Are Microplastics Really Making Us Sick? | Dr Stephanie Wright

0:00Dr Karan: Microplastics are everywhere, including our food, and some celebrities are even having their blood completely removed and filtered to get rid of them. But are they really harming our health? That's what I'm asking microplastics researcher Dr Stephanie Wright today.

0:23Dr Karan: I'm Dr Karan, and in this podcast, I speak to the world's foremost experts in science and medicine to cut through the BS of modern health advice. Thanks as always to Loam Science for sponsoring the show, the world's first invisible fiber blend with clinical trials. Dr. Stephanie Wright, thank you so much for joining me. I want to talk about microplastics. You're an expert in that. There's a lot of information out there, especially a lot of fear-mongering about microplastics. At this point in time, what do we actually know about the human health impact of microplastics?

0:55Dr Stephanie Wright: Well, I would say not much, to be honest. I think we know we're exposed probably every day in some way or another, but there are still question marks over what it's doing to the body. And that's probably deeply rooted in some analytical challenges we face when it comes to measuring them in the human body as well.

1:13Dr Karan: You specifically focus on microplastic toxicity. What does that actually define as?

1:19Dr Stephanie Wright: So toxicity, I guess, is the potential or ability for an agent or substance to cause some kind of harm or adverse effect, whether that's a molecular, cellular or animal or even person level. So we typically look at increasing doses of a challenge or a substance and see what it does, see if there's any negative effects because of that. That could be biological or physiological. So it could be an effect on the metabolism, It could be oxidative stress. It could be inflammation, a whole range of different biological events.

1:55Dr Karan: Now, a lot of the evidence we have on general health impacts of microplastics has been looked at predominantly in animal models, rats and mice. And there's increasing evidence that polystyrene beans, for example, have harmful reproductive impacts on rats and mice. What is actually going on there to cause that?

2:15Dr Stephanie Wright: That's a good question. So these animals are exposed to very high levels of one type of plastic of one type of size in one go, essentially in a laboratory or experimental context. For something to have an effect, it either has to travel around the body, accumulate somewhere and cause a direct effect there. Or it could be having an effect far away from the body, for example, in the digestive tract or in the lung. And that has a knock on effect for somewhere far away in the body. So with the reproductive animal studies, it's still hard to say exactly what's going on because often the particles that are being used in these studies are too large, at least based on what we know from sort of decades of research in pharmaceuticals and nanoparticles.

3:01Dr Stephanie Wright: They seem to be too large to be getting to these parts of the body that are being affected, such as the reproductive system. And I guess another challenge in microplastics in general is making a distinction between what the plastic material or particle is doing versus what a chemical being released from the particle is doing. And that's something we don't typically characterize or measure in experimental studies.

3:26Dr Karan: And those animal studies we have, can we extrapolate any of the data to humans? And is there any evidence that we're seeing that in humans?

3:35Dr Stephanie Wright: Well, I mean, you know, it's challenging because obviously we're not exactly the same as rats and mice, but often they are used as a model species to infer what is going on in humans. And we often use them to essentially set limits or thresholds as to what humans should be or should not be exposed to. So I think, you know, fundamentally we can take something from it, but it's not a direct translation to what is going on in a human.

4:01Dr Karan: Given that you said that the size of microplastics limits them from getting to certain places in the body, for example, potentially crossing the gut barrier or getting into certain capillaries or, you know, smaller to pass filters in the body. Should we then be more concerned about nanoplastics?

4:19Dr Stephanie Wright: Definitely. So I guess one thing I should say is it's not impossible. It's just really unlikely. So there are some really old studies from, I think, the 60s, late 60s, where humans were given capsules of non-digestible starch granules. 10 minutes later, half an hour later, one hour later, blood was taken. And these starch particles, which I should have said were about 100 microns or a tenth of a millimetre in size, were actually observed in the blood. So there's this old theory about a process called persorption, which permits larger things to cross the gut. However, it's really rare. it doesn't happen to every particle.

