Polychlorinated Bipenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs) are both man-made chemicals developed for flame-retardant applications. They were used in a wide variety of applications such as plastics, paint, foam, electrical equipment, and motors.


PCBs are a group of chemicals made up of chlorine, carbon, and hydrogen and are not found in nature. They were manufactured in the U.S. from 1929 until their ban in 1979. The most common PCBs mixture made in the U.S. was manufactured under the trade name Archlor. Pure PCBs can be thin, light-colored liquids to yellow or black waxy solids. They do not breakdown easily and can remain in the environment for a long time. PCBs can accumulate in plants, food crops, fish, and other small organisms, and have a bioaccumulation tendency. PCBs are known to cause cancer in humans in addition to a variety of health issues related to the immune, reproductive, nervous, and endocrine systems; skin and eye issues; liver toxicity; and high blood pressure, triglycerides, and cholesterol.

Although PCBs manufacturing is banned, new releases of PCBs into the environment are still occurring today due to “legacy” PCBs. For example, PCBs in light ballasts made before 1978 that are still being used in buildings. PCBs can off gas from the lights or if the housing cracks PCBs can leak out.

According to the U.S. Environmental Protection Agency (USEPA), these PCBs enter the environment through a variety of pathways including:

  • Poorly maintained hazardous waste sites that contain PCBs;
  • Illegal or improper dumping of PCB wastes;
  • Leaks or releases from electrical transformers containing PCBs;
  • Disposal of PCB-containing consumer products into municipal or other landfills not designed to handle hazardous waste; and
  • Burning wastes in municipal and industrial incinerators.


PBDEs are made of bromide, carbon, and hydrogen and are not found in nature. Most PBDEs are produced as mixtures, but three pure PBDEs are produced (pentaBDE, octaBDE, and decaBDE). U.S. production of pentaBDE and octaBDE stopped in 2004 as the sole U.S. manufacturer voluntarily phased out the chemicals. In addition, two U.S. producers and the main U.S. importer of decaBDE promised to phase out the compound in 2013. However, decaBDE continues to be the most widely used PBDE throughout the world. Like PCBs, PBDEs do not breakdown in the environment and can bioaccumulate. Trace amounts of PBDEs have been found in human blood, tissue, and breast milk. Studies of mice exposure to PBDEs show that the chemicals cause neurodevelopmental toxicity, weight loss, and kidney, thyroid, and liver toxicity as well as dermal disorders. They also can be an endocrine disruptor. Exposure to PBDEs has not been shown to cause cancer, although decaBDE is a potential carcinogen, according to the USEPA. Because PBDEs are still made outside of the U.S. and were manufactured recently in the U.S., PBDEs can still enter the environment through a number of ways, including the manufacturing process and from products made with PBDEs via recycling, landfill leachate, and volatilization.

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