News Coverage
Stirring the Waters
Fish's Health Benefits Contend with Contaminant Advisories
Published June 23, 2003
Even in beef country, summers can inspire Coloradans to throw a salmon steak or other hearty fish on the backyard grill.
But are fish fans helping their hearts, as seafood long has been proclaimed to do? Or are they poisoning their brains, as the mercury increasingly found in the nation's waters can do?
The Environmental Protection Agency this month released an updated list of advisories warning the public of contaminants in the nation's waters. Nearly 3,000 advisories were added last year, 75 percent of which were related to mercury.
The issue creates another snag for nutritionists, who for years have tried to reel in fish-haters because of the nutritional value of the food. Yet they say there are ways to acknowledge mercury concerns and still net the benefits of a fish-inclusive diet.
Good fish
"Fish is high in protein and low in fat," said Eileen Faughey, director of Nutrition Connections in Boulder. The finned creatures are loaded with vitamins and contain heart-healthy omega-3 fatty acids, she said.
"One thing they say the omega-3 does is help the body burn fat more efficiently," said Mary Schreiner, a nutritionist with the American Heart Association. That's important in a nation where skyrocketing obesity is considered a health crisis and heart disease is the No. 1 killer.
Omega-3 studies also suggest benefits such as lowering triglycerides, decreasing depression, preventing blood clots and boosting brain development.
For most people, the benefits probably outweigh the risk of mercury poisoning, which would require hefty and constant consumption over a long period of time. Mothers-to-be and young children are the exception, which creates a Catch-22, said Kathy Gaines, a registered nurse and program director for the Colorado chapter of the March of Dimes.
"On the one hand, pregnant women are being told to eat fish, that they need the omega-3 now more than ever," Gaines said, referring to recent studies suggesting fish can reduce the risk of preterm labor, decrease postpartum depression and improve brain development in fetuses.
But mercury-tainted fish also can sabotage that brain growth, Gaines said.
Bad fish
In 2000, the National Academy of Sciences estimated that as many as 60,000 babies are born in the United States every year with neurological problems that lead to poor school performance as a result of mercury exposure in the womb. The main culprit: fish in the diet.
Mercury occurs naturally in the environment; coal-fired plants also spew it into the air. It settles to the bottoms of lakes, streams and coastal waters, where it combines with organic materials and creates methylmercury, a form of the metal that can build up in fish and humans.
The risk of high mercury levels in Colorado's waters is lower than in states where industrial pollution is higher. But the state's waters are not immune.
The Colorado Department of Public Health and Environment has posted advisories for seven bodies of water, mostly in the southern part of the state, all but two related to mercury levels (see sidebox). Parents are urged to check the EPA site (www.epa.gov/ost/fishadvice) for a list of lakes and game fish to avoid.
Bob McConnell, manager of the state department's monitoring unit, said budget constraints force limited testing in Colorado.
"We try to target roughly one reservoir a year if we can find the resources to do that," McConnell said. That means some waters have never been tested. Many, such as Bear Lake and Cherry Creek Reservoir, have not been checked for 15 years, he said.
Big fish
Methylmercury, a potent neurotoxin, is most dangerous for children, fetuses and babies with rapidly developing brains. It forms at the bottoms of bodies of water and invades plankton. Small fish eat the plankton and larger fish eat the smaller fish. As the food chain progresses, so does the potential for mercury buildup.
Children and women who are pregnant, nursing or planning to become pregnant should not eat shark, tilefish, swordfish or king mackerel, according to the Food and Drug Administration.
All other fish should be limited to 12 ounces a week for adults and two ounces for children under 6.
The EPA's limits are stricter, and the FDA's exclusionary list is contested by consumer and environmental groups as not being long enough (see side box).
While scientific evidence is not conclusive on whether fish can cause neurological problems in adults, both the EPA and the FDA advise all consumers to limit consumption of predatory fish because of their greater potential for high mercury levels.
Many experts, including Dr. Kennon Heard, a toxicologist with the University of Colorado Health Sciences Center, believe the problem is being overstated.
"Personally, I don't think it's a health issue," he said. "I think the EPA guidelines that have been released are based on a lot of theoretical evidence and very little science. I certainly don't have a hesitation to say the stuff you buy in the store is safe."
The EPA acknowledges that its guidelines are conservative.
Dr. David Gilmore, a toxicologist with Kaiser Permanente, agrees that the issue is overblown.
"My wife is Japanese, and we eat sushi like crazy, and it's absolutely nothing I worry about," he said. "I worry more about parasites and bacteria."
But there are recorded cases of patients complaining of neurological symptoms - tingling, vision problems, fatigue, memory loss - whose mercury levels tested high, said Caroline Smith Dewaal, food-safety director for the Center for Science in the Public Interest in Washington.
When fish was removed from the diet, mercury levels dropped and symptoms subsided, she said, though the studies were not scientifically sound.
Yet Smith Dewaal said giving up fish because of mercury is not the answer.
"Overall, fish is part of a healthy diet," she said. "We're not saying don't eat fish. We're just saying choose carefully."
Lakes to avoid
The state has posted advisories for the following bodies of water that are open to fishing. The EPA Web site, www.epa.govost/fishadvice, offers more information, though it might take time and patience to navigate.
McPhee Reservoir, Montezuma County
Narraguinnep Reservoir, Montezuma County
Navajo Reservoir, Archuleta County
Sanchez Reservoir, Costilla County
Sheldon Lake, Larimer County
Sweitzer Reservoir, Delta County
Teller Reservoir, Pueblo County
Willow Springs Ponds, El Paso County
Fish to avoid
Some environmental and consumer groups consider the Food and Drug Administration's list of fish to avoid - shark, swordfish, king mackerel and tilefish - too short. The Environmental Working Group suggests pregnant women, nursing mothers and all women of childbearing age not eat:
tuna steaks
sea bass
Gulf Coast oysters
halibut
pike
walleye
white croaker
largemouth bass
The group also believes women should eat no more than one meal per month of:
canned tuna
mahi-mahi
blue mussel
eastern oyster
cod
pollock
Great Lakes salmon
blue crab from the Gulf of Mexico
wild channel catfish
lake whitefish
Source: Centers for Disease Control and Prevention
Effects of mercury poisoning
High levels of mercury passed from mother to child can cause:
brain damage
mental retardation
lack of coordination
blindness
seizures
inability to speak
Children ingesting excess mercury can have damaged:
nervous systems
digestive systems
kidneys
Effects on brain function may include:
irritability
shyness
tremors
changes in vision
changes in hearing
attention deficits
memory problems