Science Lessons: PCBs

A report yesterday from Environmental Health News explores the link between prenatal PCB exposure and attention problems in Massachusetts children. Here’s a refresher on Polychlorinated Biphenyl (PCB).

PCBs are man-made chemicals. They were produced in the US from 1929 until their manufacture was banned in 1979. Because of their chemical stability, non-flammability, and electrical insulating properties, they were used extensively in industrial and commercial applications.

PCBs still lurk in materials produced before 1979.  These include:

  • transformers and capacitors
  • voltage regulators, switches, and electromagnets
  • oil used in motors and hydraulic systems
  • old appliances containing PCB capacitors
  • fluorescent light ballasts
  • thermal insulation material
  • oil-based paint
  • plastics
  • floor finish

PCBs entered the environment during their manufacture and use. They continue to pollute from sources such as hazardous waste sites, leaky transformers, improper disposal of PCB-containing products, and burning of some waste in municipal and industrial incinerators. New York City must replace light fixtures in 800 public schools after “pure product,” oil with one million parts PCBs per million, was found dripping from ballasts in a classroom.

PCBs do not break down. They are carried long distances and found all over the world. They accumulate in plants and food crops and are stored in the bodies of small organisms and fish.

PCBs have been demonstrated to cause cancer and to adversely affect the immune system, reproductive system, nervous system, and endocrine system. The types of PCBs that accumulate in fish and other animals are the most carcinogenic. Read more about the health effects here.


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