Dioxin. Computer artwork of a dioxin molecule. This is TCDD (2,3,7,8-tetrachlorodibenzo-p- dioxin). Atoms (rods) 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. TCDD is one of the most toxic of the dioxins.