Mercury is highly toxic. It causes birth defects, brain damage, kidney damage, and neurological damage with impacts on attention, memory, language, and motor skills. High doses result in seizures, severe neurological damage, or death.
Bioaccumulation of mercury results when consumption of mercury is higher than our ability to release it from our bodies.
Mercury becomes more concentrated as it moves up the food chain. Organic mercury is changed into a more dangerous form, methylmercury, by bacteria. Plankton eats the bacteria, small fish eat the plankton, larger fish eat the smaller fish, and humans eat the fish. The larger game fish have much higher concentrations of mercury due to bioaccumulation in the muscle tissue.
While we’ve been warned about the risk of eating seafood caught in the oceans—tuna (steaks or albacore), shark, swordfish, King Mackerel, Tilefish, sea bass, and marlin are among the fish we should either avoid or rarely eat—little has been said about the contamination of America’s lakes, rivers, and streams. According to the U.S. Geological Survey and the EPA, 33 states have issued fish consumption advisories due to mercury contamination.
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The EPA and the states advisories promote fish as a healthy food, while warning about x
Mercury is a naturally occurring element, but most of the mercury pollution is caused by mankind. More than 100 tons of mercury are released from industrial sources each year including coal-fired power plants (40% of the U.S. emissions), cement and chemical manufacturers, incinerators, and mining operations.
Mercury contamination is spreading throughout the animal kingdom. The
National Wildlife Federation reports elevated levels of mercury are now found in aquatic birds and in forest-dwelling birds.
Other animals with mercury levels high enough to affect their health include otters, raccoons, Florida panthers, alligators, minks, bats, crayfish, bullfrogs, salamanders, turtles, polar bears, and whales.
Fish and Mercury Contamination
Issue 3 | January 2010
