Plastic Podcast Episode 9: Plastic and Human Health - What We Do and Do Not Know.

Episode Description: 

In this revealing episode of "Plastic Podcast," host Clark Marchese delves deep into the alarming gaps in our understanding of plastics and human health. Joined by Dr. Sarah Dunlop, Dr. Bhedita Seewoo, and Dr. Louise Goodes from the University of Western Australia, the discussion centers around their extensive research documented in the Plastics Human Health Map. This comprehensive project aggregates all known research linking plastics and their associated chemicals to human health outcomes, highlighting vast uncharted territories in scientific knowledge. The episode explores the daunting realities of microplastics and chemical exposures, the societal and environmental justice issues surrounding plastic pollution, and the urgent need for global policy changes. Listen in for an in-depth conversation that not only uncovers the hidden dangers of plastic but also emphasizes the critical need for further research to safeguard future generations.

Episode Guests: 

Dr. Sarah Dunlop on LinkedIn and publications on Research Gate

Dr. Bhedita Seewoo on LinkedIn and publications on Research Gate

Dr. Louise Goodes on LinkedIn and publications on Research Gate

Plastic Human Health Map here

Learn more about the Minderoo Foundation here.

More information about the episode and the Plastic Podcast

Episode Transcript  and more information on the Pine Forest Media Website

Follow Pine Forest Media on Instagram @pineforestmedia

Hosted, produced, written, and edited by Clark Marchese 

Cover art and PFM logo by Laurel Wong. 

Theme music by Tadeo Cabellos 

Transcript: [00:00:09.860] - Clark

Hello, and welcome to another episode of Plastic Podcast, the show that tells the science and the story of our relationship with plastic. I am your host, Clark Marchese, and today we are talking about plastic and human health, what we do and do not know. Okay, so this is actually a really big episode. You're definitely going to need to buckle your seat belt for this one. We're even going to do the trivia question at the end today, so stick around for that. But We just have to get started right away. This episode actually wasn't supposed to come out for a couple more weeks, but I did the interview and I was so shocked by what I heard. I decided to move it up to right now. Now, Plastic and Human Health. From the moment I decided to make this podcast, I knew I needed to cover health in some way. So I was looking and I was looking and I was looking on Google Scholar, and it was really hard for me to find anything that has been published, which links the consumption of microplastics to an actual human health outcome. And the reason for that is because there hasn't been anything published.

[00:01:21.050] - Clark

Okay, a couple of caveats to that. Nothing has been published in English. Nothing has been published since before 2022. And also, a distinction to make is that there has been some work published linking chemicals associated with plastic and even polymers to health outcomes, but nothing about microplastics themselves. Again, in English, and unless it happened within the last year and a half. Now, the reason I know this is because I spoke to a team of three scientists who put together what is called the Plastic Human Health Map, which was a large scale project that aggregated anything ever published that established a link between either plastic or their associated chemicals with a human health outcome. The goal of this was to identify our knowledge gaps on the subject. What they found were big gaping holes. I was honestly shocked to realize how much we just do not know. I think a lot of us assume that scientists and doctors just know the answers to things. And thank God that they do a lot of the times. But when it comes to plastics, we really cannot assume that everything is fine, as I have learned in this episode.

[00:02:29.480] - Clark

Now, these three scientists are going to explain it a lot better than me, so we should really just start talking to them right away. But here's who they are. We have Dr. Sarah Dunlop, who is a neuroscientist. We have Dr. Bhedita Seewoo, who is also a neuroscientist. And we have Dr. Louise Goodes, who is a physiotherapist. Now, these three are all researching at the University of Western Australia, and they are a part of the Plastics and Human Health Research Unit at the Minderoo Foundation. Incidentally, this research unit was founded and is directed by Dr Dunlop. I got talking to them about this large-scale project called the Plastics Human Health Map, how it was done, and what the results show about where our knowledge starts and stops. Buckle up, as I said, because it's going to be dense, but we're going to get through it together. I should probably just give them the microphone starting right now.

[00:03:27.550] - Dr. Sarah Dunlop

Perhaps I should start. My My name is Sarah Dunlop. I'm Head of Plastics and Human Health at Minderoo Foundation, and I'm also Professor Emeritus at the University of Western Australia. I'm a scientist. My PhD was in heavy metal toxicity, and I had a career in neuroscience, which is where I met the other two speakers who you'll meet shortly. Perhaps Bhedita next.

[00:03:53.090] - Dr. Bhedita Seewoo

Hi, I'm Bhedita Seewoo. I'm a research associate at the Minderoo Foundation. I moved to Australia in 2012. I'm originally from Mauritius. I did my PhD in neuroscience, a similar background to Sarah Dunlop. Then I joined the team, Plastics and Human Health team, at the end of 2020 to specifically work on the Plastic Health Map. But I've been working on many other things involved in submitting various submissions to the Global Plastics Treaty negotiations. I've been looking into starting up a project, looking at social and environmental justice around exposure to bisphenols and bisphenol alternatives.

