Any in a family of over 200 chlorinated organic chemicals (all heterocyclic hydrocarbons). The term is most commonly applied to a particular chemical, 2,3,7,8-tetrachlorodibenzo-paradioxin (2,3,7,8-TCDD, simply called TCDD), which is an impurity in the defoliant Agent Orange and in the pesticide 2,4,5-T (see auxin). Dioxins are also produced when chlorinated materials such as plastics are burned. Dioxins are known to cause skin diseases (chloracne), birth defects, miscarriages, and cancer.