Polychlorobiphenyls (PCB) are halogenated hydrocarbons (chlorinated aromatic compounds) of high molecular weight. The are made up of a biphenyl with up to five atoms of chlorine on each phenyl. There are 209 different PCBs.
Uses of PCBs
Before being banned in France in 1987 they were used for their insulating properties (in electrical transformers) and for their chemical and physical stability (in inks and paints).
Risks of PCBs
Because of their stability and resistance to decomposition, PCBs are classified as persistent organic pollutants. Over time and due to accidental discharges they have accumulated in the environment, particularly in marine sediments and fresh water sediments. They are claimed to be toxic to man.
PCBs are halogenated hydrocarbons. © D.328, Wikimedia, GFDL 1.2