Posted on August 1, 2011 - by

Mercury in Seafood: How to enjoy your fish without going mad

Today’s guest blog post is brought to you by FishWise, a non-profit sustainable seafood consultancy that helps seafood businesses improve the sustainability of their seafood offerings.

Mercury is a toxic metal that builds up in the food chain and can be found in some popular seafood items, posing a health risk to those who frequently eat them. Developing infants and young children are at the highest risk for mercury contamination and may suffer brain damage and learning disabilities from prolonged or repeated exposure, so it is important for women of child-bearing age to minimize their consumption of fish containing high levels of mercury.

Mercury is found naturally in the environment, but levels have increased dramatically since the rise of industrialization in the 19th century. Mercury enters natural water bodies via rain and surface water run off, where it can be converted by bacteria to an organic form called methylmercury. This form of mercury is more toxic and bioaccumulates through the food chain, which is why large predatory species like shark and swordfish are typically higher in mercury than species like anchovy, Alaskan salmon, and shellfish that are lower in the food chain.

Other contaminants which can be found in seafood are PCBs, or polychlorinated biphenyls, which are toxic industrial compounds. As with mercury, they pose serious health risks to developing infants and children, who may suffer developmental and neurological problems from prolonged or repeated exposure. PCBs are carcinogenic and thus harmful to adults as well. Although they were banned from manufacturing in the United States in 1977, PCBs are slow to break down and can persist in the environment at dangerous levels.

For a guide to seafood choices that are tested to be both low* in contaminants and more environmentally responsible**, download a copy of FishWise’s Seafood Low Mercury List, developed in collaboration with the Environmental Defense Fund.

* Safe for a 154 lb adult to eat 8 oz a week or a 144 lb woman of child bearing age to eat 6 oz a week, based on EPA standards and currently available data on mercury and PCBs
** ‘Best Choices’ or ‘Good Alternatives’ according to the Monterey Bay Aquarium’s Seafood Watch Program


FishWise is a non-profit sustainable seafood consultancy that helps seafood businesses improve the sustainability of their seafood offerings through environmentally responsible business practices, such as policy development, employee training, sourcing assistance and point of sale information. This approach empowers consumer to make environmentally informed choices when purchasing seafood.

To learn more about sustainable seafood, visit or sign up for their mailing list.



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