[00:04:31.940] - Dr. Lousie Goodes

My name is Louise Goodes. I'm actually also a research associate at Minderoo Foundation and have an adjunct at UWA. My background is in physiotherapy, followed by a period of doing clinical research along with Sarah and Sarah's lab at UWA, where we worked on spinal cord injury, and then decided to follow Sarah with the move to Minderoo, joined the foundation in 2020, and was the project lead for the Health Map. Since launching the map, we've been using the database in many ways to inform Minderoo's position on plastic pollution, and also to work with policy experts in our team to prepare submissions to various organizations and government bodies, regulatory bodies, with a view to driving change.

[00:05:19.890] - Clark

Okay. Well, it's lovely to meet you. Welcome to the show. Thank you for being here. I like hearing that your stories and your careers have all followed each other along the way. I didn't write this question down, but I'm curious. Now, we've got two neuroscientists and a physiotherapist, and the applications for those fields are almost infinitely broad. I'm wondering what made you decide to dedicate your expertise to plastics?

[00:05:42.040] - Dr. Sarah Dunlop

It's a spot on question because at the moment, I think what humanity is doing is an enormous experiment on itself from industrial chemicals, of which plastic is a physical signature. You can see the stuff. I think it's very serious what we're doing because there are over 350,000 chemicals that have been made by us as humans. Plastic pollution is very visible in the environment. And so that started attracting us. But as I started thinking about it, I was thinking What does plastic do to human health? And so while I was working with Andrew Forrest, founder of the Minderoo Foundation, on his PhD, I interrogated the literature of plastic and human health, and I was absolutely horrified at what I found. We know they're getting into us, and we know that they're associated with harms to human health. This was the world that I threw myself into, this long dark tunnel, and discovered in The first searches I was doing, over 800,000 papers on it. Holy moly. And the other thing that was so really striking at that stage, Clark, was that everyone seemed to be talking about plastic pollution of the environment, but there was very little attention on human health.

[00:07:02.150] - Dr. Sarah Dunlop

If you want to change something, you need to get people's attention on it and their own health they're very vested in. That was the beginning of the journey.

[00:07:11.650] - Clark

What about you, Dr. Goodes, as a physiotherapist?

[00:07:14.820] - Dr. Lousie Goodes

Perhaps I could just add that it was also very satisfying to pivot into such a much needed area of research, I think. I've realized that what I could bring, although I knew nothing about plastic chemicals in the beginning, and that was real education, but also understanding human health from a health professional's point of view, was really an advantage to come on in and make some sense of all the literature and be able to help to structure a classification system for these health outcomes we were going to read about in the research and need to code. That was really satisfying for me.

[00:07:44.430] - Clark

Yeah, I Can you imagine a project like this? You need a wide range of expertise and collaborations, and each of you bring something different to the table. This team you have is part of the Minderoo Foundation. Help me understand who they are, and then we'll jump into the project.

[00:07:59.250] - Dr. Sarah Dunlop

One of Minderoo's signatures is to take on large intractable problems that no one else has solved. We do things precisely because they are difficult. That's why I called up Lou and said, Please, can you come and help me because I can't do it on my own. And amazing skill sets that she has and the others in the team enabled us to really get cracking on this. So the Minderoo Foundation is really for a fairer future. There are a lot of problems in the world and are Our organization encompasses three main areas. One is gender and equality. Another is communities, particularly vulnerable communities. So that could be global slavery. I mean, that is a massive problem out there, and it's on our doorstep. Then there's all the other issues around, particularly the ocean. The Ocean's team looks at overfishing, marine-protected areas, how we're importing our seafood, and the such It's a fairly broad foundation in its goals, but enshrined on those three specific focus areas. We actually sit in the ocean's main area, not because we look at the plastic in the ocean, but everything that we are doing is just try and stop it getting in there in the first place.

[00:09:20.430] - Dr. Sarah Dunlop

We're using human health as a driver to come to our senses on the plastic problem.

[00:09:26.810] - Clark

Can you tell me about what inspired this project? Why did you decide take this on?

[00:09:31.180] - Dr. Sarah Dunlop

This is all about trying to eliminate the harmful effects of plastic on people on the planet by using evidence, and when we don't have enough evidence, go and get it, and then doing something with the evidence. Just because there are so many chemicals and so many human health outcomes that we're beginning to learn people started to study, we needed a map, and we needed a map to navigate our way through it so that people could find out who'd done what, which chemicals have been studied, which health outcomes have been looked at. We built this extraordinary team. There are others besides Bhedita and Lou, but Bhedita and Lou were the main drivers behind all of this.

[00:10:13.680] - Clark

How do you make a map of research?

[00:10:18.010] - Dr. Sarah Dunlop

Perhaps that's over to you, Bhedita, to describe the methodology and how we actually did it.

