Microplastics carry viruses and pose a risk to children playing on the beach, a study has found.
Scientists have proved for the first time that viruses can survive and stay infectious for up to three days by "hitchhiking" on microplastics in fresh water.
Microplastics are carried into rivers from household water waste, deposited in cosmetic products or from laundry, with microfibres from synthetic textiles forming a major source.
They also come from run-off from roads, which goes into sewer systems. Microplastic from either source can make its way into rivers and the sea even if the water is treated at sewage works.
The study suggests that they can then combine with viruses in the sewage system, meaning they can persist for longer and are more likely to contaminate water and make swimmers and beachgoers ill.
Researchers at the University of Stirling added viruses to microplastic pellets soaked in water from a nearby lake, and then tested them to see if the virus stayed on the surface of the plastic.
'Novel pathway for viral dissemination'
The results, published in the journal Environmental Pollution, suggest that plastic pollution could become a new way for viruses to spread.
The finding "emphasises the potential for plastic pollution to act as a novel pathway for viral dissemination and persistence in the environment", the study concluded.
Testing showed that viruses such as rotavirus and norovirus, which cause vomiting, survived more effectively than the flu virus.
Viruses can also bind to natural surfaces in the environment, but plastic lasts a lot longer than those materials, the authors said.
Swimmers have become sick after swimming in river and sea water around the UK, amid growing concern about raw sewage releases and the effectiveness of current water treatment methods.
Earlier this month, research by the campaign group Surfers Against Sewage found that 55 per cent of those who had tried wild swimming had fallen ill afterwards.
'It doesn't take many virus particles to make you sick'
Professor Richard Quilliam, the lead researcher on the project at the University of Stirling, said: "We found that viruses can attach to microplastics, which allows them to survive in the water for three days, possibly longer.
"Even if a wastewater treatment plant is doing everything it can to clean sewage waste, the water discharged still has microplastics in it, which are then transported down the river, into the estuary and end up on the beach.
"We weren’t sure how well viruses could survive by ‘hitch-hiking’ on plastic in the environment, but they do survive, and they do remain infectious.
"Microplastics are so small that they could potentially be ingested by someone swimming, and sometimes they wash up on the beach as lentil-sized, brightly coloured pellets called nurdles that children might pick up and put in their mouths.
"It doesn’t take many virus particles to make you sick. And if the viruses then release themselves from the plastic into the water or the sand, their persistence in the environment is increased."
