High Mercury Levels Found in Californians

Californians who volunteered for a nationwide study of mercury contamination had among the worst levels, with nearly one-third of those tested having concentrations in their tissues that exceeded safe levels.

The study, organized by two national environmental groups, Greenpeace and the Sierra Club, does not provide information about Californians in general because the volunteers were not a random sample.

Nonetheless, the tests of more than 6,000 people who sent hair samples to researchers provide insights into the extent and causes of mercury contamination. Details of the study were released in a report Wednesday.

Experts say that mercury exposure has little to do with proximity to pollution sources. Instead, it is determined by diet. Mercury concentrations in the study were strongly linked to how frequently the volunteers ate fish and other seafood, a finding that has been documented in other studies worldwide.

For volunteers who ate no fish, the average mercury level in hair was 0.06 parts per million, while those who consumed eight or more servings per month averaged 0.90, just below the federal government’s health guideline of 1 part per million.

No link was found to dental fillings or vaccines.

“We saw a direct relationship between people’s mercury levels and the amount of store-bought fish, canned tuna fish or locally caught fish people consumed,” said Steve Patch, co-director of the Environmental Quality Institute at University of North Carolina-Asheville, which conducted the hair tests for the environmental groups.

Among those who volunteered for the tests, New Yorkers were the most highly contaminated. But residents of California were not far behind, with mercury levels substantially above the study’s national average. Midwesterners were the least contaminated.

Asian Americans who volunteered had average levels more than twice as high as African Americans and 75% to 82% higher than whites and Latinos.

A majority of the volunteers did not exceed the 1 part per million concentration that the U.S. Environmental Protection Agency considers safe for pregnant women and children. But one out of every five women of childbearing age who volunteered for the study nationally, and one of every three in California, exceeded it.

Pregnant women are the population of greatest concern for experts, because a fetus is susceptible to mercury’s toxic effects on the brain.

Children exposed prenatally to levels above the EPA guideline show subtle declines in intelligence.

The reasons for the disparate geographic patterns reported were not clear.

Californians consumed seafood as often as Illinois residents, but their mercury levels were twice as high, tests showed. Seattle residents had lower mercury levels than San Franciscans, even though they ate seafood nearly twice as often.

Data for Southern California was not available. Of the 1,090 Californians tested, 122 were from San Francisco, home base of the Sierra Club.

The regional variations may be somewhat artificial, determined by who chose to participate, said Dr. Michael Gochfeld, professor of environmental medicine at the Robert Wood Johnson Medical School in New Jersey.

The types of fish eaten could also be a factor, experts said.

Fish contain different amounts of mercury, based on their size, where they are on food chains and, to some extent, the waters they inhabit. Fish caught in New York state and San Francisco Bay commonly are much more contaminated than fish from the Midwest.

The study, which is continuing, is the largest test of mercury exposure in the nation, organizers said. Participants were volunteers who joined the study by visiting the greenpeaceusa.org or sierraclub.org websites and sending $25 with each sample.

People who often eat fish are probably overrepresented.

As a result, the mercury levels in the volunteers are higher than those of the general population. About 10% of U.S. women in a study by the national Centers for Disease Control and Prevention exceeded the EPA’s mercury guideline, compared with 23% in the Greenpeace/Sierra Club study.

EPA officials said they will continue to use the more scientific data from the Centers for Disease Control.

“As the authors emphasize, this is not a representative sample of the U.S. People volunteered to participate; presumably many felt they might be at risk because of fish consumption,” said Gochfeld, who led New Jersey’s Mercury Task Force.

“Actually, I am a little surprised that they didn’t find even higher mercury levels in people who consumed fish eight times a month,” Gochfeld said.

EPA spokeswoman Eryn Witcher said it is generally understood that people living on the coasts have more exposure, because they eat more fish than those who are landlocked.

Greenpeace and the Sierra Club have been conducting the mercury survey because they are advocating stronger federal regulations for coal-fired power plants, the leading U.S. source of mercury.

California has no major sources of mercury because it has no power plants that burn coal or chlorine factories. San Francisco Bay is highly contaminated with mercury, primarily from abandoned gold mines in the Sierra Nevada.

The EPA has reported that mercury from U.S. industry is responsible for very little of that contained in the nation’s waters. Asia is the global leader in emissions.

Fish and shellfish, which are high in omega-3 fatty acids and protein, are considered important to a healthful diet.

But because of mercury, women of childbearing age and children should eat no swordfish, shark, tilefish or king mackerel, and limit all other fish to two 6-ounce servings a week, the U.S. Food and Drug Administration says. Relatively high mercury levels are found in canned white tuna, albacore, orange roughy, yellowfin and marlin, according to a January FDA report.

Among fish and shellfish with low levels are salmon, shrimp, catfish, cod, flounder, tilapia and trout. Small fish, including anchovies, herring and sardines, are especially nutritious and safe for pregnant women.

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Mercury levels

A study of hair samples sent in by volunteers found that these states had the highest percentage of participants with mercury levels exceeding one part per million. The EPA considers mercury exposure at those levels unsafe for pregnant women and children.

Percentage of participants with at least 1.0 ppm of mercury

New York: 40.2%

Florida: 33.4%

Colorado: 30.4%

California: 30.0%

Washington: 28.8%

Virginia: 27.5%

Massachusetts: 27.1%

New Jersey: 27.1%

Oregon: 26.2%

Michigan: 20.9%

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The study was based on hair samples sent in by more than 6,000 volunteers. The states listed above are the top 10 among 20 states that had at least 100 participants.

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Sources: Environmental Quality Institute, University of North Carolina-Asheville