Mercury levels in fish bought in and around Madison, Wisconsin
EXECUTIVE SUMMARY:
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Because of the negative health consequences that may result from the public’s growing fear of eating fish, the nonprofit Center for Consumer Freedom (CCF) sought to examine the mercury and selenium levels of commercially available fish in a single region of the United States. The city of Madison, Wisconsin was chosen because it was the planned site of the Eighth International Conference on Mercury as a Global Pollutant, scheduled for August 2006.
Over a three-day weekend (May 5–7, 2006), 142 fish samples were collected from the Madison, Wisconsin region. Fish species were selected based on their availability at Madison-area restaurants, grocery stores, and fish markets. They included 25 cans of tuna; 44 specimens of fresh, store-bought fish; 28 samples of sushi and sashimi; and 45 orders of cooked restaurant fish.
An independent laboratory in Seattle performed scientific tests to determine the concentrations of mercury and selenium in the samples. Individual mercury levels ranged from 0.001 parts per million in a fresh catfish sample to 3.480 parts per million in cooked swordfish. Selenium levels were “undetectable” (less than 0.1 parts per million) in many catfish samples, and as high as 3.215 parts per million in cooked walleye.
Even before accounting for selenium, a careful reading of the Food and Drug Administration’s description of its mercury “Action Level” indicates that no fish sampled in this study is unsafe to eat.
The FDA has written that its Action Level (currently set at 1.0 part per million) “was established to limit consumers’ methyl mercury exposure to levels 10 times lower than the lowest levels associated with adverse effects.” Adjusting for this 1,000-percent cushion, 10.0 (ten) parts per million is actually the minimum level that the FDA believes might represent a health concern for the fish-buying public.
The highest mercury level measured in this study was less than 35 percent of what the FDA describes as “the lowest level associated with adverse effects” to human health. And since health risks from trace levels of mercury in fish are hypothetical—and predicted only after a lifetime of exposure—consumers in the Madison area should be reassured that the fish in their community is safe to eat.
The rich presence of selenium in most fish should make consumers even more confident about including seafood in their diets.
The U.S. Environmental Protection Agency describes selenium as an element that is “antagonistic to the toxic effects of mercury.” It is increasingly clear that talking only about mercury levels in fish—and ignoring selenium’s protective effects—misses half the story. On average, every fish species we tested (and over 97 percent of the individual fish samples) contained more selenium than mercury, providing consumers with adequate protection from any theoretical mercury-related harm.
Overblown mercury warnings, along with a lack of public understanding about the protective effects of selenium, can have negative public health consequences if consumers react by steering clear of fish and its many well documented health benefits.
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