Surf’s up for a plastic-free lifestyle! Seafood is often seen as a smart, nourishing choice that’s loaded with protein, omega‑3s, and other nutrients our bodies need.
As we strive to eat healthier, it’s worth asking what else might come with that plate of fish or shellfish. Increasingly, researchers are finding microplastics in seafood. Many marine life that we consume as seafood act as filters for the ocean [1]. As plastics used in packaging, textiles, larger plastics, and even fishing equipment pollute our water, they break down into particles smaller than 5mm. Fish eat these microplastics, and then we do too! Microplastics are becoming increasingly common in human blood. Here’s what we need to know to eat seafood safely!
What Are Microplastics and How Do They Get Into Seafood?
Microplastics are tiny fragments of plastic that are usually less than 5 millimeters in size. Most microplastics begin as larger items, such as bottles, bags, and food wrappers, all made with plastics that gradually break down under the force of sunlight, wave action, and weather [2].
Heavy rains and runoff also carry plastic waste from landfills and streets into rivers, which deliver it straight to the sea.
Once plastics enter the ocean, they continue to break down into small particles, spreading through marine environments and even drifting to the deepest sea trenches. This process keeps our waterways loaded with microplastics, making them nearly impossible to remove and introducing health concerns for both sea life and people.
We can contribute to microplastics in seafood from the very actions we take in our homes. Everyday products, like synthetic clothing and personal care items, can also end up in the ocean after being washed down drains [2][3].
We should use clothing made with natural fibers and fragrance-free products as much as possible to avoid contaminating our bodies and the environment.
Microplastics in fish also occur from the act of fishing itself. Plastics used in fishing line, nets, and even fishermen's clothing can pollute the ocean. These chemicals can affect marine life and contaminate the seafood we eat.
Are Fishing Nets Made of Plastic?
Have you heard of the Great Pacific Garbage Patch? The Great Pacific Garbage Patch is made up mostly of fishing-related plastic, with studies showing that 75% to 86% of the waste comes from fishing gear [4].
Modern fishing relies heavily on plastic-based materials, such as nylon nets, lines, and rope. Whenever this gear is lost or discarded, it slowly breaks apart and releases microplastics into the water.
In fact, synthetic ropes alone can shed thousands of microplastic particles every time they’re used…especially as they wear down!
Does Plastic Packaging Cause Microplastics in Seafood?
Seafood often picks up microplastics long before it ever reaches our kitchens, and plastic packaging adds another layer to this problem. From the moment marine animals are caught, many are processed in plastic-lined facilities, stored in plastic containers, then wrapped and shipped in yet more plastic before hitting store shelves.
This routine handling means fish and shellfish destined for retail can actually collect more microplastics from packaging and surfaces than freshly caught seafood, amplifying contamination beyond what’s found in wild habitats.
Recent surveys found microplastic particles in over 94% of analyzed seafood products [5]. Microplastics are especially high in seafood that is canned in sauces and oils.
A 2024 study found that every type of canned seafood tested was contaminated with microplastics, with octopus in tomato sauce and tuna in olive oil showing some of the highest levels, averaging approximately five microplastic particles per can [6].
Tomato sauces are acidic, which can speed up the breakdown of plastics in containers, including bisphenols used to line cans. Tuna in olive oil was also highly contaminated, likely because oily, fatty liquids can absorb and hold more chemicals and microplastics from packaging.
While rinsing fish and shellfish fillets before preparation can remove some surface microplastics, it does not eliminate particles that are already embedded in tissue. Opting for fresh, paper-wrapped seafood and using it quickly can help cut down on additional microplastic exposure from packaging. However, addressing plastic pollution on a wider scale will be essential for reducing microplastics in our food supply long-term
Which Seafood Contains the Most Microplastics?
Mollusks tend to have the highest levels of microplastics among seafood. Why?
These bottom feeders filter large volumes of water to find food. This natural filtering process makes them especially vulnerable to picking up microplastic particles floating in their environment.
Which Fish Have the Most Microplastics?
Small pelagic fish like sardines, anchovies, and herring are especially vulnerable to microplastic contamination. The reason for microplastics in pelagic fish is common in part because of their feeding habits and how they’re consumed.
These fish often feed near the ocean’s surface. That’s where floating microplastics tend to concentrate. Pelagic fish filter these small particles along with their natural food.
In fact, up to 96% of sardines and over 90% of anchovies sampled in different regions have contained microplastics, primarily in their digestive tracts [7].
Herring are also frequently found with bits of plastic inside, since they filter lots of seawater, and their small prey can be mixed with plastic particles.
