What is chromium (Element)?
Chromium is a chemical element with symbol Cr and atomic number 24. It is a silver-colored transition metal.
Chromium Discovery
In 1761, Johann Gottlob Lehmann found in the Ural mountains orange-red mineral which he named Siberian red lead, because he thought it was a lead compound with selenium and iron. Later it turned out that he had found the mineral Crocoite, consisting of lead (II) chromate (PbCrO4).
Several years later, Peter Simon Pallas visited again and found the location that the Siberian red lead was very suitable as a pigment in paint. Soon thereafter, the material was popular and there appeared also to be a bright yellow dye can be made from Crocoite.
In 1797, the Louis Nicolas Vauquelin succeeded to isolate chromium oxide Crocoite by mixing it with mineral acid. A year later turned out that French chemist able to isolate from chromium oxide, metallic chromium by heating it in an oven. He later discovered that some gems (like Ruby) also contain trace amounts of chromium.
Until the early 19th century chromium was primarily used as a paint component. Then came chromium increasingly popular as metal alloys.
The name chromium comes from the Greek chroma, meaning color.
Applications
Since chromium has a good corrosion resistance and good is to be machined is much used to make tools from. Other uses include:
-As a catalyst in chemical reactions
-The chromium-containing chromite mineral is used in the production of refractory bricks as a template, because it has a high melting point, slightly expands, and retains a stable crystal structure.
-In the glass industry as a colorant, it gives glass an emerald green color.
-Chromium is used for the manufacture of stainless steel
-In paint and pigment; lead (II) chromate is a yellow dye
-Potassium is widely used in chemical laboratories as reagent and to clean glassware
-Chromium (IV) oxide is used as the magnetic material in type II Compact cassettes to the poorer quality of iron (III) oxide of type I to replace straps
-Radioactive chromium-51 (51Cr) is used in biomedical applications
-Chromium salts, such as chromium (III) sulphate, are used for tanning leather
Notable features
Cr3 + is very important for the metabolism of sugar in the human body. However, an excessive intake of Cr3 + can cause skin rashes. Cr6 + is a dangerous form of chromium. This diffuses through the skin cell membrane and DNA, and may oxidize. In contrast to most of the other metals that occur as a trace element in organisms, chromium does not bind to proteins.
In the oxidation state +6 chromium in an acid environment is a very powerful oxidizer.
Appearance
The main source of chromium is the mineral chromite (FeCr2O4) mainly in South Africa, Kazakhstan, India and Turkey are sourced. In 2000, achieved annually about 15 million tons of chromite from the ground, which produces about 4 million tons of metallic chromium.
Sometimes, metallic chromium is found in the earth.
Toxicology and safety
Chromium is irritating to eyes and skin and may be carcinogenic hexavalent form when ingested by oxidation of the DNA. Also, Cr (VI) to diffuse through the skin, that is why it should not be touched with bare hands. In 1958 it was decided by the World Health Organization that the chromium concentration in drinking water up to 0.05 mg / l may be.
Their potential to cause dermal sensitization is well known by dermatologists. The relatively rare compared with dermal respiratory manifestations can be partly explained by under-diagnosis and under reporting. When epidemiological studies are carried out after the discovery of a case of occupational asthma, frequently diagnosed several cases.
In 2008, than normally found in the hair of schoolchildren around IJmuiden higher doses of chromium; this may be related to the emission of this substance by the then steelmaker Corus.
Chromium in the diet and as a supplement
About the importance of chromium in the diet is not very much known. However, it is known to play a role in the metabolism of carbohydrates and lipids. The biologically relevant form of chromium is (probably) the trivalent ion Cr3 +. That chromium is an essential part of our diet, research showed patients receiving tube feeding that was therein chrome. Some showed diabetes-like symptoms that do not respond to insulin. By administration of chromium the symptoms disappeared. The action of chromium is dependent on insulin. Mertz and colleagues assumed, wrongly, we now know that the chromium in the body became part of a larger molecule, called Glucose Tolerance Factor (GTF). GTF shows an artifact (it does not exist), it was formed during the use of the analysis method chosen by the researchers. Since then there have been several studies on the effect of chrome on the metabolism of glucose and lipids in order to determine whether it could improve diabetes-like symptoms. Chromium supplementation had no effect in normal healthy people. In diabetics improved glycemic somewhat, but it had no effect on cholesterol and other blood fats.
Chromium supplement
Overall, one can distinguish two types, organic chromium such as chromium (III) picolinate, chromium (III) di- and trinicotinaat and chromium (III) ethanol amine phosphate and inorganic chromium such as chromium (III) chloride. A number of case reports reporting an association between the use of chromium (III) picolinate and the occurrence of rhabdomyolysis (muscle breakdown), kidney failure and a disturbed mind. Laboratory tests showed sometimes see DNA damage, however there is no evidence that this would be relevant to humans. A safety assessment of chromium picolinate, the European Food Safety Authority concluded that the intake of chromium (III) picolinate in food supplements and fortified foods are no risks entails, as long as the dosage does not come from above 250 micrograms per day. The World Health Organisation suggests that daily supplementation with chromium not more than 250 g / day would be.
Supplementation with chromium is only useful in people with chromium deficiency. And that only occurs in a small number of people who receive tube feeding (see above section). It is also true that chromium is in very many foods, albeit in small quantities. With a normal diet you walk so no deficit. Relatively much chromium is in broccoli and whole grain products. Products that a lot of sugar (fructose and sucrose) contain have an adverse effect on the amount of chromium in the body.