A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it. It can also cover substances which are present in much higher concentrations than are usual. A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... A crab is an example of an organism. ... Look up substance in Wiktionary, the free dictionary. ... In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ...

For example, drugs such as antibiotics are human xenobiotics because the human body does not produce them itself nor would they be expected to be present as part of a normal diet. However, the term is usually used in the context of pollutants such as dioxins and polychlorinated biphenyls and their effect on the biota. Natural compounds can also become xenobiotics if they are taken up by another organism (eg uptake of natural hormones excreted from humans by fish downstream of sewage treatment plant outfalls). Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ... Staphylococcus aureus - Antibiotics test plate. ... Pollutants are substances which directly or indirectly damage us or the environment. ... 3D model of 2,3,7,8- tetrachlorodibenzo-p-dioxin Structure of 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) Dioxin is the popular name for the family of halogenated organic compounds, the most common consisting of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs). ... It has been suggested that this article or section be merged with Polychlorinated biphenyls (PCBs). ... Biota can refer to several things: The plant and animal life of a region; see biota (ecology) A municipality in Zaragoza, Aragon, Spain; see Biota (municipality) A superdomain in taxonomy; see Biota (taxonomy) Biota Holdings, the Australian biotech company This is a disambiguation page — a navigational aid which lists...

The body gets rid of xenobiotics by xenobiotic metabolism. This consists of the deactivation and the secretion of xenobiotics, and happens mostly at the liver. Secretion routes are urine, faeces, breath and sweat. Hepatic enzymes are responsible for the metabolism of xenobiotics, by first activating them (oxidation, reduction, hydrolysis and/or hydration of the xenobiotic) and then conjugating the active secondary metabolite with glucuronic or sulphuric acid, or glutathione, followed by excretion in bile or urine. An example of a group of enzymes involved in xenobiotic metabolism is the hepatic microsomal cytochrome P450s.

Enzymes that metabolize xenobiotics are very important for the pharmaceutical industry, as they are responsible for the breakdown of drugs.

The term xenobiotic is also used to refer to organs transplanted from one species to another. For example, some researchers hope that hearts and other organs could be transplanted from pigs to humans. Many people die every year whose lives could have been saved if a critical organ had been available for transplant. Kidneys are currently the most commonly transplanted organ. Xenobiotic organs would need to be developed in such a way that they would not be rejected by the immune system. With the development of vitrification transplantable organs could be stored in organ banks for long periods. In biology, an organ (Latin: organum, instrument, tool) is a group of tissues that perform a specific function or group of functions. ... An organ transplant is the transplantation of an organ (or part of one) from one body to another, for the purpose of replacing the recipients damaged or failing organ with a working one from the donor. ... In biology, a species is one of the basic units of biodiversity. ... The heart and lungs, from an older edition of Grays Anatomy. ... Species Sus barbatus Sus bucculentus Sus cebifrons Sus celebensis Sus domesticus(Sus scrofa domesticus) Sus heureni Sus philippensis Sus salvanius Sus scrofa Sus timoriensis Sus verrucosus Pigs, also called hogs, swine, boars (male) or sows (female), are ungulates native to Eurasia collectively grouped under the genus Sus within the Suidae... The kidneys are bean-shaped excretory organs in vertebrates. ... A request has been made on Wikipedia for this article to be deleted in accordance with the deletion policy. ... A vitrification experiment for the study of nuclear waste disposal at Pacific Northwest National Labs. ...

Xenobiotic substances are becoming an increasingly large problem in Sewage Treatment systems, since they are relatively new substances and are very difficult to categorize. Antibiotics, for example, were derived from plants originally, and so mimic naturally occurring substances. This, along with the natural monopoly nature of municipal Waste Water Treatment Plants makes it nearly impossible to remove this new pollutant load. Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from sewage. ... Staphylococcus aureus - Antibiotics test plate. ... In economics, the term natural monopoly is used to refer to two different things. ...

See also

• xenotransplantation
• Artificial organ
• Organ donation
• Medical grafting

Xenotransplantation is the transplantation of cells, tissues or organs from one species to another such as from pigs to humans. ... An artificial organ is a man-made organ that is implanted in a human to replace a natural organ. ... Organ donation is the removal of specific tissues of the human body from a person who has recently died, or from a living donor, for the purpose of transplanting or grafting them into other persons. ... In medicine, grafting is a surgical procedure to transplant tissue without a blood supply. ...

External links

• Re-engineering the toilet for sustainable wastewater management
• International Society for the Study of Xenobiotics