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| - Heavy metal poisoning, or more properly metal toxicity is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. Often heavy metals are thought as synonymous, but lighter metals may also be toxic in certain circumstances, such as beryllium, and not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when considered in abnormally high, toxic doses.
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| abstract
| - Heavy metal poisoning, or more properly metal toxicity is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. Often heavy metals are thought as synonymous, but lighter metals may also be toxic in certain circumstances, such as beryllium, and not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when considered in abnormally high, toxic doses. Toxic metals sometimes imitate the action of an essential element in the body, interfering with the metabolic process to cause illness. Many metals, particularly heavy metals are toxic, but some heavy metals are essential, and some, such as bismuth, have a low toxicity. Most often the definition of “heavy metals” includes cadmium, lead, mercury and the radioactive metals. Metalloids (such as arsenic, polonium) may be included in the definition. Radioactive metals have both radiological toxicity and chemical toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium(III) is an essential trace element, but chromium(VI) is a carcinogen. Toxicity is a function of solubility. Insoluble compounds as well as the metallic forms often exhibit negligible toxicity. The toxicity of any metal depends on the molecules it is bound to. In some cases, organometallic forms, such as methylmercury and tetraethyl lead, can be extremely toxic. In other cases, organometallic derivatives are less toxic such as the cobaltocenium cation. Decontamination for toxic metals is different from organic toxins. Because toxic metals are elements, they cannot be destroyed. Toxic metals may be made insoluble or collected, possibly by the aid of chelating agents. Alternatively, they can be diluted into a sufficiently large reservoir, such as the sea, because immediate toxicity is function of concentration rather than amount. However, bioaccumulation has the potential to reverse this. Toxic metals can bioaccumulate in the body and in the food chain, Therefore, a common characteristic of toxic metals is the chronic nature of their toxicity. This is particularly notable with radioactive heavy metals such as radium, which imitates calcium to the point of being incorporated into human bone, although similar health implications are found in lead poisoning| or mercury poisoning. The exceptions to this are barium and aluminium, which can be removed efficiently by the kidneys. The only part of the body that is not adversely affected by metal toxicity is the bones, although strontium and cadmium can weaken bones because they are both chemically similar to calcium. Heavy metal toxicity is, in most cases, a zebra diagnosis – the condition itself is rare and the variety of symptoms mimic many other diseases. As a result, metal toxicity has a very high mortality rate even when victims seek timely medical treatment. In many other cases, the diagnosis is delayed long enough for permanent damage to occur. However, it is often found in clusters as from an epidemiological standpoint, the two most likely reasons for heavy metal toxicity are environmental contamination and occupational exposure. However, iron and lead exposure are fairly common and are usually diagnosed in a timely manner. However, the link between metal and mortality is ancient in origin, having been first described by Hippocrates who saw consistent symptoms in men who ran smelting operations. There is also a strong link between metal exposure and certain types of cancer In some cases, metal toxicity has been traced to food or nutritional supplements which were either tainted or were in and of themselves toxic. For example, Maria Palko poisoned her husband with a folk medicine that contained gold salts, and Arlene Cuddy used a folk remedy that contained a lead salt. Many athletes have deliberately injected themselves with mercury in the mistaken belief that it builds muscle mass. In one infamous case, cardiomyopathy among beer drinkers was traced to cobalt used to stabilize the head of foam. Toxic metals have also been found in illegal drugs.
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