Microplastics are ending up in oysters and clams – after being shed from sports clothing in the laundry.
Researchers found 11 microplastic pieces per oyster and nine per clam on stretches of coastline known for their ‘pristine’ waters.
The study revealed invasive microfilaments are being shed into the sea from yoga pants, fleece jackets, and sweat-removing clothing at a rate of up to 700,000 per laundry load.
Co-author Britta Baechler, of Portland State University in the US, said: ‘Those particles then travel out through greywater into wastewater and to the coast.’
The environmental experts found microplastics at every site and in all but two of the roughly 300 organisms sampled, including oysters and clams (stock)
Blame for the pollution is often pinned on fisheries and oyster growers, whose derelict fishing gear can be a source of microfibers.
But researchers said there was ‘no scientific consensus’ for that belief.
Miss Baechler, a PhD student, added: ‘It’s not because people aren’t managing our fisheries well or are being unclean in their practices.
‘We’re all using plastics on a daily basis. We are all the source of contamination in our seafood.
‘And microplastics are not just in our seafood. We know that they are in our beer, in our salt, in our drinking water.’
The team collected samples of Pacific oysters and razor clams from 15 sites along the Oregon coastline, in the northwest of the US, during the spring and summer of 2017.
They were aiming to explain microplastic concentrations in the organisms, which are a key part of Oregon’s economy and maritime culture.
The environmental experts found microplastics at every site and in all but two of the roughly 300 organisms sampled.
Study co-author Professor Elise Granek, also of Portland State University, said: ‘Whether it was a fairly urban site or a rural site, estuary or open-coast beach, both species had microplastics.
‘Although we think of the Oregon coast as a much more pristine coastline compared to California, Puget Sound or the Eastern Seaboard, when we are talking about microplastics, we’re still seeing that human footprint even on our cleaner coastline.’
Microplastics – tiny plastic particles measuring less than five millimetres are pictured under a microscope
Microplastics (pictured in this file photo) have hit headlines over recent years, as they have been detected in marine water, wastewater, fresh water, food, air and drinking-water, both bottled and tap water
There were more microplastics in spring oysters than summer ones, which the researchers say could be due to rainfall and clothing typically worn in the chillier season.
The researchers said more work is now needed to understand how microplastics affect organisms and the humans who consume them.
Other studies have shown that microplastics can cause reproductive and growth impairments on oysters and clams.
The study revealed invasive microfilaments are being shed into the sea from yoga pants, fleece jackets, and sweat-removing clothing at a rate of up to 700,000 per laundry load
Miss Baechler added: ‘If reproduction or growth is impaired, that could really affect not just individual clams or oysters, but possibly local populations of these organisms as well.’
Engineers are now designing filters to attach to washing machines. But researchers say it is unclear whether they can prevent microfibers from entering the sea, or whether the general public would be able to afford them.
The study was published in the journal Limnology and Oceanography Letters.
Microplastics enter the waterways through a variety of means and finish suspended in the liquid. They can be transported long distances both in water and via the air, taking them to the furthest corners of the world