4:57Dr Stephanie Wright: For every two particles of every thousand that you ingest would cross the gate in that way. That likelihood increases the smaller the particle gets and definitely so for nanoplastics. I should also say that nanoplastics for microplastic people are particles on the nanoscale below a micron in size or a thousandth of a millimeter in size. This is a little bit different to the nano community which would describe them slightly different, even smaller to be a nanoparticle.

5:26Dr Karan: I guess microplastics, you'd consider them inert substances generally, where they're not having a chemical impact on the body and they may accumulate and we just don't know the impact of that. So it seems to be logical thinking that if someone consumed microplastics, they should just pass through the body without interacting chemically in the body in any way. They're inert, right? But what is potentially going on there from a mechanistic point of view? Is it causing harm, do you think, because of interactions on a cellular level with the microbiome? What do we think in terms of if we just had to hypothesize certain things?

6:05Dr Stephanie Wright: Yeah. So plastic is a polymer, which is a long chain of individual molecules, if you like, joined up to make the hard plastic we know plus additives or plus chemicals so when we say plastic we actually mean the hard material plus the chemicals inside it and we know those chemicals can be released and they're not always inert and then secondly um you know in the human body what we would say are inert but persistent can have an effect right because they're well they are foreign bodies. If our immune system finds them, they're going to try and get rid of them. If they're very persistent and durable as plastic is and our cells, our immune cells can't get rid of them, then some damage is caused just from that process alone.

6:53Dr Stephanie Wright: So whilst we think of them as inert, I think there are definitely ways that an inert material can still cause harm. In these studies, what we're generally seeing is I would say quite a classic particle effect. So we see things like at the cellular level, whether the particles are internalized by the cell or not. We see things like oxidative stress, inflammation, so a release of inflammatory signaling molecules. And we see effects on the metabolism of the cell as well. The reason I say it's a particle effect is because these types of effects are quite, well, they're not unique to plastic. You see the same for say air pollution particles or zinc particles, you know, so it's not something unique to plastic, but plastic is doing something similar to these other particles.

7:43Dr Karan: So just to elaborate on the particle effect, is that similar to the tattooing particles where they're causing the immune system to recognize it as a foreign substance, try to encapsulate it? And in addition to that, maybe the abrasive nature of microplastics on that molecular cellular level, maybe grazing the gut lining in some way and cumulatively causing low grade damage. Is that also feasible?

8:09Dr Stephanie Wright: Potentially. I mean, I think in the gut, you know, we do have the microbiome. We do have a mucus lining. And so it's actually quite hard for something to get to that raw layer of cells if you want our gut wall. If a particle does get there and it is persistent, potentially there is some kind of superficial lesion, grazing, like you say. But there are also places along our digestive tract where we have specialized cells whose job it is to engulf particles from the digestive tract. So there are also mechanisms that would allow a particle to pass through because cells are actively trying to ingest them and capture them.

8:50Dr Karan: Right now, how are we tracking and measuring microplastic burden in the body? Is it just, you know, blood draws in detecting that or stool samples, urine samples?

9:03Dr Stephanie Wright: People are looking at everything. I'm pretty sure every tissue in the body has been studied. um so obviously i think you know stool would tell us uh what's been eliminated and of course what we were exposed to but it's not the whole picture um because as mentioned there is a potential for a fraction of the smallest particles to be absorbed um so it's not a complete picture but potentially a good proxy of what we've been exposed to blood um that that's quite a good tissue to study because that essentially integrates what we have inhaled or ingested that has been able to absorb across the lung wall, the gut wall, and enter systemic circulation in the blood.

9:44Dr Stephanie Wright: So it's good because it integrates both of those exposure pathways, and it's what's bioavailable and potentially able to redistribute and accumulate somewhere else. But there's so much we don't know about blood, like, you know, do we see spikes? How important is it if we've eaten or we fasted? How long is it in residence for? How long does it circulate for? Does it partition with other cells? Does it get trafficked to fat? Is it being cleared by the liver? So there's still quite a lot of questions we don't know about how useful blood is to tell us about our exposure. Apart from that, it tells us it's gotten there and therefore has potential to go somewhere else.

