Well, I guess the picture above gives away what RCRA 8 metal is next on the list. Part 7 of 8 is about Selenium. Now Selenium is not a “popular” heard metal used; like mercury, or silver, or lead. However, Selenium is commonly present in our everyday normal life; both good and bad.
Selenium is an essential trace mineral in the human body. This nutrient is an important part of antioxidant enzymes that protect cells against the effects of free radicals that are produced during normal oxygen metabolism. The body has developed defenses such as antioxidants to control levels of free radicals because they can damage cells and contribute to the development of some chronic diseases. Selenium is also essential for normal functioning of the immune system and thyroid gland.
Plant foods are the major dietary sources of Selenium in most countries throughout the world. The content of Selenium in food depends on the Selenium content of the soil where plants are grown or animals are raised. For example, researchers know that soils in the high plains of northern Nebraska and the Dakotas have very high levels of Selenium. People living in those regions generally have the highest Selenium intakes in the United States. In the U.S., food distribution patterns across the country help prevent people living in low-Selenium geographic areas from having low dietary Selenium intakes. Soils in some parts of China and Russia have very low amounts of Selenium. Selenium deficiency is often reported in those regions because most food in those areas is grown and eaten locally.
Selenium also can be found in some meats and seafood. Animals that eat grains or plants that were grown in Selenium-rich soil have higher levels of Selenium in their muscle. In the U.S., meats and bread are common sources of dietary selenium. Some nuts are also sources of Selenium.
On the flip side, however, Selenium is toxic at high concentrations. Hydrogen Selenide is the most acutely toxic Selenium compound. Short-term exposure to Elemental Selenium by inhalation results primarily in respiratory effects, such as irritation of the mucous membranes, pulmonary edema, severe bronchitis, and bronchial pneumonia. Epidemiological studies of humans chronically (long-term) exposed to high levels of selenium in food and water have reported discoloration of the skin, pathological deformation and loss of nails, loss of hair, excessive tooth decay and discoloration, lack of mental alertness, and listlessness.
Now, let me ask you. Is it worth taking a selenium supplement if you eat local food that is grown in soil with high levels of Selenium?