Apart from intentional manufacture, PCBs could be
also generated incidentally as byproducts, e.g. in production of
chlorinated solvents, chlorinated alkanes, chloronaphthalenes,
chlorophenylsiloxane adhesives, organosilicone drugs, organic
intermediates and pigments, PVC production, during thermal
processes including waste incineration, and volcanic eruptions as well as in thermal and combustion operations