hard. What does this toxicology data mean when we don't really know how much of these small particles we're exposed to?
Dr Rupy: Got you. And just for the sort of physics geeks out there listening to this, of which there will be many, myself included. What kind of laboratory equipment do we use to actually measure plastic in the environments?
Dr Stephanie: Sure. So there are two types. So one is a physical chemistry technique called vibrational spectroscopy. There are two variants of this. One uses infrared energy, the other uses single wavelength, typically nearer infrared energy. And these are called infrared spectroscopy and Raman spectroscopy. They're almost always coupled to a microscope to enable the analysis of microparticles. And so it's micro Raman spectroscopy, sorry, Raman microspectroscopy and micro infrared spectroscopy.
Dr Rupy: Okay. And I mean, your research focuses on micro and nanoplastic exposure and how that contributes to disease and, you know, measuring it in human tissues. How do you measure plastics in the body?
Dr Stephanie: So I focus on Raman microspectroscopy. It just has a smaller size resolution, spatial resolution, which means that we can characterize the composition of particles down to much smaller sizes than would be possible with the other technique. There is one more technique that I didn't mention, it's an analytical chemistry technique. So it's gas chromatography mass spectrometry, but the sample introduction at the start is done via pyrolysis. So you superheat your sample to like 600 degrees in an inert atmosphere, and that's needed to break down plastics because they're very resistant and thermally stable. So you need these high temperatures to break apart plastics in your sample. And then they break into these smaller molecules, which we use as markers to indicate the presence of the original plastic.
Dr Rupy: Okay. And the tissues of interest for you, what would those be? I mean, I'd be interested in testes, brain, ovaries. What sort of tissues are you looking into?
Dr Stephanie: Different ones actually. So this is interesting. So, well, initially we've focused on the gut and we have interest in the lung. And that's really just at the very fundamental stage at these points of contact, because really those two barriers are where you will first contact microplastic, either ingested or inhaled microplastic. Do they gain access to these barriers or across these barriers? Because it's from there that they will then enter circulation or the lymphatics, they'll circulate around the body and then distribute to the secondary organs. But then on the secondary sort of tissue side of things, so where are these things ending up? I'm interested in points of accumulation, I guess. And that's for two reasons. So firstly, the levels that we measure in the environment are actually quite low compared to other particles. And so therefore, where they end up in the body is probably where they're going to accumulate. And they're persistent, right? They're very persistent, resistant to degradation. And so you will see this accumulation happen. And so I think it's more, I think there's probably going to be more of a chronicity to the effects or like a longer term health outcome that we want to look at wherever these are accumulating in the body.
Dr Rupy: Yeah, that's a really important word, accumulation, that I want to come back to a little bit later. You mentioned plastic-associated chemicals at the start here. So these are chemicals, like you said, that give different properties to plastic. This is a silly question. Are plastics one thing that have these chemicals added to it to give the different types of plastics that we see and we work with every day, like, you know, the bendy plastic in our water piping, the plastic that we use for athleisure wear or, you know, in the kitchen, for example? Is it, am I being silly in saying that?
Dr Stephanie: No, no, no, yeah. So, I mean, that plastics is a massive umbrella term, right? So fundamentally, and this is I guess for the chemistry geeks, a plastic is a synthetic organic polymer. So the organic part being organic carbon being the sort of fundamental ingredient in it. Synthetic being that we make it, we synthesize it ourselves. And polymer being that the overall chemical structure is a chain of units, single units. So they're these sort of organized chains and then aligned chains and like there's linkages between the chains and and this is kind of builds up and builds up and builds up to build a plastic material as we would know it with the addition of chemical additives. So yeah, I mean, plastic describes a wide range of materials. I guess there are around six plastics that comprise most of the production volume. So the most common is polyethylene. You get low and high density varieties. Polypropylene is very common as well or comprises a large production volume. Then it's polyvinyl chloride, then polystyrene. I think you have polyamide in there, polycarbonate as well. So I would say those are kind of the main plastic materials in our everyday world if you like. But now, of course, this description or definition goes much wider because we've got alternative materials coming in as substitutes, but they're still plastics. So whether you get the carbon from oil and gas or from plants, for example, you're still making a plastic material. Some petrochemical-based plastics which are biodegradable and some plant-based plastics which aren't biodegradable. So yeah, so the definitions are getting very murky, there's lots of crossovers and I guess a lack of clarity, but they're all plastics.
Dr Rupy: I want to ask about plant-based plastics. Rubber, is that the same thing?
