CLEAN-UP PROCEDURES FOR SPILLS OF INORGANIC MERCURY

Inorganic mercury spills can occur from broken thermometers, manometers and blood pressure apparatus, and in any process where mercury is used, such as scientific research or preparing dental amalgams. Exposure to mercury vapour can have adverse health effects if prolonged. Short term low level exposures do not usually cause any significant health effects, but spills should be cleaned up promptly to minimise the possibility of long-term exposure occurring. Liquid mercury vapourises readily at room temperature, and this can lead to significant mercury vapour levels being present from liquid spills.

Most mercury spills in the University involve only a small amount of liquid from a broken thermometer. These spills can usually be cleaned up fairly easily by laboratory staff with the right equipment and knowledge. Some situations of mercury spillage are more serious, such as if a thermometer is broken within a hot oven, where there is an immediate hazard from release of mercury vapour.

Thorough clean-up is important to prevent chronic exposure. If mercury is not cleaned up using appropriate methods, it can remain trapped in crevices and cracks, and continue to vapourise over a long period of time.

Sweeping and mopping clean-up methods should not be used. Do not use household vacuum cleaners, as this will only generate more airborne mercury.

Wear personal protection during clean-up: lab coat or gown to protect your clothes from contamination and impervious disposable gloves - PVC or rubber gloves, or double glove with surgical type gloves. If it's a large spill also wear enclosed footwear and a mercury vapour respirator.

More information on dealing with:

Small spills

For small spills on impervious surfaces (eg. vinyl, concrete, lino, tiles etc)

  1. Contain the area of the spill and thoroughly examine the area to detect all visible droplets of mercury. Droplets of mercury can travel some distance, so a large area around the spill point should be checked.
  2. Pick-up droplets using pasteur pipette, eye-dropper, suction bottle, or strips of adhesive tape, avoiding skin contact.
  3. Sprinkle sulphur powder, calcium polyphosphide with excess sulphur, zinc dust or proprietry products like Mercurisorb, HgX on contaminated area, using at least twice as much powder as volume of spill. Mix well if possible. Allow time for mercuric sulphide, etc to form, which can take from half an hour to 24 hours. Sweep or vacuum up the powder, avoiding generating dust. Use only special vacuum cleaners fitted with charcoal filters.

For small spills on carpeted areas:

  1. Use the same methods as for impervious surfaces, but then remove the carpet and repeat the methods used previously. Mercury seeps through carpets and cannot be thoroughly cleaned up.
  2. Use sodium thiosulphate (photographic fixer) solution to further decontaminate area once mercury has been collected.
  3. Place collected mercury in an impervious, unbreakable sealed container, and notify Work Health & Safety Services (WHS Services) for inclusion in the next hazardous waste collection schedule. Sodium thiosulphate can be added to the mercury in the container whilst awaiting collection for disposal.

Large spills

  1. Cordon off and ventilate the area.
  2. Make people in the immediate area aware that there has been a spill.
  3. Contain the area of the spill and thoroughly examine the area to detect all visible droplets of mercury. Droplets of mercury can travel some distance, so a large area around the spill point should be checked.
  4. Wearing personal protection, physically collect the visible mercury. Pick-up droplets using pasteur pipette, eye-dropper, suction bottle, or strips of adhesive tape, avoiding skin contact.
  5. Still wearing personal protection, sprinkle sulphur powder, calcium polyphosphide with excess sulphur, zinc dust or proprietry products like Mercurisorb, HgX on contaminated area, using at least twice as much powder as volume of spill. Mix well if possible.
  6. Allow time for mercuric sulphide, etc to form, which can take from half an hour to 24 hours. Decontaminate the area, eg using sodium thiosulphate (photographic fixer) solution.
  7. Sweep or vacuum up the powder, avoiding generating dust. Use only special vacuum cleaners fitted with charcoal filters.
  8. Collect the dust in an impervious sealed container and submit a request for hazardous waste disposal to the WHS Services. Add sodium thiosulphate (photographic fixer) solution to the container whilst awaiting collection.
  9. Use sodium thiosulphate (photographic fixer) solution to further decontaminate area once mercury has been collected.
  10. For carpeted areas, repeat the above steps once carpet has been removed. Contaminated carpet will probably have to de disposed of as hazardous waste.
  11. Remove and decontaminate personal protection. Wash hands and any other contaminated skin with soapy water.
  12. Check the area for residual contamination following clean-up using a mercury vapour measuring instrument.

Spills in ovens

  1. Evacuate the area.
  2. Turn off the oven and allow it to cool to room temperature.
  3. Ventilate the room. If air-conditioned, block off any return air ducts.
  4. Do not allow people to re-enter the room until the mercury level has been tested, using a mercury vapour measuring instrument, and found to be below the permitted exposure level
  5. Decontaminate the area, following the steps and methods listed above for clean-up of small and large spills.