Magazine

A sea change in thinking on plastic waste

Plastic waste of all shapes and sizes is now ubiquitous in the oceans. Resource talks to marine litter expert Professor Richard Thompson about how microplastics have infiltrated the natural environment – and how we might solve the crisis

Professor Richard Thompson talks to Resource about marine plastic pollution.

Plastic is everywhere. Over the past year we have seen report after report on how it’s harming the environment, both on land and at sea, with society’s laissez faire attitude towards one of the world’s most versatile and useful materials coming increasingly under the microscope. Ocean plastic has particularly captured the public imagination, with few more influential in bringing the issue to light than Richard Thompson, Professor of Marine Biology and Director of the Marine Institute at the University of Plymouth.

Thompson is one of the foremost experts on marine plastic pollution in the world, leading the University of Plymouth’s International Marine Litter Research Unit and co-authoring the EU Marine Strategy Framework Directive text on marine litter. With over 170 publications on the subject, his work has gained international recognition, leading him to receive an OBE for services to marine science in the 2019 New Year Honours List.

Such success is not possible without a sincere passion for his work – a recent study published by the Research Unit contained many samples collected while Thompson was on his honeymoon (!) – but where did it all start? “It was really when I was doing my PhD and training to be a marine biologist,” recalls Thompson. “I’d have bits of litter arriving in the experiments that I was doing on the shoreline every day and I got curious about what it was and where it was coming from.”

His interest piqued, Thompson began to work with the Marine Conservation Society on beach clean-ups, where he was struck by the fact that surveys tended to focus on the larger pieces of plastic litter while ignoring smaller pieces. He sought to address this oversight when he moved into teaching, asking his students to go to the beach and search for the smallest item of plastic they could find.

Analysis of their sand samples revealed something surprising. “Almost from the first sample we looked at we could see pieces that certainly didn’t look like sand grains, pieces that looked like plastic amongst the sand itself,” says Thompson. “We later confirmed that they were indeed plastic pieces, some of them less than the diameter of a human hair. We described those very small pieces using the word microplastic.”

Thompson’s paper, ‘Lost At Sea: Where is all the plastic?’, published in the journal Science in 2004, was the first to use the term ‘microplastic’. Since then, it has become common parlance for the miniscule pieces of plastic found everywhere from the guts of fish on our plates to the deepest, darkest parts of the ocean.

Microplastics are currently classed as any plastic smaller than five millimetres in size. While this “isn’t technically micro”, Thompson says, it was a “pragmatic cut off point” to refer to all the plastic pieces that were more readily ingestible by marine creatures. These tiny plastic particles are “formed by the fragmentation of larger items” or are produced intentionally, such as those added to cosmetics like facial scrubs – a practice now banned in the UK thanks in part to work by Thompson. The smallest plastic particle currently detectable is 20 microns (0.02 millimetres), though the research community suspects there may be smaller.

Despite mounting concern over the presence of microplastics in the marine environment, it is still unclear how much damage they are doing to the organisms that ingest them. “The work done so far doesn’t tell us about harm, but perhaps it guides us as to where to look and how to look,” says Thompson. “We need to have a better understanding of what kinds and types of particles might accumulate. It’s the dose that’s the poison. Plastics are relatively inert and in small quantities probably aren’t a problem, but substantial accumulations might be a problem.”

There are three potential ways microplastics can cause harm, Thompson explains: physical disruption caused by accumulation; chemical transfer from chemicals included in the plastics, such as flame retardants; and chemical transfer from chemicals in the sea attaching to the microplastics. These ideas are yet to be proven, but the scientific community is certainly waking up to the necessity of proving them.

Growing interest from scientists means it is hard to know if the amount of microplastics in the ocean has sky-rocketed in recent years, or if there is now just much more research into the problem. “I’d say there were 400- odd studies last year and we’re also seeing an increase in our ability to detect the other smaller particles, so it’s difficult to separate changes in the actual environmental concentration from changes in our ability to detect particles”, says Thompson. One thing is for certain, however: the flow of plastic waste into the oceans must be stemmed.

There has been much debate over where the responsibility for marine pollution lies. A much-quoted 2017 study from the Helmholtz Centre for Environmental Research suggested that 90 per cent of all plastic in the oceans comes from 10 rivers in Africa and Asia, leading to calls for developing countries to improve their waste management systems, with help from developed countries. “It’s clear that a lot of litter is coming from rivers in some developing countries where the level of waste management infrastructure is not as advanced as our own”, Thompson concurs, but adds that in many cases, “the products that they’re struggling to deal with are products that have been exported from developed nations, to some extent in the knowledge that [the importing nations] don’t have the infrastructure in place to deal with the end-of-life consequences.”

It’s not simply a case of transplanting the waste management systems of developed nations into countries that are lacking them, Thompson says – our own beaches are often still litter-strewn. Instead, the entire way we think about plastics needs to be altered: “The current business model for the way we design, produce, use and dispose of plastics is not working. Something needs to change.”

Should we, as some have put it, look to turn off the plastic tap, or switch to alternative materials if we want to reduce the impact of plastics on the environment? Thompson is clear that we should focus our energy on preventing plastic from reaching beaches and oceans in the first place – “I would invest 95 per cent in stopping plastic getting to the oceans and five per cent on
clean up” – and he doesn’t see switching to alternative materials as the panacea to the plastic problem, given that “plastics are inherently fairly recyclable”. The problem, he says, is more in how they are being used. PET, for example, is a high-value recyclable polymer, but at the manufacturing or design stage it is often “contaminated or made very difficult to recycle by introducing pigments which can halve the value in recycling, or by wrapping the bottle in a full-height sleeve which can camouflage the bottle from our best recycling infrastructure.”

Thompson is also hesitant on the use of compostable or biodegradable plastic packaging. A recent study by the International Marine Litter Research Unit found that biodegradable and oxo-degradable plastic carrier bags were still present in soil and marine environments after three years – though compostables fared better – and as such are not a solution to plastic litter.

This article was taken from Issue 96

Manufacturers of these products were quick to agree, stating that they should only be disposed of in industrial composting facilities. But they can also cause confusion for consumers who might put them in with the general plastic waste stream, Thompson warns, posing problems for recyclers: “The last thing a recycler wants to see is a product that’s got a self destruct function in it.”

He continues: “There isn’t a single answer. It’s not about switching to a different material, it’s not about trying to make it all recyclable, it’s not about trying to make it all compostable – it’s about making sure that we’ve got the best fit in order to achieve a better overall environmental outcome than what we’re achieving at the moment.“

The issue of plastic and plastic waste looks set to occupy Thompson for some time to come. New concerns, such as the way plastic microfibres are released from clothing when washed, are beginning to draw attention, with some high street garments “shedding fibres four to five times faster than other garments”, according to Thompson. It is an issue he is already working on: “I think the issue of fibres has only recently come to the attention, but ours was the first paper to highlight just how many fibres could be released from a single wash – some 700,000 fibres.”

Whether he’s studying microplastics in the ocean or microfibres in our washing machines, Thompson’s message is clear: “It’s not about not using plastics, it’s about using plastics more responsibly.”