By Janet Raloff
In the mid-1980s, some researchers in the northern Midwest, Canada, and Scandinavia began reporting alarming concentrations of mercury in freshwater fish. Curious about Florida’s largemouth bass and other finned delicacies, state scientists there began assaying lake fish. Thomas Atkeson, then a Florida state wildlife biologist, recalls that most of the fish he examined fell just under the limit then recommended by the Food and Drug Administration. “We were scratching our heads as to whether this was a big deal,” he recalls, until his team reached the Everglades. In these wetlands, mercury contamination of fish routinely averaged more than twice the concentrations seen elsewhere in the state. Indeed, their mercury values were among the highest ever reported for U.S. freshwater fish.
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“There was no quibbling that these levels were high and a potential health concern to humans and wildlife,” Atkeson says. Eating mercury-tainted fish can trigger a variety of problems, ranging from hair loss and chronic fatigue in adults to nervous system impairment of fetuses and children (See Mercurial Effects of Fish-Rich Diets).