These fish are often eaten whole. Therefore, people are exposed to whatever plastic the animals have picked up along their lives…starting from the plankton-rich upper layers of the ocean all the way to their final meal.
This same problem doesn’t stop with sardines and anchovies. Fish such as mullet, catfish, hake, sprat, and sole have also tested positive for microplastics.
This shines a light on a more widespread issue. When microplastics are so common across different environments and life stages, each meal is a reminder to think about ocean health and how plastic waste connects directly to our own dinner plate
Small Pelagic Fish (Often Eaten Whole)
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Sardines (Sardina pilchardus): Up to 96% of samples positive for microplastics, with high particle counts per fish.
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Anchovies (Engraulis encrasicolus, E. japonicus): Frequently show high contamination rates (up to 91% of samples).
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Herring (Clupea harengus): Regularly found with microplastics in their digestive tracts.
Other Commonly Consumed Fish
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Mullet (Mugil cephalus): High microplastic loads, especially in fish from river estuaries (up to 16 particles per fish on average).
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Chub Mackerel (Scomber japonicus) and Atlantic Mackerel (Scomber scombrus): Both have been documented to ingest microplastics, with some studies showing 100% of samples contaminated.
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Catfish (e.g., Bagok catfish): Notable contamination in riverine environments, with 7–8 particles per fish near urban areas.
Other Noteworthy Species
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King Mackerel (Scomberomorus cavalla)
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Horse Mackerel (Trachurus trachurus)
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Hake (Merluccius merluccius)
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Sprat (Sprattus sprattus)
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Blue Whiting (Micromesistius poutassou)
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Bream (Pagellus acarne)
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Common Sole (Solea solea)
Are Microplastics In Fish Harmful to Humans?
Microplastics in fish are a concern because they can expose our bodies to chemicals known to disrupt hormones or even increase cancer risk. However, there are practical steps everyone can take to reduce potential harm and still enjoy seafood with confidence.
First, opt for fresh fish whenever possible. Prepare your fresh catch at home, where you can control how it's cleaned and cooked. Choosing fish muscle and fillets, instead of consuming fish whole, is another easy way to limit intake, especially with small pelagic fish like anchovies and sardines.
Try to limit fish that tend to filter and ingest more microplastics, such as sardines, anchovies, and herring, and instead choose larger fish from deeper waters, like cod, haddock, or trout, which have been shown to retain fewer microplastics in their edible muscle tissue [8].
Make meals with fresh ingredients, rinse seafood thoroughly, and get creative with recipes that allow you to select the best quality fillets. By staying informed and mindful of sourcing, everyone can set themselves up for better health while still enjoying the nutritional benefits of seafood.
Tips for Limiting Microplastic Intake from Seafood
If you're trying to cut down on microplastic exposure, be mindful of the seafood you eat. Some fish put you at a higher risk, such as shellfish like mussels, oysters, and scallops, which tend to absorb more since they filter large amounts of seawater.
Choosing unpackaged fish and checking for clean sourcing can also help you avoid extra plastic contamination.
Making food at home? Try swapping out single-use plastics for reusable containers, and avoid heating food in plastic. Finally, contributing to efforts that keep our oceans and waterways clean ensures our community spaces are cleaner.
The Importance of Testing and Monitoring for Microplastics and Associated Chemicals
Understanding your exposure to plastic-related chemicals is an empowering first step toward a healthier lifestyle. Substances like BPA and phthalates are harmful chemicals used in the production of many household plastics and packaging materials.
Microplastics can release these chemicals, which are now found in food, water, and even synthetic clothing. Since they’re so ubiquitous, it’s easy to feel uncertain about what steps to take next to protect your health.
The Million Marker Test gives you clarity by measuring your personal exposure to chemicals commonly used in microplastics, including BPA and phthalates. With a simple mail-in urine test, you’ll learn which products or habits are contributing the most to your total "plastic load."
Then, using your personalized report and recommendations, you can confidently make small changes, such as swapping plastic containers for glass, filtering your drinking water, and choosing cleaner personal care products. These small steps in your immediate surroundings will help reduce your exposure and support your overall well-being.
Resources
[2] https://www.sciencedirect.com/science/article/abs/pii/S0045653522008475
[3] https://pmc.ncbi.nlm.nih.gov/articles/PMC9294843/
[5] https://neptjournal.com/upload-images/(38)D-1617.pdf
[6] https://pubmed.ncbi.nlm.nih.gov/38518443/
[7] frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.574663/full
[8] https://www.oaepublish.com/articles/wecn.2024.07