[00:10:23.200] - Dr. Bhedita Seewoo

Yes. As Sarah mentioned before, we found that there are over 800,000 papers out on plastics and Human Health. There's actually a recent report that came out that says that there's over 16,000 chemicals that's being used in plastics. The methodology came down to three components. The first one is the plastic chemicals component. Which chemicals do we actually want to look at? At the end, we decided to include micro and nanoplastics. We know that these are tiny little plastic particles. They are sometimes intentionally added to many consumer products such as cosmetics and face washes, and they are also produced and released over time when plastic products degrade. As such, they are pretty much everywhere in the environment, and there's a high potential for human exposure to them. Secondly, we decided to include polymers which are basically the main building blocks of plastic itself. We also included plasticises and flame retardants. They are the two most common types of plastic additives, which have the highest concentration ranges in plastic materials. Lastly, we We included two additional plastic chemical classes called bisminals and pfas because they have known human health concerns and they are also common in plastics. At the end, in total, we included around 1,500 chemicals in the map.

[00:11:43.780] - Clark

Okay, so that's a lot. In the interest of time, we won't run through exactly what each of these chemical categories are, but suffice it to say that if they were included in the study, we are exposed to them through our interaction with plastic. If you are particularly interested, the map is open access and can be found in the episode description.

[00:12:01.970] - Dr. Bhedita Seewoo

The second part of the methodology was about mapping the health outcome measures themselves. While most systematic reviews that people would have read, they focused on specific diseases or specific health outcomes, we decided to include any change in structure or function in the human body, so any change at all, whether it was undertaken at a clinical level, functional level, physiological or cellular level. Then we also had to categorize those changes. All these health outcome measures, they were classified according to what we call the international classification of diseases, the ICD-11. We also added an extra classification on top of that called the Health-Related Measures, not related to a specific system because we also wanted to extract changes in, say, oxidative stress or gene expression changes, which are not really related to a body system. But there are changes that we want to capture in the map.

[00:12:58.630] - Clark

Okay, so just like the categories of chemicals, I won't run through all the categories of health outcomes, but they were equally as comprehensive. They cover everything from our circulatory system, our digestive system, prenatal period, and also anyone who's interested can look to find the full list in the show notes. We have these categories identified. What happens next?

[00:13:20.870] - Dr. Bhedita Seewoo

The third and largest step of the project was basically to conduct the search, screen the data, and extract the data. We conducted a really complex search in two separate databases involving all the synonyms and chemical terms. After removing about 54,000 duplicate results, we ended up with 100,000 articles that we had to screen. We went through all the titles and abstracts of those papers, and we found that about 6,000- Of 100,000? Of 100,000, yes. Oh, my gosh. We found that about 6,000 were potentially relevant. Then we went to get the full text of those 6,000 papers After looking at the full text, about 3,900 were relevant. Then we finally extracted data on about 3,500 papers.

[00:14:08.690] - Clark

Okay, that's a lot of papers. When you looked at each of these articles, what exactly were you looking for?

[00:14:14.270] - Dr. Bhedita Seewoo

We We collected data on the population characteristics, the study characteristics, the chemical names, and the health outcome measures that the study looked at. This data was then grouped by chemical class and the different health outcome measure classifications that I talked about just then. We visualized them in the form of a heat map and trends over time in the Plastic Health Map project. The various population and study characteristics that we extracted, such as the year of the publication, the country of the population that was studied, the age, the sex of the population, and so on, they were added as filters in the map so users could find the articles based on the specific details that they want to look into. That's the whole Plastic Health Map in a nutshell. Took about three years to do the project.

[00:14:57.660] - Clark

Okay, my next question was going to be, how long did that take You also mentioned that you took the 100,000 and you chopped it down and chopped it down. I'm wondering what things would disqualify, could we say, or on what basis would you consider an article not relevant for inclusion?

[00:15:13.280] - Dr. Lousie Goodes

Perhaps I can answer that, Clark. Basically, we were interested in just the articles that described studies that were done in human beings for a start. They needed to be published in peer-reviewed journals, and they needed to be in English. That was just a practical consideration for our team because we were wrestling with so many articles as it was. And they needed to be primary studies. They weren't reviews or systematic reviews, but the primary initial study. And also they needed to be studies that involved human participants, where the chemicals or the plastic particles were tested for and detected in the human body from a bias sample from participants, and also where a health outcome was analyzed. So we would have to exclude a study where, for example, phthalates might have been measured in the body of all the participants, but that might have just been about trying to get a handle on how much exposure there was in that population only, and that was it. We needed to exclude that because it didn't have a health outcome measure that was then analyzed.

[00:16:13.360] - Clark

Okay, got it. This is an important distinction to make. Last week, we talked to a researcher identifying microplastic concentrations in food items, but because there was no health link in those articles that we talked about, they would not have been included. And that work is really important, but it's not the only kind we need, right? And I notice a lot of work has been successful in establishing that a certain chemical or chemicals are, quote, hazardous or toxic. But what does that actually mean as far as what they do to our bodies? We need to go one step further. And 3,500 articles is not enough to really give us a full understanding. And also 3,500 cents win, right? Because that seems like a big number. And I'm sure it felt like a lot when you were combing through them one by one. But in relation to all of the research that we do about human health, that's very few. I believe that you went back as far as 1960. So in 82 years, that's all we have, 3,500. I mean, that many articles could be published in one journal alone over the course of one year.

