The Quick Facts: Mercury is a toxic metal that can damage a child’s developing nervous system. The FDA and the EPA have advised pregnant women, nursing mothers, and young children to avoid eating shark, swordfish, king mackerel, and tilefish (all of which contain high levels of mercury); to limit the intake of low mercury-containing shellfish (e.g., shrimp, canned light tuna, salmon, pollock, and catfish) to 12 ounces (2 average meals) per week; and to limit the intake of albacore (white tuna) to six ounces per week (1 average meal).
Since my daughter’s second birthday, I have slowly been introducing fish and shellfish into her diet. Our pediatrician recommends waiting to introduce both seafood and peanut butter until a child reaches the age of two. (Other doctors may recommend a different timetable so consult your pediatrician to find out what is right for your child). While my daughter seems to enjoy the fish morsels that she has had thus far, for over a month now I have been putting off feeding her tuna fish due to my concern that I will also inadvertently expose her to mercury. Finally, I decided to do some research in order to learn how much mercury really is in fish and whether I could feel comfortable giving her a tuna fish sandwich after all.
The Benefits of Eating Fish and Shellfish
According to the U.S. Food and Drug Administration (the ‘FDA’), fish and shellfish are parts of a well-balanced diet. They contain protein and other essential nutrients, are low in saturated fat, and contain omega-3 fatty acids. According to the American Heart Association, eating fish rich in omega-3 fatty acids may prevent sudden death and fatal cardiac arrests by regulating the heartbeat and preventing the irregular rhythms that are associated with sudden death from cardiac arrest. For children, the benefits of eating fish are linked to a fatty acid, DHA, which is naturally found in breast milk and fish. One study found that 2-year olds who received higher levels of DHA as infants could concentrate and stay on task better than their peers, and a study published in the January 2003 edition of the journal Pediatrics found that 4-years olds had higher IQ scores if their moms took DHA supplements during pregnancy and while breastfeeding.
So with all of the benefits to be gained from eating seafood, why am I so reluctant to feed my daughter tuna fish, a staple in the diet of most American kids?
Seafood and Mercury
Many mothers with whom I have spoken have never heard of a link between tuna fish—or any other seafood for that matter—and mercury. This is not surprising as the link is not an obvious one. According to the Sierra Club, a nonprofit organization whose mission is to explore, enjoy, and protect the wild places of the Earth, mercury, a toxic metal, is released into the environment from natural sources such as volcanoes and from man-made sources such as power plants, silver-colored dental fillings, vaccinations that contain the preservative Thimerosal (see our Fall 2005 newsletter for an article entitled, ‘The Safety of Vaccines: Fears and Facts about Thimerosal-Containing Vaccines,’ which can be found in our Archives), broken thermometers, and occupational exposures. The major source of mercury releases into the environment is the burning of coal at power plants in order to generate electricity. Once released into the atmosphere, mercury falls to the earth in rain droplets and runs into our lakes, rivers, streams, and ultimately into the ocean. Through this process mercury is converted to methylmercury, a highly toxic substance, which binds to fish protein. Larger fish (e.g., shark, swordfish, king mackerel, and tilefish) that have lived longer have the highest levels of methylmercury because they have had more time to accumulate it. Importantly, this type of mercury can not be eliminated through the cooking process.
Risks of Mercury Exposure to Young Children and Women
According to the U.S. Environmental Protection Agency (the ‘EPA’), nearly all fish and shellfish contain traces of mercury. According to the Sierra Club, children are highly susceptible to the effects of mercury because their bodies are still developing. Studies show that the adverse health effects associated with mercury exposure in humans and animals include: neurological defects such as numbness in the arms and legs, slurred speech and difficultly walking. In children, developmental effects may also include learning disabilities and difficultly paying attention.
The EPA has estimated that one in six U.S. women of childbearing age has mercury levels in her blood high enough to put her baby at risk. The EPA and the FDA have issued a joint warning to pregnant women, women who may become pregnant, and nursing mothers, which warns against eating shark, swordfish, king mackerel, and tilefish as they have been found to contain high levels of mercury. The EPA and the FDA further advise that such women, as well as children, should limit their intake of fish that contain low-levels of mercury (e.g., shrimp, canned light tuna, salmon, pollock, and catfish) to 12 ounces (2 average meals) a week and limit their intake of albacore (’white’) tuna (which has more mercury than canned light tuna) to 6 ounces (1 average meal) a week. In addition, 45 states and territories have issued warnings, advising people not to consume fish from local lakes, rivers, and coastal areas due to unsafe levels of mercury in some of the waterways. Accordingly, fish caught by family and friends at local lakes, rivers, and coastal areas should be checked against local advisories. If no advisories are available, the EPA advises women and children to eat no more than 6 ounces (one average meal) per week of such fish.
