ochratoxin A (OTA) is a mycotoxin, i.e. a toxin produced in very small quantities by certain moulds, found in a range of food and beverages such as cereals, beer, coffee, cocoa, and wine. It has been shown to be carcinogenic and nephrotoxic (causing kidney damage) and has been reported in grapes and grape products since the mid 1990s. Studies have identified Aspergillus ochraceus, A. carbonarius and Penicillium verrucosum as the main synthesizers of OTA on grapes. (See also bunch rots and sour rot.)