[00:17:18.230] - Clark

We really do not have many answers at all then. Speaking of answers, let's talk about your results. Now, you looked at a lot of variables and you analyzed results in three main categories, which we call metadata, which were one, population, two, chemical exposure, and three, health outcome. Let's start with population, that first group of metadata. Did you identify any noticeable trends in all of the literature?

[00:17:43.890] - Dr. Bhedita Seewoo

The problem that we saw there was that there was a social and environmental justice issue in available literature regarding health outcome data. Investigations into the effects of plastic-associated chemicals exposure on human health outcomes have predominantly been conducted in high-income countries, where waste management is generally well-regulated and of a high standard, I would say. In contrast, relatively, really few studies have been conducted to date within populations originating from low or middle-income countries, where the risk of exposure to plastic The Associated Chemicals is thought to be higher due to a combination of increased production and use of plastic and also import of plastic waste, as well as mismanaged waste in terms of disposal and recycling. Out of the 3,500 studies that we included in the map, only three were conducted in low-income countries. Only three. That's a big gap. We also didn't find any studies on eight of the countries that are listed in the top 10 countries that have the highest mismanaged waste. I would like to investigate the difference in exposure levels in these populations from these vulnerable countries compared to less vulnerable populations.

[00:18:52.990] - Clark

When we say high-risk populations, you were mentioning that populations that have a higher exposure to waste. Do you also to account for populations that have a higher exposure in terms of their proximity to production of plastics?

[00:19:06.840] - Dr. Bhedita Seewoo

Yes, 100%. That would include fence-line communities and people with occupational exposures as well. In, say, Indonesia, waste pickers might have a high exposure because they don't normally wear the necessary PPE and then might have high exposure to PBDE, which is something that we did find in many of the studies that we screened.

[00:19:30.450] - Clark

Okay, a couple of things to mention here. I heard the term fence-line community. A fence-line community is one that lives directly next to an environmentally hazardous site. This could be a number of things, from a dump to a landfill to an oil refinery, to manufacturing facilities, et cetera, anywhere along the entire chain of production of plastics. We've mentioned a couple of times on the show before that when we analyze plastic, we have to start all the way at the beginning of the production line from the extraction of fossil fuels, all all the way down to disposal and degradation, or else we leave out a big piece of the puzzle. These fence-line communities as well, as you might imagine, are low income. I can speak to the United States. There is a huge racial dimension there as well when it comes to environmental justice. I also heard the term waste picker. Now, I'm not going to go into it too much because it's actually a big part of next week's episode. But some countries around the world, their waste management systems rely on what we would call informal actors, so not the government. And these waste pickers are people whose job it is basically to sort through waste for a number of reasons.

[00:20:35.830] - Clark

Perhaps they sell it to a recycling facility. So both members of fence-line communities and waste pickers have a higher exposure due to on just economic systems. For example, we'll go into it more next week, but in 2010, the United Kingdom was sending over 70% of its waste to other countries around the world who are inundated, overwhelmed, suffocated by our trash. Then we go around and say that they have poor management strategies. If we're going to expose other parts of the world to our plastic waste, we should also be funding research to fill that gap that Dr. See you just highlighted about what the consequences of that actually are.

[00:21:13.700] - Dr. Lousie Goodes

Perhaps, Clark, I could add a little on population, some of the findings and gaps. One of our observations were there were many papers describing mother-child care studies, which are really important. This is about the exposure that the mother has that will pass on to her child. And around about a third have included articles in the map are these mother-child peer studies. And this is really important. It's exposure while we're growing in utero as a little human being is a really huge concern. Many of the plastic chemicals are endocrine disrupting, so they back our hormones, and this can cause problems while the fetus is developing at that crucial time of development, and that can result in permanent changes in the baby. It could be an anatomical problem, a physiological or metabolic change, And that can affect health outcomes through life or later stages of life. And in addition, plastic chemicals can transfer to the mother's milk. So breastfeeding is then transferring more chemicals to a growing baby, again, at a crucial developmental stage. It was great that we saw those studies. We need more longitudinal studies. We saw that only about 400 of that 1,000 or so mother-pair child studies were longitudinal studies.

[00:22:26.560] - Dr. Lousie Goodes

But one of the gaps, on the other hand, were studies on the health of children whose fathers were exposed to plastic chemicals. This is so important as well, because both maternal and paternal studies are needed to sort out, investigate what happens to the next generation, and as well as transgenerational transmission. So from the grandparents down to the parents, down to the babies, there can be potentially transfer of issues that result from exposure in the grandparents. And also, just to add, very few papers we saw on older adults This is, again, very important because as we age, and it is a growing population in most parts of the world, elderly experience an increased burden of disease. As they age, it's more difficult to maintain health and physiological balance. Exposure to plastic chemicals can be more of a problem, complicated by those underlying diseases and nutritional issues as we age. We really need to see more studies in those populations.

[00:23:25.570] - Clark

It makes sense that these longitudinal studies would be important to allowing us to understand how plastic us over time. But I just have a question about science method. How would you go about isolating one variable like plastic and how it affects someone's health over their entire lifetime when there are so many different things that could be causing high blood pressure, for example?

