According to the U.S. EPA, PCBs have been demonstrated to cause cancer in animals and are considered to be a probable human carcinogen. They have also been shown to cause a variety of other adverse health effects on the immune system, reproductive system, nervous system and endocrine system. Exposure to PCBs can result from breathing in contaminated air, ingesting contaminated food or water, or skin/eye contact with PCB-containing materials.
Prior to the ban in 1979, PCBs entered the environment during its manufacture and use in the United States. Since then, PCBs can still be released into the environment from poorly maintained hazardous waste sites, illegal dumping of PCB wastes, leaks from PCB-containing electrical transformers and illegal disposal of PCB-containing products in landfills.
Once in the environment, PCBs do not readily break down. Therefore, they may persist for long periods of time cycling between air, water and soil. PCBs can be carried long distances and have been found in snow and sea water in areas far away from where they were released into the environment. As a consequence, PCBs are found all over the world.
Because PCBs persist in our environment, they can accumulate in plants and food crops and, in turn, be ingested by humans or animals. They can also be taken up directly into the bodies of small organisms and fish. As a result, people who ingest meat, dairy or fish may be exposed to PCBs that have bioaccumulated.
Important factors for understanding possible health effects from exposures to PCBs include how an exposure occurs (skin contact, inhalation, or ingestion) and how long an exposure occurs. Because PCBs are present today in our environment, exposures can occur in everyday life. Both the type of contact with PCBs as well as the duration of contact determines the extent of an exposure, and whether a health effect may occur.