Organic mercury, toxic effects

There are several different types of organic mercury, but by far the most important in terms of health effects is methyl mercury. When atmospheric mercury is deposited on the ground or in the water, it is converted to methyl mercury by bacteria. Mercury compounds are very toxic and this is the bacteria s way to detoxify mercury. Small animals then consume the bacteria, along with the methyl mercury and bigger animals in turn consume the smaller animals, thus increasing the concentrations of methyl mercury. Methyl mercury accumulates in the larger carnivorous animals, most important of which are fish such as tuna, pike, and shark. 

Neurotoxins The term refers to a specific target organ characterization of effect. Neurotoxins are chemicals which produce their primary toxic effects on the central nervous system. Signs and symptoms are narcosis, behavioral changes, and decrease in motor functions. Examples are mercury and carbon disulfide. 

Mercury exists in three forms elemental, inorganic, and organic with different toxic effects. Elemental mercury is absorbed as a vapor and may enter the CNS and cause toxicity there. Inorganic mercury is poorly absorbed, but the cysteine conjugate of mercury is concentrated in the kidney by active transport. The kidney is the main target organ (also gastrointestinal tract if exposure by that route). 

Different roles in aquatic ecosystems, from acting as nutrients for living organisms (nitrogen and phosphorus compounds) to exerting toxic effects on such organisms (arsenic and mercury). 

Mercury (11) is a frequent component of industrial wastewaters, remarkably toxic at concentrations higher than 0.005 mg The World Health Organization (2006) and national environmental agencies recommend a limit of 0.006 mg of inorganic mercury in drinking water. The health hazards due to the toxic effect of mercury at Minamata, Japan, and Iraq are very well known (Bockris, 1997). 

Mercury is unique among the heavy metals in that it can exist in several physical and chemical forms, including elemental mercury, which is a liquid at room temperature. All forms of mercury have toxic effects in a number of organs, especially in the kidneys [188]. 

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