#42 The Basics: Microplastics

Microplastics: The Invisible Problem (or is it?)

Brooke Kelly from Reditus joins Gunnar and James to unpack microplastics. From penguin carcasses and seal scat (that's science code for poo) to human exposure, they explore where microplastics come from, how they are measured, and why they are everywhere. There is a lot of hype surrounding microplastics and some evidence of ecological harm exists, but human health impacts remain largely observational. They tackle analytical limitations, media-driven panic versus scientific uncertainty, and the parallels with PFAS. 

The episode lands on a pragmatic note: while the science evolves, a precautionary approach and simple exposure reduction strategies are worth considering.

Links from the episode:

NEJM: https://www.nejm.org/doi/full/10.1056/NEJMoa2309822

https://shirtloadsofscience.libsyn.com/prof-michaela-lucas-465

Broadscale microplastic assessment | EPA

https://aahms.org/publications/microplastics-precaution-and-biomonitoring-needed/

https://theconversation.com/scientists-may-be-overestimating-the-amount-of-microplastics-in-the-environment-and-the-culprit-is-lab-gloves-258545

Below the Surface: The PFAS Health Advice

Recorded on 17 April 2026

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Contact: bts@4pillars.com.au

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The necessary disclaimer: The views, thoughts, and opinions expressed in this Podcast are the speakers’ own. They do not necessarily represent the views, thoughts, and opinions of 4Pillars Environmental Consulting Pty Ltd or any Client, Supplier or other party related to 4Pillars or the speakers. 

(c) Gunnar Haid and James Hammond

Transcript

Gunnar Haid (00:00:01)

So, Brooke, you... How have you guys met? How did you end up on our podcast? Well, you I know, but Brooke...

James Hammond (00:00:05)

Me and Brooke? Well...

Yeah, we've met before. Amy introduced us. So Brooke works with the Reditus team. Can't even remember when it was Brooke, whether we were on a project or what it was. But I think the first time I you in person was at the, was it Envirolab's Christmas function last year was actually the first time we, I met you in person, which was very nice. And we had a good chat. So yeah, it was through Amy, our mutual friend and colleague, Amy.

Brooke Kelly (00:00:34)

Yeah, and like all good relationships, it began with a B. So he went from there.

Gunnar Haid (00:00:40)

Okay, that's it.

James Hammond (00:00:42)

And I mustn't have bored you too much, Brooke, because you've agreed to come on the podcast now.

Brooke Kelly (00:00:47)

Thank you very much for having me. It's pleasure.

Gunnar Haid (00:00:51)

 We pay a lot of attention to the fact that we don't advertise anybody, any of our guests or... Right? But Reditus, I have a lot of respect for you guys over there. There's a bunch of really smart people working at Reditus.

James Hammond (00:00:58)

Even ourselves.

Brooke Kelly (00:01:09)

Thanks for that. They're a really good bunch of people. They're all good at their jobs and they're all passionate about the work they do. And I think that's half the job, right? That's the important stuff. So I'm an environmental scientist. Got six years under my belt. I started off at one of the bigger engineering fans, just doing groundwater, soil, air, soil vapor, kind of monitoring and assessment. And we're doing a bit of work at

Gunnar Haid (00:01:20)

So what do you do there?

Brooke Kelly (00:01:38)

with remediation or Reditus. So it's a very solutions-based company.

Gunnar Haid (00:01:42)

And you are somehow a microplastics expert, otherwise you wouldn't be on our podcast today because we're talking about microplastics. What happened there? How come you know so much about that?

Brooke Kelly (00:01:55)

Expert is a loose term. No, I'll take it. So yeah, like all good passions, it just sort of began with a passionate supervisor. So while I was at uni, met the, Amanda would be my supervisor for my master's thesis. So my master's was on microplastics and he was studying the same thing. He was looking at microplastics in

Birds, Vs, migratory birds. I think I his eye because at one of the field works, I won the King's Cup. And I think that's when I impressed him. and then basically, yeah, he just said, look, there is a fellow researcher down at Phillip Island, a good friend of mine. She basically has a freezer full of penguin carcasses. So little penguin who had died natural death. He also saw me because he said she's also got.

some seal poo.

Gunnar Haid (00:02:53)

 Straight out of uni, I'm gonna go and dig in seal poo, yeah good one.

Brooke Kelly (00:02:59)

 There was a researcher at Phillip Island Nature Parks who like 20 years ago, 25 years now, found a bit of plastic in some seal poo, is we call it scat. So scat is a scientific terminology for poo. So basically they were doing a diet assessment of the seal colony there.

They found this plastic, they said, gosh, that's not really meant to be in there, is It's not a natural diet for these seals. So over 20 years, they had collected any plastic that they found while they were doing this diet analysis. And then basically waited for someone to come along when the sort of scientific techniques were available to put all that information and all that data into a report. So it was just my master's thesis.

Gunnar Haid (00:03:49)

Before we go any further, you mentioned the King's Cup. Let me show you my ignorance. I don't know what that is.

Brooke Kelly (00:03:58)

That is a drink.

Gunnar Haid (00:04:00)

James Hammond (00:04:03)

You

Gunnar Haid (00:04:04)

I thought, wow, there's a scientific thing I've never heard of here.

