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Department of Ecology News Release - June 20, 2003
03-121
OLYMPIA - The state Department of Health has issued a statewide fish-consumption advisory for bass after a Department of Ecology study found elevated mercury levels in bass across the state.
More than half of the smallmouth and largemouth bass collected contained mercury at or above the level that causes health concerns. As a result, the health department is advising women of childbearing age and children under age six to eat no more than two meals of freshwater bass from Washington waters per month.
"The results from this study are consistent with national data showing that bass have higher levels of mercury," said Ecology Director Tom Fitzsimmons. "It wasn't isolated to one side of the state or the other, or to urban versus rural areas. It is a statewide problem affecting all of us."
The study sampled 185 bass from 18 lakes and two rivers around the state. Results showed 51 percent of the bass had mercury concentrations at or above 150 parts per billion (ppb), the threshold used by the state Department of Health. Twenty-three percent of the bass tested had mercury levels at or above 300 ppb, the measure used by the federal Environmental Protection Agency to evaluate water bodies and fish. The lowest mercury concentration found in the study was 22 ppb, with a high of 1,280 ppb.
"There was a clear correlation between age and size of the bass and mercury concentrations," said Bill Backous, who manages the Ecology division that conducts scientific studies and monitoring. "Smaller bass had lower levels of mercury, while older, larger bass had higher concentrations. The results were consistent in all of the water bodies."
State Health Officer Dr. Maxine Hayes said, "While eating a variety of fish and shellfish as part of a balanced diet helps reduce your chances of stroke or heart attack, people need to know that some kinds of fish are very high in mercury, and that is a problem."
Although mercury can cause health problems for everyone, the risk could be higher for women who are or who may become pregnant, and for young children. Pregnant women who eat fish contaminated with large amounts of mercury place their babies at greater risk for changes in their nervous systems. These changes can affect a child's ability to learn. In adults, mercury can lead to possible problems of the central-nervous and cardiovascular systems.
"Fish is an excellent low-fat food and a great source of protein, vitamins, and minerals," Hayes said. "While we don't want to scare people away from eating all fish, women who are or who might become pregnant should choose fish that are low in mercury."
For the study, scientists collected up to 10 largemouth or smallmouth bass from each water body and tested the edible muscle tissue. Bass were selected due to their wide distribution in Washington, their known tendency to accumulate mercury, and because they are a long-lived fish that preys on smaller fish.
All but one of the water bodies produced bass with mercury levels at or above 150 ppb - but only small bass were collected at the water body that was the exception. Smaller fish typically have lower concentrations of mercury.
"If we had been able to find some larger bass there, we probably would have found higher mercury levels there, too," Backous said.
Methylmercury is the kind of mercury that contaminates fish. It binds to fish muscle, so cutting off the skin and fat, filleting or preparing fish in a special way does not reduce mercury levels in the flesh of fish. The key to reducing exposure while still gaining the health benefits is choosing fish with lower mercury levels.
Sport fish that typically have lower levels of mercury include salmon, trout, kokanee and pumpkinseed. Store-bought fish and shellfish low in mercury include shrimp, pollock, salmon, cod, catfish, clams, flounder, crab and scallops.
A fact sheet with more information, including the list of water bodies there
were examined, is available at
http://www.ecy.wa.gov/biblio/0303036.html, and commonly asked questions at
http://www.ecy.wa.gov/biblio/0303037.html
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Media contact: Sheryl Hutchison, Ecology communication
director, 360-407-7004
Donn Moyer, Department of Health Communications, 360-236-4076.
Web links
Fish-tissue/mercury fact sheet:
http://www.ecy.wa.gov/biblio/0303036.html
Frequently asked questions:
http://www.ecy.wa.gov/biblio/0303037.html
Fish-advisory Web site:
http://www.doh.wa.gov/ehp/oehas/EHA_fish_adv.htm (Link removed 06/04/07.)
Fish-tissue/mercury report:
http://www.ecy.wa.gov/biblio/0303026.html
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
