How to Manage Polychlorinated Biphenyls (PCBs) Waste?

Find out how to manage and dispose of waste that contains Polychlorinated Biphenyls (PCBs) without causing harm to the environment or human health.

What are Polychlorinated Biphenyls (PCBs)?

Polychlorinated Biphenyl (PCB) is a term used to describe a group of synthetic organic chemicals that were first manufactured in the early 1920s.

PCBs are halogenated aromatic hydrocarbons that have excellent insulating and fire retardant properties. They also have high electrical resistivity and do not easily generate vapors. Furthermore, PCBs are resistant to both chemical and biological degradation and therefore persist in the environment.

They were used widely throughout the 20th Century in a wide variety of applications, including:

  • Electrical, heat transfer, and hydraulic equipment;
  • As plasticizers in paints and in pigments and dyes.

Due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, the most common usage was in electrical equipment, e.g., transformer coolants, capacitor impregnators, wire and cable coatings, and fluorescent lighting fixtures.

Concerns over the use of PCBs were first expressed following the accidental contamination of rice-cooking oil in Japan and Taiwan during the 1960s and 1970s.  The contamination exposed thousands of people to high concentrations of PCBs, and a significant increase in the number of miscarriages and birth defects was reported. Because of these incidents, many countries developed legislation to restrict the manufacture and use of PCBs and associated compounds.  For example, in 1979, the USA banned PCBs manufacturing, processing, and distribution.

What are the Types of PCBs?

PCBs are a group of synthetic organic chemicals that are made up of 209 separate chemicals or congeners.  All these chemicals have the same basic chemical structure and similar physical properties.  PCBs are either oily liquids or solids that range in color from clear and colorless to light yellow, and they have no smell or taste.

Trade names for PCBs included Aroclor, Asbestol, Askarel, Chlorextol, Clophen, Diaclor, DK, Dykanol, Elemex, Fenclor, Hyvol, Interteen, Kennechlor, No-Flamol, Phenoclor, Pyralene, Pyranol, Saf-T-Kuhl and Santotherm.

Commercial PCB mixtures contain a variety of isomers.  These mixtures are described by the percentage of chlorine present.  For example, Arochlor 1254 indicates 54% chlorine saturation.  The greater the chlorine content, the more resistant the compounds are to metabolic degradation.

Why are PCBs dangerous?

PCBs are resistant to chemical and biological degradation and therefore persist in the environment.  They are also soluble in fats and oils and therefore tend to accumulate in the fatty tissues of living organisms (bioaccumulation).

Studies in animals have provided conclusive evidence that PCBs cause cancer. Epidemiological studies of workers exposed to PCBs have found increases in rare liver cancers and malignant melanomas, which strongly suggest that PCBs are probable human carcinogens.

The types of PCBs that bioaccumulate in fish, animals, and sediments tend to be the most carcinogenic.  Therefore people who ingest PCB-contaminated fish or other animal products and who contact PCB-contaminated sediment may be exposed to PCB mixtures that are even more toxic than the PCB mixtures contacted by workers and released into the environment.

Studies also provide evidence that PCBs cause significant toxic effects on the immune system, the reproductive system, the nervous system, and the endocrine system. Children born to women who worked with PCBs in factories showed decreased birth weight and a significant decrease in gestational age with increasing exposure to PCBs. Studies in fishing populations believed to have high exposures to PCBs also suggest similar decreases.

How to Identify PCB-containing Equipment?

Although PCBs are no longer manufactured, many older transformers and capacitors still contain fluids that contain PCBs.  In practice, this has meant that there may be a few transformers or equipment that are known or suspected to contain PCBs.

Equipment such as electrical transformers and capacitors suspected of containing PCBs should be treated as such until documentary evidence exists to verify that they are PCB-free.  In most cases, it will be possible to contact the equipment manufacturer to confirm whether it contains PCBs.  If this is not possible, the equipment should be tested.  Although test kits are available, tests should be carried out by an accredited laboratory using Gas Chromatography (GC) techniques. GC enables the concentration of each isomer to be measured, which is important because each isomer has a different degree of toxicity and hence a different environmental significance.

Because PCBs are very persistent and widely dispersed in the environment, it is common for PCBs to be detected at low concentrations.  For this reason, many countries have specified threshold concentrations above which wastes are considered to contain PCBs.  In the absence of national standards, the US and European regulations can be followed, which state that transformer oil is regarded as being contaminated when the concentration of PCB equals or is greater than 50 ppm or 50 mg kg-1.

If equipment contains PCBs, an assessment should be made to determine if the soil in the vicinity has become contaminated.  If the equipment has been placed in a concrete bund (dyke) and the concrete is in good condition, it should not be necessary to perform any testing.  In the absence of suitable containment, the soil should be tested. Check your own national guidance to determine whether clean-up is necessary.

How to Store PCB-containing Equipment and Waste?

