organic chemicals that have been found to have toxic effects on human health and the environment. They were manufactured beginning in 1929 until they were banned in 1979 based upon the discovery of their toxicity and accumulation in the environment[sc:1].
Because PCBs are highly stable and insulating, they served as ideal chemicals for many different industrial and commercial uses, including electrical equipment, heat transfer equipment, hydraulic equipment, plasticizers, plastics, rubber, pigments, dyes, flame retardants, adhesives, pesticide extenders, surface coatings, wire insulators, metal coatings, and carbonless copy paper. Consumer products made before 1979 that could contain PCBs include fluorescent lighting fixtures, electrical devices, appliances, microscope oil, and hydraulic oil[sc:1][sc:comma][sc:2][sc:comma][sc:3].
Prior to their ban, PCBs pollution of the environment occurred during the time of manufacturing and use. Today, such pollution can still occur from leaks from hazardous waste sites that have PCBs in them, improper disposal of PCB wastes, leaks from electrical transformers that have been manufactured with PCBs, and the burning of PCB-containing waste in incinerators[sc:1].
Because they are persistent organic pollutants, PCBs can remain in the environment for many years, and pollute air, water, and soil for long distances away from the location of the initial PCB pollution. In fact, PCBs are now found in many places around the world today[sc:1].
PCBs can bioaccumulate in plants and animals such as fish, and have the potential to cause negative health effects in the humans that consume them, such as cancer and problems with the immune system, reproductive system, nervous system, and endocrine system[sc:1].