Dioxins Poisoned Viktor Yushchenko, But What Are They?: "'Dioxins' refers to a group of chemical compounds that share certain chemical structures and biological characteristics. Dioxin is the common name used to refer to the chemical tetrachlorodibenzo-p-dioxin or TCDD. These chemicals are produced during combustion processes, such as waste incineration, forest fires and backyard trash burning, and during manufacturing processes such as herbicide manufacture and paper manufacture. e.g. dioxin was a contaminant of the herbicide Agent Orange used as a defoliant by U.S. forces in Vietnam."

(Via HealthTalk.)