James Hammond (00:04:08)

I King's Cup during fieldworks, I knew exactly what you're talking about. One of those late nights after all the work's been done and you have some dinner and what do you do? You play a good old fashioned drinking game.

Gunnar Haid (00:04:20)

Okay, I'll leave everybody else to Google that.

Brooke Kelly (00:04:25)

All scientists understand that robust data can be a bit monotonous. So we got to do what we got to do.

Gunnar Haid (00:04:31)

Exactly. Hey, before now that we know that you are a scientific alcoholic or an alcoholic scientist or whatever it is. Our famous and or infamous warm up question. Yes. We sent you a few of them. Which one did you select?

Brooke Kelly (00:04:52)

I've thought long and hard about who's playing me in a movie.

Gunnar Haid (00:04:56)

The movie, which actress or actor have you picked?

Brooke Kelly (00:05:00)

I've decided that in order for people to watch this movie it's gonna have to be a musical. First of all I love musicals and if any of my life has any trials and tribulations and if that can be put into a musical number with a bit of dancing and a bit of singing then you know I'm gonna be rich one day because this movie will actually sell. Because of that I've chosen Anna Kendrick. Mostly for her voice and acting abilities. I choose Anna.

Gunnar Haid (00:05:31)

 That's definitely one of my favourite actresses, yes.

James Hammond (00:05:36)

 I like your take that you know to spice up the story it has to have a bit of a musical edge. Are you musical yourself?

Brooke Kelly (00:05:43)

Absolutely not, no. But I will go and watch and enjoy. And therefore I think more people will come and watch my movie.

James Hammond (00:05:52)

I think I would go to see Microplastics the musical. I think I would go to that. There's something there, Brooke. You should run with that, I reckon, yeah.

Brooke Kelly (00:06:01)

 Let's do it. We will start the music flow.

Gunnar Haid (00:06:05)

with broke featuring Anna Kendrick speech perfect three. Okay. Fair enough. There we, there we have it. All right. Let's ease into the first obvious question. Tell us microplastics. What are they microplastics, macroplastics, nanoplastics. Explain that to us. Where did they come from and why are we worried?

Brooke Kelly (00:06:28)

used with Pico Plastics, which is underneath Nano, so it just keeps going and going. Which is part of the story, right? So microplastics are any plastic item that is measured between one micrometre and half a centimetre. So the way that I sort of envision that is the width of a spider's web to the width of a pencil's eraser. Microplastics, they can be manufactured to be that small. Things like microbeads in your...

you know, face exfoliants, seeing your body exfoliants and nurdles are another commonly used term. So nurdles are the raw manufactured item that all plastic is made out of. So they're also called version resin pellets. So if you imagine if you've produced tens of thousands of nurdles and you're shipping them to a manufacturing facility, say your shipping container spills into the ocean, that's a direct source of microplastic collision.

But the indirect source, is probably more common, is the breakdown of larger plastic items into micro plastics. And then when you get the low one micrometre, that's then what we call a nanoplastic. If you imagine, say, take a plastic bag, it's flown off into the ocean from your, you know, shoreside picnic. The UV exposure might sort of break down that plastic kind of with its smaller and smaller pieces. Or say it's, you know, it spends days or months or years being abraded against like a rocky cliff.

that will also break it down. So the reason that we're concerned about these is because they are so small, right? So they can get into humans and animals and all sorts of receptors either through inhalation, so nanoplastics are inhalable, ingestion, so you can eat, say, a contaminated bit of seafood that's ingested, some microplastics, and also dermal contact, actually.

is coming up.

Gunnar Haid (00:08:25)

So living, in other words, exposure pathway is living. Living in a modern world and you are your exposure path. this is okay. We have a perfect modern fear topic here. They're obviously everywhere. They're invisible, poorly understood and impossible to avoid. Excellent. all. And we can measure it in parts per trillion. So we created ourselves a problem.

Brooke Kelly (00:08:52)

Yeah, well, it's one of those man-made issues that man is now dealing with.

James Hammond (00:09:00)

So plastics are polymers, right? So they're made up of, correct me if I'm wrong, chains of hydrocarbon chemicals. Can those hydrocarbons, like even the individual monomer elements, can they exist or can they come about naturally? Or is it only through human processing of crude oil that plastics are actually created?

Brooke Kelly (00:09:21)

Yeah, so plastic is made by fossil fuels, one of those man-made, those synthetic items. And the problem is that when we make plastic, there are so many different versatile uses for it, right? So we make plastic that is shiny, that is sparkly, that is pink and white and green, that is durable and hard and soft. And so the way that we do that is we add all of these plasticizers, all of these additives.

And those chemicals in themselves can be stored in that microplastic. And then when a microplastic becomes bioavailable, so it's ingested or inhaled or whatever it may be into an animal, those toxins can leach from the plastic and enter the animal that way. That is how we say that plastics are a source of contamination. So they're a physical, yes, but they're also a source of other chemicals.

They're also what we call a sink of other chemicals. So because of their large surface area to volume ratio and all sorts of physical like hydrophobicity and all sorts of physical attributes, plastic can actually absorb chemicals from its surrounding environment. So in that way, your microplastics are a vector of all other sorts of contamination that can come from a different country. It can come from an industrial site because

Microplastics are so small, they're in the air, they're in the ocean, they're transported via the water cycle, they're in the rain, they're in the snow, like basically they are a worldwide problem.

