What are dioxins and PCBs?
Dioxins are members of a large group of substances with similar chemical structures. They are not deliberately produced, but are formed during fires and most forms of combustion (e.g. in fires, bonfires, incinerators, automobile engines), and as trace contaminants in the synthesis of some chemicals and some industrial processes. Some members of another group of substances, the dioxin-like polychlorinated biphenyls (PCBs) are also included in the assessment because they have similar biological activities. There are many other PCBs which do not have dioxin-like properties. Dioxins remain in the environment for a long time and accumulate in all living things. Dioxins are known to cause a wide range of toxic effects in animals, some of which have been seen at very low doses. These effects may have significant consequences for human health. All the dioxins exhibit similar types of biological effect. One compound (2,3,7,8-tetrachlorodibenzo-p-dioxin, which is referred to as 2,3,7,8-TCDD or T
