Polychlorinated Biphenyls (PCBs) and Polychlorinated Terphenyls (PCTs) Health and Safety Guide 68

The PCBs are chlorinated hydrocarbons that are manufactured commercially by the progressive chlorination of biphenyl in the presence of a suitable catalyst (e.g., iron chloride). Depending on the reaction conditions, the degree of chlorination can vary between 21 and 68% (w/w). The yield is always a mixture of different compounds and congeners. Thus, a total of 209 different chemical components may exist, but only about 130 of these are likely to occur in commercial products or mixtures of these compounds.