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Chemical Warfare in the Deep: Biomagnification Making Its Way to Our Dinner Table

Image courtesy of Gregor Moser

Fishing, for many communities, is a tradition and way of life. Moreover, seafood and freshwater fish make up a large part of protein and Omega-3 fatty acids in people’s diets. At Seaside Sustainability, we’ve researched sustainable solutions to seafood and begun to understand how to avoid perpetuating harmful practices of overfishing; however, we should also be cognizant of toxic chemicals and heavy metals in the fish we eat. Considering the potential mercury poisoning people can experience from consuming certain types of fish, how should consumers avoid this risk when selecting their entree? All fish have some level of mercury that bioaccumulates in their system; however, as smaller fish are consumed by larger fish, the levels of mercury multiply, causing higher concentrated levels up the food chain. Eventually, this magnification of mercury is deposited into our bodies by way of consuming fish and other seafood.

Biomagnification is a process where harmful toxins and heavy metals, such as mercury and PCPs (Polychlorinated biphenyls), become more concentrated in organisms higher up in the food chain as a result of consuming organisms lower on the food chain that contain these toxins and heavy metals. This chemical warfare below the water is caused by unassuming human pollutants and their anthropogenic activities such as mining, incinerating coal, groundwater extraction, chemical explosions, and more. Ultimately, these oceanic pollutants alongside untreated sewage, oil spillage, and microplastics, are deposited into the fish we eat, causing major harm not only to the ecosystem. People are dying from cancer, suffering neurological and kidney damage, and other correlated diseases due to consuming unsafe levels of these toxins via the seafood in their diet. Children and developing fetuses are especially vulnerable to the effects of mercury and can suffer from life-long learning disorders and other disabilities because of it.

How did our aquatic ecosystem get to be this toxic? Since the rise of industrialization in the late 19th century, mercury levels in our air, land, and water have increased significantly. The never-ending amount of plastic entering the world's oceans is estimated to be 6.4 million tons annually, making it the principal component of marine debris. Sewage water consists of domestic wastes, pharmaceutical chemicals, and agricultural run-off. When this contaminated water is dumped into the oceans, it causes a wide range of problems for ocean life. High concentrations of nutrients (ammonia, nitrates, and phosphates) enter the waterways in eutrophication and form algal blooms which cause a decrease in oxygen and reduce the overall quality of water, fish, coral, and other marine populations. Seaside Sustainability investigated the harmful effects of per-and polyfluoroalkyl substances (PFAS), also known as “forever chemicals”, in clothing manufacturing companies and reported on the contaminated surrounding environmental damage in air, land, and water. All these pollutants can be minimized with a collective effort to reduce, reuse, recycle, and compost. In addition, water and air quality standards must be upheld to protect all aquatic ecosystems.

Individually, we can balance the health benefits we gain from eating high-quality fish and the potential risks of ingesting heavy metals and chemicals. This may be possible through proper cleaning and cooking methods (removing skin, fat, and other organs containing concentrations of toxins). However, it is best to consult local fishing and health authorities to gain information on local consumption advisory and conservation management. Most importantly, limiting our consumption of predatory fish such as tuna, shark, and swordfish will help mitigate the effects of biomagnification making its way up in the food chain to our dinner plates.



Mohammad, Belal H., et al. "Metals Bioaccumulation in 15 Commonly Consumed Fishes from the Lower Meghna River and Adjacent Areas of Bangladesh and Associated Human Health Hazards." Toxics, vol. 10, no. 3, 2022, pp. 139. ProQuest,, doi:

Lim, Kok P., et al. "A Meta-Analysis of the Characterisations of Plastic Ingested by Fish Globally." Toxics, vol. 10, no. 4, 2022, pp. 186. ProQuest,, doi:

Saeed, Farzeen, and Muhammad F. Malik. "Oceanic Pollution; A Threat to Life." Pure and Applied Biology, vol. 11, no. 2, 2022, pp. 483-490. ProQuest,, doi:

References from Anna O'Brien

Mercury in Seafood. Seafood Selector. (2013, June 5). Retrieved July 1, 2022, from

Mercury in fish. Mercury in Fish | Department of Environmental Conservation. (n.d.). Retrieved July 1, 2022, from

Canada, E. and C. C. (2013, July 9). Government of Canada. Retrieved July 1, 2022, from

The Maine Family Fish Guide: Advice from the Maine Center for Disease ... (n.d.). Retrieved July 1, 2022, from


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