From Natural WellBeing
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History of Zinc Usage
Artifacts from the third century AD containing zinc have been found in several places around the world. It was used in the manufacture of brass, which is a combination of copper and zinc. There have been writings found that indicate its appearance as a bi-product of other smelting procedures. Artifacts have been found in Romania, France, Spain and other European countries.
Zinc is very abundant in the earth's crust. It is usually found with metals such as lead and copper in ores. Zinc sulfide is the mined most frequently due to its concentration of zinc. Although it has been known and used for many centuries, the first practical commercial procedure was established in 1752. The United States, Canada and Australia contain large reserves of zinc. The largest reserve has been found in Iran.
Modern industrial uses
Zinc compounds are instrumental in about ¼ of all of the zinc output in the US. Zinc oxide is used as the pigment in white pain and is a catalyst in rubber manufacturing. Zinc is also instrumental due to its semiconductor properties in the field of photocopying. Zinc chloride is the material used as a fire retardant in lumber manufacturing as well as a preservative.
It is used occasionally in model rockets as a propellant and has been proposed as a salting material in the use of nuclear weapons. As an agent to prevent corrosion, it is used to iron and steel. The use for galvanization uses 47% of all zinc usage. Zinc is more reactive than other metals and therefore attracts local oxidation until it is gone. The protection from oxidation will continue after the zinc is scratched, but will degrade as the zinc corrodes. Galvanization is most commonly used in suspension bridges, metal roofs, light posts, heat exchangers and car bodies.
Modern medical uses
The ingredient label on most vitamin bottles will contain zinc. Scientists have reported that it contains antioxidant properties. This reportedly prevents aging of the muscles and skin. That study is controversial, but still used in commercial products. It is also instrumental in the healing injuries to the body.
Zinc oxide can prevent skin damage to the skin protecting from winter winds and summer sun. It has also been used as the predominant ingredient in ointments to prevent diaper rash in babies. It must be used during each diaper change to be effective.
Zinc lactate is found in toothpaste. It is reportedly instrumental in the prevention of halitosis. In shampoos, it has anti-dandruff functions.
Biological roles of zinc
Plants and animals require zinc as a trace element. It is second only to iron in the metals found in organisms. In humans it will interact with ligands and is instrumental in the metabolism of both DNA and RNA. The brain contains and stores zinc to modulate excitability. It is also instrumental in learning and in the function of the central nervous system.
The recommended allowance (RDA) is 11mg/day for men and 8mg/day for women. The highest concentration of foods is found in red meats such as lamb, liver and beef. The presence in plants is dependent on the amount of zinc in the soil.