A
polychlorinated biphenyl (
PCB;
CAS number ) is a synthetic organic chemical compound of
chlorine attached to
biphenyl, which is a molecule composed of two
benzene rings. There are 209 configurations of
organochlorides with 1 to 10 chlorine atoms. The
chemical formula for a PCB is
C12H10-xClx. Of the different PCB arrangements and orientations 130 are used commercially.