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Earthtalk: High Mercury Levels Found in Fish

Eating big fish is becoming a big problemin the United States and increasingly around the world. Mercury in the fish we like to eat is a big problem. The problem is mercury, a naturally occurring element that is present throughout the environment and in plants and animals.

But human industrial activity (such as coal-fired electricity generation, smelting and the incineration of waste) ratchets up the amount of airborne mercury that eventually finds its way into lakes, rivers and the ocean, where it is gobbled up by unsuspecting fish and other marine life.

Once mercury gets into the marine food chain, it “bioaccumulates” in larger predators, which is why larger fish are generally riskier to eat than smaller ones. Those of us who eat too much mercury-laden fish can suffer from a range of health maladies, including reproductive troubles and nervous system disorders.

The U.S. Environmental Protection Agency (EPA) reports that human fetuses exposed to mercury before birth “may be at an increased risk of poor performance on neurobehavioral tasks, such as those measuring attention, fine motor function, language skills, visual-spatial abilities and verbal memory.” Up to 10 percent of American women of childbearing age carry enough mercury in their bloodstreams to put their developing children at increased risk for developmental problems.

In partnership with the U.S. Food and Drug Administration, the EPA issues determinations periodically in regard to how much mercury is safe for consumers to ingest from eating fish. 

As for which fish to avoid, the non-profit Environmental Defense Fund (EDF), which runs the handy Seafood Selector website, reports that people with mercury concerns should steer clear of bluefin tuna, walleye, king mackerel and marlin. Bluefish, shark, swordfish, wild sturgeon, opah and bigeye tuna carry a proportionately large mercury burden as well. Also of concern, but to a slightly lesser extent, are orange roughy, Chilean sea bass, blue crab, lingcod, Spanish mackerel, spotted seatrout, wahoo, grouper, snapper, halibut, tilefish, rockfish and sable fish, as well as blackfin, albacore and yellowfin tuna.

Beyond what individuals can do to avoid mercury, the U.S. government and states have begun working together to reduce mercury emissions from power plants. Earlier this year the EPA proposed new “Mercury and Air Toxics Standards” regulating mercury emissions from utilities across the country, with the goal of reducing the amount of mercury emitted by coal burning by 91 percent by 2016.

Connecticut-based EarthTalk® is written and edited by Roddy Scheer and Doug Moss.

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