Dr Stephanie: Yeah, so this synthetic organic polymer term includes thermoset plastics and thermoplastics, which are kind of like the common plastics you'd be used to, like polyethylene, polyethylene terephthalate, polystyrene. But then there's an extra group called elastomers or rubbers. So they all come under this synthetic organic polymer heading if you like. I would say it's more like a cousin rather than like a brother or a sister. But often when we talk about microplastics, we include tyre wear within that. So the breakdown of synthetic and natural rubber tyres on cars, vehicles. So I would say it's closely related and often kind of just bunched under the heading. Obviously, rubber has quite different properties to plastics, right? It's elastic. So it absorbs energy differently, but also a slightly different composition, different set of ingredients if you like, with respect to the additives, the chemical part.
Dr Rupy: Okay. Plant-based plastics. From my very naive, perhaps naturalistic fallacy biased mind, if I see a bag or some sort of plastic that has come from plant-based materials, I automatically assume that's better for the environment, it's easier to break down, etc, etc. Is that a complete the wrong approach?
Dr Stephanie: Well, I would say it's better for the environment because the carbon's come from a renewable source rather than the finite petrochemical source. But really, unless it is, if unless it says it is fully biodegradable or compostable, and that, by the way, could mean in home compost or in industrial compost. So compostable doesn't always mean it will break down in the environment or it will break down in your home compost. Sometimes it requires very specific conditions, temperature, oxygen, pH, which you get in industrial composting heaps in order to catalyze the breakdown. So not all plant-based material is biodegradable. Sorry, not all plant-based plastic is biodegradable, but the source of carbon is better.
Dr Rupy: Right. Okay. So if I go to a store and they've got plant-based plastic and it says biodegradable on it, just the word biodegradable, not whether it's industrial compostable or what should I, should I?
Dr Stephanie: Yeah, I mean that, that's, yeah, what is biodegradable? It's a very vague. I think normally that would probably mean under industrial composting conditions. You know, biodegradable could mean it will start to biodegrade, but under what time order? So I think that the definition of biodegradable with respect to plastics, especially thinking of end of life and waste management, things like that, just needs strengthening a bit and I think there needs to be better clarity for the consumer.
Dr Rupy: Got you. Yeah. Wow. Okay. Yeah, this is conjuring up a whole bunch of suspicion in my mind about some of these.
Dr Stephanie: This is the thing, right? So I go to coffee shops. I like coffee. And you know, sometimes I'm guilty of forgetting my keep cup, but I need that coffee. So I get a takeaway cup from the coffee shop and it's like green, green wear, blah, blah, blah. This is great. This is compostable or it's like a green plastic. But when you see the recycling loop, it's not going to go into the normal recycling as we know it. It's only going to be compostable if it gets into industrial composting. And that's not a loop we have in the UK. There are no bins for that in London, right? In central London, for example. So it's just it's all part of greenwashing essentially and it really frustrates me because I come away with this cup, the cafe think they've done a good thing. I look at it and I'm like, well, all I can do is put that in the general waste stream because it won't get recycled, it's not recyclable, and there's no industrial composting bin here for me to put it into.
Dr Rupy: So even though it could be composted, it's compostable in an industrial composting pit, we don't have the facility for that in this country and then so it's just going to go to landfill.
Dr Stephanie: There are sites around the UK that do it, but that's typically for green waste, like your garden waste. So they'll take that waste or food waste, you know, from like the home curb side collections. But there's not, for example, centralized industrial composting waste infrastructure. There's no bin for that in public spaces in London or well anywhere in the UK.
Dr Rupy: Got you. So you've got to take it home.
Dr Stephanie: Take it home, stick it in your, yeah, food bin if you have one.
Dr Rupy: That not always going to do. I mean, I don't have a food bin. We don't have a food bin in our area, which is really frustrating because we do the separation, but it's kind of futile because basically it just goes into landfill.
Dr Stephanie: Yeah.
Dr Rupy: Which is really upsetting.
Dr Stephanie: Yeah.
Dr Rupy: Gosh. Okay. Within this sort of world of, I mean, you just mentioned the coffee cup and that made me think of the lining of the coffee cup. So, you know, I might be drinking from a cardboard coffee cup, but it's lined with plastic, right? To maintain the integrity of the cup.
Dr Stephanie: Yes, yeah.
Dr Rupy: Such that the hot contents don't, you know, start composting it. Yeah. What about those?
Dr Stephanie: Yeah, well, it's the same. I mean, that's not going to compost and it's, you know, probably quite problematic from a recycling perspective because it's a mixed material. And it would require separation and there's not always that capacity or or, you know, you're not always allowed to do that depending on where you are in the UK, for example. And there's also evidence to suggest that when you drink from those coffee cups that there is a certain amount of particles that are shed or released from that lining. Wow. Um, because of the heat stress from the hot water. And either it's the heat kind of degrading it and shedding these particles or the particles were there left over from the manufacturing process and then they're released into the liquid when it's filled with it.
