Mercury in Fish

William Mitchell College of Law student Michael Niemann prepared this post:

My wife (who is expecting) and I were talking with another couple (who also have children) about the relative risks that mothers have to consider when pregnant. One of the issues that came up was mercury. I became curious because we eat a decent amount of fish, especially during Lent. I searched and found a few articles. Here's one written by a mother who has read the report referenced below. Here is one describing tests on sushi and other fish around New York.

The first article references a study (summarized here) commissioned by Oceana, an environmental group. Its conclusions are troubling. According to Oceana,

“recent independent laboratory testing of 94 samples of fish and sushi bought in 26 U.S. cities revealed that the mercury content of fresh tuna and swordfish approaches or exceeds levels that may pose risks to human health, particularly for children and women thinking of having kids.”

Volunteers purchased fish in 26 American cities and had samples tested by an independent laboratory using standard techniques. They found that mercury levels in sushi tuna and swordfish were commonly in excess of the one part per million threshold published by the FDA.

The findings call into question the FDA’s understanding of mercury in fish and, according to Oceana, militate for a more serious warning from the FDA. Though the FDA has issued a memo to consumers on mercury in fish, the volunteers in the study asked fish vendors about mercury risks and found that most knew nothing. There is a sign (left) issued by the FDA to warn consumers, but note that tuna, a common form of sushi, is not listed there.

This report raises serious questions for consumers. Clearly the report, though drawn from a small sample size, points to both higher levels of mercury than the FDA assumes, as well as to the fact that it has been years since the FDA studied mercury in fish. What other thresholds or research are out of date? Fortunately, we are not big sushi eaters, and there are many fish varieties that are considered quite low in mercury content. But with many sources singing the praises of fish as a part of a healthy lifestyle, consumers may be ingesting more mercury than they know.

Thank you to William Mitchell College of Law student Michael Niemann for preparing this post.