Gunnar Haid (00:11:02)

Alright, so we found them in sealed pool and polar bear testicles and human eyelashes. Right? Just about everywhere. Hammond and I, we've both done a fair bit of reading on that subject because we are... we are just... it's one of those subjects where I had no idea about it. I only heard about it. It's very similar to the PFAS.

podcast where we had no idea and we really had to read up on it. So on this one's right. You know, there's, there's a handful of studies. The famous 2024 New England journal of medicine study where, you know, 300 people where what they measured was presence of microplastics in clogged arteries of their patients. And over 34 months.

they found that patients with plastic in their arteries had a higher risk of a primary endpoint event. And I'm like, what the hell? You know, a primary endpoint event in that study was, here we go, a myocardial infarction. It's like, all right, code for heart attack. Or a stroke or death of any cause. So they had a 34 % increased risk. Sorry, I don't know how much. It was over 34 months, but they had a higher risk of a primary endpoint event.

That's a highly quoted study that is there. I don't know where to go from here. Well, guess a study with 304 people is of course, you know, when you have a 304 and you have not a super high. My next question then of course is, okay, how did you control for, because these are mainly I'm saying is like the presence of microplastics in any everywhere is one thing.

And I'm not saying that's a good thing. But from what I have been able to find out in my primitive research here is that just the presence doesn't necessarily correlate with any harm. And I think that's one of the big, big points again, which reminds me a little bit of the PFAS discussion we had with the panel members of New South Wales Health.

James Hammond (00:13:20)

Well, to take it back a step, think what was something that I found really interesting as well was because I know you've given presentations on microplastics at Ecoforum and in other settings, right? And so we've been talking for a while about this, but for whatever reason, it just seemed that over the last, I would say the last four months or three months, there just seemed to be this kind of wave of activity and discussion around microplastics. And I'm willing to some of the examples of that in the show notes, because we had all this reporting in the Guardian and in other outlets.

questions around sample methods, analytical methods, and that sort of thing, and kind of questioning some of those studies like the one that Gwynne just mentioned. And then we had these series of reports and stuff that came out through mostly government agencies. And so we had the EPA release a report that was really focused on just monitoring, so just gathering primary data about how much microplastics are in aquatic and marine environments.

But then one of the most recent ones that was released just at the end of March that really caught my eye was an evidence brief from the Australian Academy of Health and Medical Sciences, which dealt with...

Gunnar Haid (00:14:27)

Thanks for sharing that with me before the podcast,

James Hammond (00:14:29)

Keep going on.

James Hammond (00:14:34)

Let it go on the record that I sent Gunnar an email in our chain with this document. So the reason they call my eye is because it covers microplastics and forever chemicals, so PFAS, and other contaminants. So PFAS and some of these other emerging contaminants have been kind of lumped in with microplastics and discussed in this evidence brief that's been produced.

Yeah, by the Academy of Health and Medical Sciences. And a big angle, I guess, in that report is that there's a precautionary approach that probably needs to be taken. But it's funny you say that you felt some similarities going on between when you were looking into microplastics and when you were looking to PFAS, because clearly, I mean, the Academy here has seen the issues as being similar enough to lump them in together in this report. So, sorry, we're talking too much, Brooke, but this is a bit of a roundabout way. We just want to kind of set the context right, but for whatever reason... there seems to be this surge of reporting. So maybe I'll ask you about that, Brooke. Do you actually think there has been a surge of reporting around microplastics recently? if so, why do think that is?

Brooke Kelly (00:15:37)

So I think the surge has definitely come from your regulators, right? So your New South Wales EPA, let's say your federal government, but that report that you were talking about from the medical institute. It's got a timeline. say prior to five years ago, we were still building the scientific rigor, the scientific basis, the scientific, like foundational understanding.

of where microplastics were in the environment, if they were in humans, how they got there, what they were doing in humans. PFAS and microplastics are both considered emerging contaminants. Now that's definitely a spectrum of definition. PFAS, already have a national environmental management framework, which has toxicity reference values. Because microplastics are so small,

because we don't have standardized detection techniques, because we don't have standardized laboratory techniques for the classification and the detection of microplastics and all sorts of environmental and biological samples, we do not yet have those numbers. The research is getting there, but it's not quite there yet. But I think with plastics, you can still do a preventative assessment. We know that it's ubiquitous in the environment and it's in every facet of the human body.

We have seen laboratory and animal studies where microplastics have caused all sorts of harms. There's endocrine disruption, there's inflammation, there's, it has led to mortality and things like this in all sorts of different species. So we have the basic fundamental understanding that these are probably going to be really bad. And the science in five or 10 years time is going to tell us that it was really bad.

Gunnar Haid (00:17:30)

 I need to slow you down there. Sorry. Yes, there are studies out there where they show a correlation between, for example, inflammation and the presence of microplastics in whatever tissue. It is my understanding, and please chime in, that the causation...

has not been shown in any of those studies, like none. Is that right?