Whenever possible, PCB-containing Equipment, particularly transformers, should be drained and the PCB liquid stored separately. Draining activities should only take place once a risk assessment has been performed and should take place on an impermeable surface. All equipment that comes into contact with PCB should be treated as PCB-contaminated waste and managed accordingly.

When the equipment has been drained, it should be stored on a steel tray to contain minor leaks.  Liquids containing PCBs should be stored in approved steel drums. Each item should be appropriately labeled to identify that it contains PCBs.

PCBs are non-flammable, but their degradation products are potentially hazardous. Therefore PCB waste should be stored away from flammable materials. Fire precautions should be in place to deal with emergency situations.

Storage areas should drain to a blind (sealed) sump, and adequate supplies of absorbent materials should be made available to deal with potential spills.

The design and operation of storage areas for PCB wastes may be subject to local legislative requirements such as the need to:

  • Dispose of the waste within a specified period;
  • Record PCB concentrations and volumes;
  • Document equipment identification numbers.
For this reason, check your own national standards before storing PCB equipment and waste.

How to Collect and Transport PCB Waste?

The management of PCB waste is a specialist activity, and guidance on how to prepare PCB waste for transport should be obtained from the waste management contractor.  However, the following general advice should be followed.

A form that documents the transfer of waste from the waste producer to the point of final disposal should accompany the waste.  In most cases, national regulations will specify which document should be used. 

Because PCBs are potentially hazardous, they should be transported with great care because the consequences of spillage are more significant than most other wastes.  The UN has classified PCB wastes as Class 9 - “Miscellaneous Dangerous Substances,” and in the absence of national regulations, the associated UN recommendations regarding the marking of containers should be followed.

If it is necessary to transport large items such as transformers or capacitors that cannot be placed in approved steel drums, they should be transported in standard ISO shipping containers. Before placing these items in the container, they should be wrapped in heavy gauge (500 gauge) clear polythene sheeting. In order to contain any leaks, the base of the ISO container should be lined with a steel tray with a 150-mm lip around the perimeter.  Items within the container should be suitably secured using wooden props or equivalent.

Treatment and Disposal of PCBs

Some companies may offer to replace PCB-contaminated oil present in a transformer with uncontaminated oil.  However, this practice does not remove all the PCB material present in the transformer, and after re-testing, PCB levels may be found to have increased. 

PCBs require relatively costly and sophisticated disposal technologies, and public concern is such that few facilities have been licensed to manage them. In the United States, disposing of commercial PCB waste in accordance with the regulations is outlined in Title 40 of the Code of Federal Regulations in part 761. The list of approved disposal facilities can be found on the US EPA site.

Several countries currently lack disposal capacity for PCB wastes.  In such circumstances, waste producers should explore the possibility of exporting the waste to another country.  However, this is a complex area that is regulated by the Basel Convention.  

A number of different disposal technologies have been developed to manage PCBs. Which are;


The most effective disposal method for PCB wastes is incineration. Incineration should take place at a temperature of at least 1,100 degrees Celsius, and the residence time for flue gases at this temperature should be in excess of two seconds.  If these conditions are not met, highly toxic dibenzofurans and dibenzodioxins can be generated, and these chemicals are potentially more hazardous than PCBs.  Because of public concern about these chemicals, few incinerators are licensed to process PCBs, and most are based on rotary-kiln technology.

Large items such as transformers and capacitors should be pre-processed before incinerating. This is to ensure that the PCB contained in the equipment is completely burnt out and that no residual chemicals remain. Sealed items such as capacitors should also be punctured to prevent them from exploding. This can be achieved by shredding or by manual disassembly.

Chemical Treatment

Chemical methods for treating PCB-contaminated oils are generally based on reactions with an alkali metal (sodium or potassium), either as an organometal or as the metal oxide or hydroxide. The chorine contents of the PCBs are converted to inorganic salts, which can be removed by filter or centrifuge.  The organic fraction forms non-toxic polymeric by-products. Other methods of chemically treating PCBs include wet air oxidation and electrochemical techniques.

Biological Treatment

Some micro-organisms are capable of using biphenyls as their sole source of carbon and are, therefore, able to biodegrade PCBs. Fungi such as mycorrhizal fungi are also capable of degrading PCBs.  However, this is a slow process; generally, PCBs with the least amount of chlorination are degraded most readily.

Because these are slow processes, biological methods are not used as a waste disposal technology but may be employed for the in-place treatment of contaminated soils.

The removal of relatively low concentrations of PCB from effluent can also be achieved using biological treatment based on the activated-sludge process or fixed film trickling filter technology.  Such processes can be used to remove PCBs from the water and then allow bacteria to degrade the PCBs in a dedicated tank or reactor.

Other Treatment and Disposal Options

PCBs with low chlorination can be degraded via photolysis under strict laboratory conditions.  However, this has not yet been developed commercially.

While disposal of PCB waste to land (e.g., in shafts of salt mines) is common practice in some countries and may be permitted by local legislation, residues will eventually find their way into the surrounding environment, and this option should not be considered.

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