Polychlorinated biphenyls (PCBs) are a class of organic compounds
with 1–10 chlorine atoms attached to a biphenyl molecule.
They were commercially produced as complex mixtures since
1929, and have been widely used as dielectric fluids in transformers,
capacitors, coolants and for other applications based on their
chemical stability and physical properties The total amount of PCBs manufactured
worldwide was estimated to be 1.5 million metric tons
(t) (Ivanov and Sandell, 1992). In China, approximately 10,000 t
of PCBs were produced in the decade from 1965 to 1975, and were
known as PCB3 and PCB5 (Fu et al., 2003). PCB3 and PCB5 were reported
to be similar to Aroclor 1242 and Aroclor 1254, respectively
(Jiang et al., 1997)