PCBs

PCB Fact Sheet

Polychlorinated biphenyls (PCBs) are defined by Mosby's Medical and Nursing Dictionary (2nd Ed., 1986) as "a group of more than 30 isomers and compounds used in plastics, insulation, and flame retardants and varying in physical form from oily liquids to crystals and resins. All are potentially toxic and carcinogenic. The toxicity varies with the type of PCB and concurrent exposure to other substances, as carbon tetrachloride. Mild exposure may cause chloracne; severe exposure may result in hepatic damage."

PCB is a generic term for a group of synthetic, organic compounds consisting of two linked benzene rings, having up to five chlorine atoms attached to each ring. Chlorine atoms may be bonded by any of the numbered sites shown in the figure below.

 

 

 

 

 

There are 209 different chlorinated biphenyls which may be collectively referred to as PCBs that can enter the environment in many ways; (see "Fate and Transport of PCBs.")

PCBs are man-made groups of toxic organic compounds and are one of the most stable groups of organic compounds known. Their properties include low solubility in water, low flammability, low vapor pressure, low electrical conductivity and high heat capacity. These properties are what made PCBs so well suited to a large number of uses.

First introduced to this country in 1929 by the Monsanto Company, PCBs were marketed under several industry trade names, such as Aroclor, made by Monsanto, and Pyranol, made by General Electric; (see GE/PCB Timeline for a brief history of PCBs in the Housatonic watershed.)

PCBs have been used as coolants or insulators in heat exchangers, hydraulic brake fluids, capacitors, transformers and other electrical components. They were also used in the manufacture of ironing board covers, adhesives, printer's ink, plasticizers, carbonless carbon paper, photocopier toner, paints, sealants, caulking compounds, food packaging and soap.

To learn more about HVA and other organization's efforts on behalf of PCB clean-up of the Housatonic, go to PCB Update.