Mercury is an element that occurs naturally. It is released into the environment by both natural processes and human activity. This means there are small amounts of mercury in lakes, rivers and oceans.
It happens through the food chain. In the bottom sediments of rivers, lakes, and oceans, mercury undergoes methylation, a process carried out by bacteria in certain conditions. Small fish eat small snails, crawfish and insects that have eaten even smaller things containing methylmercury. Then larger predator fish, like bass, eat the smaller fish. Since bass are at the top of the freshwater food chain, they can build up methylmercury. Methylmercury then gets into the food chain and results in mercury exposure to persons who eat fish.
In 1993, The Louisiana legislature began funding The Mercury Program and over the last decade the program has grown, adding additional sampling locations each year. The Louisiana Departments of Environmental Quality and Wildlife and Fisheries sample fish from lakes and rivers across the state. The Louisiana Department of Health and Hospitals then evaluates the data that is provided and determines the need for an advisory.
Mercury usually causes no symptoms at low levels. However, if high levels of mercury build up in the human body, they can affect the brain and nerves. In addition, effects that can occur at high levels include learning problems and birth defects in children. Among people of all ages, high mercury levels can cause tingling or numbness in the mouth, hands and feet, and vision and hearing troubles. The primary source of environmental exposure to mercury in the general population is through consumption of contaminated fish. That’s why prevention of mercury build-up in our bodies is so important. Those who should be most careful when eating fish are:
It is not likely that there is an immediate need to be concerned about the health effects of mercury. Fish advisories are issued as a precaution. However, you should consult your doctor if you are concerned. (Tests are available to measure mercury levels in the body. Mercury in whole blood or in scalp hair is measured to determine exposure to methylmercury. Your doctor can take samples and send them to a testing laboratory).
Doctors recommend fish as an important, low fat source of protein, but where mercury is present in those fish, it is important that certain people know the rules when eating fish caught from waters under mercury health advisories. The fact that mercury is found in fish from some Louisiana waters does not mean you have to quit eating fish. But if you eat large amounts of fish which contain mercury over a long period of time, you might experience health problems. There are no special cleaning or cooking methods that will take mercury out of fish. But there are some things you can do to reduce your health risks:
Call 1-888-293-7020, toll-free, for more facts about mercury in fish and to request a current list of mercury advisories issued for Louisiana waters.
For information on the US Environmental Protaction Agency's (EPA) Fish Advisory Program including the March 2004 Federal Advisory for women who might become pregnant, women who are pregnant, nursing mothers and young children, go to www.epa.gov/ost/fish/