ntr307 discuss4 - Sarah Sarosdy Due Monday NTR 307...

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Sarah Sarosdy Due: Monday, November 29, 2010 NTR 307 Discussion Questions 4 1. Fish contain mercury as a result of the toxic mercury released into our atmosphere by burning fossil fuels, particularly coal. Mercury also enters our atmosphere as a result of municipal waste incineration. Once in the atmosphere, the mercury pollutants eventually enter rivers, lakes, and oceans and are converted to methylmercury (MeHg) by sulfate reducing bacteria. MeHg is absorbed by fish as they consume small organisms and other fish; thus seafood is a leading source of mercury in the human diet. The highest amount of mercury bio-accumulates in large fish. This is why the bigger, older fish higher up on the food chain like tuna and shark contain higher levels of mercury; they have lived and eaten in a mercury contaminated environment for longer time, compared to the small shorter life-span fish like tilapia, salmon and shellfish. Unfortunately mercury contamination cannot be removed by cooking fish due to the fact that MeHg binds to proteins in the muscle tissue of fish. Upon human consumption, 95% of MeHg will be absorbed by body tissues within two days of consumption and remain in the adult body for 70 to 90 days. The National Academy of Sciences suggest that consumption of MeHg should not exceed 0.1ug Hg per kg body weight per day because greater consumption may cause dangerous mercury accumulation in tissues, specifically in the kidneys, brain and muscle. Because mercury is a neurotoxin, and can damage the brain and nervous system, toxicity has been linked to neurological effects even disconnected from the time of exposure to the onset of symptoms. Eating fish that contain high levels of mercury can cause learning disabilities, motor skill impairment, and increase
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the risk of developing cardiovascular disease. It has been suggested that MeHg accumulation in the
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ntr307 discuss4 - Sarah Sarosdy Due Monday NTR 307...

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