Dangerous viruses can remain infectious for up to three days in fresh water by hitchhiking on plastic, the researchers found.
Enteric viruses that cause diarrhea and upset stomach, such as rotavirus, were found to survive in water by attaching to microplastics, tiny particles less than 5mm long. They remain infectious, researchers at the University of Stirling found, posing a potential health risk.
Professor Richard Quilliam, principal investigator on the project at the University of Stirling, said: “We found that viruses can attach to microplastics and that allows them to survive in water for three days, possibly longer.”
While previous research had been conducted in sterile settings, this is the first research on how viruses behave in the environment, Quilliam said. However, he used standard laboratory methods to determine whether the viruses found on microplastics in the water were infectious.
“We weren’t sure how well viruses could survive ‘hitchhiking’ on plastic in the environment, but they do survive and remain infectious,” he said.
The findings, part of a £1.85m project funded by the Natural Environment Research Council looking at how plastics carry bacteria and viruses, concluded that microplastics enabled the transfer of pathogens in the environment. The article is published in the journal Environmental Pollution.
“Being infectious in the environment for three days is enough to get from sewage treatment works to the public beach,” Quilliam said.
Wastewater treatment plants failed to capture microplastics, he said. “Even if a sewage treatment plant is doing its best to clean up sewage waste, the discharged water still has microplastics in it, which are then carried down the river, into the estuary, and end up on the beach.”
These plastic particles are so small that swimmers could swallow them. “Sometimes they wash up on the beach as brightly colored, lentil-sized pellets, called nurdles, that children can pick up and put in their mouths. It doesn’t take a lot of virus particles to make you sick,” Quilliam said.
While the impact of microplastics on human health remains uncertain, “if those microplastic fragments are colonized by human pathogens, then that could be a significant health risk,” Quilliam said.
The researchers tested two types of viruses: those that have an envelope around them, “a kind of lipid layer,” like the flu virus, and those that don’t, enteric viruses like rotavirus and norovirus. They found that in those with a coating, the envelope quickly dissolved and the virus died, while those without an envelope successfully bound to the microplastics and survived.
“Viruses can also stick to natural surfaces in the environment,” Quilliam said, “but plastic pollution outlasts those materials much longer.”
The researchers tested the viruses for three days, but their goal is to study how long they might remain infectious in future research.
Another study by Quilliam’s team last month found that fecal bacteria levels on baby wipes and cotton swabs washed up on beaches posed a health risk. They first found sewage bacteria “hitchhiking” on plastic pellets on Scottish beaches in 2019.
Source: www.theguardian.com