[00:23:46.610] - Dr. Sarah Dunlop

There's a lot of statistical analysis that needs to be done in that space, and you're absolutely right. When we do these cohort studies, you need large populations of humans so that you can document all of the different possible confounding factors, and then you use statistical methods to take them out. If that's possible to do, and it often is, then you still end up and you see this signal of an increased risk to that particular health outcome as a result of increased exposure to that chemical. One of the real issues in this space is trying to get it caused. So longitudinal studies where you can see over time what's happening to human beings as their exposure changes with time and their health outcomes worsen or not is one very powerful way to do it. Okay.

[00:24:43.840] - Clark

Then moving on to that second metadata group of exposure, the actual chemicals that you analyzed. What can you tell me about your findings and any variations in the results?

[00:24:55.600] - Dr. Sarah Dunlop

Perhaps I should talk about the microplastics now. The surprising, but not at all surprising, but I think, from this map was the complete absence of papers in humans where we had both exposure to the microplastics and a health outcome.

[00:25:13.880] - Clark

I want to make sure I read this correctly because I was in disbelief. But out of the 100,000 articles that you thought might be eligible and you reduced it down, how many did you find that focused on the intersection of micro/nanoplastics and human health outcomes?

[00:25:32.240] - Dr. Sarah Dunlop

Zero.

[00:25:33.620] - Clark

Zero?

[00:25:34.920] - Dr. Sarah Dunlop

None, because we can't measure them properly yet. And you know what? When you start talking to the public and when you see the press, everybody is talking about microplastics. And yes, we have every reason to be concerned, because if you look in tissue culture, you can see it's doing damage. You can see it's causing obstative stress and inflammation and killing cells. You can see it's getting into animals. They're very important studies. And this area of research is very much in its infancy for two reasons. One, contamination of your samples. So you have to control for that because otherwise, you're going to falsely elevate the exposure. And when you think of how much plastic is actually falling out of the air, either walking down the road or in a surgical suite, you have to have the right controls in your studies to pick those up so that you can tell whether or not you really have got plastic in the human tissues. The second issue is to do with the size of the particles that we're chasing. So microplastics, there are good techniques. You can actually see them because they're big enough. A microplastic is microns big, and human hair is about 70 microns across, so that's quite big and visible.

[00:26:55.610] - Dr. Sarah Dunlop

The much smaller nanoplastics, which are a thousand times smaller, again, are the ones we think we should be really worried about? Is there small enough to get across biological barriers?

[00:27:07.320] - Clark

Wow. I mean, that is just shocking that there were zero, but I think even I was experiencing that as I was approaching this topic from a journalistic point of view, trying to find someone to tell me what the health outcome is of microplastics inside, and I couldn't find anything. Then if these articles that you analyzed are not focusing specifically on micro and nanoplastics, they must be focusing on the additives and the chemicals associated with plastic. Did you see any that were, I don't want to say overrepresented because we can never have too much, but did you see any that were highly represented or any that were left out?

[00:27:43.330] - Dr. Bhedita Seewoo

Yes. Out of the 16,000 chemicals that we know that are used in plastic production, we investigated, as I mentioned before, around 1,500 chemicals, and only about a quarter of those have been studied for the effects on human health. As you asked, the overrepresented group groups are things like PCBs and phthalates, which have known health impacts. But among the three-quarter of the chemicals that we included that were not investigated, we looked at them, and many of them are produced at high volumes, and they have shown to be toxic in the lab. Even more importantly, they are being detected in humans. It's just that there hasn't been any human health impacts investigated for those chemicals yet in humans.

[00:28:29.250] - Clark

Okay, so we We know less than we don't know, which I guess is always true philosophically when it comes to science in a way. But here we're really just barely even scratching the surface. What about that third category of metadata, the health outcomes? What did your map reveal there?

[00:28:45.850] - Dr. Lousie Goodes

Yes, I can answer that. The health map shows which health effects have been studied in relation to the plastic chemicals we included. And across all the studies, at least one health outcome was evaluated within each of the 21 categories within the ICD system that Bredita mentioned, the international classification of disease, which our structure for health outcomes is based on. But the highest number of studies investigated health impacts in that category of hormones and metabolism, endocrine disruption, that thing, with a focus on thyroid health, so the thyroid gland, which, of course, is important for hormone production, diabetes as well, and also sex hormones. So other highly studied health domains include reproduction and also neurodevelopment in babies and children, which is also a big concern. But definitely the endocrine metabolic nutritional area was the one that was most studied in relation to plastic chemicals.

[00:29:42.930] - Clark

Okay, so every health category that you identified was published on at least once. But one of the things I noticed when I looked at the map was that some of them were addressed less than 10 times. Also, if we're cross-referencing the categories of health outcomes with the categories of chemical classes, only two of the health outcomes were analyzed across every single chemical category.

[00:30:04.420] - Dr. Lousie Goodes

That's correct. So for all classes of chemicals, there were gaps in terms of health outcomes investigated. And that makes some sense. You wouldn't really expect that this research is driven by concern about a particular pathway that might cause a particular type of health outcome. So you would expect clusters of research based on observations that led up to that work or laboratory studies, different concerns in the community and so on. But still, there are There are gaps where you would like to see other domains of health investigated for any given chemical class for sure.

