Toxic Mercury in Fish
by Elaine Sullivan
The New York Times published an article on January 23, 2008 stating that high levels of mercury are found in tuna sushi. Laboratory tests performed on tuna from 20 Manhattan stores and restaurants found so much mercury in tuna sushi that a regular diet of six pieces a week would exceed the levels considered acceptable by the EPA (49 micrograms of mercury a week). Analyzed by Dr. Michael Gochfeld, Professor of Environmental and Occupational Medicine at the Robert Wood Johnson Medical School in Piscataway, NJ and Dr. Joanna Burger, Professor of Life Sciences at Rutgers University, the tuna from some of these establishments had mercury levels so high that the FDA could take action to remove the fish from the market.
Mercury in fish is not a new phenomenon. In March 2004 the FDA and EPA teamed up to issue a warning to the public about mercury in fish. The joint advisory stated that although fish and shellfish are important parts of a healthy diet and are good sources of protein and other nutrients, some of us should monitor how much we eat. The FDA and EPA warning states: “…depending on the amount and type of fish you consume it may be prudent to modify your diet if you are: planning to become pregnant; nursing; or a young child.” The advisory went on to list three recommendations for selecting and eating fish and shellfish that would allow the consumer to “…receive the benefits of eating fish and shellfish and be confident that they have reduced their exposure to the harmful effects of mercury.”
FDA and EPA recomendations 1. Do not eat Shark, Swordfish, King Mackerel, or Tilefish because they contain high levels of mercury. (Tuna was not tested in this study but should also be avoided.) 2. Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. (Select animals lower down on the food chain, but not North American lobster which is very high in methylmercury.)
3. Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, limit consumption to 6 ounces (one average meal) per week of fish you catch from local waters, but don’t consume any other fish during that week. For a more extensive list, go to: www.cfsan.fda.gov/~frf/sea-mehg.html The FDA and EPA are supposed to warn the public of health risks such as this, but, the advisories don’t go far enough. They tell us to reduce our “exposure to the harmful effects of mercury”, but not how long mercury stays in our bodies or how to get rid of it.
According to Drs. Mercola and. Klinghardt in “Mercury Toxicity and Systemic Elimination Agents” an article published in the Journal of Nutritional and Environmental Medicine (March 2001), “Mercury in the central nervous system causes psychological, neurological, and immunological problems in humans. Mercury bonds very firmly to structures in the central nervous system through its affinity for sulfhydryl-groups on amino acids. Other studies have shown that mercury is taken up in the periphery by all nerve endings and rapidly transported inside the axon of the nerves (axonal transport) to the spinal cord and brainstem. Unless actively removed, mercury has an extremely long half-life of somewhere between 15 and 30 years in the central nervous system.” So, reducing exposure to the harmful effects of mercury may help you from accumulating more mercury in your system, but does little for the mercury that is already there. A process called chelation can be employed to speed the removal of mercury from the body, it uses a regimen of diet change and cleansing for several days to help flush mercury from the system.
Sources of Mercury
Mercury is a naturally occurring element in the earth. Natural sources of mercury, such as volcanic eruptions and emissions from the ocean, have been estimated to contribute about a third of current worldwide mercury air emissions, whereas humancaused emissions account for the remaining two-thirds. According to the EPA, “These estimates are highly uncertain. Much of the mercury circulating through today’s environment is mercury that was released years ago, when mercury was commonly used in many industrial, commercial, and residential products and processes. Land and water surfaces can repeatedly re-emit mercury into the atmosphere after its initial release into the environment.” Human-caused emissions are roughly split between these re-emitted emissions from previous human activity, and direct emissions from current human activity.
The EPA estimates that 83% of the mercury deposited in the US originates from international sources, with the remaining 17% coming from US and Canadian sources. Most of this mercury is from power plants and municipal and medical waste incinerators. Mercury in the air eventually settles into water or onto land where it can be washed into water. Fish and shellfish are the main sources of methylmercury exposure to humans. Once deposited, small creatures, such as plankton, convert the mercury into a highly toxic form called methylmercury. The plankton is eaten by small fish and crustaceans where it accumulates in the animals flesh. These small fish and crustaceans are eaten by larger fish which in turn are eaten by predator fish like tuna, swordfish, shark, king mackerel and others. Along this chain the mercury accumulates and concentrates; because the large fish also have longer life spans they can accumulate toxic levels of methylmercury. This, unfortunately, is passed along the food chain to us. Eating fish and shellfish that are lower on the food chain; shrimp, salmon, and tilapia can help to reduce the amount of mercury you get, but you will have to do some research to determine which fish and shellfish are safest to eat. The FDA and the EPA have extensive lists of fish and their mercury levels.
According to the EPA website US mercury emissions account for about 3% of the global total, of that about one third is deposited within the contiguous US the remainder enters the global cycle. Asia is reported to contribute 53% of global emissions with Africa following at 18%, Europe 11%, North America 9%, Australia 6% and South America at 4%. The Clean Air Network Fact Sheet of August 1999 cites “The Electric Power Research Institute calculates that up to 10% of the mercury released deposits within 62 miles of a power plant; 50% within 621 miles and the rest is transported regionally and globally.”
According to the EPA website, “The United States is leading an effort within the United Nations Environment Programme to create a program that would establish partnerships designed to help developing countries reduce mercury emissions. The partnerships will leverage resources, technical expertise, technology transfer, and information exchanges to provide immediate effective action that will result in tangible reductions of mercury use and emissions. It accelerates the work of the UNEP Mercury program, originally proposed by the US at the 2003 UNEP Governing Council meeting.”
The US has cut its own mercury emissions from 220 tons per year in 1990 to 115 tons in 1999 with the biggest changes in the municipal waste combustors and medical waste incinerators. Regulations that were issued in the 1990s to control mercury emissions burning waste require more than a 90% reduction in emissions from these facilities. However, President Bush has tried to do an end run around these regulations through the Clear Skies legislation which would allow for 3 times the amount of mercury emissions as the Clean Air Act.
In spite of attempts by the Bush administration to gut mercury emission regulations, the US remains a very small contributor to global mercury emissions. However, the whole world shares the same oceans, so reducing mercury pollution is a global, not just a national, problem. Since many types of fish are caught and sold internationally, effective exposure reduction will require reductions in global emissions. In the meantime, don’t eat the spicy tuna roll.