Dr Rupy: Wow.
Dr Stephanie: There is another hypothesis that there are even smaller molecules of plastic, kind of the same recipe if you like or ingredients, but smaller than what we'd say is a particle. And we call these oligomers rather than polymers. There's like a step down from from a polymer and it's it's probably around a nanometer in size, but it's not a solid particle per se. And there is a hypothesis that these are the things that are being shed into hot water and then in the lab when we filter that hot water, we dry our filter, we look at it under a microscope or we take a drop of the water and dry it and look at it with our equipment, the particles we see are actually more like precipitates. And that originally in the liquid, they weren't the size we saw, they were much, much, much, much smaller.
Dr Rupy: Much smaller. Okay. Yeah. Got you. BPA, PFAS, phthalates, are these these plastic-associated chemicals? Is that?
Dr Stephanie: Yeah.
Dr Rupy: How do we classify those? Because those are the three that I think get a lot of attention, but are there some others that perhaps we don't are just not mainstream yet?
Dr Stephanie: Well, I mean, I guess they are a mainstream, but flame retardants are another big class of chemicals with obviously, you know, flame retarding properties that are prolific in plastics. And here in the UK, we have much stronger or rigorous fire regulations than other places in Europe. So a lot of the materials in the home, for example, like upholsteries, carpets, curtains, have a much higher load of these compounds than other countries across Europe. Yeah, I think flame retardants, plasticizers, BPA, PFAS like you say, antimicrobials, UV stabilizers, heat stabilizers.
Dr Rupy: Antimicrobials?
Dr Stephanie: Yeah, yeah. So like antimicrobial things to to to to like things that we put on surfaces and.
Dr Stephanie: Yeah, exactly. So they're part of plastics as well, some plastics.
Dr Rupy: Oh, wow.
Dr Stephanie: Um, heat stabilizers have historically in the past have been things like lead, which is obviously being phased out, but so in PVC, which is used for, you know, piping, window frames, kind of it's a much more rigid plastic that had a lot of, first of all, it had a lot of phthalates in it, a very high proportion of phthalates to make it soft and usable, but it also would contain lead heat stabilizers. So I guess when we think of these groups, they're not just, I guess, organic chemicals, it can even include metals as well. So they are a real mixture, these materials.
Dr Rupy: I don't think I fully appreciated that.
Dr Stephanie: Yeah.
Dr Rupy: That we're mixing with different materials and stuff because, you know, you get a lot of these pans and stuff and they say, you know, it's PFAS free, whatever, and they're made out of ceramic, but they have coatings on them. And these coatings, I'm imagining are different types of plastics.
Dr Stephanie: Yeah. So I don't know enough about the composition, but I do know that ceramic is quite a loose term in itself. And actually, I think a proportion of that can be some kind of polymer or plastic. I don't think ceramic is a thing if that makes sense. It's kind of a blend or a mix of a few different substances. And so I think there are just a few pan manufacturers in the world that are actually making things that are sort of toxic chemical-free pans. But yeah, I mean, any coating, I mean, often what happens in plastics is like for like is replaced. So BPA was a common additive, found to have endocrine disrupting properties. It was replaced with something called BPS and I think BPD. They are there to do the same thing, so they have very similar chemical structures and of course then actually behave in a very similar way to BPA. Often, you know, chemicals, there are tens of thousands of chemicals in plastics, if not hundreds of thousands, and the smallest proportion of these have been tested.
Dr Rupy: Gosh.
Dr Stephanie: A lot of them are in use but have not been tested. And then there are mixtures, the mixtures might be doing things or behaving differently or leading to different effects than each compound would alone. So it just becomes a really complicated thing.
Dr Rupy: Yeah. This is super complicated because I guess, you know, from a consumer's point of view, if I see a product that is clearly a plastic and it proudly states that it is BPA free, from your perspective, should we be approaching them with the same degree of suspicion as a BPA containing product?
Dr Stephanie: Well, I mean, I would definitely question what what is there in its place? What's in the place of BPA? I guess, you know, we've perhaps not got the same weight of evidence or evidence base for these replacements as we have for BPA yet, but it takes time and mounting studies to do that. So I would definitely, yeah, I, yeah, I personally try and avoid plastic and it's it's not just from the particle aspect, it's really driven by the chemicals as well and the mixtures.
Dr Rupy: Yeah. Okay. Um, just as a side note, when did all this start? When did we start using plastics and when did they become just so commonplace across everything?