[00:30:36.410] - Clark

Did you notice any trends over time in the data across any of the metadata groups?

[00:30:42.120] - Dr. Lousie Goodes

Well, we can say that overall, there was an exponential increase in the number of papers, these primary papers that have been published since 1960, which is when we went right back to and all the way to January 2022. And over 45 % of that published work has come out in the last five that the map has trapped so far. So that's a big increase. And that reflects, as I say, the increasing concerns that clinicians have and researchers have about human exposure to plastic. And also sometimes when there's an accident or a group of people highly exposed to a chemical, for example, the PFAS chemicals, which are used in firefighting foams and have linked out into the environment from factories and so on. And some of that work made the press and people have been exposed by their farming animals and their water sources for drinking water. And when those committees were highly exposed, that, of course, inspired more human health research into those chemicals. And so basically, we saw that, as As Bredita mentioned before, PCBs were the most investigated class of chemicals, and that does stem in some part from those accidental exposures and poisoning events that happened where people, unfortunately, had really bad health problems.

[00:31:57.790] - Dr. Lousie Goodes

And that led to a flurry of research.

[00:32:01.100] - Clark

Okay, again, the health map is open access, and in the show notes, if you want to see the full distribution of studies around different chemical groups. But it's a bit unfortunate that accidents or horrific events are prompting research, when perhaps if we had done the research before we sent these chemicals out into the world, they could have been avoided.

[00:32:18.210] - Dr. Bhedita Seewoo

I can probably continue talking to that point, Claire. One other major trend that we have seen is that the research on the human health impacts of plastic chemicals doesn't get going until they have been used for years. So global regulation of plastic chemicals normally assumes safety until it has been proven otherwise. But we are finding again and again that this is not an assumption that we should be making because where we look, we find harm. So increased regulation of some of the plastic-associated chemicals in response to emerging evidence of harm from the literature, and also increased public awareness about the health impacts of those exposures, has led to manufacturers introducing substitutes to the chemicals that are being regulated. Some of these substitutes are organophosphate-blimic retardants. There's also some plasticizers that are substitutes. The problem is that these substitutes have no safety data in humans when they're introduced in consumer products, and they might be called regrettable substitutions. For example, regulations, as they have been introduced for BPA, many manufacturers switched to what we call BPS or BPF. Significant bodies of research on the potential health effects of this substitute did not actually even start six years after there has been marked increase in their usage.

[00:33:33.650] - Dr. Bhedita Seewoo

Part of the reason of this lag in research might be because of transparency issues. If we don't know which chemicals are in the plastics, we don't know what to test for, and also how long it takes for the scientific community to actually obtain funding and set up such research and run these studies.

[00:33:48.930] - Clark

There's a lot of gaps, and they all need to be filled, so I don't know how useful this question will be, but are you able to identify any areas which you believe should be addressed with the most urgency?

[00:34:00.270] - Dr. Sarah Dunlop

It's a really good question because we can't do it all. I think, as we'll discuss later, we have to get to the source of the problem and change the system. We've got to completely change the system so we know what chemicals are out there and that they have been tested properly and that we can test for harm. But we've already discussed the micro and the nanoplastics, and that's, I think, very urgent that we do need to look at that and work out how to measure them. But there are two others, I I'd like to highlight. We've targeted perhaps the usual suspects. What we need to do now is start shifting the attention on emerging chemicals of concern, and there are a number in that space. The UV stabilizers are turning out to be very toxic. They stop products from splitting apart in the sun. They stop tires and cars from bursting under pressure. We really We need to rank the worst ones that are coming up so that we look at those. But really, ideally, we should not be having to wait to find harm to human health when we know that they're hazardous in order to ban them.

[00:35:15.280] - Dr. Sarah Dunlop

But having that human health data does help drive the change that we need in regulation because sometimes they will say, Well, we haven't got human data. Unless we've got that, it's only in animals and it's not as powerful. So there's the emerging chemicals that we know about, but I'm afraid there's a whole bunch of chemicals that we don't know about. And these are called suspect chemicals. And you need a different... You need a technique for screening human biosmeticmen, such as urine and the such like, to pick up what else are we carrying, what else has got into us. We can't just focus on the usual suspects. We have to say the problem is much bigger We can't tackle it one chemical at a time.

[00:36:04.080] - Clark

On that theme, other than researchers like yourselves, who do you hope that this project reaches? Who is the intended audience?

[00:36:11.220] - Dr. Lousie Goodes

Well, we've made the map for many stakeholders, Clark, but really, primarily other researchers will find the map the most useful. Also, those working in regulation, so that might be people in government agencies and chemical regulatory bodies, and also health professionals. Obviously, the doctors and other health professionals out there will to be interested in certain health conditions and to have a look at which chemicals have been studied. And also NGOs, other interested individuals who are scientifically curious and happy to delve into the research and read scientific papers or just get a glimpse of the overarching findings, have a look at the heat maps and see what's showing up and where the gaps are. Might be really interesting to members of the public. But we're finding that when we present, often there'll be regulatory bodies who are looking at a particular class of chemical with the view to regulating it more or asking the question of the research community, what do you think about these chemicals? And we've been able to respond by mining our map for that data and letting them know what's been studied and what hasn't so far and what our take is on that group of chemicals, which is really important.