Brooke Kelly (00:18:03)

So the issue there is contamination tends to be considered more thoroughly when there is an impact to human health. The ethical assessments of different types of animal species have been easy to get across the line. So therefore we have microplastics assessments of different types of animal species that prove impacts, that prove...

ecological harm at a population level, at an individual level. Human health risk is a completely different problem and you're so right. Okay, so all the data that we have at the moment about microplastic exposure in humans and therefore implicated health effects are observational. You can't expose a human population or a human individual to, you know, X amount of microplastics and then see if that causes Y and Z impacts.

So you're right, that's sort of the data gap, right? And it's a good data gap to have because we're open-air.

Gunnar Haid (00:19:07)

You know, well also because they're so omnipresent, it's almost impossible to have a controlled environment where you because you have no zero exposure levels anymore. Right. This is that. That's another one of those things. By the way, Brooke, how do we actually measure microplastics? How do you, what's the lab analysis? send you, I take a liver of one of your dead penguins and send it to a lab and say, Hey, give me microplastics in, I don't know.

Count per, I don't even know, what is it, counts per percent or counts per units? How are we going there and how do they do that?

Brooke Kelly (00:19:47)

Yeah, you and I, as a environmental scientist, used regular labs, right, commercial labs. And if I were to send a water sample to one of, you know, many commercial labs, they would be able to assess it for microplastics. So the analytical techniques still exist. There's actually like Australian standards as well, not quite for like the, it's not for the methodology, it's more so for the principles of assessing microplastics.

There's a few different ways. Microplastics, would generally look at microscopy. And then nanoplastics, you're generally looking at spectrometry.

Gunnar Haid (00:20:24)

So sorry, the first part was you actually count. Somebody looks through a microscope and counts the pieces. All right, well, I can get on board with that.

Brooke Kelly (00:20:31)

You can count, you can describe as well. So a big thing is the morphology of a microplastic. So how big is it? What type is it? Is it a fragment? Is it a fibre? What colour is it? What size is it? How is it going to act in your environmental sample? So that's important for things like laboratory blanks. So we know that the project is in like airborne dust, for example. So if you're working in a laboratory, you will have a

dish with a blank piece of film on top of it and that petri dish will ensure that any airborne microplastics are considered as potential cross-contamination of your sample. So for example, if you are wearing a blue synthetic lab coat to the lab every day, which won't happen if you're doing microplastic analysis, it's all cotton based, it's all natural firers in the lab.

But say you were wearing a blue synthetic coat and your laboratory was blank, it had lots of fibres that happened to be blue and they are the same width, they're the same length. And you put that under a microscope and you can probably determine a bit of custom combination there. That's quite helpful to understand the sources of your microplastics. So for example, my research found a lot of fibres in my samples and that sort of opened a can of worms as to, okay.

where were the silk colonies that I was assessing, where were their colonies geographically, and what was the distance between waste water treatment plant outputs, right? And that we found like quite a strong correlation. So one of the main sources of marine microplastics is synthetic fibres from the washing of your synthetic clothes. Because

the wastewater treatment plants may not necessarily filter to the right side.

Gunnar Haid (00:22:25)

Well, they don't. I mean, they definitely don't filter to the nanos. Can you imagine filtering sewage to... Yeah, right.

James Hammond (00:22:29)

Australia.

James Hammond (00:22:38)

It's such an interesting point. don't think this can't be just me. mean, I'm in the industry and you just saying that, the washing of synthetic clothes and that effluent, you know, that grey water that then goes from your washing machine into the sewer out of the ocean. I just didn't really, it just isn't something that's front of mind for me. So if you asked me to name you a number of sources of microplastics, I don't think that would have even come into my head. But when you think about it, I'm sure that would be a

a significant source because it's something that just happens all the time if you're just constantly pumping out into the environment.

Brooke Kelly (00:23:13)

the biosolid waste that we get from wastewater treatment plants are directly applied as fertilizer to our farms. therefore you've got a huge amount of microplastics in our farmland soil, which is therefore getting either uptaken by our crops or it's being grown into the grass that our cows eat, for example. That's how we're getting microplastics in our beef and in our light soil.

James Hammond (00:23:41)

Obviously microplastics are to some extent resistant to breaking down, but am I right in thinking that those biosolids, for example, that get into farmland and they're not really breaking down in any way. There's no natural or biological processes that are typically breaking those down and to a point where they may...

Brooke Kelly (00:23:58)

biological processes specifically? Right. The answer is yes. They do exist. Imagine the example of microplastics in a cow's paddock, right? So you've got hemiphylbration from like UV light. You've got like the mix up of the microplastics in the soil through sort of subsurface animals, let's call them. There is biological breakdown as well. It's something sort

 my memory.

James Hammond (00:24:29)

but in terms of biological conversion into other kinds of compounds like non-plastic compounds.

Brooke Kelly (00:24:34)

Sort of like the degradation of the plastic full stop, I can't talk to, but definitely like the desorption of any like additives or any other contaminants that have been sort of along the way tapped onto the plastic, that would definitely happen. it's all about becoming bioavailable, right? So PFAS has been associated with it, all sorts of PCBs, heavy metals have been associated with plastics that have been up taken by an animal and then become bioavailable within the animal.

James Hammond (00:25:09)

Awesome, thanks. Sorry, Gunnar, I will throw back. Let's get back to the blood now.