Dr Stephanie: So they were invented at the end of the 1800s and early 1900s. That was when they were first invented. And I think the very first polymer was called something like celluloid or something. And then there was something called Bakelite. And these very early plastics were designed to, were very clear functions or applications in mind. So I think it was Bakelite, it was in response to the need for a replacement or substitute for ivory, which was being widely used in like piano keys, billiard balls. And obviously there was hunting and poaching of elephants and rhinos and things and it was to curb that. So there was a kind of call if you like for someone to design or engineer a replacement material and that's where it came from originally. So that super specific application in mind. And then I think some kind of some of the major chemical companies kind of caught wind of this potential new material and the properties, designed some of the other types of polymers as well. And then it was really during the war that some wider applications were found. So the Second World War. You know, things like tarpaulin, parachutes, helmets, this kind of thing. And so then an economy formed around plastic. And then the war finished and the economy sank post-war, right? And so then there was this real drive to to basically invest in plastic and build this plastic economy. And so that then mass production began in the 50s. There was this whole, you know, have a convenient life, throwaway lifestyle. You never have to wash up plates again. You can just use these disposable ones. We can use plastic for everything. So so it was really the capitalization on, I guess, the remnants of this war-based economy as a boost to then the global economy and that kind of vision, which is where the plastics industry started.
Dr Rupy: Gosh, that's fascinating, isn't it? It's just crazy how marketing has led to this generation of like a plastic-laden world. And so if we fast forward to today, if, you know, you live in London, I live in London, if you're living in an urbanized environment, where do you think the biggest sources of plastic exposure are coming from people living in cities around the world as well?
Dr Stephanie: That's really good. So I guess, yeah, we think of plastic, right, as these big materials or macro materials if you like. But when we think about our exposure, aside from the chemicals that are released from these plastics, our exposure is then to these particles. And and I think that's the interesting thing. The materials were developed with very specific purposes, applications. We considered them safe, but we'd never had to consider that they might get into our bodies. And so I think that's the kind of the interesting aspect in all of this. So they break down into these micro and nanoparticles. These are in the air, they're in our diet. There's a whole range of different sources. In an urban environment, if we consider tyre wear as plastic, then tyre wear is definitely one of the main sources of inhalation exposure.
Dr Rupy: Tyre wear?
Dr Stephanie: Yeah.
Dr Rupy: Wow. Just from like, just cars on the road, lorries.
Dr Stephanie: Yeah, yeah. So so it's just the abrasion of tyres against the road, braking and different speeds and driving conditions, road surfaces, all of that contributes to the degradation of tyres. You know, you have to replace your tyres, right? It's because they've been shaved on the road. And there's evidence to suggest that those particles released during that process, some are small enough to be inhaled, some can reach your central airways and a proportion can reach your deep lung as well. And so they're not the main component, but a well, no, I think they are one of the main components of air pollution in these important size fractions that reach the airways and deep lung. And it's predicted to worsen, not necessarily that we're exposed to more, but just as, I guess, tailpipe emissions decrease as we get cleaner cars, more, you know, electric vehicles, then the proportion of material from the tyres, from the road, from the brake pads, that obviously increases because we've got less of the other stuff coming out of the.
Dr Rupy: Okay, so as a proportion of pollution, it will increase, but that doesn't mean the absolute amount will increase unless we, you know, like Sadiq Khan has his way and just removes all cars from the city.
Dr Stephanie: I just say, I think there are projections that do predict that the amount is also going to increase because the vehicle fleet is increasing and there's more and more traffic on the road.
Dr Rupy: Okay, so no good news.
Dr Stephanie: Yeah. And also the electric vehicles, whilst there is technology and improvements, they are heavier. And so there is more of that type of emission.
Dr Rupy: Yeah, so it's complicated.
Dr Stephanie: Yeah, so complicated. Because you're like, okay, well, let's all go electric because that's obviously going to be better from a particulate matter perspective, but they're heavier, so there's going to be more plastic in the air. So there's always, there's never a solution, it's always a trade-off.
Dr Stephanie: I know, yeah, and and yeah, one problem causes another or one solution causes a new problem.
Dr Rupy: Sure. Yeah.
Dr Stephanie: But then another main source of plastic is textiles, like in in our environment, I guess, in urban environments, it's people, it's the clothes they wear, you know, sitting in synthetic upholstery or wearing synthetic materials or walking on synthetic carpets. Again, that all contributes to the wear and breakdown. So I think there was a study which estimated, you know, thousands, if not hundreds of thousands of plastic microfibers are released from a person in a day just from kind of walking about, the wear and tear of clothes or it's, you know, it's wear that you can't really see. It's it's um, but then it kind of makes sense if you think about dust, right? If you see a dusty surface in your house, so much of that you can see are little fibers, not hairs, but like tiny fibers. And that's just the bit that you can see. So yeah, so so I think um, synthetic materials is another key source in urban environments because there are so many people and so much upholstery around us and textiles and yeah.