[00:37:18.380] - Dr. Lousie Goodes

And people can use the map to do that themselves. The other thing to mention is that we're also using the map to support submissions for the UN Global Plastics Treaty negotiations, where we're really active in that space and really hope to make a difference.

[00:37:33.790] - Clark

I'm curious, have any of you in the past or are currently working on any research that would have been eligible for inclusion in this health map?

[00:37:41.430] - Dr. Sarah Dunlop

Another study that we're doing, which is actually a randomized controlled trial. Now, it's not legal to deliberately give people nasty chemicals and see what it does to their health. We're doing it every single day, thanks to the petrochemical industry and our insatiable use for this lifestyle that we have of convenience. What we're doing is we've actually flipped it round, and we've worked out a way to reduce plastic exposure. It's called, very cleverly, I'm sure you'll get this, It's called the Perth Trial, where we live in Perth, which stands for Plastic Exposure Reduction Transforms Health.We've.

[00:38:24.460] - Clark

Figured out clever.Clever..

[00:38:26.810] - Dr. Sarah Dunlop

There's a massive team at the University of Western Australia headed by a clinical immunologist, Professor Mikaela Lucas, and we've worked out how to reduce exposure. We're doing that through food, because one of the major sources to these chemicals is through packaging and food processing, food and drink, through personal care products, and also food preparation in the kitchen and taking out plastic chopping boards and plastic utensils and all that stuff, and not heating things in the microwave in plastic containers. We were able to reduce exposure very convincingly this group. We've got to that stage now, and we're writing that up and about to launch the trial proper, the actual trial. There are other studies that we're funding. For example, we're looking at various cohorts around the world. This is where groups of people, in this instance, pregnant women, are gathered together into a cohort, and samples from their urine are taken during pregnancy, and then the children are followed up. There's one in Norway called MOBA, Mothers and Babies. It's a massive study, and we're very fortunate to have a collaboration with the Norwegian Institute of Public Health on that. There's a similar cohort that we're working with, this time in Australia, based in Melbourne, called the Balman Infant Study.

[00:39:47.290] - Dr. Sarah Dunlop

There, there's a lot of work in that space, but we're particularly focusing on child neurodevelopment, so autism and ADHD. The primary literature is quite consistent in that space, and we need better studies. We are making sure that that's being funded with some very interesting findings.

[00:40:10.780] - Clark

Wow. Well, I do thank you very much for your work in this space. We are going to start to close out now, and there's a couple of questions I'd like to ask towards the end. This was not perhaps the most uplifting episode we've ever done. Is there one piece of good news that you can each share with us that's come out recently in your field?

[00:40:27.720] - Dr. Sarah Dunlop

Perhaps. Who? Do you want to go I was just going to say, Sarah, that just the fact that in the last couple of years, the awareness around plastic being a human health problem and not just an environmental problem is really growing.

[00:40:43.900] - Dr. Lousie Goodes

That's really fantastic. There's been a huge interest from the public and many non-governmental organizations around the world. I just wanted to start with that. I know you've got more to say.

[00:40:53.120] - Dr. Bhedita Seewoo

I would like to touch on the willingness of the governments to actually do something about the plastic problem. I feel like that's a a really big step forward. The negative impacts of plastic waste on the planet has led to many countries banning single-use plastic products. The biggest step of all was in 2022 when the United Nations Environmental Assembly endorsed a resolution to end plastic pollution to safeguard the well-being of current and future generations. The resolution incorporates a really holistic approach in looking at the complete life cycle of plastic. This will be achieved through establishing an internationally binding Agreement known as the Global Plastics Treaty. That's really good news for us at the moment in the field.

[00:41:37.180] - Dr. Sarah Dunlop

The last thing I'd like to add, Claire, is, and I just want to preface this by saying that the reason we were able to solve the problem is to of the hole in the ozone layer so swiftly was because we had alternatives to the CFCs. We need alternatives here. It's going to be a bigger issue, but there's really exciting work, particularly for the single-use plastic. They have to have of certain properties, and they are some very interesting work. You can see, you can feel this groundswell of support around this space, but we still have a lot of work to do to make sure all of that happens. But I'm very confident that it will.

[00:42:16.100] - Clark

Yeah, there are a lot of people trying to crack that code of alternatives. I think we haven't quite done it, but we've got a lot of people on the job. Also, I like having three guests because then I get three pieces of good news back to back. The last question is, what did we miss today? What else do we have to mention about plastics and health and knowledge gaps?

[00:42:33.540] - Dr. Bhedita Seewoo

There's something I would like to mention quickly. We cannot really define safe in the absence of information. In order to ensure safety of people and the planet, there's three things that we must do. First thing is to regulate the existing chemicals and chemical groups based on existing hazard information and hazard criteria. We also need to rigorously test those chemicals and new chemicals in the laboratory setting before they are released into the market. Lastly, following the introduction into the market, we need to comprehensively monitor those chemicals in humans so we know what people are actually exposed to.

