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Polychlorinated biphenyls (PCBs) are a group of extremely toxic organic chemicals. They are fire-resistant and do not conduct electricity. They were used mainly as oils in electrical transformers and capacitors from 1929 to 1977.

Although PCBs were banned in 1979, it is estimated that 135,000 transformers, over 3 million large capacitors and over a hundred million small capacitors (e.g. T.V.s, fluorescent light ballasts, and air conditioners) were manufactured before the ban and may still be in use.

AFSCME members may be exposed to PCBs in several different ways.

  • Transformers in buildings can leak, exposing custodians, electricians, maintenance workers or anyone else who may be in the vicinity.
  • Transformers can burn, transforming the PCBs into much more toxic chemicals called dioxins and dibenzofurans, and exposing everyone in the building.
  • PCB spills or illegal dumping on roads can expose highway workers or groundskeepers, and can flow into the sewage system, exposing wastewater treatment plant workers.
  • Capacitors used by electrical utilities on power lines can overheat and explode during unusual power surges, scattering PCBs over surrounding streets, fields and yards.
  • Older fluorescent light ballasts often contained PCBs. These can leak and contaminate a room or office area.

Health effects

Acute (short term) health effects are usually not serious, although they can include eye, nose and throat irritation, vomiting, stomach pains, loss of appetite and fatigue.

Chronic (long term) effects are more serious. PCBs can damage the liver at very low levels and are known to cause reproductive problems and cancer. Other chronic effects include swelling of the eyelids, excessive pigmentation of the skin and swelling of joints. They can cause a skin disorder called chloracne, a severe rash. Chloracne may last a short time, but can also cause permanent disfigurement.

PCBs can be absorbed through the skin and accumulate in the fat. Small exposures can, therefore, build up to cause toxic effects at a later time.

Safe work procedures

  1. All workers exposed to PCBs should be trained about hazards and safe work procedures.
  2. Protective clothing including gloves, hair covers, shoe covers and full suits which are impermeable to PCBs should be worn. Note: A recent NIOSH study found that most protective gloves on the market do not protect against PCBs. Most gloves (i.e. neoprene, butyl rubber, polyvinyl alcohol, etc.) actually soak up PCBs within three minutes. The best glove material, according to NIOSH, is Viton.®. All gloves must be discarded after each use.
  3. Respirators should be used in areas whenever measurements indicate levels greater than 1.0 microgram per cubic meter (µg/m3) of air. Respirators should be self-contained breathing units or type C supplied air masks. Full face negative pressure masks with organic vapor and particulate cartridges may be used only if air measurements indicate levels below 1.0 µg/m3.
  4. Other measures such as decontamination showers, separate lockers for work clothing, leak procedures and medical exams are recommended by NIOSH.
  5. PCB leaks from fluorescent light fixtures also require a detailed cleanup procedure. EPA has issued a document on how to clean up PCBs in light fixtures.
  6. All contaminated materials (clothing, rags, gloves, drapes, carpets, etc.) must be disposed of properly in an EPA approved site.

Special Precautions. Transformer Fires

Transformers can overheat due to electrical malfunctions. When PCBs are hot enough, they will decompose, producing polychlorinated dibenzofurans and dioxins, both of which are much more toxic than PCBs. These chemicals can be spread around an entire building through the ventilation system and are extremely difficult to clean up safely.

Workers who suspect that electrical malfunction or a fire has occurred in a PCB transformer should immediately notify the EPA and other appropriate officials.


  1. OSHA: The Occupational Safety and Health Administration has standards for only two types of PCBs: 
    • The Permissible Exposure Limit (PEL) for Chlorodiphenyl (42% Chlorine) is 1 milligram per cubic meter of air (1 mg/m3);
    • The PEL for Chlorodiphenyl (54% Chlorine) is 0.5 mg/m3

      Both of these standards were developed before it was known that PCBs can cause cancer and reproductive effects, and they do not cover many other forms of PCBs. 
  2. NIOSH: The National Institute for Occupational Safety and Health recommends a PEL of 1 microgram per cubic meter level, 1,000 times less than the OSHA standard.
  3. EPA: The Environmental Protection Agency has several important regulations dealing with PCBs: 
    • The EPA requires that all PCB-containing equipment be posted with a large yellow label. The exterior of the vault, machinery room door and any other means of exit must also be marked with PCB identification labels.
    • All transformers containing more than 50 parts per million of PCB-containing oil in the vicinity of food or feed products must be inspected weekly. All other PCB-containing transformers must be inspected for leaks every three weeks. Leaks must be repaired within two days and reported to the EPA within five days.
    • In order to prevent PCB fires, EPA recently required that high voltage network transformers be removed and that enhanced electrical protection be added on many types of PCB transformers in commercial buildings.
    • All PCB transformers must be registered with the local fire department.
    • All PCB transformer locations must be cleared of stored, combustible materials (solvents, paints, paper, etc.)

For more information about protecting workers from workplace hazards, contact the AFSCME Health and Safety Program at (202) 429-1215, or 1625 L Street, N.W., Washington, DC 20036.

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