PCBs are mixtures of various isomers based on biphenyl. There are 209 individual possible PCB variants (also known as congeners). Approximately 100 of these congeners are present in various technical mixtures of PCBs that were produced commercially in large quantities until the late 1970s. Australia banned the importation of PCBs in 1975.
PCBs are amongst a broader group of harmful persistent organic pollutants (POPs) that are toxic, persist in the environment and animals, bioaccumulate through the food chain and pose a risk of causing adverse effects to human health and the environment. They are listed under the Stockholm Convention on Persistent Organic Pollutants for phasing out and eventual elimination. More information is available here.
PCBs have been used as coolants and lubricants in electrical equipment (such as transformers and capacitors), hydraulic fluids, additives in paint, carbonless copy paper, plasticisers and dye carriers. PCBs were used as they do not burn easily and are good insulators.
Substance name: Polychlorinated biphenyls
CASR number: Many
Molecular formula: General Formula: C12H10-nCln (where n = 1-10)
Synonyms: PCBs, chlorinated biphenyls, Aroclor, Clophen, Fenclor, Kaneclor, Pyralene
PCBs range in appearance from colourless, oily liquids to more viscous and increasingly darker liquids, to yellow to black resins. The appearance depends on the chlorine content of the PCB. Some PCBs can exist as a vapour in air. They have no known smell or taste.
PCBs are chemically stable, have good insulating properties and do not degrade appreciably over time or with exposure to high temperatures. They are very soluble in organic solvents.
The National Pollutant Inventory (NPI) holds data for all sources of Polychlorinated Biphenyls in Australia.
Symptoms experienced by people exposed to large amounts of PCBs are skin conditions such as acne or rashes (also known as chloracne) and irritation and burning in the eyes. Blood and urine tests indicate damage to the liver for affected people.
Other symptoms include nausea, lethargy, brown pigmentation of skin and nails, swelling of the face, distinctive hair follicles, excessive eye discharge, swelling of the eyelids, visual disturbances, gastrointestinal disturbances, jaundice and decreased lung function. These are only likely to be evident in those who work with PCBs and who do not wear appropriate protective clothing.
In the general population these effects are not considered likely.
Women exposed to relatively high levels of PCBs either in the workplace, or from consuming contaminated fish, may have babies that weigh slightly less at birth, and have an effect on the gestational period and head circumference. The babies may also have abnormal responses in tests of infant behaviour, such as motor skills and short term memory. Affected babies may also exhibit an altered immune system.
Animal studies indicate that consumption of large amounts of contaminated food for short periods of time causes mild liver damage. Animals that consumed tainted food of lower concentration over a longer period of time developed various kinds of health effects, including anaemia, acne-like skin conditions, liver, stomach and thyroid-gland injuries. The immune system was affected, behavioural alterations were noted, and reproduction was impaired.
The Australian Safety and Compensation Council considers PCBs as probable human carcinogens, or compounds capable of causing cancer. This is based on evidence of carcinogenicity in both humans and animals.
Entering the body
PCBs can enter the body by ingestion, inhalation of vapours, or by absorption through the skin.
Exposure to PCBs may result from using old fluorescent lighting fixtures and electrical devices and appliances made over 30 years ago; eating contaminated food such as fish caught in contaminated waterways; breathing air near hazardous waste sites and drinking contaminated well water; and in the workplace during the repair and maintenance of PCB transformers, accidents, fires or spills involving transformers, fluorescent lights and other old electrical devices, and disposal of PCBs or materials containing PCBs.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standards for particulate matter through the workplace exposure standards for airborne contaminants. These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
- Maximum eight hour time weighted average (TWA): 0.5 mg/m3
- Maximum short term exposure limit (STEL): 1 mg/m3
- Maximum eight hour time weighted average (TWA): 1 mg/m3
- Maximum short term exposure limit (STEL): 2 mg/m3
- Maximum eight hour time weighted average (TWA): 0.2 parts per million (1.3 mg/m3)
Drinking water guidelines
There is no guideline for PCBs in the Australian Drinking Water Guidelines.
PCBs do not readily break down in the environment and may persist for long periods of time.
PCBs can accumulate in fatty tissues of animals. The longevity of PCBs and their affinity for fatty tissue can result in PCBs moving up and concentrating through the food chain, resulting in levels that may be many times higher than in the water. Research has found that some animal species, such as young fish, are particularly sensitive to PCBs. PCB contamination may cause mutations in plants, decline in some bird populations and reduced reproduction in sea mammals.
Entering the environment
PCBs can enter the environment as a result of their manufacture, use and disposal; from accidental leaks during storage or transport, or from leaks or fires in products that contain PCBs. PCBs may also enter the environment from hazardous waste sites, illegal or improper disposal of industrial wastes and consumer products, and from burning some wastes in incinerators.
Where it ends up
PCBs are capable of traveling long distances in air or water. Most PCBs will adhere to organic particles and sediments in the water bodies and will bind strongly to soil.
Currently there are no air quality environmental guidelines for PCBs.
In 2000, the Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) established trigger levels of 0.01-1.7 micrograms of PCBs (as Aroclor 1242 and Aroclor 1254) per litre of fresh water. No trigger levels were established for PCBs in marine water.
PCBs are generated and released into the environment as unintentional by-products of chemical manufacturing and incineration.
Previously, PCBs were imported into Australia. This practice ceased in 1975, however, PCBs may be present in many hazardous waste sites and in equipment still containing PCBs.
Diffuse sources, and industry sources included in diffuse emissions data
There are no sources of PCBs that arise from diffuse sources.
PCBs do not occur naturally in the environment.
There are no sources of PCBs that arise from transport.
Previously, PCBs were used as dielectric fluids for capacitors and transformers, heat transfer fluids, plasticisers, additives in paint, carbonless copy paper, lubricants and many other industrial and commercial products.
Sources used in preparing this information
- Agency for Toxic Substances and Disease Registry (ASTDR), ToxFAQs: Polychlorinated Biphenyls, accessed June 2007.
- Australian and New Zealand Environment and Conservation Council (ANZECC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) (2000), Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Volume 1, The Guidelines, accessed June 2007.
- Department of the Environment and Water Resources: Restrictions on PCB imports fact sheet, accessed July 2007.
- Department of the Environment and Water Resources (2006): Stockholm Convention on Persistent Organic Pollutants, Australia's National Implementation Plan, accessed August 2007.
- Environment Writer, Chemical Backgrounder: Polychlorinated Biphenyls (PCBs), accessed July 2007.
- Merck and Co. 2006, Merck Index, 14th Edition, USA.
- Office of the Australian Safety and Compensation Council, Exposure Standards: PCBs, accessed June 2007.
- Technical Advisory Panel 2006, Final Report to the National Environment Protection Council.
- United States Environmental Protection Agency, Integrated Risk Information System (IRIS): PCBs, accessed June 2007.
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed February 2019.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018.