 |
 |
|
 |
||
Water Facts:
Almost half ot the 'impairments' for Minnesota lakes and streams are the result of mercury pollution. Where does this mercury come from?
With some exceptions, almost all of the mercury that contaminates Minnesota’s lakes, rivers, and fish comes from the air. Mercury can be carried great distances on wind currents before it is deposited on our land and lakes and streams. As a result, about 90 percent of the mercury deposited from the air in Minnesota comes from other states and countries. Coincidentally, about 90 percent of Minnesota’s mercury emissions are deposited on other states and countries.
Most of the mercury in the environment originates from human activities, especially the burning of coal to produce electricity. Coal contains naturally occurring mercury (which is released when the coal is burned along with numerous other pollutants). Other sources include processing taconite, and using mercury in products, such as fluorescent lights, dental fillings, and some types of thermostats and switches. Mercury is used also in manufacturing processes.
Thanks to citizen pressure, Minnesota has taken strong steps to reduce mercury pollution. Laws that promote energy efficiency and wind and solar power will help curb coal-burning. Minnesota also has some of the strongest mercury-free product legislation in the country.
Once in a lake, mercury is converted to methylmercury by bacteria. Fish absorb methylmercury from their food. Mercury is tightly bound to proteins in all fish tissue, including muscle. There is no method of cooking or cleaning fish that will reduce the amount of mercury in a meal. Larger, older fish and fish which eat other fish accumulate more contaminants than smaller, younger fish which eat less contaminated prey.
Mercury builds up in your body over time. It may take months or years of regularly eating contaminated fish to accumulate levels which are a health concern. Large amounts of mercury may harm the nervous system. Young children, developing fetuses and breast-fed babies are at most risk, because small amounts of mercury can damage a brain that is just starting to form or grow. Too much mercury may affect a child’s behavior and lead to learning problems later in life. The first symptoms of adult mercury poisoning include incoordination and burning or tingling sensation in the fingers and toes. As mercury levels increase, your ability to walk, talk, see, and hear may all be affected in subtle ways. The consumption advice given by MDH is intended to keep the mercury in your body below levels that damage the nervous system.
http://www.health.state.mn.us/divs/eh/fish/faq.html#howcontam