10:22Dr Karan: How do we account for contamination? So if someone has like a biopsy of a liver, brain, or even a blood draw, how do you show that it's not just contamination from lab equipment, for example?

10:37Dr Stephanie Wright: It's a great question because that is a very difficult challenge in the lab. Microplastic is everywhere, including the contemporary laboratory environment in air from our clothes. And you walk in a lab and everything we use in a lab that is a single use consumable is plastic, right? So there are obviously ways of minimizing plastic. We can use glass, we can avoid single-use plastic, we can use metal, we can cover our samples, we can work in clean rooms, clean environments, wear cotton clothing. We have to filter our reagents and chemicals that we use to make sure they're not contaminated before we begin.

11:15Dr Stephanie Wright: So there are a lot of steps we can take. However, it's still very difficult to completely eradicate any contamination at all. So what's really critical is that you have something called a procedural blank running with your samples. So these are samples that are treated exactly the same and come into contact with the same environment, the same materials, the same, you know, chemicals, everything. It just doesn't have a sample in it. And what that lets us do is see what's in our background.

11:42Dr Karan: Ah, okay. So you account almost like, you know, when you're weighing something, you do a tear to count for the weight of the equipment or something.

11:50Dr Stephanie Wright: So this is the baseline before we even look at a sample. And then we can correct based on that, or we can use that to decide what we can confidently quantify above that.

12:01Dr Karan: There were a lot of really scaremongering headlines not too long ago about microplastics being found in the brain. And there was also a rebuttal to that where actually there was significant limitations and flaws found in those studies. Can you talk a little bit more about that? Like why that study was limited by various methodological flaws?

12:22Dr Stephanie Wright: Yeah, we kind of started talking about how do we look in the body? And we spoke about the tissues we can look at. But the other side is then obviously, how do we analyze those tissues? There are two main types of techniques. I'm going to start with the one that's received more criticism, I guess, or has kind of opened up these conversations around the challenges. So it's called pyrolysis gas chromatography mass spectrometry. That's a mouthful. I'm just going to call it pyrolysis. And without going into the exact technical details of how it works, The problem is that it can generate false positives because it doesn't directly measure plastic in a sample.

12:59Dr Stephanie Wright: It measures the breakdown of plastic. So if I take polystyrene and I superheat it, which is what happens in pyrolysis, it will degrade into sort of three main different compounds. These compounds together indicate polystyrene is present, but alone, they might not be particularly unique for polystyrene and there might be other things in your sample that generate them. So the criticisms that have arisen from the brain paper is that the main plastic they found was polyethylene and this has been shown to be the type of plastic that suffers the greatest interference from predominantly fats in a sample.

13:39Dr Stephanie Wright: The brain is a very fatty tissue as well. So essentially if there's any fat in your sample you get these false positives and you can potentially misclassify the fat as the plastic.

13:50Dr Karan: Wow.

13:51Dr Stephanie Wright: Yeah. And it's not just exclusive to biological fats. You know, there are studies showing in air pollution samples, black carbon, soot, all these things we find in the air can also interfere with these plastic signals too. So for pyrolysis as a technique at the moment, in terms of how accurate it is, we can accurately say compounds are present, but we can't accurately say it's definitely because the plastic's there because of this interference.

14:20Dr Karan: How much plastic on average does the average person contain at any given point? Like how much microplastics or plastics in general do we have?

14:28Dr Stephanie Wright: Yeah, no, it's a great question. I mean, in terms of what we're exposed to, it can vary so widely from paper to paper, model to model, you know, estimate to estimate. I think on the conservative side, we're exposed to a few hundred micrograms per week. So a microgram is a thousandth of a gram, just for context. So a few hundred of those a week. On the other side of the scale, people have estimated up to five grams, but that's probably quite an overestimate and not an accurate scenario for most people.