Dr Rupy: Wow. Okay. So tyres, clothes. We haven't gone down to cups or anything like that yet, but what other key sources would you say?
Dr Stephanie: Yeah, well, dietary sources are another major pathway for our exposure. I mean, I guess the thing is the stuff in the air, there is a connection to the gut anyway, because first of all, some of what we inhale is quite large and isn't small enough to penetrate into our airways and lungs, and so we swallow it, deposits in the nose or mouth and you quite rapidly will swallow it and therefore leading to exposure in the gut. Secondly, what is in the air obviously deposits, some or some a fraction of the particles in the air will settle out and deposit and so you might get contamination of food, of drinks and things and passively ingest things that way as well. But then yeah, food is another source and and there are different ways by which food might be contaminated. So first of all, you've got the kind of environmental pathway if you like. So we'll take seafood as the example. The earliest observations of microplastics were in the sea and so kind of the evolution of research has come from the sea. Like us. But um, and so um, there's a lot of research looking at shellfish, fish, and and sort of other types of seafood that we eat. And that's because microplastic is in the marine environment, these things accidentally ingest it and then we harvest it and then we eat it. Um, it's mainly a problem for things with with when we eat the gut as well. So a lot of fish, you know, we take out the gastrointestinal tract. The problem is if there's anything in the fillets itself. There are some fish we eat the whole thing, like anchovies and sardines. And then shellfish is obviously the other thing that we eat whole. And so that's very much like a food chain pathway leading to our exposure. The other of a option is then um, I guess contamination that happens within a food system, right? So it could be packaging could be the source of contamination or it could be a factory environment and the air in the factory or machine parts or again the people in the factory. So I think there's kind of the processing, packaging side as one way in which things are contaminated and then there's the kind of environmental processes leading to transfer in the food chain, which is the other.
Dr Rupy: Got you. What about drinks? So you mentioned packaging there. I mean, drinks in plastic bottles and now water bottles, sorry, glass bottles are getting a lot of attention as a source of plastic. Is this a major source of plastic ingestion for for us or is it down the list of things after the ones that you've just mentioned?
Dr Stephanie: No, I think for bottled water, it is probably one of the main types when we look at the levels or the amounts found. Tap water, I think generally very low concentrations are found in tap water. If you move to bottled water, it's higher. One of the early studies looking at bottled water, however, first of all found that reusable bottles had a higher microplastic load than single-use plastic bottles.
Dr Rupy: Okay.
Dr Stephanie: Which is quite depressing. But potentially the reuse, the opening, closing, the wear and tear maybe sheds microplastics and that's why. But it also found that glass bottles had the highest concentration of microplastics with no plastic component at all.
Dr Rupy: How does that happen?
Dr Stephanie: So, I mean, clearly there the bottle's not the source. It's then a question of, I guess, the source of water or the what's going on in the factory, the hygiene, like I don't mean hygiene from like an infection perspective, I mean from like a particle perspective. And again, it just points towards other sources of exposure in a food processing or drinks processing environment.
Dr Rupy: Wouldn't you find the same because a lot of these companies have the bottles of the plastic variety and the glass variety. So you'd assume that it's coming from the same source.
Dr Stephanie: Yeah.
Dr Rupy: So surely you'd see a higher amount of plastic either way because you're.
Dr Stephanie: Yeah, I'm trying to think. I don't know how they designed their experiment. I can't, I don't know if they focused on a one brand with two types of packaging or if it was just two different brands, two different factories. Not sure. But but I think like on average or or at least the highest levels they were finding were thousands of particles or microplastics per litre. And so then if you think in some countries, you know, people just rely solely on bottled water, you have a couple of litres a day, every day of your life. That's really why water is one of the main, I guess, sources of exposure relative to other food groups. Totally. But also there's a bit of a gap, like in the literature around food groups in general. Some are really heavily studied, whereas others are quite understudied. So cereals, for example, you know, meats and proteins is becoming there's an increasing number of studies, but again, much fewer than there has been for for water, for seafood. And it's again, probably just the evolution of the field and the progression.
Dr Rupy: Yeah. Yeah, that's super interesting. I mean, I'm just thinking back to when I was traveling during medical school in Southeast Asia and I was just living off plastic water bottles because you can't take the risk, you know.
