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25. ManganeseName: Manganese
The metal is gray-white, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes cold water slowly. Manganese is present in quantity the floor of oceans. It is an important component of steel. Manganese is an essential trace nutrient in all forms of life. It is an important trace element and may be essential for utilisation of vitamin B. The classes of enzymes that have manganese cofactors are very broad and include such classes as oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The best known manganese containing polypeptides may be arginase, Mn containing superoxide dismutase, and the diphtheria toxin. Manganese was in use in prehistoric times. Paints that were pigmented with manganese dioxide can be traced back 17,000 years. The Egyptians and Romans used manganese compounds in glass-making, to either remove color from glass or add color to it. Manganese can be found in the iron ores used by the Spartans. Some speculate that the exceptional hardness of Spartan steels derives from the inadvertent production of an iron-manganese alloy. In the 17th century, the German chemist Johann Glauber (although some people believe that it was discovered by Ignites Kaim in 1770) first produced permanganate, a useful laboratory reagent. By the mid 18th century, manganese dioxide was in use in the manufacture of chlorine. The Swedish chemist Scheele was the first to recognize that manganese was an element, and his colleague, Johan Gottlieb Gahn, isolated the pure element in 1774 by reduction of the dioxide with carbon. Around the beginning of the 19th century, scientists began exploring the use of manganese in steelmaking, with patents being granted for its use at the time. In 1816, it was noted that adding manganese to iron made it harder, without making it any more brittle. Manganese in excess is toxic. Exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m3 for even short periods because of its toxicity level. Acidic permanganate solutions will oxidize any organic material they come into contact with. The oxidation process can generate enough heat to ignite some organic substances. Parkinson's Disease has been linked to manganese exposure and the welding industry especially. Scientists have reported that welders studied had an average of the onset of Parkinson's Disease 15 years prior to the rest of the general population. Listed on the Hazardous Substance List, manganese is regulated by OSHA due to its high level of toxicity. Quick links
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