Plastic on Your Plate: Microplastics in Seafood
- Irleen Kaur
- 13 minutes ago
- 4 min read
Irleen Kaur
Plastic pollution has been a hot sustainability topic for the past decade. Reusable bags, metal straws, and plastic free packaging have all become part of daily life. Unfortunately, a much smaller problem has been brewing alongside these plastic limiting initiatives.
Microplastics, tiny plastic fragments invisible to the naked eye, have made their way into marine environments, and increasingly, onto our plates. With global seafood consumption increasing, what ends up in the ocean undoubtedly will end up in humans as well. It’s important to stay informed, and understand what ingesting microplastics means for human health.
What are Microplastics?
Microplastics are plastic particles less than 5 mm in size. Microplastics that are produced at this size are called primary microplastics, whereas secondary microplastics result from the breakdown of larger items.
Microplastics enter the environment simply through using products laced with microplastics. These particles can travel via wind, rain, as well as through stormwater runoff into terrestrial and aquatic ecosystems.
Microplastics in the marine ecosystems are often found as pellets, fragments, or fibers. They are composed of diverse polymers of varying density. Polyester, for one, is denser than seawater and is expected to sink. Polyethylene, on the other hand, is lighter than seawater and can be found floating at the surface.
In addition, depending on their morphology, microplastics vary by shape, including cubic, spherical, and rod shapes. These shapes impact their level of risk to humans and the environment. For example, sharper microplastic particles can cause toxicity through physically stimulating the human body.
Like any other synthetic chemical, microplastics degrade and persist in oceans. The rate of degradation and persistence depends on the polymer type, shape, density, and purpose of the plastic. These characteristics also determine where in the water column plastics may be found.
It is important to consider all these factors when conducting risk assessments for microplastics.
Where do Microplastics Accumulate in Marine Organisms?
Marine organisms encounter microplastics constantly. Fish can directly ingest microplastics by mistaking small particles for food, or indirectly, by eating other organisms that have already ingested plastic.
Feeding habits also impact the rate at which microplastics accumulate in marine organisms. Shellfish, like mussels and oysters, are filter feeders, meaning they draw large volumes of water through their bodies and capture whatever’s in it, including microplastics. Non-selective feeders tend to accumulate more microplastics in their bodies compared to selective feeders.
Fish from upper waters tend to have a greater amount of microplastics in their body as well compared to fish from deeper waters. This is simply because microplastic pollution is more abundant at ocean surfaces.
Studies have found that plastic particles are concentrated in an organism’s digestive tract and organs involved in respiration. Micro- and nanoplastics can translocate from the intestinal tract to the circulatory system or surrounding tissues. Microplastics can additionally accumulate in the fats of marine organisms, especially because they are fat soluble.
What We Know About Health Effects For Marine Life and Humans
Studying the impact microplastics have on marine and human health has proven difficult. Current studies fail to take into consideration the variety of sizes, types, and shapes of all plastic particles, which make it difficult to pinpoint a specific health hazard. Nonetheless, there are still generalizations that are beneficial to know.
Microplastic exposure can make fish and birds more vulnerable to infections. Not only that, but studies have linked microplastics to increased inflammation, impaired immune function, deteriorated tissues, altered metabolic function, abnormal organ development, cell damage and more. A study done by the University of California, San Francisco has found that exposure to microplastics can harm reproductive, digestive, and respiratory systems and suggested links to colon and lung cancer.
Additional studies using human cells and animal models have linked microplastic exposure to:
Oxidative stress, which can damage cells over time
Disruption of gut microbiome, potentially leading to digestive symptoms
Endocrine disruption, since many plastic additives interfere with hormones
Changes in the intestinal microbiome, leading to gastrointestinal symptoms, such as abdominal pain, bloating, and changes in bowel habits
Neurotoxicity
What Can You Do?
As there is still limited research on the effects microplastics have on human health, there is no need to completely remove seafood from our diets. Here are some steps that can help reduce your microplastic exposure in seafood:
Choose deep-water fish over fish that reside in surface waters.
Opt for fillets over whole fish to avoid consuming the digestive tract.
Be mindful of fatty tissues by trimming visible fat.
Look for sustainably certified seafood.
Beyond individual choices, collective action also matters. Beach cleanups are one of the most direct ways to prevent plastic from entering marine ecosystems in the first place. Every piece of plastic removed is one less item that could end up in our marine organisms and seafood.
Organizations such as The Harborkeepers and the New England Aquarium also work to limit microplastics in local marine environments.
Microplastics may be small, but their impact on our food systems and health is anything but. By staying informed and making conscious choices about our environment, we can all play a role in reducing microplastic pollution. The ocean’s health and our own are more connected than we might think. What’s good for the ocean, is, inevitably, good for the plate.
Citations
Lee, Y., Cho, J., Sohn, J., & Kim, C. (2023). Health Effects of Microplastic exposures: Current Issues and Perspectives in South Korea. Yonsei Medical Journal, 64(5), 301–308. National Library of Medicine. https://doi.org/10.3349/ymj.2023.0048
Savchuk, K. (2025). What’s the deal with microplastics, the material that “never goes away”? News Center. https://med.stanford.edu/news/insights/2025/01/microplastics-in-body-polluted-tiny-plastic-fragments.html
Smith, M., Love, D. C., Rochman, C. M., & Neff, R. A. (2018). Microplastics in Seafood and the Implications for Human Health. Current Environmental Health Reports, 5(3), 375–386. Springer Link. https://doi.org/10.1007/s40572-018-0206-z
Sun, X., Meng, L., Liang, J., Li, Q., Du, J., Zhu, M., Zhao, Y., & Zheng, S. (2025). Microplastic Distribution Patterns in Fish and Implications for Safe Consumption. Environmental Science & Technology, 59(33), 17393–17402. https://doi.org/10.1021/acs.est.5c02907
