PCBs are a group of man-made organic chemicals made up of carbon, hydrogen, and chlorine atoms. The number of chlorine atoms and their location in a PCB molecule determine many of its physical and chemical properties. PCBs have no known taste or odor, and vary in consistency from an oil to a waxy solid.

PCBs belong to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. PCBs were manufactured in the country from 1929 until manufacturing was banned in 1979. They have a range of toxicity and vary in consistency from thin, light-colored liquids to yellow or black waxy solids. Due to their non-flammability, chemical stability, high boiling point, and electrical insulation properties, PCBs have been used in hundreds of industrial and commercial applications, including:

  • Electrical, heat transfer and hydraulic equipment.
  • Plasticizers in paints, plastics and rubber products.
  • Pigments, dyes and carbonless paper.
  • Other industrial applications.
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Although no longer produced commercially, PCBs may be present in products and materials produced before the 1979 PCB ban. Products that may contain PCBs include:

Transformers and capacitors, electrical equipment including voltage regulators, switches, reclosers, bushings and electromagnets, oil used in motors and hydraulic systems, old electrical devices or apparatus containing PCB capacitors, fluorescent light ballasts, cable insulation, material thermal insulation, including fiberglass, felt, foam and cork, adhesives and tapes, oil-based paint, caulking, plastic, carbonless paper, floor finish.

The PCBs used in these products were chemical mixtures made up of a variety of individual chlorinated biphenyl components known as congeners. Most commercial PCB mixtures are known in the United States by their industrial trade names, the most common being Arochlor.

PCBs can be transported long distances and have been found in snow and seawater in areas far from where they were released into the environment. As a consequence, they are found all over the world. In general, the lighter the form of PCB, the more it can be transported from the source of contamination.