Selenium – occurrence and effects
Selenium is one of the rare trace elements and is usually only found together with more common elements in minerals and rocks. These are washed out in mountains by rain, weather influences and erosion. Substances with a weak selenium content also end up in the groundwater and other bodies of water. Selenium-containing waste is often generated as a by-product of industrial processing processes.
solubility in water
Elemental selenium is not soluble in water. However, there are compounds containing selenium, such as selenic acid (the chemical formula is H2SeO4) or selenious acid (H2SeO3), which are sometimes very soluble in water. The water solubilities can be up to 10,600 g/l for selenic acid and up to 3,250 g/l for selenious acid.
Benefits of selenium-containing compounds
Although it can be toxic in high doses, selenium is a very important trace element for plants, animals and humans in lower doses. Some plants not only use it to maintain their metabolic processes, but also store large amounts of this element to protect themselves from animal predation. In mammals and humans, selenium-containing amino acids are incorporated into proteins (the body's own protein) and thus fulfill important functions in terms of body structure and metabolism.
Selenium deficiency can lead to anemia in humans. This disorder, also known as anemia, refers to a lack of red blood pigment (also known as hemoglobin), which is important for the ability of red blood cells to transport oxygen from the lungs to all cells in the body. Selenium deficiency can also result in increased blood pressure, infertility, arthritis, muscle problems and premature aging.
The amount of selenium consumed by a person can normally be between 60 μg and 200 μg per day. The normal requirement for a person is between 60 μg and 75 μg per day.
Problems and damage due to excessive selenium content
As already mentioned, this element can also be toxic in higher doses. The limit values for the WHO, the EU and Germany are 0.01 mg/l.
Symptoms of selenium poisoning include body odor, stomach pain, vomiting, diarrhea and difficulty breathing. From around 2400 μg per day there is acute selenium poisoning, which can also affect the central nervous system. Taken over a long period of time, such doses can even be fatal.
Since compounds containing selenium are also used in the electronics sector and for many industrially manufactured products, those responsible should exercise particular caution. After evaporation of liquids containing selenium, dust containing selenium can be produced. These can lead to inflammation of the respiratory and digestive organs. In other areas of work and leisure there are actually no problems in this regard.