15:01Dr Karan: So given that error bar, that threshold that you've outlined to micrograms to grams, there's obviously a significant portion of that which is being excreted in bodily waste and breathed out urine waste etc but also there's a portion of that which is just accumulating in our body potentially yeah yeah you know and that's going to continue to increase over someone's lifetime and right now is there any indication because you know i see a lot of clinics now advertising therapeutic plasma exchanges and various things like that is that complete bunk do you think to kind of warrant any sort of you know removal of microplastics?

15:41Dr Stephanie Wright: Yeah well I would say there are a few challenges there you know number one we don't even have a good understanding of the methods that can tell you exactly what plastic is in blood and exactly how much. Number two we don't know exactly if it's bad or not you know we're still kind of I guess in the early stages of that whole body of research and then number three the efficacy of of these products to do that without introducing contamination into the blood because they are plastic etc is also still unclear to me so I mean I get it people have anxiety around this and I know it's not surprising and I have sometimes divide myself into the scientist and the person and the person is quite worried about this but the scientist has to stop and look at the evidence but so I get why people are concerned and why they would do that I just don't think there's solid evidence to say that there's an advantage to doing that at the moment.

16:33Dr Karan: A lot of people, myself included, have significantly reduced their consumption of single-use plastics, especially things like plastic bottles. I try to avoid buying and drinking from plastic bottles. Having said that, I also, the economist in me does still have a lot of empty plastic bottles at home, which I feel probably should try to limit that. That obviously is done to limit microplastic exposure. Are they really the worst offender? And if so, what would be even worse than that?

17:01Dr Stephanie Wright: I mean, the literature definitely suggests that in any way, when we heat anything in plastic, that is definitely leading to a higher release of particles. Whether they are truly micro or nanoplastic or they're just more agglomerates of plastic chemicals is yet to be determined. But either way, there's a high particle exposure from heating things. So the first thing I would do is stop using your polypropylene takeaway containers in the microwave, avoid any boil in the bag, anything that involves is heating. Tea bags are another source. And even the kind of plastic free tea bags, there's often still plastic used in the sealant to seal the tea bag together.

17:42Dr Stephanie Wright: So I think that would be a worst case scenario for me. On the inhalation side, tyre wear, you know, tyres are another source of microplastic to the environment and therefore we're exposed to it when we inhale it. They're part of the particular air pollution, especially in urban environments and around, you know, busy roads. And so the way we would minimise our exposure to air pollution, you know, avoiding those main roads, walking down side streets, windows up when we sat in a traffic jam, that would minimize exposure to tire wear microplastic.

18:16Dr Karan: I want to talk about something that's quite personal to me and about some medical conditions that I suffered from. I used to have high cholesterol and fatty liver disease and that primarily stemmed from a severe lack of fiber in my diet. And on my quest for finding the perfect fiber supplement over the last few years that could help me add more fiber into my diet, I couldn't find one. That ticked all the boxes that I wanted and the high bar that I set for myself. So I built Loam Science. What I'm most proud of is not the product. I know that's great, but it's the fact that we've run two clinical trials on it, two randomized controlled trials, which is far more than the vast majority of supplements on the market will ever do.

18:52Dr Karan: And we've got even more coming because I'm a doctor first and foremost and a scientist. And I wanted to build something that I could actually stand behind with data and not just rely on good branding. So if you want to understand what's inside Loam Science and why, the science is all on the website and the link is in the show notes. Now, microplastics are omnipresent in the air, in the water, in the foods that we eat. Is there any particular type of foods that likely have the highest burden of microplastics when we consume them?