Dr Stephanie: That's it, right? I mean, for some people, some places, like that's the choice. And it's obviously it's not their fault, but um, we're just, I guess we're just becoming aware of this now, but on balance, do you drink a few thousand particles a day or do you drink an infected water source? You know, so I think then you have to kind of bring in that element of balance and the reality is even though it sounds bad, there are some situations where it's probably still the best, best option or the best of two bad options or however you want to put it.
Dr Rupy: Totally, yeah. No solution, only trade-offs. You mentioned clothes as a as this this source of plastic exposure. What kind of materials in clothing are some of the worst offenders or the commonly used plastics in clothing?
Dr Stephanie: So I think one of the most common types of plastic observed from clothing or from textiles in general is the polyesters. So there's a plastic called polyethylene terephthalate that would be a polyester, but it's also got applications in things like drinks bottles and stuff. So so it kind of has a few different applications, but as a fiber, it's one of the most common types. I guess that's the thing, like we would normally attribute fibers in samples to textiles, carpets, clothing, because where else is that really come from in terms of a product. But for particles, it's much harder. Like you see a particle and you can analyze it, it says it's polyethylene terephthalate or PET, but you can't be on that say what it's come from. It could have been a bottle, it could have been like a fragment from a fiber, it could have been packaging, it could have been something else. So I think it's quite hard to attribute sources apart from if you've got very clearly you've got fibers. Another common type is polyamide or nylon. That's another one. We in a study we did in in central London, we actually found a predominance of a polymer or plastic called polyacrylonitrile, which is it's like a synthetic wool or acrylic wool material. So generally used for, I guess, more outdoor applications like outwear, tarpaulin. It is more of like one of the more robust plastics.
Dr Rupy: And and is that coming from clothing or like other sort of like tents or?
Dr Stephanie: It's hard to say. So we took these samples on a roof in central London, a campus roof. So it's 50 meters high. And we found so it suggested the source was possibly from an area with like high footfall, like high population density in the day. So it could have been coming from the people. But also there's so much construction going on in London. And so polyacrylonitrile is also a substitute for asbestos in cement. So they use these carbon, they call them carbon fibers, the polyacrylonitrile plastic fibers to reinforce cement as an asbestos replacement. And so I guess if you've got mixing or aerosolization of a dry formula of this, or you've got demolition, and also tarpaulin, you know, buildings are covered in it undergoing renovations or construction. So it's really hard to again to pinpoint down to where that was coming from.
Dr Rupy: Yeah, and I mean, I guess it's, you know, you've just got the natural elements, wind, when we recently had a storm and stuff, like high wind. So you don't know where it's coming from in London. You might not be living near a construction site, but if it's 50 meters in the air.
Dr Stephanie: Yeah.
Dr Rupy: It's just going to be all these different currents bringing.
Dr Stephanie: Yeah, definitely. And there are definitely studies which have shown um, like, yeah, population centers are a source and then like wind and meteorological patterns can carry it away and move it around to other places geographically, you know, even mid to long range.
Dr Rupy: Gosh. Yeah. Okay. So we've got it coming from lots of different clothes. Has this, has this changed your sort of choice of clothing? I mean, we'll get into some of the tips a little bit later on, but.
Dr Stephanie: Yeah, I try really hard, right? So I think there are a couple of conflicts, like sometimes I'm just very focused on second hand. I'm like, oh, it's second hand, great. And I almost forget to think what's it made of. And then in that scenario, I'm like, is this bad? This is second hand, it's probably quite worn and if it's synthetic, is it just going to wear, is the rate of wear going to accelerate because it get weaker and weaker, does more and more fragment as you go and wash it. I generally try and pick natural materials, like especially if I'm buying something new. So yeah, I do, I do have that in my conscious, I'd say 90% of the time. As with most things and every so often I have a lapse and then it's only afterwards that I didn't even think about that. Just something comes over you and you're like, I need that. I want that. And then it's only afterwards that, but you know, we're human.
Dr Rupy: Yeah, totally. And so there's natural materials, I'm assuming cotton.
Dr Stephanie: Cotton, yeah. And and this is the thing that we were talking about, you know, the kind of one solution could cause another problem. Because cotton requires so much water. It's not very sustainable, right? I think hemp's actually like one of the best because I think it sequesters a lot of carbon and it's very quick to grow and requires less water. So I think hemp's probably the more sustainable one, but I don't think I've got any hemp clothing.
Dr Rupy: No. I've got some bamboo.
Dr Stephanie: Oh, well, that's okay. Well, yeah, I mean, that's okay, I would say. No, again, it's you've just burst my bubble about bamboo.
