Xenobiotics are chemicals found in organisms, but not expected to be produced or present in them; or they are chemicals found in much higher concentrations than usual. Organs transplanted cross-species are also called xenobiotic.
An example of a xenobiotic is an antibiotic; the human body does not produce them, and they are not expected to be present in the normal human diet. It is more commonly used to describe dioxins and polychlorinated biphenyls, which affect biological organisms in a variety of ways both fatal and nonfatal.
Xenobiotics are eliminated from the body through xenobiotic metabolism, in which the xenobiotic is deactivated and secreted away from the body. The liver is typically the primary focus of xenobiotic metabolism, and secretion can occur through urine, feces, breath, and sweat. Hepatic enzymes metabolize xenobiotics. An understanding of xenobiotic metabolites is critical for the pharmaceutical industry because they are responsible for the breakdown of drugs.
Sewage is increasingly contaminated with xenobiotics of all sorts, from human waste to antibiotics to dioxins. Sewage treatment systems have more trouble sorting out some of these xenobiotics than they do with other contaminants. This is because many newer xenobiotics are derived from plants, and closely mimic these natural substances. It can be nearly impossible to remove these new pollutants.
Web Resources On Xenobiotics
History of Xenobiotic Metabolism
Book Resources On Xenobiotics
Regulation of Enzymatic Systems Detoxifying Xenobiotics in Plants by Kriton K. Hatzios (Ed.)
Biochemistry of Redox Reactions by Testa & Caldwell