Polychlorinated biphenyls (PCBs) (C.A.S. 1336-36-3) are a family of man-made chemicals that contain 209 individual compounds with varying levels of toxicity. The seven classes of PCBs described here include 35 percent of all PCBs and 98 percent of PCBs sold in the U.S. since 1970, most of which are known in the U.S. by their industrial trade name, Aroclor.

Because of their insulating and nonflammable properties, PCBs have been widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment.

The manufacture and use of PCBs in new products stopped in the U.S. in October 1977, because of evidence that PCBs accumulated in the environment and could cause human health hazards. Although PCBs are no longer manufactured, exposure still occurs. Many older transformers and capacitors, which have lifetimes of 30 years or more, still contain fluids made with PCBs. Old fluorescent lightingfixtures may contain PCBs as well.

PCBs have been used as a slide-mounting medium for microscopes and still are used occasionally for this purpose since this use has been exempted from federal use restrictions under the Clean Water Act.

Eating contaminated fish can be a major source of PCB exposure to humans since PCB levels can be high in some species of fish found in contaminated waters. A National Academy of Sciences report released last month said that PCB contamination of fish remains a major health problem for people who eat fish, and that all the long-term impacts of those health hazards are unknown, but include possible damage to a fetus and an increased cancer risk.

Another major source of PCB exposure is from contaminated indoor air in buildings that contain devices made with PCBs.

Chemical properties:

Aroclor products are identified by a four-digit numbering code in which the first two digits (12) indicate that the parent molecule is biphenyl and the last two digits indicate the percentage of chlorine content by weight. The exception to this formula is Aroclor 1016, which has an average chlorine percentage of 41.5 percent.

PCBs are very soluble in organic solvents. Their melting points and flammability limits are unknown.

Once in the air, PCBs can be carried long distances; they have been found in snow and seawater in the Antarctic.

The PCBs with a high degree of chlorination (1248, 1254, and 1260) are resistant to biodegradation and appear to be degraded very slowly in the environment.

All the Aroclor formulations contain differing percentages of these formulations of PCBs: C12H10; C12H9Cl; C12H8Cl2; C12H7Cl3; C12H6Cl4; C12H5Cl5; C12H4Cl6; C12H3Cl7; C12H2Cl8; and C12H1Cl9.

Identification:

• Chemical Name: Polychlorinated Biphenyls (PCB)
• Regulatory Name: AROCLOR 1260      AROCLOR 1221      AROCLOR 1232      AROCLOR 1248      AROCLOR 1016      AROCLOR 1242
  PCBS
       AROCLOR 1254      Polychlorinated Biphenyls

• DOT Label: Class 9
• CAS:  11096-82-5 11097-69-1 11104-28-2 11141-16-5 12672-29-6 12674-11-2 1336-36-3 53469-21-9

• STCC: 4945196
• CHRIS: PCB
• UN Number: 2315

Health effects:

PCBs are classified by EPA as carcinogens, particularly with regard to the liver. Reproductive and developmental effects may also be related to occupational exposure to PCBs and eating contaminated fish. Studies indicate that PCBs concentrate in human breast milk. PCBs can be passed easily into the bloodstream from a pregnant woman to a fetus, and from a breastfeeding mother to a nursing infant. Slight effects on birth weight, head circumference, gestational age and/or neonatal behavior have been reported in infants of mothers who were consumers of PCB-contaminated fish.

Exposure to PCBs can also be by inhalation or skin contact. Studies show that irritations such as lesions, rashes, and burning eyes and skin can occur in PCB-exposed workers.

Populations at high risk of exposure to PCBs include nursing infants whose mothers consume large amounts of contaminated fish; embryos, fetuses, and neonates; and people who work or live in buildings that have high concentrations of PCBs in the indoor air supply.

Exposure Values:

• IDLH: 5 mg/m3; Not applicable for Cholrodipheyl (54% chlorine), a potential human carcinogen. (NIOSH, 1997)
• TLV TWA: 0.5 mg/m3 For chlorodiphenyl (54% Chlorine). Skin. (ACGIH, 1999)
• TLV STEL: 1 mg/m3 For Chlorodiphenyl (54% Chlorine). Skin (ACGIH, 1999)
• NIOSH REL: Ca TWA 0.001 mg/m3
• OSHA PEL: TWA 1 mg/m3.

Economics:

U.S. manufacturer of Polychlorinated Biphenyls is Monsanto, the sole domestic manufacturer of PCB's /manufactured/ this chemical in its Sauget, IL plant.

PCBs are no longer produced or used in the production of new products in the United States. Disposal of PCB materials that are still in service is controlled by federal regulations.

Annual U.S. production of PCBs peaked in 1970 when 85 million pounds were produced. Monsanto, the sole U.S. manufacturer at the time production was banned, had been producing Aroclors 1016, 1221, 1242, and 1254 at a facility in Sauget, Illinois.

Regulation:

The Food and Drug Administration (FDA) has issued permissible levels of PCBs in food and packaging. PCBs are regulated by the U.S. Environmental Protection Agency under the Clean Water Act Effluent Guidelines.

Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986, releases of more than one pound of polychlorinated biphenyls into the air, water, and land must be reported annually and entered into the Toxic Release Inventory (TRI).

National Overview of 1998 Toxics Release Inventory

See EPA's Toxic Release Inventory.

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