Scientists sound alarm over high microplastic exposure in US seafood

Researchers at Portland State University, US, have found particles from plastic packaging, clothing and other products in the edible tissues of six species of seafood caught near the state of Oregon’s shores. 

“We do not want readers to take away from this that seafood is bad — it is only one of many sources of anthropogenic particles in our environment. Instead, we hope that the reader recognizes that the more plastic we use and then dispose of, the more microplastic there will be ending up in our environment, and eventually on our plates or in our drinks,” Elise Granek, study lead and professor of environmental science and management at Portland State, tells Packaging Insights.

The study found anthropogenic particles (AP), those “produced or modified by humans,” in black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey and pink shrimp purchased at Oregon fishing vessels and grocery stores. 

“Unfortunately, we find microplastics in all kinds of F&B items, not just seafood. Microplastics have also been found in the air we breathe, and there are frequently microplastics in our drinking water and definitely in our bottled water as well as in sea salt, beer, honey and more.”

Concerning levels of pollution

The study, published in Frontiers in Toxicology, looked at 182 samples (122 finfish and 60 crustaceans) and found 1,806 “suspected” AP, such as fibers, fragments and films.

Elise Granek, study lead and professor of environmental science and management (Image credit: Portland State).Of the six species sampled, selected for their economic and cultural significance to Oregon’s residents, pink shrimp had the highest concentrations of plastic particles. In contrast, chinook salmon had the lowest, followed by black rockfish and lingcod.

“Many contaminants bioaccumulate up the food web, such that animals higher on the food web have more than those lower on the food web. So it was a bit surprising to see that the highest concentrations of APs were in those species at the lower end of the food web (and the lowest concentrations of APs were in the fish that are highest in the food web),” says Granek.

“However, when we think about how and where pink shrimp, herring and riverine lamprey feed, it makes sense that they encounter more anthropogenic particles than carnivores (those higher in the food web).”

Granek tells us that, overall, there was no significant difference between the levels of microplastic pollution found in seafood acquired from research fishing vessels and those from supermarkets.

Human health and ecology

Further discussing the potential human health risks of microplastics in food, Granek says that “a growing body of research from the medical community is finding a strong correlation between health issues ranging from gut inflammation to male fertility to cardiac disease and the concentration and types of microplastics found in the relevant human organs (gut, testes, heart tissue).”

“A 2023 study found that there are microplastics in much of the other protein sources humans consume — beef, chicken, veggie burgers and tofu, so seafood is not the main or only source of food microplastics. That said, microplastics from all of these sources may create a risk for human health.”

In addition to human health, microplastics found in marine food webs can have adverse health effects on marine and freshwater species, thus having broader ecological implications.

“There is a body of research that indicates that exposure to microplastics by freshwater and marine species that have been studied can lead to a number of effects — false satiation and therefore insufficient nutrition resulting in growth effects, reproductive effects, inflammation, among others,” explains the researcher. 

“Put more broadly, growth and reproductive effects may potentially lead to changes in populations of marine and freshwater species.”

The researchers found microplastics in six seafood species acquired from US fishing vessels and supermarkets (Image credit: Portland State).Reducing pollution

Granek asserts that industries need to lower their use of conventional plastic to prevent microplastics from entering marine ecosystems.

“Much of what we see in the ocean is fibers. These likely come from the laundering of clothing. Interventions to reduce microfibers from entering waterways and oceans are important to reduce this source.”

Rachel Coppock, a marine ecologist at the UK’s Plymouth Marine Laboratory, recently told Packaging Insights that bioplastics are also a source of marine pollution. They were found to not degrade naturally and to negatively impact the ocean’s ecosystems.

Another recent study conducted in the US discovered that humans are digesting microplastics in 109 countries, notably in rapidly industrializing countries in East Asia, where contamination of F&B was the highest due to ocean pollution and food processing. 

Granek says that avoiding “low quality, highly shedding fabrics” is vital to reducing the microfibers entering waterways. She points to the fast fashion industry as a key polluter.  

“But back to the question of seafood: if one is interested in avoiding microplastics, rather than avoiding a specific type of food (since many types of food have microplastics), avoiding water and other drinks bottled in plastic and avoiding processed foods packaged in plastics may reduce microplastic ingestion,” she says.