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Mercury is an odorless, shiny, silver-white liquid, highly toxic to humans and animals. It is neuro-toxic, hence poisonous to the nervous system. In our everyday life mercury can be found in food and water and also in thermometers, barometers, fluorescent light bulb and amalgam dental fillings. There are two main forms of mercury: organic (mercury and carbon compound) and inorganic (mercury combined with non carbon substances). Methylmercury is the most common and most dangerous form of organic mercury.

Although it occurs naturally in the environment, only 30% of the mercury found in our environment can be attributed to natural sources (volcanic eruptions, earth's crust). The remaining 70% is a result of human activities such as power plant coal burning, traffic emissions, disposal of industrial wastes and mining. Burning of medical materials also significantly increases the presence of mercury in the air (1). In addition, there is concern that an increase in ice melts caused by a warming climate may release some past mercury emissions that have been trapped in polar ice. Moreover, mercury deposited on the surface of the Arctic vaporizes each spring when the sunlight returns, causing high concentrations in the atmosphere (2). Once airborne, mercury will end up in the water, where plankton will transform it into methylmercury. Fish and shellfish that eat it are now considered to be the main source of methylmercury exposure to humans. 

Exposure to different kinds of mercury affects our health in different ways. When breathing in elemental mercury vapors, about 80%, will enter the blood system through the lungs, and then quickly to other parts of the body, including the brain. Eventually, most mercury will accumulate in the kidneys and might stay there for a long period of time. Methylmercury is absorbed mainly through food consumption. People who were exposed to methyl mercury for long periods of times have suffered irreversible brain and kidney damage. Exposure to both elemental and methyl mercury affects different parts of the brain and may cause changes in personality structure (shyness, irritability), tremor, changes in vision, defenses, lack of coordination and memory difficulties (3).

Fetuses are most vulnerable to mercury exposure. Many studies have shown that in utero exposure to mercury causes developmental problems later on in life. In Japan, the Faro Islands and Iraq, scientists identified children suffering from various developmental and neural problems after their mothers were exposed to high doses of mercury through their food (fish and grains, mainly) (5). Scientists have also found out that in utero exposure to methylmercury resulted in a small but significant and irreversible reduction in IQ levels and cognitive skills (5).

On December 2011 the U.S. Environmental Protection Agency (EPA) has issued new Mercury and Air Toxics Standards. Therse standards require power plants to reduce emissions of mercury and other toxic pollutants like arsenic, acid gas, nickel, selenium, and cyanide by roughly 90%.EPA estimates that these new standards will prevent as many as 11,000 premature deaths and 4,700 heart attacks a year. Also, the standards are expected to prevent 130,000 cases of childhood asthma symptoms and result also in 6,300 fewer cases of acute bronchitis among children each year.