’s Operation Safe Seafood finds hazardous levels of mercury in supermarket fish throughout the Des Moines-Ames Corridor, Iowa

By August 31, 2010Got Mercury?
High levels of mercury found in supermarket
swordfish and tuna in Iowa

Ames, IA- An investigation led by a concerned citizen of Iowa found hazardous levels of mercury in grocery store swordfish and tuna located throughout the Des Moines-Ames Corridor.  Directed by the public health advocacy group, 20 samples of swordfish and tuna were purchased at thirteen supermarkets and analyzed for mercury content by an independent laboratory.

Of the 20 fish samples, thirty percent contained mercury levels exceeding the U.S. Food and Drug Administration’s (FDA) mercury action level of 1 part per million.  One piece of swordfish registered 300 percent over the limit.  For a detailed report and mercury results please click here.

The fish samples were tested for methylmercury levels by an accredited laboratory.  Most of the samples were high in mercury, a known neurotoxin dangerous to infants and children and should be avoided by pregnant women and those planning to become pregnant.

“It is clear from this study that eating tuna and swordfish could be harmful to your health,” said Buffy Martin Tarbox, Campaign Coordinator for, based in Forest Knolls, CA.   “We have never seen swordfish and tuna mercury levels as high as what were found in parts of Iowa.”

“I am very concerned that unsuspecting people may be eating fish that is contaminated with exceptionally high levels of mercury,” said Thomas Skadow who volunteered his time to collect the samples.  “I will not be eating swordfish again in the future.”

All the samples contained mercury, a troubling finding since eating fish is the number one source of mercury exposure in the United States according to the Environmental Protection Agency (EPA).   In its own studies, the EPA has detected mercury in every fish sample within the continental U.S. The EPA has set a mercury action level at 0.5 ppm for recreational fish, half the level of the FDA standard for commercial fish.

This testing was conducted as part of national effort initiated by called Operation Safe Seafood. Mercury testing is occurring in communities across the U. S. A similar investigation conducted early 2010 in California found over forty percent of fish being sold in grocery stores exceeded the FDA’s mercury action level.

About works to protect people and the environment from mercury.  Because of the ubiquitous nature of mercury in the environment and because federal and state public health agencies are not doing enough to raise public awareness and protect the public from mercury, developed the free online mercury-in-fish calculators that have received millions of hits since 2002.

According to the calculator, a woman who weighs 140 pounds and eats a six-ounce portion of swordfish will be exposed to a mercury level that is 273 percent above government exposure guidelines.


The FDA has issued a warning to women of childbearing age and young children to not eat swordfish and to limit consumption of tuna due to high mercury levels.

Mercury contamination of seafood is a widespread public health problem, especially for women of childbearing age, pregnant and nursing women and children.  Mercury ingestion can lead to memory loss, developmental and learning disorders, vision loss, heart disease and, in extreme cases, can result in death.

Currently there are no federal legal requirements to warn people about mercury in fish. has been seeking action from the California State Legislature, Congress and the FDA to mandate mercury in fish warning signs at grocery stores and restaurants but government has been slow to act.