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Updated Warning for Women and Children About Mercury in Fish and Shellfish
Edited by: Mary Schroeder, M.S., R.D. & Pat Kendall, Ph.D., R.D., Colorado State - Spring 2004
As part of a low fat, heart-healthy diet, consumers are hearing the message to include more fish in their diets. The omega 3 fatty acids found in fish and shellfish are particularly important in ensuring the proper growth and development of the child, both in the uterus and after birth. These same fish, however, harbor methylmercury, a contaminant that if consumed in large enough quantities can damage the developing brain, causing severe learning disabilities and other neurodevelopmental problems in babies and young children. It also may be linked to risk of heart attack and sudden death in adults.
How Does Mercury Toxicity Occur?Mercury is an element found naturally in the environment. It primarily gets into our food supply as a byproduct of industrial pollution. According to the Environmental Protection Agency (EPA), major sources of mercury emissions include coal-burning power plants, municipal waste combustors, medical waste incinerators and hazardous waste combustors. Mercury emissions from these and other sources are transported through the air and eventually deposit on water and land, where humans, wildlife and fish are exposed. Mercury can also directly contaminate land and water through industrial wastewater runoff. As mercury accumulates in streams and oceans, it accumulates in fish and animal tissue in its most toxic form, methylmercury. Fish absorb methylmercury as they feed in contaminated waters. The risks from mercury in fish and shellfish depend on the amount of fish and shellfish eaten and the levels of mercury in the fish and shellfish. Larger fish that have lived a long time have the highest levels because they've had more time to accumulate it. When we regularly eat fish containing high amounts of methylmercury, it begins to accumulate in our blood systems. Once in our bodies, methylmercury is removed from the body naturally, but it may take over a year for levels to drop significantly.
New AdvisoryThe Food and Drug Administration (FDA) and EPA have long advised women of childbearing age about the connection between fish and methylmercury. In March, 2004, this advisory was upgraded to include albacore tuna and tuna steaks in the list of fish with high levels of mercury and to include children in the list of those who should monitor their fish intake. The new guidelines were issued after a FDA study found levels of mercury in fish and seafood are greater than previously believed. Specifically, new findings show "white" canned, albacore tuna has three times the mercury levels as the "light" tuna. The following guidelines target women who might become pregnant, women who are pregnant or nursing, and young children:
- Do not eat Shark, Swordfish, King Mackerel, or Tilefish, because they contain high amounts of mercury.
- Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish. Because albacore ("white") tuna and tuna steaks are higher in mercury than canned light tuna, no more than 6 of your 12 ounces of fish per week should be albacore tuna.
- Check local advisories about the safety of fish caught by family or friends in local lakes, rivers and coastal areas. If no advise is available, it's ok to eat up to 6 ounces per week of fish caught from local waters, but don't consume any other fish during that week.
According to the EPA, about 7 million women and children are eating mercury-contaminated fish at or above the level it considers safe. Furthermore, recent Centers for Disease Control and Prevention (CDC) findings indicate that 8% of women of childbearing age in the U.S. have unsafe mercury levels, translating into over 300,000 babies born at-risk each year. The EPA's methylmercury upper limit is based on bodyweight, also known as the reference dose. EPA's methylmercury reference dose is 0.1micrograms/kg body weight per day. Because body weight is a key factor in determining safe upper limits of fish consumption, amounts that may be safe for adults may in fact still be too high for young children. No specific limits on serving size are given for children. As a result, many advocacy groups think the new advisory is not protective enough. According to Michael Bender, director of the Mercury Policy Project, a 22 pound toddler eating only 2 ounces of albacore tuna per week with the average concentration found by the FDA would have an intake nearly 3 times the EPA's reference dose. Furthermore, consumers eating the advisory's upper limit of 12 oz. of certain high mercury fish in a given week could easily result in exposures well over the EPA reference dose.
Prudent AdviceThe latest research on mercury measurements in fish is both reassuring and disturbing. It is clear that mercury contamination is a real health risk world wide to those who rely on and enjoy fish as part of their daily sustenance. However, it is reassuring to know that many types of fish can still be safely consumed on a regular basis. The new FDA/EPA advisory focuses its attention on those most affected by possible mercury toxicity. It also gives the general population an increased awareness that it is prudent to plan fish-containing meals around these guidelines. The advisory fact sheet can be found at U.S Department of Health Web Site..
Source:- What You Need to Know About Mercury in Fish and Shellfish. U.S. Department of Health and Human Services and U.S. Environmental Protection Agency Fact Sheet. March 2004.
- Mercury in Fish. U.S. Environmental Protection Agency America's Children and the Environment (ACE).
- U.S. Environmental Protection Agency's National Forum on Contaminants in Fish. San Diego, CA. January 25-28, 2004. Speakers: David Achesen, FDA. Kate Mahaffey, EPA.
- FDA's Revised Mercury in fish Advisory Not Protective Enough for Women and Children. Mercury Policy Project. Press Release by Michael Bender. March 24, 2004.
