• Certain viruses can hitch a ride on microplastics to increase their odds of survival.
  • Viruses attached to plastic particles can stay infectious for up to three days.
  • Microplastics may come into contact with stomach bugs in sewage systems and deposit into rivers and lakes.

Plastic pollution in lakes and rivers is not only a risk to water-dwelling wildlife, but also to humans who may get sick after swimming.

More than half of Brits who have tried "wild swimming" in untreated waters have subsequently fallen ill, including many cases of gastrointestinal distress, the advocacy group Surfers Against Sewage reported in June.

Viruses that cause vomiting and diarrhea can stick to microplastics and stay infectious for up to three days in freshwater, according to a study published in the journal Environmental Pollution.

Researchers at the University of Stirling, in Scotland, experimented with tiny plastic pellets similar to those found in waterways around the world. They found that viruses were able to survive longer on the microplastics compared to natural materials.

Microplastics have been found in virtually every corner of the world since their discovery more than 20 years ago. They're no larger than grains of rice, and humans and animals unknowingly ingest them by drinking water and breathing air.

While scientists aren't entirely sure how microplastic consumption affects human health on a wide scale, recent research has revealed that plastic pollution can influence the survival of viruses in foreign environments, which has the potential to affect the spread of disease.

Plastics may pick up viruses in sewer systems

Microplastics can come from household waste and road run-off, either depositing directly into rivers or making their way through sewers.

The authors of the pollution study suggested that plastic particles meet viruses in sewage systems, since humans shed various pathogens in their poop.

Stomach bugs like norovirus and rotavirus are found in particularly high concentrations in human waste, they noted. Even after sewage is treated, these viruses have been detected in the sludge that's deposited in waterways and have been known to contaminate shellfish beds.

The same research group previously found sewage-borne pathogens, including the bacteria E. coli, on plastic waste that had washed up on beaches in Scotland.

Some viruses stick to plastics better than others

When viruses or bacteria combine with microplastics in the sewage system, they can survive for longer and travel further than they would on their own, increasing the risk to beachgoers and wildlife.

The researchers found that the rotavirus, a gastrointestinal virus that affects babies and children, stuck to the plastics better and was more likely to survive compared to the other virus tested. 

The rotavirus shares some structural similarities with other stomach bugs and the viruses that cause common colds, in that it lacks a viral envelope. Non-enveloped viruses may have a better chance at sticking to plastics, the authors concluded.

"It doesn't take many virus particles to make you sick," lead researcher Richard Quilliam told The Telegraph. "And if the viruses then release themselves from the plastic into the water or the sand, their persistence in the environment is increased."

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