Gunnar Haid (00:25:12)

That's okay. So there is counting as a method and you know, we can all agree this is okay. We count fine. If you can see them, but that only goes to, you're already struggling with asbestos fibres and they are most certainly in the micrometre scale. Below that, what's the next thing you mentioned gas chromatography. How does that work? And what are the drawbacks there?

Brooke Kelly (00:25:35)

Yeah, in an assessment of nanoplastic that's when you would basically bring in the mass spectrometry so that will break down any sort of proteins in your biological sample and leave your synthetic materials available for you to look at there. That makes it a bit difficult when we're dealing with protein-rich samples, so say a blood sample. They've also looked at microplastics in the brain and the potential causes to dementia or

potential linkages to dementia. In that case, MS is sort of a bit of a problem, right? So if you had a water sample, you can send that off to MS tomorrow. But for the biological samples, it's a bit more difficult because of that limitation of the technique.

Gunnar Haid (00:26:21)

Yeah, the way how I understand it is that the signal that microplastics send to the gas chromatograph are very, very similar to the signals that certain proteins or fat molecules would send to the gas chromatograph. there has been, I mean, this is one of the big criticisms of the New England Journal of Medicine study where it was that the lab methods they used was gas chromatography.

And a lot of it was very fatty tissue because they were looking at cholesterol in arteries. And it is quite well known that, yeah, that they have a tendency for false positives, which is, which is, which is bad. we we're having something that we're looking for something in at, at a scale that is tiny, tiny. And we're getting false positives from something that is very, very present and heavily present in my sample. All right.

So you mentioned before that the presence of the microplastics themselves may not be so bad, except for that they allow other contaminants to hitch a ride into biological systems. A fantastic podcast on the subject is Dr. Carl's Shirtload of Science. And he interviewed Professor Michaela Lucas from WA. She's done.

A lot of research there. It's a fantastic podcast. link to it. She mentions that especially the bisphenols and the phthalates. So phthalates are the stuff in plastic that make it soft. So your, glad wrap would have a lot of phthalates in it. And that they were suspect that these would be mimicking human hormones and hence would also act as endocrine disruptors. So they interfere with the hormonal system.

Again, not a lot of causal effect there, but a lot of correlations there. Are you aware of that research? And you already mentioned the endocrine disruptors and the mimicking of hormones. Just give us a few words on that.

Brooke Kelly (00:28:32)

Yeah, as a physical contaminant, we don't know the extent of impact in humans. I can definitely talk to animals. basically the ingestion of macro plastics and also, you know, macro plastics and all sorts of things can obstruct your gut, for example, your gastrointestinal tract, and that can lead to fatalities has been proved in marine species. The other concern is basically - If you imagine it's quite a famous image of like a seabird carcass, for example, and its stomach is just full of plastic, right? So it's a gut obstruction, yes, but it's also like this feeling of being full, which means that basically they can't pass through the macro and microplastics. They can't pass that through their system and therefore they have no space to eat their natural food. So that won't be necessarily a problem in humans.

Except for maybe, maybe, maybe children. But definitely, I think from like a physical annoyance, I would be a bit more worried about the respiratory aspect of things.

Gunnar Haid (00:29:42)

Hang on, is that actually a physical problem because they are so big that they obstruct the gastrointestinal system of seabirds? okay.

Brooke Kelly (00:29:50)

I mean, that would be more so macro plastic. Yes. I mean, it depends on the size of your animal, right? Microplastic is my all-power.

James Hammond (00:29:58)

I was going to say that that classic image that you mentioned like the carcass of the bird with, you know, the bottle cap and everything else in its stomach. think my non-expert understanding was, yeah, it's that kind of mix. And we know that macroplastics or I suppose you could call that litter. I don't know if that's the right term, but it is also important because ultimately it will degrade and break down into those smaller...

plastics right? Like you said it depends on the size of the animal and I guess and the size of their digestive tract but I imagine that also even for larger animals it's going to be a mix of macro and micro and together yeah they can form those kinds of obstructions.

Brooke Kelly (00:30:31)

Yeah, definitely. And if you imagine the GIT track of any animal, it's not a very pleasant environment to be in. So chemical degradation can occur within the animal. so your size can be reduced and therefore, you know, your, whether your, your plastic particles become able to pass the barrier between cells is a problem.

James Hammond (00:30:57)

We haven't really talked about, I guess, like policy responses to this and how we control things upstream, but I feel like to get a big part of getting broad public support for controls on things that are really useful like plastics.

those emotive images can be sometimes be really helpful, I guess, to build that broad public support from people who are not in the industry and not dealing with this stuff every day. And so that image, and I'm sure everyone can imagine it, right? So that's not entirely accurate for microplastics, but I'm just wondering, like, yeah, what we kind of need some kind of image that really cuts through for microplastics that really, it makes it hit home for people who don't deal with this stuff every day. Those emotive things are really important in building public support for action.

Brooke Kelly (00:31:41)

That's so true. know, micros and nanos are difficult to even see in the labs. It's difficult to put that into a visual impact. But unfortunately for me as a scientist, I think the scary stuff, the emotive stuff comes from the data, right? So there was recently a study in Australia, I think it was in Queensland, and they looked at sort of six different areas of everyday life and was there...

microplastics in airborne dust. So there was, you know, an office, a car, living room, and then a childcare centre. And guess who was most exposed to airborne microplastics? But the children. Literally, and their playpen is made of plastic, right? So I think it's like facts like that where that's where the emotive response comes from.