Dr Stephanie: No, no. I don't honestly know enough about bamboo, but I guess the question is, is it bamboo fiber in the way that it's kind of cotton or is it bamboo that's been made into like a bioplastic fiber? Do you know what I mean? Is it similar to like cellulose acetate, the carbon comes from plant material, but it's still very much a plastic. That's something I don't know about bamboo stuff.
Dr Rupy: That's a really good point because it does feel too good to be true sometimes. I wear these bamboo products. I won't mention the brand. But um, they do feel really good and like this is like my athletic wear, but it's made out of bamboo. So this is better.
Dr Stephanie: I'm sure it's good. Or I mean, it's definitely better than but again, that comes down to the source of the carbon in it. Right. Because I think still what we don't really know when we think then about what happens when it gets into the environment or the fibers are shed, do they break down? Like cellulose eventually, right? And and probably bamboo then because of that too. But it depends how much I guess processing they've undergone, what additives have been incorporated to them, how they've been processed to make the fiber. But then like for us, we don't have cellulase, right? We don't break down cellulose. That's why we poo fiber. So and and the same goes for the airways. So if we were to ingest these fibers or inhale them, then they'd probably, you know, persist in a similar way to plastic. But there are just some other characteristics that might make them less harmful. Like they're very flexible, like softer if you like compared to a plastic. And so our immune cells that are there to try and clear up the plastics or sorry, any foreign material in the body might have an easier job of engulfing a piece of cotton or a fiber of cotton compared to a slightly more rigid but still flexible plastic fiber.
Dr Rupy: Got you. The other thing I was going to ask about clothing was the coloring as well, the dyes. Are those plastics?
Dr Stephanie: So the dye isn't plastic. The dye is a soluble chemical dye or not completely soluble because it stays attached to the clothes. But um, but it it's not plastic, but it is very much a chemical and some of them are probably synthetic in origin. Some of them are metal-based again. So um, you know, yeah, there's definitely issues with dyes as well. I'm sure some dyes are nicer than others from from that respect. So I would consider dye as like another additive if you like or another type of additive.
Dr Rupy: Yeah, yeah. Okay. Um, okay. So we've talked about some scary topics. It's basically everywhere. Um, you know, there's potential health impacts even though we can't be sure. You know, as a pragmatist, I would say better to avoid something than to learn about the negative impact of said exposure after 10, 15 years when you can't do anything about it. And particularly as these things accumulate in our body as well. I don't know if you can speak to this idea of accumulation or bioaccumulation.
Dr Stephanie: Yeah, well, I mean, I guess once you know where these things or how they distribute in the body, if you've got a repeat exposure every day of your life, for example, a proportion of that is going to reach that location and build up and build up. And I think that's why we need to be thinking. So I'm interested in the liver, for example, as a clearance organ in the body. But the liver's huge and it's heterogeneous. So how you would even start to look at the liver is complicated. I think things like lymph nodes, you know, where where again, we know you get clearance of material via the immune system and a bit of a storage going on. I think that's interesting. The spleen, it's involved in in again, in clearance related to the immune system. I think these would all be really interesting organs to study and to start to consider the longer term effects because accumulation is probably occurring, sorry, possibly occurring to a threshold if you like, where you might then tip over into some adverse effects. And I guess it also suggests that age is also an important factor, right? The older we get, potentially the more we have in our body because it is persisting and accumulating somewhere.
Dr Rupy: Totally. And as everyone is like sort of obsessed with longevity and aging better these days, myself included to be honest, but I'm not a biohacker. I think, you know, this comes into consideration in terms of our exposures and how that um, makes us more susceptible to things like DNA breaks and hormone disruption and inflammation in general that tends to creep up as we age.
Dr Stephanie: Yeah.
Dr Rupy: But what I would say with respect to accumulation, I guess the first step is actually crossing the barrier. And um, focusing on the gut, let's focus on the gut because we're interested in food and the diet. Um, we've evolved, right, with particles in our environment and solid particles that we can't necessarily digest or degrade. So I guess our body is quite good at keeping things out and we also have our microbiome and so our gut is actually kind of well-defensed, I would say, and quite tight. However, that doesn't mean that stuff can't get through. But anyway, I guess what I'm saying is most of what we ingest is probably eliminated, right, with our within stool and feces. I think a small proportion will be absorbed across the gut. And that's dependent on size, or I'd say the likelihood is governed by the size of the particle. Again, what we talked about for particles that are say a tenth of a millimeter in size, it's a low likelihood, 0.002% of those ingested will cross the gut. For smaller particles, and this is around a thousandth of a millimeter, so around a micron in size, the likelihood starts to increase and it increases as it gets smaller. And then from there, it it is then kind of dependent on whether they enter the lymphatics or the blood, right? We have the portal vein going from the gut to the liver. And so I guess stuff in the bloodstream will be cleared or will enter the liver. We have Kupffer cells in the liver, which are like resident macrophages, so immune cells that are there to kind of engulf and clean up debris and foreign material. However, they're not necessarily 100% efficient. And so I imagine of the what I will call bioavailable microplastic, right, the stuff that does reach the blood, some of it will bypass the liver and redistribute elsewhere. And so we do have these studies reporting on plastics in placenta, in kidney, in lymph fluid, in I don't know, all sorts of different tissues. In fact, it seems like every tissue that's been studied has microplastic in. But then there's the conflict of the particle size distribution in these tissues not quite matching up what is at least mechanistically believed to be possible.
