What are microplastics?

If you look out at the sky at night, you might be able to see a glimpse of the 100 billion stars in our galaxy. It’s an extraordinary and unfathomably large number. Consider then, that there are 500 times more microplastic particles in the sea than stars in the galaxy. So should we be concerned about the vast number of microplastics in our waterways? Anglia Ruskin University’s Danni Green…

Danni - A microplastic is essentially as the name would imply, a small piece of plastic. Now there's been lots of different definitions, but the one that's generally accepted was defined by Hartmann et al. in 2019 and a whole group of other scientists. And it is that it's pieces of plastic that are less than a thousand micrometres, so less than one millimetre in size. This can include a range of different polymer types and they can come from different places. They can either come already small, such as primary microplastics, things like the microbeads in exfoliants, if you remember that kind of thing and abrasive cleaners. But more commonly microplastics are formed by the breakdown of larger items and these are called secondary microplastics.

Will - I do remember when I was doing my Master's and someone came in to talk to us about microplastics and a really striking representation of just how prescient they are is they had a bottle of shampoo, a clear glass bottle and said, this is the amount of microplastics in it. And maybe 40% of the capacity of the bottle was made up of these little things.

Danni - Yes, exactly. The micro beads, I mean, in the environment, the beads are actually very rare. I've only ever found, in my own research, I only ever found one off the coast of Portugal somewhere, this little blue micro bead <laugh>. But the majority of microplastics that we find in the environment are different shapes. So fragments, films, fibres, car tire particles, so little bits of car tire that are broken off and things like that. But yeah, there's a huge diversity of microplastic types.

Will - We all hear the word plastic, but there's loads of different kinds of plastic. Presumably that means there's loads of different kinds of microplastics.

Danni - Yes, exactly. Yeah. Lots of different types of plastics, different types of microplastics, lots of different additives that go into plastics, different coatings and things. So it does get very complicated trying to define them.

Will - Crucially though, none of them are good. Is that fair to say?

Danni - No, exactly. They're not something that we want in the environment or contaminate us either.

Will - So to that end, how widespread are they?

Danni - Extremely. I mean, I'd be a lot more surprised if you could tell me somewhere they're not. We found microplastics down the bottom of the Mariana Trench, all the way up from Mount Everest. You know, not completely surprising. because we've found plastic bags as well at the bottom of the Mariana Trench, you know, so we're finding big bits of plastic too. So of course there's going to be microplastics there. So microplastics are everywhere. They're in the air that we breathe, they're in the water that we drink, they're in a lot of foods that we eat. They're in organisms, macro fauna, fish, mammals, pretty much everything really.

Will - That kind of implies then that we do end up interacting with them daily and quite a lot.

Danni - Yes. And there, there is evidence for that because we have found microplastics in human placenta, in faeces, blood, and other organs. I would note as well that there are some discrepancies between academics amongst the exact amount of microplastics because some of these studies didn't include very good quality controls, but it's not to say that there's disagreement that they are in humans, it's that we're disagreeing over how many there are. But yes, we are definitely interacting with them.

Will - As a recent study came out said that there's 250,000 microplastic particles in every bottle of water, we are inevitably going to consume and ingest a fair amount of them. I mean, what's the worry with that? Is there a potential health harm?

Danni - There is potential health harm. It's difficult to tell at this stage because obviously you can't experiment on humans, right? We're not going to get ethical approval to do experiments to see exactly what the impacts are. But we do know from studies on animals and invertebrates that it can have effects on development and growth and general kind of health and immune responses even and things like that. So it's not a huge leap to say that there might be impacts on people. And there are some studies coming out from the medical profession that there's correlations between the size of babies that have been born and the amount of microplastics, but it's more correlation than causation at this stage. And I'd say we should be applying the precautionary principle anyway. We don't really need to wait and find out do we?

Will - Are the microplastics themselves the only concern, obviously we're concerned about them and they're seen basically near ubiquitous at this point, but are they also enabling other harmful chemicals as well?

Danni - Yeah, so the interesting thing about plastics as a contaminant is that they're essentially a double-edged sword or potentially triple-edged. You've got the physical contaminant, so the actual solid piece of plastic itself, and then you've got this chemical contaminant. So you've got either persistent organic pollutants that they might absorb from the environment and then release all the plasticisers and different chemicals that they're made with to begin. And these can also leach out. And then you've got the biological aspect of microbial communities living on them, which might also have an effect. So you've got this sort of triple edged sword in one contaminant. There's also forever chemicals of course that are a huge concern at the moment. These have been found in the environment and in organisms in marine freshwater, terrestrial, in human food stuffs and water as well.

Will - Do they have a particular relationship to microplastics?

Danni - Yeah, so a lot of plastics, particularly food, plastics, are made with these per and polyfluorinated alcohol substances or PFAS substances. These help to improve the function of the item by repelling water and oil. So they make the plastic function better, but there might be a negative consequence of that in terms of human health.