James Hammond (00:32:20)

The one with all the plastic toys in there, right?

Gunnar Haid (00:32:34)

Okay, let me read the asshole again here, okay?

James Hammond (00:32:41)

 That is your shtick on this this podcast. If people don't know that already, haven't been listening long enough.

Gunnar Haid (00:32:49)

 It looks to me like we are far away from knowing any negative, okay, not any negative effects, but health effects. At this stage, it almost looks like, the easiest solution is we stop living, stop breathing, stop eating. Do you even spoke about dermal absorption? So at this stage, it is so omnipresent. And I know this was exactly the argument that the, in the early days of asbestos that came along.

Brooke Kelly (00:33:01)

Okay.

James Hammond (00:33:19)

And stop making and using plastic, right? So like stopping the sauce as well, like if we want to take-

Gunnar Haid (00:33:24)

Good luck with that one. But that's what they said. I'm very much aware. That is what the one of the main counter arguments against the phasing out of asbestos was. So I'm very much aware of that. At this stage, it looks to me though, that there is a lot of literature out there and a lot of, I wouldn't even call it literature, but there's a lot of meteor storms out there with all sorts of nice pictures and my God, we found it God knows where.

Well, the actual negative health effects haven't been shown yet. They have not been correlated to the microplastics. So I don't know when Hammond, when you asked for what kind of emotive picture can we find to make everybody aware of it, I'm thinking, do we really need one? Before we have any conclusive scientific evidence that we are actually having a microplastics health problem in humans at least. And I know I'm not thinking of the crustaceans and the...

 Polar bear testicles here. I think you know where I'm coming from here. This is early days. It is very early days. And for something that is so of research that is in such early days, we are making an awful lot of noise.

Brooke Kelly (00:34:41)

Yes, my first argument back at you is it's not all human health. There are lots of other species on this earth. I understand what you're saying. think there are a lot of scientists out there who would argue, even though my research doesn't 100 % prove causation, please just look at what I am hypothesizing.

Lots of research about it. are links to be made between different diseases and microplastics exposure. And yes, like, you know, a lot of the cause is from chemicals that are associated with microplastics. Microplastics is going to be, you know, a vector of additional chemicals that can cause these problems. Then why not reduce them?

James Hammond (00:35:39)

Yeah.

Gunnar Haid (00:35:40)

I agree completely. is no argument here. I'm a little bit less of someone who wants to pull the panic button here, which happens a lot. With PFAS, it's a classic one. There's a complete worldwide panic going on while we haven't got any evidence yet. I see similarities here on that subject as well.

Yeah, there's a nice... Keep researching and look, no question. We shouldn't find plastics in everything. You cannot find a sample of anything anymore without microplastics. It's impossible. So that shouldn't be happening. There's no question about that. Whether we should panic about it is another question.

Brooke Kelly (00:36:23)

 The other thing to consider is bioaccumulation, right? Which is a huge factor here. Biomagnification throughout the food chain, humans as an apex predator, definitely need to factor that into your consideration of the importance of this issue.

James Hammond (00:36:37)

What you're talking about there Brooke is that it's that precautionary principle, isn't it? And when we were talking on the PFAS pod, we were talking about how the management or the regulation of PFAS and its control and how far PFAS management has come. Like you were saying, we've got national guideline limits. We've got a whole range of criteria now that we can use that are quantitative, even though there is not definitive proof.

of its health impacts on humans. That can be seen as one of the successes, I think, of the precautionary principle in modern time. What we talked about on that was very similar here, which is like, you've got these contaminants that have a set of criteria, like persistence in the environment, like they're bioaccumulative, like they have vectors for other chemicals and a range of other things. And so even though we may not have definitive proof of their impact, the fact that they meet those criteria, none of which are very good, is reason enough to have that push to phase them out.

The most challenging situations that I think of around this is like where you have a situation where you're talking about reducing or phasing out microplastics, but on the other hand, you have another beneficial environmental outcome. And the example that comes to mind with this is the reuse of any kind of recovered material. So on the one hand, you've got an environmental benefit in that you're...

using reclaimed or recycled materials to offset virgin products and all the, in particular the carbon cost that comes with that. And on the other hand, you know, they contain microplastics in varying degrees. And on the other hand, you have expected or potential impact of microplastics that we haven't quite quantified yet. They're the really difficult situations that I find at the moment. Like, do you want to just comment on that and how you see those things being weighed up and decisions around that?

Brooke Kelly (00:38:25)

I think it could be two birds with one stone, right? So get rid of plastics, get rid of the chemicals associated with it. Yeah, I think acting on one worked on the other. And I think that's a women's scenario that we shouldn't take for granted.

Gunnar Haid (00:38:40)

Do there is a chance that we re-engineer our plastics if we decide, hey, all right, this is enough, this is enough, we can't have those plastics running around in our environment and causing potential havoc? Do you think that there will be a technical solution to this where material scientists come up with, all right, here is a plastic or a plastic-like substance that doesn't break down like this or where the smallest...

peace in breakdown is still reasonably filterable or visible to humans. Because I tell you what, I have very little hope of phasing out of our lives.