19:22Dr Stephanie Wright: This is an interesting one. So a few studies have started to look into this. I've seen one kind of large scale systematic review that has looked at individual food groups and essentially built models, you know, based on demographic and geographical region, a person's daily intake of microplastics. and actually the Southeast Asian region came out worse because of the dominance of seafood in the diet. So that's one, probably one kind of key source, but clearly context dependent on where you are in the world and what your diet is. The other kind of set of studies that have started to look in stool and sort of monitor, you know, what we find in the stool relative to different diets actually suggest that it's not necessarily a key food group, but it's more the type of diet you have, whereby an ultra processed diet seems to lead to a higher microplastic exposure.

20:14Dr Karan: You know, a lot of microplastics are found in the soil. So is there any sort of concern that, you know, root vegetables, just plant food in general could have a higher risk of that? Because I know there've been some concerns, or at least there's going to be a higher contamination of plant foods with heavy metals, for example. It's also a reason that they might also have microplastics because it's found in the earth's crust.

20:37Dr Stephanie Wright: There are definitely laboratory studies and experimental studies from the lab that showed that nanoplastics, I think around 50 nanometres in size, can be absorbed through the root system of plants. But I imagine that process is somewhat size limited. The kind of key knowledge that we know that microplastic and to a degree nanoplastic contaminates soils, but we have no data on this 50 nanometre size class because the smaller you get, the harder it is to measure. and so often what we know about our exposure compared to what we know drives an effect or accumulates are vastly different in terms of the particle sizes we're talking about.

21:16Dr Stephanie Wright: So sometimes it is like comparing apples and oranges and so I think if nanoplastic around 50 nanometres in size is contaminating soils you know and happens to intercept a plant root of course it probably could be absorbed but I just think we know so little about that size range in soils in the actual environment, it's really hard to say if that is a concern at the moment.

21:37Dr Karan: There are also some, you know, in the last few years after 2020, a few headlines that made the rounds suggesting that microplastics were also found in placental tissue, in fetuses as well. You know, number one, how did they do this? Is it just biopsies that they did of this and sort of why would they explore that? And secondly, given that the burden of microplastics is only going to continue to rise and more humans are probably going to be born pre-polluted with microplastics. Could we be seeing the downstream consequences of this in decades to come? And do we have any research that's planning to follow children born in this era and beyond?

22:18Dr Stephanie Wright: So firstly, how do they deal with the placenta? Obviously that is a kind of excess tissue, I guess it's surplus at the end of birth. And so there's a lot of placenta as well. but I saw one recently when I gave birth you know I was like whoa um so you know there's a lot of tissue to take but you know the question is how homogenous or how um even is a placenta throughout the whole thing and I think it's actually very different so you could take something from one place and it might be different to somewhere else um but but essentially people will take pieces of placenta digest it in the laboratory so you subject it to harsh chemicals or enzymes it liquefies it you filter that and then the plastic particles within it are resistant to those chemicals and concentrate on the filter and it's the filter that's then analyzed like it's like a little piece of paper basically with a fine mesh or pores in it.

23:11Dr Stephanie Wright: Those studies do often find microplastic but especially where techniques are used that allow you to see and visualize and size the particles they're often very large and so again it kind of raises a whole new question around what can actually absorb and what can redistribute around the body. The placenta makes sense to find plastic there because it is actually a kind of place where we eliminate a lot of waste. It acts as a filter between, you know, it's there to protect the fetus from anything in the mother's blood that might be untoward. So it makes sense that things would accumulate there and it's kind of a natural excretion pathway.

23:48Dr Stephanie Wright: But yeah, the sort of sizes observed, again, just don't really make sense relative to what we'd expect to find. I don't know how the foetuses are samples, but again, it would be a similar way, I guess, in that, you know, tissue is taken and processed in the lab. But the kind of projection or, you know, this aspect of the chronicity of microplastic and the burden is really interesting because, yeah, it would be awesome to have a plastic cohort that we start now and we follow over decades because that's what it took to look at smoking and lung cancer, for example, we're expecting this to be something that builds and has an effect over a long time rather than something being acute.

