PCBs are a family of man-made, organic chemical compounds which are manufactured by the replacing hydrogen atoms on the bipheyl molecule with clorine). As PCBs are resistant to acids and bases, as well as to heat, they were commonly used as an insulating material in electric equipment, such as transformers and capacitors, as well as heat transfrer fluids and lubricants. Other uses include: lubricants, fluorescent light ballasts, paints, glues, waxes, carbonless copy paper, inks including newspapers, dust-control agents for dirt roads, solvents for spreading insecticides, and cutting oils. PCBs are stable compounds and although they are no longer manufactured, they are extremely persistent and remain in huge quantities in the atmosphere and in landfill sites. They are not water-soluble and float on the surface of water where they are enter the food chain. PCBs are fat-soluble, and are therefore easy to take into the system, but difficult to excrete. (Source: draft based on GEMET -PZ / PHC)