[00:43:11.320] - Dr. Sarah Dunlop

That's exactly right. I think also I'd like to add that we've got some very clear asks of the Global Plastics Treaty, and that is, for goodness' sake, we have to reduce production. When you think about it in terms of health, by reducing the production, it's actually a form of primary prevention health care. You're reducing the exposure. We have to be able to reverse not only the burden of proof, as Bidita was talking about, but the cost burden, because at the moment, industry is externalizing the health costs or the cost, the true cost of plastic onto both environmental and human health.

[00:43:53.020] - Clark

And you, Dr. Goodes?

[00:43:54.770] - Dr. Lousie Goodes

The thing is, we can't recycle our way out of the problem either. We do support Recycling, in theory, when it's done well, and it could be perhaps done better to protect human health. But we do need to be aware that recycled plastic does contain a volume of chemicals that are known to be causing human health problems.

[00:44:14.610] - Clark

Those are all very good things to keep in mind. The last question is, where can people follow you and keep up with this work that you're doing?

[00:44:21.540] - Dr. Lousie Goodes

Probably, I think all three of us are in LinkedIn, so you can find us that way, if our name is just in LinkedIn. The Minderoo Foundation has a website, and you can find out about our work in there as well, where we've published about our map.

[00:44:37.080] - Clark

Okay, so links to this and much more can be found in the episode description. On that note, I want to say thank you so much, first and foremost, for the research that you're doing and the important work. I feel very honored to play a part in sharing it with the world. Also, thank you so much for giving me your time today and for coming on the podcast and talking with me.

[00:44:57.070] - Dr. Sarah Dunlop

Thank you. It's been a fascinating conversation.

[00:45:10.590] - Clark

Wow. What even to say about all of this. What the Plastic Health Map shows us is horrific. There's not really any way around that. But I think the value lies in what this tool that these scientists and the entire team at the Plastics and Human Health Research Unit of the Minderoo Foundation have given us. We know what we need to do now, but that does not mean the work is done. The work has barely just started. One of the things I heard these scientists say is that researchers need support. Science takes a lot of time, and science is really expensive. One of the goals of the project was to provide evidence for decision making. As far as policy is concerned, unfortunately, empirics are often needed to substantiate what we can see plainly. But I do believe that this will help not only influence policy for health, but also, hopefully, social justice surrounding these issues and also funding for future research. But these changes will be on account of the empirical evidence these scientists were able to collate. The lack of empirical evidence may be equally useful. Also, I should have asked them what their hypothesis was or if they anticipated that this many areas would be so under-researched.

[00:46:20.100] - Clark

But whether that was expected or not, these gaps themselves provide, in my opinion, a very solid ground for the precautionary principle. That is not assuming chemicals are safe until we find out otherwise and maybe, hopefully, get us to pump the brakes a bit on plastics. Now, I know this was a long episode, but we're going to close it out on a lighter topic. We will end with the Trivia Question. So Spotify listeners can answer directly on the episode page of the app, and everyone else can DM me on Instagram at pineforestmedia. Stick around to the end of the credits of next week's episode to find out the answer, and those who get it right will be entered into a raffle for a monthly prize. Okay, here we go. Which animal is known to have the highest blood pressure? Is it A, an elephant, B, a blue whale, C, a giraffe, or D, a bison? You've been listening to Plastic Podcast. You can find more information about this week's guests and links to their work in the episode description. Next This week, we will be speaking with guests from Thailand and Malaysia about the global plastic waste economy, so make sure you're following the show so you don't miss it when it comes out.

[00:47:37.960] - Clark

Cover art was done by Laurel Wong, and the music you're listening to was done by Tadeo Kbejas. I am your host, Clark Marchese, and this episode was produced, written, and engineered by me. So if you loved it, I will not only see you here next week, but I would really appreciate a five-star rating across platforms and a review on Apple Podcasts. Plastic Podcasts is part of a larger network of sciencey podcasts called Pine Forest Media, and you can find more information about us in the episode description as well, or at pineforestpots. Com or Instagram and TikTok at Pineforest Media. We've got some exciting science podcast coming out this year, and that review I was talking about really helps the entire network to grow. All right. Thank you to all of you who have made it this far. And a special thank you to M3, who says, What an adorable host. So smart and extremely knowledgeable. I love, love, loved this. Now, in all honesty, I do not know who M3 is, but it's got to be one of my friends. So if it was you, text me. Now, for the answer to last week's Trivia Question, the correct answer was...

[00:48:40.460] - Clark

Arichibuti Orophobia, which is the fear of getting peanut butter stuck to the top of your mouth. Anyone who has this fear, it can be traced directly back to Shell Silverstein. If you got that reference, I'm proud of you. He wrote a poem about this king who gets his mouth glued shut with a peanut butter sandwich. I think it's called peanut butter sandwich. All we have time for today. And I'll talk to you soon.