A 3D space filling molecular model of 2,3,7,8-tetrachlorodibenzo-p-dioxin, (TCDD). This molecule is the most toxic dioxin which became well known as a contaminant of Agent Orange, a herbicide used in the Vietnam War. Later, dioxins were found in Times Beach, Missouri and Love Canal, New York. Polychlorinated dibenzodioxins (PCDDs) are a group of halogenated organic compounds which are significant because they act as environmental pollutants. The term 'polychlorinated dibenzodioxins' can be abbreviated as PCDDs, but they are commonly referred to as dioxins for simplicity in current technical literature because a dioxin skeletal structure is at the center of the chemical structure of a PCDD molecule. Typically, the p-dioxin skeleton is at the core of a PCDD molecule, giving the molecule a dibenzo-p-dioxin ring system. Members of the PCDD family have been shown to bioaccumulate in humans and wildlife due to their lipophilic properties, and are known teratogens, mutagens, and suspected human carcinogens.