Essay On Selenium

Selenium - The Element
In 1817, Jöns Jacob Berzelius found out an unknown substance with properties similar to that of tellurium and named it as Selenium, from the Greek word Selene, which denotes goddess of the moon1. Selenium is one of the rarest elements that are found naturally in the earth’s crust. It occupies group 16 (chalcogens) of the periodic table of elements with atomic number 34 and symbol Se. Selenium exists in multiple allotropic forms but only three are recognised. The most stable form is a metallic gray crystalline hexagonal selenium, second is crystalline monoclinic selenium which is deep red in colour and the third one is amorphous selenium, which appear red in powder form and black in vitreous form. Selenium is not only used in glass industry, xerography, agriculture and horticulture, etc., but it also has a biological role.

Earlier, selenium was recognised only for its toxicity, but its importance in human body cannot be ignored. In spite of its scarcity, it plays a vital role; it acts as an antioxidant and prevents cell damage by free radicals. It prevents development of certain cancers, cardiovascular diseases, etc. Though required in minute quantity, it is to be included as an essential component of human diet. Insufficient intake of selenium

It is either consumed in supplementary form or indirectly through diet. The most common forms of selenium in dietary supplements include selenomethionine, selenocysteine and selenite. The influence of chemicals on the cultivation land determines the amount of selenium in the soil, which indirectly determines the amount of selenium entering our body system. The plants convert inorganic forms of selenium to organic making it available for humans. The selenium content of plant foods varies from one country to another and also shows regional variation. Similarly, in case of animal foods, it depends on the pattern of livestock. Other dietary sources