Posted by: Lawyer Sanders | September 22, 2008

Lawyer Sanders says mercury emissions from coal-fired utility plants to be next battle field in environmental law.

According to U.S. EPA, natural sources of mercury—such as volcanic eruptions and emissions from the ocean—have been estimated to contribute about 40 percent of current worldwide mercury air emissions, whereas human-made sources account for the remaining 60 percent. It is estimated that the United States presently accounts for 3 to 5 percent of total global mercury air emissions, whereas Asian countries are estimated to contribute about one-half of the human-made air emissions.

Mercury emitted from coal-fired power plants comes from mercury in coal, which is released when the coal is burned. Coal-fired power plants are the largest remaining source of human-generated mercury emissions in the United States.

Recent estimates of annual total global mercury emissions from all sources — both natural and human-generated — range from roughly 4,400 to 7,500 tons per year.  Concentrations of mercury in the air are usually low. However, atmospheric mercury falls to Earth through rain, snow and dry deposition and enters lakes, rivers and estuaries. Once there, it can transform into, methylmercury, and can build up in fish tissue.

Americans are exposed to methylmercury primarily by eating contaminated fish and shell fish. Because the developing human fetus is the most sensitive to the toxic effects of methylmercury, women of childbearing age are regarded as the population of greatest concern. Children who are exposed to methylmercury before birth may be at a substantially increased risk of poor performance on neurobehavioral tasks, such as those measuring attention, fine motor function, language skills, visual-spatial abilities and verbal memory.

Both saltwater and freshwater fish, depending on their relative position in the food chain, contain varying amounts of methylmercury. “Bottom-feeding” fish, such as catfish, flounder, and shellfish, have some of the lowest mercury concentrations; whereas, large carnivorous fish, such as shark, swordfish, and king mackerel, have the highest mercury concentrations. Smaller carnivorous fish, such as tuna and bass have intermediate mercury levels. Within fresh water bodies in the Southeast, bass generally have higher mercury concentrations than catfish. And farm-raised fish generally test lower in mercury than those caught in “natural” surface waters.


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