Selenium is a mineral found in the soil, which naturally appears in water and a variety of foods. Although human beings require only a small amount of the mineral, selenium plays a key role in metabolism. Overtime, selenium has caught the attention of many individuals worldwide, due to its powerful antioxidant properties. Research has shown that antioxidants can protect cells from damage related to aging, lifestyle choices, and environmental stressors, such as pollution. Nevertheless, human beings must consume selenium in very little amounts, as too much of the mineral can be extremely toxic.
SELENIUM: SOURCES
In nature, selenium tends to be located in metal sulfide ores. The mineral can also be found in brazil nuts, seafood, organ meats, and several different foods. However, commercially, selenium is produced as a byproduct when metal sulfide ores are refined during production. Minerals that are pure selenide or selenate compounds have been found in the past, but are extremely rare. The primary commercial use of selenium is for glassmaking and creating pigments. Moreover, selenium is a semiconductor, due to its metalloid properties, thus it is utilized in photocells. While applications in electronics have mostly been replaced by silicon semiconductor devices, in some cases, selenium is still used in DC power surge protectors. Selenium is also often used as an ingredient in infant formulas, multivitamins and other dietary supplements.
SELENIUM: HUMAN HEALTH EFFECTS
Trace amounts of selenium are very important for cellular functioning in many animals, including humans, since it is an essential mineral involved in many bodily processes. Human beings cannot make this trace element, and thus need to obtain it through their diet or supplements. Selenium deficiencies are uncommon in the United States, though some health conditions, such as Crohn’s disease, are associated with low selenium levels, which can lead to infertility, mental foggy state, fatigue, weakened immune system, hair loss, and muscle weakness. Nevertheless, both elemental selenium and selenium salts are lethal even in small doses, as they may lead to selenosis. Lethargy, dizziness, and motor weakness are all symptoms of chronic selenium intoxication.
While acute amounts of selenium are needed for the human body, overconsumption of the mineral may lead to several health issues, including difficulty breathing, tremors, kidney failure, heart attacks, and even heart failure. Those most at risk of being exposed to higher than normal levels of selenium are individuals working at hazardous waste sites, as they may swallow soil and water that is contaminated, or even breathe in the dust.
Due to bioaccumulation, even a small amount of selenium can lead to several problems in the environment. Particularly, since selenium tends to be strongly bioaccumulated by aquatic organisms, even the slightest increase in waterborne concentrations of selenium may rapidly result in deformed embryos and reproductive failure.
SELENIUM: CRITICAL CASE: ELK VALLEY, CANADA
A paper published by Dennis A. Lemly showcases the potential environmental problems that can result from coal mining, since selenium is a chemical element found in small amounts in coal. In the mining process, when coal is washed prior to transport and distribution, it can mobilize selenium and form contaminated liquid waste, which then becomes a source of pollution to nearby surface waters. In Elk Valley, studies conducted showed that the watershed had areas with elevated concentrations of selenium, which resulted in reproductive failure of cutthroat trout.
Fact sheet about selenium, published by the Agency For Toxic Substances & Disease Registry (ATSDR), which answers the most frequently asked questions about selenium, and its health effects.Read more