James Hammond (00:39:23)

It seems unachievable certainly at the moment, doesn't

Gunnar Haid (00:39:28)

seems almost a step that is, yeah, unachievable as you said, Hammond.

Brooke Kelly (00:39:34)

Yeah, there's, it's an interesting debate as to plastic alternatives. If you look in New South Wales, we've banned the bag. But because of that, we now have paper bags all over the place.

Gunnar Haid (00:39:48)

Yeah, don't get me going. On that subject, that... man. Okay. I'm not allowed to rant that much anymore. But if you get me going on the phasing out of plastic bags and plastic straws, don't...

James Hammond (00:40:04)

They're usable bags, they're nylon bags, right? I mean imagine they would shed microplastics over time.

Gunnar Haid (00:40:11)

You know, not only that, but the carbon impact on one of those plastic bags is between 400 and 2000 times more than the plastic bags we had. So you have to reuse your reusable plastic bag 2000 times. Yeah, because that's what you're going to do. So we have, this is a classic step where we have most certainly meant to do the right thing and we have completely screwed it up.

Brooke Kelly (00:40:34)

Yeah. Yes. Yeah. think it's a balancing act, right? It's a juggling act and we need to consider the whole sustainability outlook on what we're doing. And yeah, to answer your initial question, if we found a plastic alternative, brilliant. There's been like stories popping up of seaweed made.

similar items that have some properties of plastic. There's quite a few like good news stories coming out in terms of remediation plans. So there's a substance that's made from jellyfish mucus, which they

Gunnar Haid (00:41:16)

 Let's get into jellyfish farming. This is like the future here.

Brooke Kelly (00:41:26)

 so yeah, I mean, it's a sustainable product. and it's basically like a microplastics filter, right? That you can apply it like a wastewater treatment plant. that's like a microplastic solution. and it doesn't exactly answer your initial question, but like, you know, finding a solution that is made from a sustainable source. there's.

Gunnar Haid (00:41:51)

Yeah, I have feeling this is where we need to go. That area. mean, not necessary jellyfish mucus, okay? But alternatives.

Brooke Kelly (00:41:54)

This is.

Brooke Kelly (00:41:59)

What might add to it? So there's something called a micro cleaner, is another like basically plastic cleanup solution. So that one is made from something called chitosan, which is basically from shellfish waste. And they're actually really cool. they're called soft and dendritic colour. It's right. So imagine the spider web like, like a branching tree. The micro cleaners can self disperse in water.

they sink to the bottom and while they sink to the bottom of the water column, they pick up all of the microplastics within the water column and they can basically float back up to the top for like removal. So for skimming removal from the water.

Gunnar Haid (00:42:45)

So we have to stop eating lobster. Because their poo is way more important.

James Hammond (00:42:53)

Now we've got to eat more of it so we can generate more shellfish waste that can be used for that.

Gunnar Haid (00:42:58)

sorry, we talking shellfish waste as in dead shellfish or shellfish poo?

Brooke Kelly (00:43:06)

question I assume it was you James, I assume that it was sort of exoskeleton sort of thing.

James Hammond (00:43:12)

shells.

Gunnar Haid (00:43:13)

well then, let's go into the Seafood buffet.

James Hammond (00:43:17)

I feel like material science as a discipline, I feel is just one of the great opportunities of the future. I just think that there's such a need for, yeah, like innovation in materials. I just think there's a big thing there. When we're talking about phasing out plastics, I think it's really important for us to distinguish between, there's different kinds of plastics, I guess. And I think my personal opinion is I think that the management approaches to them probably needs to be different. So I think that there's a big difference between say like single use plastics.

versus kind of heavier duty plastics that are used in construction or in vehicles or other things like that. And I feel like they need different approaches because the biggest issue with single use plastics is they're being discarded and often, I guess, littered and finding their way into the environment that way. Whereas with heavier duty plastics, one of their critical design elements is that they don't break down over time. But I think there's a big opportunity more for product stewardship.

on that side of things because they're higher value, used for a longer period of time, and the manufacturers could potentially have more of a role in taking those materials back, reprocessing them, and then recirculating them into new products.

Brooke Kelly (00:44:27)

We've got the same problem in terms of, in terms of like technologies for identifying plastic in environmental and biological samples, right? There's all different types of plastic and they all have different properties. And you're so right in that like one durable plastic might get more uses out of it, but therefore will it be harder to dispose of at end of life? There is, I'm going to mention the federal government in Australia, their national plastics plan.

So that was generated in 2021. They did lay out a few of the items that was sort of like calling for, right? So by 2025, the plan wanted to have the average recycled content within plastic packaging be 50%. So that's in terms of recycle, well, joking aside, I recycle plastics, but that's that. They wanted 75 % of plastic packaging to be recycled or composted.

They wanted 100 % of packaging to be reusable, recyclable or compostable. They wanted to phase out problematic and unnecessary single use plastics packaging. And then by 2030, they wanted to phase in an industry led phase in of microfiber filters. So it's good to know that people are thinking about this. federal government has thought of this and, you know, they've got plans in place to go forward with that.

