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Mercury Levels and Neurological Conditions

20/20 went shopping for fresh fish in three major cities, not to eat, but to test for mercury. (ABCNEWS.com)
Mercury in Fish Threatens Unborn
A 20/20 Investigation

Jan. 12 Pregnant women and women who may become pregnant should not eat shark, swordfish, king mackerel and tile fish because they could contain levels of mercury that could lead to brain damage in a developing fetus. The Food and Drug Administration said on Friday.

The advisory comes on the heels of an extensive report issued by the National Academy of Sciences which estimates that each year 60,000 children may be born in the United States with neurological problems as a result of exposure to methylmercury in the womb. According to the NAS report, humans are exposed to methylmercury primarily through the consumption of contaminated fish, particularly large predatory fish species such as tuna, swordfish, shark and whale.

The FDA rejected calls to put tuna on the do-not-eat list, stressing that swordfish and shark have far higher mercury levels than tuna. Vermont Sen. Patrick Leahy, who helped commission the NAS study, calls the FDA's announcement, "a step in the right direction," but the FDA's warning comes amid criticism that the agency has not been aggressive in informing the public about the risks of high-mercury fish.

In 1998 the FDA stopped testing fish for mercury and has relied on the fish industry to police itself. National Fisheries Institute president Dick Gutting says that, overall, the industrys tests show that mercury is not a problem.

Last summer, 20/20 conducted its own tests. 20/20 bought 40 samples of fresh tuna, swordfish and shark in three major U.S. cities and sent the fish to Battelle Marine Science Labs, a facility that performs food tests for the FDA and the EPA.

20/20 discovered that while the tuna samples averaged well below the FDA limit of 1 part per million (ppm), the shark and swordfish did not fare as well. Two out of four shark samples and 14 out of 18 swordfish samples had mercury levels greater than 1 part per million. Two of the swordfish samples tested had mercury levels triple the FDAs limit.

When 20/20 presented its findings to Dick Gutting, he could not explain the results but said that the fact that one particular meal is over one part per million is not significant. Gutting stressed that the average level of mercury in commercially sold fish is well below the FDA limit. Both the fish industry and the FDA say that there is a ten-fold safety factor built in to the 1ppm limit.

But Dr. Jill Stein, of the Boston Physicians for Greater Responsibility, disagrees. She says that even one meal of swordfish with levels between 2 ppm and 3 ppm could potentially harm the fetus at a critical point of brain development.

Both the fish industry and the FDA say that there is no evidence that people are eating enough of this high-mercury fish for it to be a problem. However, Dr. Jane Hightower of San Francisco, Calif., has several patients who eat large amounts of high-mercury fish in question and have blood-mercury levels as high as 15 times the normal level. Hightower says when her patients cut down on such fish, their blood-mercury level drops to normal level.

The Environmental Protection Agency added to the FDA's advisory on Friday saying that pregnant women who eat fish their family and friends catch should follow state warnings about fishing from waters with high mercury levels.

While Sen. Leahy has proposed legislation to further tighten restrictions on mercury emissions, the fishing industry worries that the public may overreact to new warnings.

Additional Resources:

Toxicological Effects of Methylmercury
The report from the National Academies of Science estimates that each year 60,000 children may be born in the United States with neurological problems as a result of exposure to methylmercury in the womb.
The National Fisheries Institute
The NFI represents the interests of the fishing industry before Congress and other regulatory agencies.
Americas Seafood: Fair or Foul?
Consumer Reports investigates fish in 6 U.S. cities for freshness, presence of mercury and bacteria.
Food and Drug Administration
FDAs consumer advisory on explains the risks of eating shark and swordfish for pregnant women and women of childbearing age.

EPA and FDA

2004 Advice for: Women Who Might Become Pregnant about eating fish and shellfish.
In Harms Way
Dr. Jill Epstein of the Greater Boston Physicians for Social Responsibility co-authored the report which provides guidelines on how much fish to consume to stay within EPA and National Academy of Sciences safety limits.
The Mercury Policy Project
This Vermont-based non-profit organization promotes policies that reduce mercury emissions and peoples exposure to mercury. Their report, The One That Got Away, criticizes FDAs seafood monitoring program.

How much tuna fish is safe to eat?   Chart below: