Urea(CAS.NO:57-13-6), also called carbamide, is an organic chemical compound, and is essentially the waste produced by the body after metabolizing protein. Naturally, the compound is produced when the liver breaks down protein or amino acids, and ammonia; the kidneys then transfer the urea from the blood to the urine. Extra nitrogen is expelled from the body through urea, and because it is extremely soluble, it is a very efficient process. The average person excretes about 30 grams of urea a day, mostly through urine, but a small amount is also secreted in perspiration. Synthetic versions of the chemical compound can be created in liquid or solid form, and is often an ingredient found in fertilizers, animal feed, and diuretics.
The discovery by Friedrich Wöhler in 1828 that urea can be produced from inorganic starting materials was an important conceptual milestone in chemistry, as it showed for the first time that a substance previously known only as a byproduct of life could be synthesized in the laboratory without any biological starting materials, contradicting the widely held doctrine of vitalism.
Urea (also known as carbamide) is a waste product of many living organisms, and is the major organic component of human urine. This is because it is at the end of chain of reactions which break down the amino acids that make up proteins. These amino acids are metabolised and converted in the liver to ammonia, CO2, water and energy. But the ammonia is toxic to cells, and so must be excreted from the body. Aquatic creatures, such as fish, can expel the ammonia directly into the water, but land-based animals need another disposal method. So the liver converts the ammonia to a non-toxic compound, urea, which can then be safely transported in the blood to the kidneys, where it is eliminated in urine.
Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. It is a colorless, odorless solid, highly soluble in water and practically non-toxic (LD50 is 15 g/kg for rat). Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, the most notable one being nitrogen excretion. Urea is widely used in fertilizers as a convenient source of nitrogen. Urea is also an important raw material for the chemical industry.
Most of the manufactured compound of Urea is used in fertilizers; when nitrogen is added to urea, the compound becomes water soluble, making it a highly desired ingredient for lawn fertilizer. The synthetic version is also used commercially and industrially to produce some types of plastics, animal feed, glues, toilet bowl cleaners, dish washing machine detergents, hair coloring products, pesticides, and fungicides. Medicinally, it is used in barbiturates, dermatological products that re-hydrate the skin, and diuretics.
Urea is the diamide of carbonic acid (HNCONH; see amide; carbon dioxide). The chief nitrogenous end product of protein breakdown in mammals and some fishes, it occurs not only in urine but also in blood, bile, milk, and perspiration. It is one of the industrial chemicals produced in vast amounts. With its high nitrogen content and low price, it is a major agricultural fertilizer and animal-feed ingredient. It is also used to make urea-formaldehyde plastics (including foamed plastics; see polyurethanes), to synthesize barbiturates, as a stabilizer in explosives, and in adhesives, hydrocarbon processing, and flameproofing.
Urea can be irritating to skin, eyes, and the respiratory tract. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis. High concentrations in the blood can be damaging. Ingestion of low concentrations of urea, such as are found in typical human urine, are not dangerous with additional water ingestion within a reasonable time-frame. Many animals (e.g., dogs) have a much more concentrated urine and it contains a higher urea amount than normal human urine; this can prove dangerous as a source of liquids for consumption in a life-threatening situation (such as in a desert).