24:27Dr Stephanie Wright: And that's partly because of it, we talked about it being this persistent irritant. So I think the question is, where is it accumulating in the body? And it has to build and build and build over time there until it does start to cause harm. So which is why I think we need to follow people long term. But then on the other side of that, if this is something we're exposed to over our whole life course, you know, from birth onwards or pre-birth onwards, would we expect older people to have a higher burden than younger people right now? So I think there are two ways of looking at it, right? The future, we're going to have higher, year on year, higher levels that we're exposed to, but equally, older people are going to be, you know, they'll have a higher level because of this accumulation that we expect to find?

25:11Dr Karan: Yeah, there was a very, I guess, poorly controlled study and mostly an observational study that I came across a few years ago, suggesting that obviously, you know, there have been changes in the anogenital distance of, you know, young boys because of the BPAs and phthalates and microplastics and whether that was contributing to, you know, hormones and how that was influencing the reproductive function and, you know, the decrease in anogenital distance, the size of the perineum was some proxy of, you know,

25:43Dr Stephanie Wright: a changing endocrine system, which, you know, I guess it's just very tangential data.

25:49Dr Karan: But I guess also there are so many other things changing in our environment as well. General pollution, you know, lack of fiber, changes in the microbiome, changes in diet, ultra processed foods. And I wonder how much of an attribution bias we're placing on these things. microplastics is the the big scary thing in the middle of everything but are we missing the forest for the trees because of all these other changes in the environment and just how we live as a society obesity rates as well what how that does the hormonal landscape and we're now just you know attributing microplastics as this big bad ugly thing and it may be one of many things, right?

26:32Dr Karan: Like, you know, another thing which is doing their rounds right now for, you know, fair reason, we're seeing a rise, a significant rise in the uptick of young adult onset colorectal cancer. All the other cancers are going down, but colorectal cancer is going up. Why is that going up? No one can quite, you know, pin the reason, you know, yes, we're all eating less fiber, we're moving less, obesity rates going up, maybe something in the environment, microplastics, maybe contributing to that we just don't know right yeah and is it a similar thing where we're actually just painting microplastics as the singular bad guy yeah yes i agree like you know

27:10Dr Stephanie Wright: in science we refer to the exposome it's like everything in the environment and it's your diet and it's your social you know economic status it's like everything that you're subjected to or exposed to that integrates and kind of works together to then have an impact on your health And so to a degree, that's very bespoke and tailored to the individual. So I'm sure it will differ person to person. But yeah, 100%, you know, the sort of rise in colorectal cancers and we could, you know, one analogy might be well has been a rise in microplastics, but it's also been a rise in plastic chemical. In fact, global synthetic chemical production almost aligns perfectly with a lot of non-communicable disease that we have today.

27:51Dr Stephanie Wright: um but then of course we think about the ultra processed diet the poor nutrition so there's so many factors and you could easily see how it's all of it so i guess like you know everything's doing something some more than others are having a worse effect than others um and there are some people who just have a bad hit of everything right um because there is this disproportionate element in society i guess ultimately you know trying to do anything that has at least a benefit to your health or is neutral just not a negative impact on your health is

28:26Dr Karan: going to be a good thing yeah and to your point about the exposome that is inherently tied to socioeconomic status and finances which a lot of people don't recognize as such a huge factor in someone's health you know if someone is living at or below the poverty line and they're trying to feed their family, there's a greater likelihood that they're going to buy packets of plastics of, I don't know, chicken nuggets or frozen meals, which are covered in single-use plastics. They're less likely to be able to afford to go to a farmer's market and buy fresh produce, which are likely to be less tainted with microplastics, assuming microplastics were this big bad thing.

29:07Dr Karan: So you can see the exposure of microplastics is going to go up from both the foods that they can afford and the dietary factor, but also maybe where they can live. They're maybe living in a busy urban environment where there's a huge spike of microplastics from cars and single uses versus someone who can maybe afford to live in a non-urban environment and has all those other abilities to maybe go on holidays more and they're going away from pollution and things like that. So yeah, that's a huge thing, right? Just the money that you have.

