Can eating fish make you mad as a hatter?

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In Lewis Carrol’s Alice in Wonderland, Alice finds herself at a weird tea party with the Mad Hatter and the March Hare. The Hatter explained that he escaped decapitation by the Queen of Hearts for “murdering time.” “Mad as a hatter” referred to symptoms of poisoning caused by inhaling mercury fumes given off by an old process used in making felt hats.

A couple of weeks ago, the U.S. Geological Survey issued a disturbing report about mercury in fish from our nation’s fresh water systems. They sampled streams in agricultural, urban, undeveloped and mined areas. They targeted predator fish and analyzed skin-off filets for total mercury.

The disturbing part is that they found mercury in all the fish they tested. Mercury concentrations in fish at 27 percent of the sites they sampled exceeded the U.S. EPA human health criterion of 0.3 micrograms of mercury per gram of wet weight fish meat.

Mercury occurs naturally in rocks and soils and cycles among the atmosphere, water, and sediments. Coal burning power plants and municipal waste incinerators release mercury into the atmosphere and increase the amount of mercury in the environment. Analysis of glacial ice cores has demonstrated that mercury emissions from human activity have increased atmospheric mercury about threefold since the industrial revolution.

Mercury released in the atmosphere can be transported long distances and deposited in aquatic ecosystems. Elemental mercury in water is transformed into methylmercury, a potent neurotoxin. Human fetuses are especially sensitive to methylmercury. Methylmercury bioaccumulates in fish. Larger and older predator fish generally have the highest mercury concentrations in their flesh.

Fish are an important part of a healthy diet. They contain high-quality protein, are low in saturated fat, and contain omega-3 fatty acids. Nearly all fish contain traces of mercury.

For most people, the risk of mercury poisoning from eating fish is not a concern. Some fish contain higher levels of mercury that may harm an unborn baby or young child’s developing nervous system. Therefore, mothers and young children should avoid eating too much of some types of fish that contain higher concentrations of mercury.

The Wisconsin DNR issues fish consumption advisories to help people avoid problems from eating contaminated fish. The most common contaminants in Wisconsin game fish are polychlorinated biphenyls (PCBs) and mercury.

The DNR advises that women of childbearing years, nursing mothers and children under 15 may eat one meal per week of bluegills, sunfish, crappies, bullheads and trout from inland waters, no more than one meal per month of bass, catfish, northern pike and other species, and no muskies.

Women beyond childbearing years and men may eat unrestricted amounts of bluegills, sunfish, crappies, bullheads and trout from inland waters and one meal per week of bass, catfish, northern pike and other species, and one meal per month of muskies.

It would be hard to eat enough Wisconsin game fish to make you mad as the poisoned hatters of old. So, eat fish. They are good for you. Mothers and children should eat game fish from inland waters in moderation, and don’t eat muskies!

Please send any comments and suggestions for this column to me at wildside@rivertowns.net.

Tags: great outdoors, mercury in fish, sports, northland, outdoors, fishing