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Mercury Contamination in Fish Threatens Women & Children
Eating lots of fish tied to high mercury levels
- Jane Kay, San Francisco Chronicle Environment Writer
October 21, 2004

A study sponsored by an environmental group has produced new evidence
linking high fish consumption to potentially unsafe levels of mercury.

Scientists at the University of North Carolina at Asheville tested hair
samples from 1,449 people nationwide who volunteered to participate in the
study after hearing about it through Greenpeace USA and other groups.

About 1 in 5 had mercury levels exceeding Environmental Protection Agency
safety guidelines. Almost half of the volunteers who had consumed large
amounts of fish exceeded the EPA guideline.

The study wasn't designed to estimate what percentage of the U.S.
population may exceed the mercury guidelines, the authors said.

The study is one of the first to examine the relationship between mercury
levels and the consumption of three categories of fish: canned tuna, locally
caught fish, and fresh or frozen fish sold in stores and restaurants.

Richard Maas, a co-author and professor of environmental science at the
University of North Carolina, noted that among those consuming the most
fish, mercury levels were several times greater than the safety guidelines.

Among the findings:

-- About 50 percent of the participants who ate seven or more 6-ounce
servings a month of fish purchased in restaurants or stores exceeded the
safety guideline of 1 part per million.

-- Almost 33 percent of those who ate four or more servings a month of
canned tuna had mercury exceeding the guideline. The study questionnaire
didn't differentiate between different types of tuna. The U.S. Food and Drug
Administration warns that canned albacore has three times the mercury as
chunk light.

-- Almost 36 percent of the people who ate three or more 6-ounce servings a
month of locally caught fish exceeded the guideline.

Coal-fired power plant emissions and natural rock formations release
mercury into the environment. The largest single source of exposure in the
United States comes from fish in the diet.

Health officials agree that fish offers health benefits, and the FDA
recommends 12 ounces a week of fish, while warning that women of
child-bearing age and children should avoid swordfish, shark, king mackerel
and tilefish. Mercury, which is toxic to the human nervous system, is linked
to learning and behavioral problems in children. In adults, mercury can
cause tremors, memory loss and other health problems.

The study was advertised at Greenpeace events and in an e-mail campaign.
Interested parties sent $25 for a kit, then sent their hair and a
questionnaire to the scientists.

"I would expect there to be some bias in our survey because the
participants were self-selected,'' said Steven Patch, statistics professor
at the University of North Carolina, a study co-author.

Patch said he believes the study may overrepresent people who eat a lot of
fish, and may underrepresent those consuming locally caught fish.

The study also examined correlations between mercury levels in the hair
samples and other sources of exposure, including dental amalgams, flu shots
in which mercury is used as a preservative, workplace exposure or hair dyes.

"The effects -- if any -- were much lower than the effects from fish
consumption of store-bought fish, canned tuna or locally caught fish,''
Patch said.

Data gathered in 1999-2000 by the U.S. Centers for Disease Control and
Prevention based on a national nutrition survey showed that 12 percent of
women of childbearing age had mercury levels above the safety guidelines.

E-mail Jane Kay at

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