Dr Rupy: Right.
Dr Stephanie: So there's still like lots of knowledge gaps and question marks. And as I say, where it accumulates is really important. But on the clearance side, um, I think we've got, yeah, the liver from the blood. And as I said, lymph nodes and spleen from the lymph system or immune system. But a large proportion will probably just be eliminated as well.
Dr Rupy: Okay. If I eat more fibre in my diet, would that help accelerate the excretion of plastics and toxins in general?
Dr Stephanie: That's a good question. I don't know is the answer. I mean, possibly. Um, but I think, yeah, I guess we haven't even spoken about mucus, right? The mucus lining of the gut as well. That's a really, that's actually like your first line of defense. And a particle's got to get through the mucus to get then into the epithelium. So I don't know if there's anything you can do to have healthier mucus or.
Dr Rupy: Oh, yeah, loads. Yeah, yeah, like soluble fiber and hydration and making sure that you're getting probiotics because all these different microbes, as you know, your colleague Dr. James Kinross will tell us about, can support that mucin layer to make sure that the the barrier is protected.
Dr Stephanie: Oh, yeah, I would say that. Do that. Okay, do that. And then and then also, um, I guess back to the microbiome, if you have dysbiosis or, you know, a change in the function or loss of diversity, that could lead to inflammation and that can make your barriers more permeable, as you've heard about leaky gut in previous shows. So I guess like supporting a healthy microbiome, supporting a healthy mucus lining, those are things that should really keep the gut tight and minimize penetration.
Dr Rupy: Got you. Are there any things that we can do to support the liver's activity at removing things like, yeah?
Dr Stephanie: Yeah, you know, I don't know much about the liver. I'm not even going to try and pretend that it's someone else's organ. I'm definitely not a liver, you know, hepatologist or hepatotoxicologist. So so, um, so yeah, but I mean, I I guess anything, but the thing is, once these particles are taken up into the liver, what happens? And, you know, I guess a real area of research that's needed is whether the enzymes in the liver are capable of degrading plastic. What does it degrade to? Is that harmful? Or does this plastic just sit within these cells? Is there surrounding inflammation? Does that progress? So I think, you know, we need a lot more knowledge, but potentially greater clearance in the liver might not be a good thing if they're just building up there and persisting.
Dr Rupy: It's a really good point. It's a really good point because I think the sort of naive view might just be anything that can accelerate those phase one and phase two reactions that lead to the degradation of the the bigger molecule into a smaller particle is a good thing. But what depending on how we can actually excrete the the metabolized product is um, is the question. And actually, are we making it more chemically active versus less? So yeah, it's a really, it's a really good. I mean, like I I um, I think of sulforaphane that that chemical that you find in cruciferous vegetables, it improving the excretion of other environmental pollutants like benzenes and stuff. And so people are supplementing with things like um, sulforaphane tablets that you get from broccoli sprouts and stuff. That's perhaps more in that environmental pollutant um, uh, field for uh, like air pollutants, so things that we ingest as a result of industrial manufacturing. But whether that's transferable to this plastics conversation as a class of pollutants, I don't know.
Dr Stephanie: Yeah. It's really interesting. I guess like fundamentally, you know, what is getting across into the blood? And then what is from that being accumulated in the liver? And then what are they breaking down to? Or are they breaking down? And then if so, what to? Like the fundamental links in the puzzle from like the gut to liver, sorry, gut to liver axis that we need.
Dr Rupy: Yeah. Dr Stephanie, this has been brilliant. I I honestly, this has been such an education for me. I think it's been a super, super cool education for the the audience as well. We've got some tips, some simple things you can do, some question marks, as always is the case with science. Um, but yeah, thank you for your time. This has been great. Really, really, really cool.
Dr Stephanie: You're so welcome. I'm so glad it was of interest. And yeah, thanks for listening to me waffle.
Dr Rupy: We can listen to you waffle all day. It's great.
