The main threats to human health from heavy metals are associated with exposures to arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg). In nature, heavy metal toxicities occur in all living organisms. The consequences of these toxicities have been described in humans. An important aspect of heavy metal toxicities resulting in carcinogenicity is due to the generation of reactive oxygen and nitrogen species e.g. super oxides, hydro peroxides and nitric oxide. Consumption of food crops grown in regions with toxic levels of heavy metals and consumption of live stock products fed produce from these regions could result in heavy metal toxicity in humans. Heavy metals, when in excess quantities, accumulate chiefly in the blood, liver and kidneys. However, researchers suggest that aluminum (Al) may be more likely to accumulate in the brains of persons whose diets are Magnesium (Mg)-deficient. In general, heavy metal toxicities in humans are not common under normal conditions. Most toxicities are caused by environmental and/or genetic abnormalities, from excessive intake, by deliberate or accidental overdose, or from induced deficiencies. Effective measures to control metal toxicities in humans include gastric lavage, ascorbic acid intake and divalent cation therapy, such as the use of calcium (Ca) and zinc (Zn). The use of a variety of chelating agents in the acute toxicity phase has also been found useful. Protective legislation against the use of metal alloy cooking utensils is the long-term control strategy. Future studies need to identify the mechanism of action for toxicity, because at present only a few have been elucidated in this context.
Keywords: Trace elements, mining, enviroment, chelation, human disease, preventive measures, metals, control measures, chelating agents
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