Polychlorinated Biphenyls (PCBs) are a group of synthetic chlorinated organic compounds which has played an important part in many industrial products.
Polychlorinated Biphenyls (PCBs) are a group of synthetic chlorinated organic compounds which has played an important part in many industrial products.
PCBs are very stable chemicals that resist change from the passage of time, wide temperature variance and the influence of acids and alkalis.
PCBs can enter the body in three ways:
PCBs tend to lodge in body fat, and stay there for a long time. The very stability that makes PCBs so useful also prevents the body from eliminating them quickly.
Excessive amounts of PCBs can cause irritation to the eyes and long term health problems with the skin, nervous system and liver. The International Agency for Research on Cancer (part of the World Health Organisation) has classified PCBs as Group 1, Carcinogenic to Humans.
Even though importing PCBs was banned in 1976, they can be present in transformers and capacitors in the electrical industry, in concrete caulking compounds, and in a range of other products that take advantage of their great stability.
Small PCB filled capacitors are fitted to electric motors, welders and fluorescent lights. Typically they contain about 50g PCBs.
Normally, PCBs are in a metal container carrying no label signifying PCB content. Metal cased capacitors usually contain PCBs. A plastic capacitor usually does not. Most capacitors with metal cases that are labelled 'Thermonol AEE' or 'Ducon' Type APS, APF, APB, APD, APU, GPU, APA, APC, or GPA do contain PCBs. There may be others not listed here. Fluorescent lights in buildings built or renovated before 1980 are likely to have PCB filled capacitors.
The Australian and New Zealand Environment and Conservation Council publication 'Identification of PCB-containing capacitors' contains a list of capacitors known to contain PCBs.
Concrete caulking compounds containing PCBs were used in expansion joints in nearly all concrete structures erected prior to 1980. Examples of these expansion joints can be found in office buildings, bridges, car parks, entertainment facilities, water storage tanks and many other concrete structures. Their purpose was to seal the joint and keep out sand and water.
Due to their compatibility with synthetic rubber, eg polysulfide caulking compounds, PCBs were used as a plasticiser. These caulking compounds may contain up to 30% PCBs. PCBs ceased to be added in 1974, but the use of existing stocks containing PCBs continued on construction sites until about 1980. The caulking compounds containing PCBs varied in colour from grey through to black.
The normal life of a caulking compound is 15-20 years, depending upon environmental conditions.
All buildings having expansion joints and built between the 1940s and the late 1970s are likely to contain PCBs in the caulking compound. Analytical laboratories can determine whether the caulking compounds contain PCBs. Unless the original supplier or laboratory analysis confirms the absence of PCBs, it may be prudent to assume the presence of PCBs in the caulking compound.
Note that bitumen has also been used as a caulking compound, mainly on roads, footpaths or other horizontal expansion joints. Bitumen is always black in colour and in general does not contain PCBs. Bitumen is identified by high flexibility and capacity to stretch. Bitumen caulking compounds can normally be seen spread out past the expansion joint since they do not return to their original shape after compression or stretching. Polysulfide caulking compounds containing PCBs are far more rigid and keep their shape.
If the concentration of PCBs is greater than 50 parts per million in solids or liquids, they should be considered contaminated.
Consultation and co-operation between employers and employees is the key to safety in the workplace. The Occupational Safety and Health Act 1984 requires employers and employees to meet to discuss hazards and formulate and put into practice effective safety and health controls.
All leaking capacitors must be replaced with non PCB capacitors, and the work must be carried out by a licensed electrical worker.
Unless accurate information on PCB content is available (eg label stating 'No PCBs') or the age of the capacitor is known, all leaking capacitors must be treated as if they do contain PCBs, and adequate personal protective equipment and clothing must be worn. Swab samples of the leaking capacitor fluid or the capacitors themselves can be sent for laboratory analysis if confirmation is needed.
Leaking capacitors which have been removed should be properly packed in a sealed container, then into a secondary container (eg steel drum) containing absorbent for transport to an approved disposal facility.
Non-leaking PCB capacitors can be left in place, however plans should be made for their eventual replacement. Regular walk-through surveys should be made to check for oil leaks under light fittings, and leaking capacitors should be replaced.
Removal or sealing should be considered when the caulking compound is:
Where the removal of PCB caulking compound is necessary, skin contact should be avoided (see information below on personal protective equipment).
The PCB caulking compound being removed should not be heated or burnt, and measures should be taken to minimise dust generated in the process. The process of removal should include engineering controls based on good occupational hygiene practices.
As with other hazardous substances, a hierarchy of control measures should be considered for the handling of PCB caulking compounds. The following order is recommended:
The removed PCB caulking compound must be treated as PCB waste and placed in plastic bags, stored in an adequately labelled steel drum and disposed of as recommended in the Safe Disposal of PCBs section of this article.
The demolition process may give rise to two types of exposure - that from the PCB caulking compound itself and that from the dust.
Prior to demolition of concrete structures built prior to 1980, any caulking compounds in the structure should be tested and those containing PCBs removed. Bulk removal only is required. Residue compound in the joint will only make up a small component in the rubble. The handling of this rubble with mechanical equipment is not considered a health risk.
As with any demolition process, dust will be generated and will constitute a hazard if it exceeds the exposure standard. Appropriate dust control methods must be used.
Soak up spilt PCB liquid (eg from capacitors, or from water contaminated with PCB caulking compound) with an absorbent (eg vermiculite, rags) as would be used for oil. Place the material in plastic bags and store in a sound steel drum. Any contaminated protective clothing should be treated the same way. The drum should be clearly labelled and stored in a secure place where there is no risk of fire, prior to disposal at an approved facility.
Personal protective equipment and clothing recommended for the handling of PCBs and PCB contaminated equipment includes:
At room temperature, PCBs do not readily vaporise. However if vapours are suspected due to a characteristic burnt smell which can occur if a capacitor begins to leak and overheats, then suitable respirators (cartridge-type suitable for chlorinated vapours) should be used. If dust is generated during removal of caulking compounds, a Class P2 (Particulate) respirator should be used.
Contaminated equipment and tools should be cleaned with a cloth soaked in a small amount of suitable solvent (eg kerosene). The contaminated cloth should be disposed of as for PCB waste.
If eye contamination occurs, remove any contact lenses and wash eyes for at least 15 minutes. Seek medical attention.
If skin contamination occurs, the liquid should be wiped off immediately and the skin washed with soap and water. Water alone is not sufficient. If clothing is contaminated it should be quickly removed and disposed of as recommended. Solvents should NOT be used to wash the skin. Seek medical attention.
PCB waste should be placed in plastic bags (for solids) or containers (for liquids) and stored in a sound, labelled steel drum for transport to an approved waste disposal facility.
Correct disposal PCBs and contaminated material will prevent PCBs entering the food chain and the general environment. PCBs cannot be dumped or hosed away safely because of their potential to enter the food chain. Ordinary incinerators are NOT effective and must not be used. Contact the Department of Water and Environmental Regulation for information on approved disposal facilities.