Dioxin. Computer artwork of a molecule of the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCCD). Atoms are represented as spheres and are colour- coded: carbon (grey), chlorine (green), hydrogen (white) and oxygen (red). Dioxins are a family of toxic by-products of a number of industrial processes, including burning waste, heating metals and bleaching paper and textiles. They have no industrial use themselves. They are persistent organic pollutants (POPs) and build up over time in living tissue (bioaccumulation). Long-term high-level exposure can cause birth defects, cancer and a higher risk of diabetes. TCCD is one of the most toxic of the dioxins.