From salmon to shrimp, microplastics are in the seafood people eat: study

According to a new study by West Coast researchers, the tiny pieces of plastic that clothing, food packaging and other products shed are widespread in fish and shellfish

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Published Jan 10, 2025  •  2 minute read

Researchers investigated microplastic pollution in six commonly eaten West Coast seafood species, including Chinook salmon. Photo by Getty Images

The tiny pieces of plastic that synthetic clothes shed when washed and car tires leave behind on roadways as they wear are making their way into the seafood people eat, according to a new study by Portland State University (PSU) researchers.

For the study published in Frontiers in Toxicology, the researchers from PSU’s Applied Coastal Ecology Lab examined particle pollution in six commonly eaten West Coast seafood species: black rockfish, Chinook salmon, lingcod, Pacific herring, Pacific lamprey and pink shrimp.

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They found 1,806 particles in 180 of 182 fish and shellfish samples — evidence of the ubiquity of microplastics in the muscle tissue that people eat. Synthetic clothing fibres comprised 82 per cent of the particles; 17 per cent were microplastic fragments and 0.7 per cent were films.

“It’s very concerning that microfibres appear to move from the gut into other tissues such as muscle,” Susanne Brander, study author and an ecotoxicologist and associate professor in Oregon State University’s College of Agricultural Sciences, said in a statement. “This has wide implications for other organisms, potentially including humans too.”

Pink shrimp had the highest concentrations of particles, while chinook salmon had the lowest, followed by black rockfish and lingcod. Store-bought lingcod contained more particles than those purchased directly from the fishing boat, suggesting it picked up more contaminants from plastic packaging during processing.

Smaller animals, such as shrimp and herring, appeared to consume the most microplastics, said Elise Granek, study author and professor of environmental science and management at PSU — likely because the small particles resemble the zooplankton they feed on.

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The researchers say their findings underscore a need for more research into how these particles end up in muscle tissue, policies to regulate microplastic pollutants and solutions to curb their entry into marine environments.

Microplastics aren’t just a seafood problem. They’re everywhere, including in the air we breathe and the water we drink, and scientists are starting to understand how they could affect human health, including increased risk of infertility and lung and colon cancers.

Researchers from the Autonomous University of Barcelona recently observed that a single tea bag can release millions of nanoplastics and microplastics into a cup of tea. In January 2024, scientists at Ocean Conservancy and the University of Toronto found microplastics in 88 per cent of 16 commonly eaten proteins, such as beef, chicken, pork, tofu and several plant-based meat alternatives.

“If we are disposing of and utilizing products that release microplastics, those microplastics make their way into the environment and are taken up by things we eat,” said Granek. “What we put out into the environment ends up back on our plates.”

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