99% of tested West Coast seafood loaded with human-made particles

PORTLAND, Ore. — If you notice a bit of crunch in your next shrimp cocktail, it might not be from the shell. A concerning new study documents widespread contamination of microplastics and other human-made particles in commercially important seafood species along the U.S. West Coast.

Plastic pollution continues to emerge as a serious public health crisis in recent years. This latest research from Portland State University’s Applied Coastal Ecology Lab demonstrates that microscopic plastic particles have infiltrated the edible portions of popular seafood, from salmon to shrimp.

Published in Frontiers in Toxicology, the study examined six seafood species caught off the Oregon coast: black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp. Samples included both commercially caught specimens and those purchased from retail markets. Most strikingly, anthropogenic particles — materials either produced or modified by humans — were discovered in 180 out of 182 individual specimens studied, suggesting near-universal contamination of our seafood supply.

Among the species studied, pink shrimp contained particularly high concentrations of these particles, with up to 36 particles found in a single shrimp. When measured by weight, vessel-caught pink shrimp contained approximately 10.7 particles per gram of tissue, while retail-purchased shrimp contained about 7.6 particles per gram. For perspective, this means consuming a modest 4-ounce serving of pink shrimp could expose someone to dozens of microscopic plastic particles.

“We found that the smaller organisms that we sampled seem to be ingesting more anthropogenic, non-nutritious particles,” explains Dr. Elise Granek, professor of environmental science and management, in a statement. “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.”

Pacific lamprey, an endangered species culturally significant to indigenous peoples of the Pacific Northwest, showed concerning levels of contamination across different life stages. Young riverine lamprey contained higher concentrations of particles (1 particle per gram) compared to adult ocean-dwelling lamprey (0.6 particles per gram), highlighting how these contaminants affect species throughout their lifecycle.

Most particles discovered were microfibers, tiny threads shed from synthetic textiles during washing or wear. These represented 82% of all particles found, while fragments made up 17%, and films accounted for less than 1%. The particles ranged dramatically in size, from as small as 2 micrometers to over 3.6 millimeters in length. For context, a human hair is typically 50-70 micrometers in diameter.

“It’s very concerning that microfibers appear to move from the gut into other tissues such as muscle,” says Dr. Susanne Brander, an ecotoxicologist and associate professor at Oregon State University who helped analyze the samples. “This has wide implications for other organisms, potentially including humans too.”

Particularly worrying was evidence suggesting that retail processing may introduce additional contamination. Retail-purchased lingcod contained significantly more particles than those caught directly from vessels, indicating that handling and packaging practices could be adding to the problem. This raises questions about current seafood processing methods and their potential contribution to particle contamination.

Analysis revealed various types of synthetic and modified materials, including polyester, polypropylene, and processed cellulose. Many particles were clear or white (72%), while blue and black particles each represented about 13% of findings. This color distribution provides clues about potential sources, as clear and white fibers are common in fishing gear and food packaging, while colored fibers often come from clothing and textiles.

As consumers increasingly seek sustainable and healthy seafood options, this research suggests a need for urgent action to address plastic pollution at its source. While traditional environmental concerns about seafood have focused on mercury levels or overfishing, the ubiquitous presence of anthropogenic particles represents a new frontier in food safety considerations.

“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,” says lead author Summer Traylor, who now serves as a NOAA Corps Officer, helping collect baseline microplastic data in the Gulf of Mexico to further expand public knowledge and understanding.

The findings arrive at a critical moment when global plastic production continues to increase, with much of it ultimately finding its way into our oceans. Researchers note that seafood likely doesn’t contribute more particles to human exposure than other foods or drinking water. Still, the high consumption of seafood by certain populations, including indigenous communities and coastal residents, raises environmental justice concerns.

In response to these findings, researchers are already moving toward solutions. Dr. Granek is leading a $1.9 million NOAA-funded project developing and testing washing machine, dishwasher, and clothes dryer filters as cost-effective filtration solutions. Additionally, through Oregon Sea Grant funding, researchers will install catch basin filters in stormwater drains across two coastal towns to evaluate their effectiveness in trapping microplastics from road runoff.

Researchers emphasize that while avoiding seafood isn’t the answer, implementing effective filtration systems and reducing plastic pollution at its source are crucial steps forward.

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