1. xenobiotic metabolites The organism removes xenobiotics by xenobiotic metabolism, consisting of deactivation/activation and excretion of xenobiotics, which happen mostly in the liver. Hepatic enzymes are responsible for the metabolism of xenobiotics by first deactivating/activating them (oxidation, reduction, hydrolysis and/or hydration of the xenobiotic), and then conjugating thesecondary metabolites with glucuronic acid, sulphuric acid, or glutathione, followed by excretion in bile or urine.