29:38Dr Stephanie Wright: 100 % and like you know a kind of a source of microplastic is actually clothing and textiles and wear and tear up upholsteries and so you know you often get like higher occupancy households as well and people are a source and just movement and wearing things down so there's definitely a disproportionate element and I think you know that goes from you know we can see that definitely probably in the UK but then globally as well and it kind of goes further than just thinking about the microplastic in the environment, it's actually our waste as well, a solid waste. We are exporting recycled plastic waste to lower middle income countries that are openly burning it because they also don't have the infrastructure to handle it as we don't.

30:23Dr Stephanie Wright: And so there's just some real social injustices going on around this for sure.

30:28Dr Karan: I also wonder, it's similar to prostate cancer in men. Most men die with prostate cancer rather and from it so at the end how much is microplastics actually doing is it just something which is a background radiation almost that we can live with it it's not accelerating our death it may or may not worsen our quality of life but doesn't necessarily shorten life span yeah i think

30:55Dr Stephanie Wright: yeah i mean these are all yeah definitely something we need to figure out um i think what we do know is that exposure to too many particles is bad. So we know that from ambient air pollution and this sort of elevated risk of mortality, cardiovascular disease, dementia, now obesity, respiratory disease, obviously lung cancers. So I think we know too many particles is bad, but that mix that we're exposed to in air pollution, it is a mix and all the different components within it will have their own different toxicities and sort of potencies. and I guess something that people are trying to figure out at the moment is which is the worst how do we rank it um to sort of even refine better regulation policy and sort of ultimately public health protection plastic is part of that but it's very very small in terms of how you know concentration really tiny fraction um so yeah I think I think it's a really good point I think the real question is is there for any reason a mechanism or some reason why our body would preferentially absorb it more than other things that are in our diet that are in the air and if so where is it heading and accumulating I think that's the only way it's going to really be having an effect it's the long-term chronic exposure if it's absolutely accumulating somewhere

32:13Dr Karan: in the body I always tell people if you're genuinely concerned about microplastic burden and the potential harm it might have to your health the easiest thing you could probably do apart from reducing single-use plastics is eat more fiber.

32:27Dr Stephanie Wright: Because there's been a lot of emerging

32:30Dr Karan: research looking at especially soluble fibers and how in the colon they're able to bind to, physically bind to, and trap in their soluble fiber matrix some of these microplastics in the same way that fibers can bind to bile acids and remove cholesterol and certain sex hormones from the body, they can do a similar thing with microplastics and prevent it interacting with the gut barrier and prevents the absorption and, you know, translocation of that. But also fiber particles are negatively charged. And I think some, you know, certainly for heavy metals, they're positively charged and fiber can have that adsorptive effect on heavy metal excretion.

33:13Dr Karan: So maybe there's something with, if there are any, you know, charging that happens of microplastics, whether they can do that. But it's specifically the soluble fibers, the sort of this mechanical binding effect it can have and just trapping it in the viscosity and removing it. So there's data suggesting. Yeah, like a gel.

33:30Dr Stephanie Wright: A gel net.

33:31Dr Karan: There's data suggesting that it's reducing the microplastics. Now, whether that has tangible health benefits from the microplastic reduction or just the halo effect of fiber increase having general overall systemic effects on health, which we know they do. it's hard to tease apart and it's emerging data we need longer term data but i think you know it's

33:52Dr Stephanie Wright: a bonus you should eat more fiber generally yeah well this is it that will have a knock-on effect

33:56Dr Karan: on your health anyway if it's you know if the bonus is it can reduce your microplastic burden yeah it seems to be a cheaper significantly less invasive way to do that than the likes of orlando bloom and brian johnson paying thousands of dollars for plasma exchange yeah yeah totally

34:10Dr Stephanie Wright: Yeah.

34:11Dr Karan: You know, overall, do you feel it's a fool's errand trying to do all of these things to reduce microplastic burden? And is that driving anxiety more? Or should we be taking these steps?

