Selenium and Mercury
Selenium and Mercury
Their Interactions and Roles in Living Organisms
The essential or toxic character of the elements depends not only on their concentration, but also on the chemical form in which they occur. This is the case of arsenobetaine, which has limited biological activity compared to the highly toxic inorganic arsenic. Some elements, however, can counteract the toxic action of others through cooperative, competitive, or availability mechanisms. A good example of this is the protective effect of some chemical forms of selenium against mercury toxicity. Cadmium causes the conversion of xanthine dehydrogenase into xanthine oxidase and abnormalities in urate transporters (hyperuricemia), observed in rats under oxidative stress, but cadmium does not have redox properties. This is because cadmium replaces other metals with redox properties. Another example is that toxicity caused by the presence of arsenic in drinking water in countries like Bangladesh is increased through selenium and zinc deficiency detected in the soil. Clearly, the essentiality or toxic character of trace elements cannot be considered in isolation, since it can be modulated by their interaction with the particular organism (its genome), with other elements, and with biomolecules, and is dependent on dose and chemical form.
Keywords: cooperation for metals, metal availability, selenium, cadmium, metal toxicity
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