If you eat fish or any kind of seafood, you are likely eating microplastics

Tiny microplastic particles that shed from everyday products like clothing, packaging, and other plastics are ending up in the fish people eat, according to new research conducted by Portland State University (PSU). 

The study highlights the need for strategies and technologies to curb microfiber pollution entering the environment and, ultimately, the human food chain.

Seafood contaminated with microplastics 

Previously, Portland State University’s Applied Coastal Ecology Lab – led by Elise Granek, professor of environmental science and management – investigated microplastics in bivalves like Pacific oysters and razor clams. 

Building on these findings, the researchers turned their attention to commonly consumed finfish and crustaceans.

Summer Traylor, who finished her master’s in environmental management in 2022, led the project with support from undergraduate environmental science major Marilyn Duncan, a 2024 graduate. 

They aimed to explore microplastic contamination in Oregon finfish and shellfish, examine differences across trophic levels, and understand how contamination might vary between fish acquired directly from research fishing vessels versus those from supermarkets and seafood vendors. 

Traylor’s work later helped her secure a position with the National Oceanic and Atmospheric Administration (NOAA), while Duncan plans to pursue microplastics research in graduate school.

Identifying microplastics in seafood species

The research team focused on six species of economic or cultural importance in Oregon: black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp. They evaluated the amount of anthropogenic particles – materials produced or modified by humans – found in the edible tissues of these species.

In collaboration with Susanne Brander, an ecotoxicologist and associate professor in Oregon State University’s College of Agricultural Sciences, the researchers confirmed a subset of suspected microplastics. 

The study, published in the journal Frontiers in Toxicology, reported 1,806 suspected particles across 180 of 182 individual samples. Fibers dominated the findings, followed by fragments and films.

Smaller species have higher contamination levels

Among the species tested, pink shrimp, which filter-feed close to the water’s surface, displayed the highest concentrations of particles in their edible tissues. Chinook salmon registered the lowest, with black rockfish and lingcod falling somewhere in the middle.

“We found that the smaller organisms that we sampled seem to be ingesting more anthropogenic, non-nutritious particles,” Granek said. 

“Shrimp and small fish, like herring, are eating smaller food items like zooplankton. Other studies have found high concentrations of plastics in the area in which zooplankton accumulate and these anthropogenic particles may resemble zooplankton and thus be taken up for animals that feed on zooplankton.”

Microplastic contamination in processed fish

Although the researchers initially believed that handling and packaging fish might introduce additional microplastics, their findings varied among the species. 

The experts rinsed off fillets and shrimp to simulate typical home preparation, suggesting that in certain cases, external contaminants on the surface may be washed away before cooking. 

Even so, the study provides clear evidence of widespread microplastic contamination within the tissues of Oregon’s marine and freshwater species.

“It’s very concerning that microfibers appear to move from the gut into other tissues such as muscle,” Brander said. “This has wide implications for other organisms, potentially including humans too.”

Microplastics are widespread in the environment 

The results signal the need for further research on how these particles move into muscle tissue, which humans consume, and on policy actions to regulate anthropogenic particles. 

“This project established critical baseline data for West Coast fisheries stakeholders and highlighted how much we still do not know about these pervasive microplastic pollutants,” Traylor noted. Now a NOAA Corps Officer, she is continuing to gather baseline microplastic data in the Gulf of Mexico.

Granek cautions against avoiding seafood altogether, reminding people that microplastics permeate many parts of our environment. 

“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,” she said. “What we put out into the environment ends up back on our plates.”

Finding solutions for safer seafood

In response to these findings, Granek’s lab is increasingly working toward finding viable solutions. 

“We’re continuing to do work to understand the effects of anthropogenic particles on animals, but we’re also moving into experimental work to test what are effective solutions to reduce microplastics entering marine ecosystems,” she explained.

Granek leads a $1.9 million NOAA-funded project exploring cost-effective filtration solutions for washing machines, dishwashers, and clothes dryers. 

Another project, supported by Oregon Sea Grant, will install six catch basin filters in stormwater drains in two coastal towns. These filters aim to reduce road runoff before it flows into waterways. Brander’s lab collaborates on both projects, further illustrating the collective effort to confront microplastic pollution.

As evidenced by this study, microplastics in marine species have broader environmental and human health implications. 

By continuing to research contamination levels, understanding the biological pathways of microplastics, and developing practical solutions, scientists hope to protect marine ecosystems and ensure that the seafood reaching dinner tables is safer for everyone.

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