Mercury pollution
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Mercury is a naturally occurring element that is found in air, water and soil.
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Exposure to mercury, even small amounts, may cause serious health problems, and is a threat to the development of the child in utero and early in life.
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Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes.
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Mercury is considered by the World Health Organisation (WHO) as one of the top ten chemicals or groups of chemicals of major public health concern.
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People are mainly exposed to methylmercury, (an organic compound) when they eat fish and shellfish and are more vulnerable to Minamata disease.
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Minamata Disease:
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A disorder caused by methylmercury poisoning that was first described in the inhabitants of Minamata Bay, Japan and resulted from their eating fish contaminated with mercury industrial waste.
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The disease is characterized by peripheral sensory loss, tremors, and both hearing and visual loss.
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Methylmercury is very different from ethylmercury. Ethylmercury is used as a preservative in some vaccines and does not pose a health risk.
Sources of Mercury:
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Natural sources: Volcanic eruptions and emissions from the ocean.
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Anthropogenic (human-caused) emissions: It includes mercury that is released from fuels or raw materials, or from uses in products or industrial processes.
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Globally, Artisanal and Small-Scale Gold Mining (ASGM): It is the largest source of anthropogenic mercury emissions (37.7%), followed by stationary combustion of coal (21%).
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Other large sources of emissions are non-ferrous metals production (15%) and cement production (11%).
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Globally, 10-20 million people work in the ASGM sector and many of them use mercury on a daily basis.
Note: Mercury is the only metallic element that is liquid at standard conditions for temperature and pressure.
Previous Year Questions:
Q 1.) Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment. Why is mercury used in the manufacture of these lamps? (2010)
(a) A mercury coating on the inside of the lamp makes the light bright white
(b) When the lamp is switched on, the mercury in the lamp causes the emission of ultra-violet radiations
(c) When the lamp is switched on, it is the mercury which converts the ultra-violet energy into visible light
(d) None of the statement given above is correct about the use of mercury in the manufacture of fluorescent lamps
Ans: (b)