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GENERAL INFORMATION ON PCB'S

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PCB's (polychlorinated biphenyls) Comprise a group of 209 possible aromatic chlorinated hydrocarbons having the chemical composition G12H10-nCln. Their manufacture produces a mixture of compounds, the properties of each depending on the amount of chlorination. In general, they are thermally and chemically stable, are insoluble in water but can be mixed with oils, and are fire-resistant.

These characteristics led to the use of PCB's in a wide range of products - in transformers and capacitors as dielectrics, as heat transfer fluids, as hydraulic fluids, and as components in brake linings. They were also used in the manufacture of adhesives, sealants, varnishes and printing inks, as plasticisers and in the production of marine anti-fouling paints.

Unfortunately, the properties which made PCB's so useful meant that they remained intact once their usefulness was over. Concern arose in the 1960s when overseas experience showed that these compounds were widely distributed, persistent and accumulating in the environment.

Experience has shown that apart from occupational exposure orInspection of a PCB site misadventure, diet is the principal source of PCB's for humans. Fish provides the greatest input,  although PCB's have been found in small concentrations in poultry, meat, produce and dairy products. They are absorbed by fatty tissues and tend to concentrate up the food chain, particularly in fish-eating birds, animals and humans, i.e., they "bio-accumulate".

In recent years their production, importation and use have been banned or tightly controlled in many countries. They were considered suitable for use in capacitors and transformers in fire sensitive locations. However, fires involving equipment containing PCB's can produce toxic by-products such as polychlorinated dibenzo-para-dioxins (commonly known as dioxins) and polychlorinated dibenzofurans. Consequently, PCB-containing equipment is now being phased out for all uses.

EMERGENCY RESPONSE AND PREPAREDNESS

Because of the known persistent nature of PCBs and their tendency to bio-accumulate, it is important to prevent entry of PCBs into the environment. Therefore:
It is essential to avoid PCB's leaking into drains or natural waterways.
All wastes and residues containing PCBs must be collected for disposal.

EMERGENCY PROCEDURE PRIORITIES

In the event of serious PCB discharge the following priority steps should be taken:

  1. Don protective clothing.
  2. Stop the flow of PCB's.
  3. Contain PCB's.
  4. Inform regulatory authorities.
  5. Keep non-essential people away from the affected area.
  6. Recover all PCB contaminated material so that it can be properly disposed of.

PROTECTION OF PERSONNEL

All non-essential personnel must be kept out of the immediate leak or spill area. The area should be roped off to prevent any spread of PCB material by vehicle or pedestrian traffic.

  • Personnel entering the leak or spill area must be provided with and use protective equipment.
  • Only personnel familiar with PCB safety procedures should be used to shut off the source of the PCB spill,  contain the spilt PCB and carry out recovery and clean up work.
  • The repair of equipment or the clean-up of spillages and leaks containing PCBs should be carried out by  competent staff only.
  • Protective clothing must be worn.
  • Where a significant area of PCB liquid is exposed to the air in an indoor situation or where adequate  ventilation is not possible, supplied air breathing apparatus must be worn.
  • Contaminated clothing which cannot be effectively cleaned for reuse is to be placed into storage containers.
  • Attention must be paid to personal hygiene.

PRIORITY ACTIONS IN THE EVENT OF A LEAKAGE OR SPILLAGE

Stop the flow of PCB's

  • Position a container to catch the flow.
  • If possible stop the leakage.
  • Close and cover leaking valves.
  • Contain the PCB's.
  • Dyke major spills with soil or other oil absorbent material.
  • If at all possible prevent PCB's entering drains, waterways or spilling onto the ground.
  • Use sand or sawdust to absorb and recover the PCB, all of this to be recovered into open top drums.
  • Also recover and drum  PCB contaminated soil.
  • If leaking from the truck tray, drive the vehicle onto a sheet of plastic to contain the PCB's.
  • Report any spillage of PCB to the regulatory authorities as soon as practicable after the spillage providing details on the estimated volume spilt and to what extent it has been recovered and the exact location of the spillage.
  • Keep non-essential staff and the public away from the affected area. If possible use a rope barrier to outline the contaminated area. "Do Not Approach" notices should be displayed at the boundary of the affected area.
  • Recover all PCB contaminated material, protective clothing and equipment and pack into suitably labelled drums.
  • Spill clean-up staff should wash thoroughly after the clean up is completed.

PRECAUTIONS IN THE EVENT OF FIRE

In the event of a fire in an area containing PCB's the Fire Service personnel must be warned of the special danger and advised which equipment contains PCB. A notice should be located beside the main fire hydrant close to any PCB equipment stating the location of the PCB equipment.

It is possible in the event of a major fire that toxic decomposition products such as polychlorinated dibenzofurans and dibenzodioxins may be produced in small  quantities from the incomplete combustion of the material.

If PCB's have been subjected to fire in a building, no access should be allowed to the building without breathing apparatus and protective clothing until it has been confirmed by the regulatory authorities that it is safe to re-enter.

Details on the prevention and management of PCB fires have been produced by the United States National Institute of Occupational Safety and Health.

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