SUNDAY, May 9, 2004 (HealthDayNews) -- Every so often, Americans get wind of some report that calls into question the safety of the nation's fish supply.
For years, people have heard about the dangers of eating fish contaminated with PCBs, a group of cancer-causing chemicals used in industrial manufacturing until the late 1970s.
There's also a risk associated with eating fish tainted with methylmercury, another known toxin that affects the nervous system and can cause permanent brain damage to unborn or young children.
In March, the U.S. government rekindled fish lovers' worries with a special methylmercury advisory. The bulletin urged pregnant women, nursing mothers, women who may become pregnant, and young children not to eat shark, swordfish, king mackerel or tilefish because they contain high levels of mercury.
While it's true the primary danger from methylmercury is to the developing nervous system of an unborn child, it is "prudent for nursing mothers and young children not to eat these fish as well," said the joint advisory from the U.S. Food and Drug Administration and the Environmental Protection Agency.
Women and children may eat up to 12 ounces a week of fish and shellfish that are low in mercury, such as shrimp, canned light tuna, salmon, pollock and catfish, the advisory said. But they should limit their intake of albacore -- or white -- tuna to no more than 6 ounces a week because that fish is higher in methylmercury.
All of this begs the question, is it safe to serve fish for dinner? With a few notable exceptions, the answer is "yes," say food safety and nutrition experts.
"I have tuna in my kitchen right now, as well as salmon," said Gail Frank, a professor of nutrition at California State University at Long Beach and a spokeswoman for the American Dietetic Association.
The joint FDA-EPA advisory seeks to avoid exposing unborn or young children to unsafe levels of methylmercury at a time when their organ systems are still developing.
That's an important message, Frank said. The trouble is, other Americans hear it and think they, too, should limit their fish intake. The general population is not at risk unless they eat fish every day, especially if they're only eating tuna, she noted.
"You don't want people to become so concerned so that they eliminate fish from their diet," said Joan Rothenberg, director of food science at the International Food Information Council in Washington, D.C.
Yet some health and environmental experts contend the latest government advisory doesn't go far enough to protect women and children from the harmful effects of mercury in fish.
Eating 12 ounces of certain fish in a given week, as the government suggests, could result in exposures well over the "reference dose" (RfD) -- the daily amount the EPA considers safe over a lifetime, according to the Mercury Policy Project, a Vermont-based group dedicated to reducing mercury exposure. The group is particularly concerned about the amount of mercury that these sensitive populations are getting in canned albacore and fresh tuna.
"A 22-pound toddler eating only 2 ounces of albacore tuna per week with the average mercury concentration found by the FDA would have an intake nearly three times the EPA's RfD," Michael Bender, director of the Mercury Policy Project, said in a statement.
Children, because of their smaller size, get a much greater dose of mercury from even a smaller serving of certain fish, Bender added. The government needs to issue more specific advice on what not to feed children based on a child's weight and the mercury content of different fish, he said.
About 3 million children aged 3 to 6 are eating mercury-contaminated fish at or above the level the EPA considers safe, according to the project.
Still, health experts insist that, overall, fish is a good, low-fat source of protein that's rich in omega-3 fatty acids and other nutrients. The American Heart Association recommends that people eat fish, particularly fatty fish such as mackerel, lake trout and salmon, at least two times a week.
Nutritionists say the best bet for overall good health is to eat a variety of foods in moderation. "If you eat a variety of foods, you create a safety net for your body," Frank said.
Charles Santerre, an associate professor of foods and nutrition at Purdue University, is conducting a survey of low-income women in Indiana who are in their childbearing years. Of the more than 500 sampled so far, 32 percent haven't eaten fish in the last year.
"To me, that's a much greater concern," he said, because they are missing out on the health benefits of fish.