34:23Dr Stephanie Wright: I guess it's kind of what you said, you know, if you are minimizing or taking steps to minimize your exposure to microplastic, there are probably some secondary benefits anyway, like maybe a healthier diet or a different walking route and lower air pollution exposure or different materials in your home or it might also have a secondary knock-on effect to minimize chemical exposures. So yeah, I mean, if it is adding to the anxiety, then, you know, I wouldn't want someone to be adding to that burden. But ultimately, I think even if we figure out, you know, in 20 years' time, this wasn't really a problem, I still think there would have been some benefits in trying to minimize exposure just due to all these kind of interconnected issues.

35:03Dr Karan: Yeah, no, I think there's a lot of scary stuff out there about microplastics, maybe some warranted, some not so warranted, you know, like the brain stuff, which has been a bit slightly debunked. But I'm glad there are experts like yourself trying to pioneer the research in microplastics because ultimately it would be good to get some tangible human long-term data on microplastics. So then we can start changing national governmental guidelines and put pressure on manufacturers and large corporations to change the world in which we live in. Because right now I feel that a lot of the onus is put on individuals that you need to stop using bottles.

35:42Dr Karan: You need to stop doing this. And again, finances is a huge lever to that. But the biggest worldwide contributor to microplastics are these big corporations. Yeah, yeah.

35:54Dr Stephanie Wright: No, 100%. We just need the evidence, right? But also, you know, again, the personal side of me rather than the scientist side of me just think, I just think people don't want microplastics in their body. They don't want to be exposed to them, you know? And so to a degree, you know, one might question why do we need the evidence to drive that? But then I guess the changes that it would take is so systemic, like the industry is so established, everything around us is plastic. So it is a big upheaval and a big change, which is why I guess we need to figure out where's the priority, deal with that first.

36:29Dr Stephanie Wright: And there are probably some cases where we need plastic, right? And we can't avoid it. And it's actually a good thing. It's just there are definitely cases where we don't need it. And that's probably a good place to start whilst we figure out if there's anything harmful we need to be thinking about for the future.

36:42Dr Karan: There was a group of researchers that found certain bacteria in kimchi, which was able to metabolize microplastics and reduce that. And I know in nature generally, there are people out there who go and bioprospect different, you know, in harsh climates, certain bacterial species which have a certain function, you know, in sort of in volcanoes and other places like thermophilic bacteria and deep sea bacteria that are protecting coral reefs. Do you think our own gut bacteria could evolve to digest microplastics given that we're exposed to them?

37:21Dr Stephanie Wright: Oh my gosh. Yeah, I don't know. That's the big question for me because I'm not a microbiologist. But we know that there are bacteria that can degrade and there's the whole PETase from bacteria that degrade PET. And I've seen lots of studies on compost and composting plastics there. And I feel like I have seen a study looking at the human microbiome and degradation. But if not bacteria, then there's definitely enzymes, right? So there is a study from a few years ago now that was looking at polylactic acid microplastics. So this is a bioplastic. So the carbon in it is not from petrochemical sources.

38:01Dr Stephanie Wright: It's from renewable sources, but it's still a plastic and it's still plastic in nature. in the small intestine where we secrete lipases to obviously degrade lipids fats in our diet it was shown that these could also break down or start to degrade this PLA plastic as well so it starts to solubilize and release very very very small molecules from it so there are definitely potential ways that our body might be able to start degrading some plastics at least I guess the question is, does that create anything harmful or do we just metabolize, excrete and we're fine?

38:41Dr Karan: You know, even though we've been exposed to these microplastics for so many decades, we're still, I guess, in our nascency of understanding everything. And I just want to thank you for joining me on this podcast to hopefully, you know, instill more confidence that there is research going on, but also to, you know, get rid of some of the fear mongering and fear that surrounds this area. So thank you so much.

39:01Dr Stephanie Wright: Yeah, no, you're so welcome. Thanks for having me.