James Hammond (00:45:51)

I was just wondering if you could spend a few minutes to go back to what we talking about. How do we get to a place where we have some quantitative measures that we can use to assess when we're talking about putting microplastics out into the environment or in human exposure scenario? And then also how risk assessors are dealing with microplastics in their work.

Brooke Kelly (00:46:09)

I think it comes back down to the fact that it's difficult to assess human health limits and toxicity limits for humans because that data isn't ready, right? It's not ready for us to put into a framework like say PFAS would be. Animal exposure, ecological exposure is to me a different story, but those criteria and that regulatory framework does not yet exist.

Like, I don't know if you guys remember before PFAS was regulated, there was one or two companies in Australia. I won't name them, but they were extremely proud of the fact that they saw this regulatory change coming. And therefore they took the steps in 2019 or whatever it was to phase out PFAS in their Fire Foam systems before it was required. I had a project.

where there was a brand new PFAS fire suppression system in sort in 2016. And I always just think that if that bloke, whoever, like my client, if he had had a chat over a beer at a pub with someone who was in the know and said, look, maybe it's not a good idea. Maybe just wait and then find an alternative. think that's sort of the state where we're at. So while we don't have it yet.

I think it will be coming especially for that ecological exposure because there is data out there on a population level and at an individual level that can inform those risk assessment decisions.

Gunnar Haid (00:47:49)

 So the bottom line of it all is it's an issue that we should probably be concerned about. But is it right that we say we are kind of a long way from knowing what to actually do about it? But several times here we have mentioned that it's all nice and good and we should have more beer and drinking games, which is something we definitely know is harmful to humans. But hey, I'm not going there again.

James Hammond (00:48:16)

I'm on your side with that one, Brooke. Maybe not so much drinking games anymore. I'm almost 40. So maybe not so many drinking games, but you know, a quiet one on a Friday afternoon. Yeah, nothing wrong with that.

Brooke Kelly (00:48:27)

 Hey, that wasn't my uni days, but those days.

Gunnar Haid (00:48:32)

Thanks.

James Hammond (00:48:33)

 I don't want to just kind of repeat what is said in other reports and that sort of thing, but Health Academy report that we talked about before did raise, I guess, four points, like four recommendations. The first one was that we have to continue building the evidence base. The second one that we need to look at who's most vulnerable to exposures. The third is that we need to review how this is regulated. Number four, that we need to look at building public awareness and exposure reduction. So guess that's that precautionary.

reduction. I mean, to me, that was quite a nice framework, I guess, as to how we on one hand, build our knowledge, I continue investing in our knowledge, but on the other hand, take steps towards phasing, you know, these materials out or removing these materials from the environment, even if we don't go sort of all the way just yet, at least start the process. Like is that kind of is that how you interpret that as well, Brooke? Or did you have anything to add to that?

Brooke Kelly (00:49:31)

Yeah, yeah, I definitely agree with all of those points. The fact we have uncertainty doesn't mean that there's a cause for inaction there. And I think, yeah, we understand who the potentially more vulnerable communities are. So those might be lower socioeconomic communities where plastic alternatives aren't available.

They might be remote or rural communities for the same reason. We know that, you know, humans that they're most vulnerable in those early developmental stages are potentially, well, they are exposed. So potential impacts might be, you know, more intense for them. So yeah, it all comes down to the precautionary measures, right? And I think plastics is...

such a widespread and obvious problem. like the research that I was saying where we know that it's in like the highest concentrations in our childcare centres. Right. If we have that data, then we can fix it. We can take steps to limit our plastic exposure. If your listener is concerned about their own safety, then limit your plastic use and exposure. Like it's that simple. It's...

whereas like the rest of the contaminants that you might be talking about on your podcast you might not have that control over.

James Hammond (00:51:03)

I mean, I think that point you made there Brooke was just kind of a nice one to end on actually, which is that to some extent, I mean, there are certain things that are outside of our control and there are things that had to be done at a higher level, but there are also things that we can do as individuals and choices we can make as individuals that can help limit our own exposure and perhaps also reduce some of the like economic demand, I guess for plastic products and that sort of thing.

Brooke Kelly (00:51:31)

Definitely, I agree with that.

Gunnar Haid (00:51:33)

Brooke, thanks for joining us and it's been a long time coming.

James Hammond (00:51:36)

That was awesome. so you're continuing to be, you're obviously continue to be involved in this space, right? So you are you actively involved in that research work in the moment? is that on hold while you're sort of, you're focusing on the field?

Brooke Kelly (00:51:48)

not actively involved in any research unfortunately. I think it's important to stick with what you know and stick with what you're passionate about so I don't think it's going away anytime soon.

James Hammond (00:51:51)

You clearly still tapped into that.

James Hammond (00:52:02)

No, that's great. No, I found that really interesting book. I've learned heaps in talking to you.

Brooke Kelly (00:52:06)

Thank appreciate all of your time and all of your effort. Those were some really good links that you guys sent through.

James Hammond (00:52:11)

Thank you, Brooke. The links that I actually did send, Kunal.

Gunnar Haid (00:52:18)

You

James Hammond (00:52:20)

Thanks, Brooke. Enjoy the rest of your afternoon.

Brooke Kelly (00:52:22)

Thank you. Thanks for your time. really appreciate it.

James Hammond (00:52:24)

 Thanks for your time Brooke, that was awesome.