Sodium selenite

Sodium selenite is an inorganic compound with the formula Na2SeO3. This salt is a colorless solid. Although it is the most common selenium compound in animal feeds, it is considered less pure compared to selenium yeast. Sodium selenite is used in the manufacture of glass, as a colorant, and as a source for selenium in dietary supplements.

Chemistry

Sodium selenite is formed by the reaction of selenium dioxide (SeO2) with sodium hydroxide (NaOH), resulting in the formation of this selenite salt along with water. The compound exists as a pentahydrate in its most stable form, Na2SeO3·5H2O. It is a soluble compound that can be found in aqueous solutions across various concentrations.

Uses

Glass Manufacturing

In the glass industry, sodium selenite is used as a decolorizing and refining agent. It helps remove color from glass by counteracting the green tint caused by iron impurities. Additionally, it can impart a red color to glass when used in higher concentrations.

Animal Feed

Sodium selenite serves as a source of selenium for animal nutrition. Selenium is an essential trace element that plays a critical role in the metabolism of all animals. It is added to animal feeds to prevent and treat selenium deficiency, which can lead to various health issues in livestock.

Dietary Supplements

In human nutrition, sodium selenite is used as a selenium supplement. Selenium is vital for the proper functioning of the immune system and the thyroid gland. However, due to its potential toxicity, the use of sodium selenite in dietary supplements is regulated, and it is generally considered less preferable compared to organic forms of selenium, such as selenium yeast.

Health and Safety

Sodium selenite is toxic in high doses. Selenium toxicity can occur if supplements are taken in excess or if there is accidental overexposure in industrial settings. Symptoms of selenium toxicity include nausea, vomiting, nail discoloration, and in severe cases, hair loss and neurological damage. It is important to handle sodium selenite with care and adhere to safety guidelines to prevent overexposure.

Environmental Impact

Selenium compounds, including sodium selenite, can have adverse effects on the environment if not managed properly. Selenium is a micronutrient for many organisms but can be toxic in higher concentrations. It can accumulate in aquatic ecosystems, leading to toxicity in aquatic life. Therefore, the discharge of selenium-containing compounds into the environment is regulated in many jurisdictions.

Regulation

The use of sodium selenite in animal feeds and dietary supplements is subject to regulation by various governmental agencies to ensure safety and efficacy. In the United States, the Food and Drug Administration (FDA) regulates the addition of selenium to animal feeds and dietary supplements, setting maximum allowable concentrations to prevent selenium toxicity.

See Also

• Selenium
• Selenium dioxide
• Selenium in biology
• Dietary supplement