Finding Low-Mercury Fish and Shellfish
Some fish are more likely to contain high levels of mercury than others. Here are some examples of how different types of fish and shellfish stack up:
The Worst: Shark, swordfish, king mackerel, tilefish. These fish have the highest mercury levels. Pregnant women, nursing mothers and small children are advised to avoid them.
Moderate: Halibut, lobster, mahi-mahi, orange roughy, red snapper, albacore (white tuna). These fish can be high in mercury; they should be consumed only occasionally.
The Best: Catfish, flounder, sole, salmon, sardines, shellfish (includes clams, crab, oysters and shrimp), tilapia, canned light tuna. These fish tend to have the lowest mercury levels. But some may still contain other contaminants, including PCBs.
Solutions To Reduce Mercury in Our Bodies and Our Environment
According to the EPA and the FDA, if you regularly eat seafood high in methylmercury, the methylmercury can stay in your body and accumulate overtime. With time, methylmercury will be removed naturally; however, it may take over a year for the levels to drop significantly. If you have been exceeding the EPA and the FDA recommendations for fish and shellfish consumption, as described above, there are things that you can do now to reduce the level of mercury in your system:
- Avoid mercury-containing fish.
- Get your omega-3 fatty acids from other sources. Omega-3 fatty acids are not only contained in fish and shellfish. Good sources of omega-3 fatty acids include: dark green vegetables like broccoli, spinach, lettuce, kale, and peas; legumes like walnuts, flax seed, beans (mung, navy, pinto, and kidney); and fruits like citrus, melons, and cherries.
- Switch to a renewable energy supplier of electricity to reduce the burning of coal. By reducing the input of mercury into the environment you will be reducing your exposure. For a list of renewable energy suppliers in your area go to www.green-e.org.
- Conserve energy whenever possible. Turn off lights when you leave the room, and when replacing electric appliances buy Energy Star approved products. Conserving energy will help to reduce the input of mercury into the environment by coal-burning electric suppliers.
- Properly dispose of mercury containing products. Some products such as fluorescent lamps contain mercury vapor and must be disposed of in accordance with local hazardous waste disposal rules or else the vapor will be released into the atmosphere and may ultimately end up on your plate.
Now that I am armed with the above information, I can make educated choices that are best for my daughter’s health and for the environment. The benefits that children gain from eating omega-3 fatty acids and the information provided by the FDA and the EPA as to what types of fish and how much to eat have helped me to get over my fear of unwittingly exposing my daughter to a mercury-laden tuna fish sandwich. Still, I plan to prepare canned light tuna instead of albacore (white tuna) and to limit her consumption of all seafood as recommended by the FDA and the EPA.
Information used in this article was found at the following sources, which you can visit if you want to find out more about this topic:
http://www.epa.gov/waterscience/fish/MethylmercuryBrochure.pdf (Brochure from the FDA and EPA advising pregnant and nursing women and children to limit seafood consumption)
http://www.americanheart.org/presenter.jhtml?identifier=3014425 (American Heart Association, a national voluntary health agency whose mission is to reduce disability and death from cardiovascular diseases and stroke; report that eating fish may lower heart rates and prevent sudden death)
http://pediatrics.aappublications.org (study by Ingrid B. Helland, Lars Smith, Kristin Saarem, Ola D. Saugstad, and Christian A. Drevon, entitled, ‘Maternal Supplementation With Very-Long-Chain n-3 Fatty Acids During Pregnancy and Lactation Augments Children’s IQ at 4 Years of Age’ found in the journal Pediatrics, Jan 2003; 111: 39 ≠ 44.)
http://www.sierraclub.org/mercury/factsheets/ (Factsheet from the Sierra Club, a national non-profit environmental organization dedicated to exploring, enjoying, and protecting the wild places of the earth, entitled ‘We Can Protect American Women and Children from Mercury Pollution)
http://www.oceansalive.org/EAT.CFM (Environmental Defense Oceans Program, national non-profit environmental organization, working to find constructive solutions to the most critical problems facing the world’s marine environments)
http://books.nap.edu/catalog/9899.html (National Academy of Sciences book published in 2000 entitled ‘Toxicological Effects of Meythlmercury’)
http://www.EnergyStar.gov (ENERGY STAR is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency)
