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The accumulation of microplastics in soil presents an emerging threat to the UK’s food security, according to scientists, MPs and campaigners who have called for legally binding targets to cut microplastic pollution.
UK agricultural soils have been identified as among the most contaminated by microplastics in Europe, often as a result of repeated applications of sludge from water treatment works as fertiliser, according to a report published by the all-party parliamentary group (APPG) on microplastics.
With extreme weather caused by climate breakdown already placing new pressures on agriculture, protecting soil from additional and unknown pressures is becoming increasingly important, it argues.
Alberto Costa, the MP for South Leicestershire and chair of the APPG, said: “Despite the evidence, the UK’s response remains limited. Existing measures tackle only a tiny proportion of microplastic emissions. We urgently need a preventative approach focused on reducing microplastic releases at source to protect human health and food security.”
Prof Cressida Bowyer, the director of the Revolution Plastics Institute at the University of Portsmouth, was the senior author on the report, produced in collaboration with the APPG and the Women’s Institute. The report follows up an earlier collaboration that focused on plastic microfibres from synthetic textiles.
Microplastics are pieces of plastic between 1 micrometre and 5 millimetres in size. They are often shed by the breakdown of everyday plastic items such as synthetic textiles, packaging, paints, cosmetics or car tyres.
Nanoplastics are particles smaller than 1 micrometre, which makes them small enough to permeate through biological membranes. “Everywhere we look, we find them,” Bowyer said. “Doesn’t matter how deep, how high, how obscure the sampling site, we will find microplastics. And similarly we’re finding microplastics now throughout the human body.”
She added: “We’re starting to realise that our exposure to microplastics is happening across the whole of the plastics lifecycle. So not just during the production phase and at the disposal end, where most people think of microplastics contamination occurring. But also during our use of plastic, when we’re using plastic packaging or when we’re wrapping ourselves in that lovely soft, cosy blanket on the sofa, or chopping our mushrooms on that plastic chopping board.”
Submissions of evidence to the report showed particular concerns around the presence of microplastics in soil, which Bowyer said “impacts the biological, the chemical and the physical functioning of the soil and the soil fertility itself”.
According to Bowyer, plastic particles affect the soil structure, changing the water capacity of soil; they affect the microbial community, the bacteria and fungi that are crucial to soil health; and they affect the soil fauna, with earthworms ingesting microplastics undergoing physiological changes.
She said it was important to remember that “soil is not an inert material. It’s a complex living ecosystem; it’s very finely balanced. [It is a] complex ecosystem that supports the growth of crops that feed us. The second thing to remember that’s really important is that microplastics, they’re not just polymer particles … they’re basically chemical cocktails.”
There are more than 16,000 chemicals used in plastics. About 4,000 are known to be harmful to health, while most of the rest have never undergone safety testing, the report notes.
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“Microplastics can also pick up from the environment further contaminants,” Bowyer said. “So they become like sponges or magnets for other things like bacteria, heavy metals, viral particles, other chemicals.”
The report makes five policy recommendations: legally binding targets for cutting microplastic pollution, regulation of the largest sources of microplastic releases, extended producer responsibility to reduce releases across the plastics lifecycle, improved wastewater, sewage sludge and soil protections, and a coordinated national monitoring and evidence system to oversee the issue.
The report’s co-author Dr Antaya March, the director of the Revolution Plastics Institute’s Global Plastics Policy Centre, said: “The UK has an opportunity to move from a fragmented response to a coordinated strategy that tackles microplastics across the plastics lifecycle. We should not wait for every scientific uncertainty to be resolved before acting where the evidence already shows that intervention can prevent pollution and reduce future risks.”
The Department for Environment, Food and Rural Affairs was contacted for comment.
