PCBs in concrete structures
- What are PCBs?
- What effects can PCBs have on humans?
- Concrete caulking containing PCBs
- PCB contamination level
- Bitumen caulking compounds
- Consultation in assessing the hazard
- Removal or sealing of PCB caulking compounds
- Demolition of structures containing PCB caulking compounds
- Personal protective equipment
- Safe disposal of PCB waste
PCBs is an abbreviation for Polychlorinated Biphenyls, a group of synthetic chlorinated organic compounds which have been an important ingredient in many industrial products.
PCBs are very stable chemicals that resist change from the passage of time, from wide temperature variance and from the influence of acids and alkalis.
PCBs can enter the body in three ways:
- Swallowed in contaminated food and drink.
- Inhaled as vapour (though the quantity of vapour given off at room temperature is not significant).
- Absorbed through the skin (this is the most likely entry by PCB from caulking compounds).
Once in the body, PCBs tend to lodge in the fat and stay there for a long time. The stability that made PCBs so useful also prevents the body from eliminating them.
Excessive amounts of PCBs in the body can cause irritation to the eyes and long term health problems to the skin, hair and liver. A persistent pungent body odour may be experienced. Other health problems have been reported as a result of accidental occupational and public exposure.
The International Agency for Research on Cancer classifies PCBs into Group 2A; that is, probably causing cancer in humans. The available studies on accidental ingestion of large doses suggest an association between cancer and exposure to PCBs.
Biological monitoring or medical examination is of limited assistance in determining effects unless high exposures have occurred and assessment is performed soon after that exposure.
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, carparks, entertainment facilities, water storage tanks and many other concrete structures. Their prime purpose was to seal the joint and keep out sand and water.
Due to their compatibility with synthetic rubber, eg. polysulphide 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 when replacement may be required. This can depend upon the environmental conditions and where they are used.
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.
The WorkSafe Western Australia Commission has stated that if the concentration of PCBs is greater than 50 parts per million in solids or liquids, they should be considered contaminated and may require special procedures for handling and disposal. PCBs are in the Safe Work Australia "List of Designated Hazardous Substances" [NOHSC: 10005(1999)] as hazardous at levels above 50 parts per million (0.005%).
Bitumens have also been used as caulking compounds, mainly on roads, footpaths or other horizontal expansion joints. Bitumens are always black in colour and in general do not contain PCBs. The bitumens are identified by their high flexibility and that they can be stretched. 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.
Polysulphide caulking compounds containing PCBs are far more rigid and keep their shape.
Application of the Occupational Safety and Health Act 1984 in workplaces requires employers to consult with and provide specific information to employees and safety and health representatives (if elected). Employers should follow a procedure that has been agreed upon by all parties in the workplace which will cover consultation and co-operation in the management and reduction of risk arising from hazards such as PCBs in concrete caulking compounds.
Removal or sealing should be considered when the caulking compound is:
- leaching PCBs to the surface and skin contact occurs;
- causing PCB contamination of the air, including dust, above the exposure standard of 0.5mg/m3; or
- penetrated by water.
Material contaminated with released PCBs must be disposed of or decontaminated (see Safe disposal of PCB waste).
Where the removal of PCB caulking compound is necessary, skin contact should be avoided.
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:
- Isolation to control the emission of PCBs or PCB contaminated dusts;
- Engineering controls to minimise the direct handling of caulking compounds and to minimise generating any airborne dust;
- Adoption of safe work practices;
- Where other effective means for control listed above are not practicable or sufficient, suitable personal protective equipment is to be used.
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 PCB Waste section of this Bulletin.
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, 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.
Personal protective equipment and clothing required for handling PCB caulking compounds include:
- Chemically impervious disposable overalls (eg. Tyvek);
- Mid-arm nitrile gloves;
- Safety glasses;
- Rubber boots, if in contact with water; and
- P2 filter respirators if dust is being generated.
If skin contamination occurs, this area of skin should be washed immediately with soap and water. Water alone is not sufficient. If clothing is contaminated it should be removed and disposed with as recommended below. Organic solvents like kerosene or petrol should not be used to wash the skin.
The correct disposal of waste PCB caulking compounds and contaminated material will prevent the entry of PCBs into the food chain and the general environment. PCBs must not be dumped or hosed away because of their potential to enter the food chain.
Solid and Liquid Contaminated Waste
Caulking compounds containing PCBs should be placed in plastic bags and stored in a sound steel drum.
Soak up water contaminated with PCBs from caulking compounds with an absorbent material, such as sawdust, vermiculite, clay, rags, etc. 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 for easy identification, and stored in a separate, secure place prior to disposal.
PCB Contaminated Equipment and Tools
Contaminated equipment and tools should be cleansed with a cloth soaked in a small amount of organic solvent such as kerosene. The contaminated material should then be placed in a suitable container and packed with absorbent material inside a labelled sound steel drum.
When cleaning up PCB contaminated tools, chemically impervious disposable overalls, mid-arm length nitrile gloves and safety glasses must be worn.
Prior to disposing of any PCB waste contact the Enviromental Management Division telephone (08)6364 6500 for information on approved disposal facilities.
Ordinary incinerators are not effective and must not be used because they produce even more hazardous dioxins from the incomplete combustion of PCBs.
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