dioxin /dī·ok″sin/ , a contaminant of the herbicide 2,4,5-trichlorophenoxyacetic acid, widely used throughout the world in forestry, on grassland, against woody shrubs and trees on industrial sites, and for rice and sugarcane weed control. Because of its toxicity it is no longer manufactured in the United States. Exposure to dioxin is associated with chloracne and porphyria cutanea tarda. Dioxin was a contaminant of the jungle defoliant Agent Orange sprayed by the U.S. military aircraft over areas of Southeast Asia from 1965 to 1970. Also called 2,3,7,8-tetrachlorodibenzo-para-dioxin.
