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Santé Montréal


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Has your occupational health team detected mercury in your workplace?

Did you know? Where is mercury found in the workplace? 

Mercury is a silver-coloured liquid metal found:

in manufacturing facilities:  electrical

  • fluorescent tubes, mercury lamps
  • neon signs
  • switches, batteries


  • manufacture of chlorine and caustic soda products

in measurement instruments: 

  • thermometers
  • barometers 
  • pressure gauges, etc. 

in the health sector:

  • dentists' offices – dental amalgam
  • health institutions – many medical and technological sources (e.g., thermometers) 

Mercury exposure 

Mercury gives off vapours that are colourless and odourless but very toxic at normal temperatures, and even more so when mercury is heated. 

  • Mercury's main pathway for entry into the body is respiratory, i.e., through inhalation of mercury vapours. 
  • Liquid mercury is not often absorbed through the digestive system.
  • Absorption through the skin is possible, and more so if the skin is broken by disease or injury.

Mercury's health effects

Mercury is especially harmful to the nervous system and the kidneys. 

  • Inhaled vapours quickly enter the blood stream and the mercury is carried to the various organs in the body, accumulating mainly in the kidneys and the brain. 
  • Mercury is mainly eliminated through a person's faeces and urine. It can also be found in breast milk. 

Health effects of acute exposure (massive doses over a short period):

  • Irritation of the airways with coughing, shortness of breath and chest pain
  • Abdominal pain, nausea, vomiting, diarrhea 
  • Skin rash, itchiness
  • Fatigue, fever 
  • Inflammation of the gums 

Health effects of chronic exposure (repeated doses over a long period):

  • Emotional instability, irritability, depression 
  • Inflammation of the gums, sometimes with abundant salivation
  • Trembling of the fingers, eyelids or lips 
  • Weak muscles, numbness 
  • Loss of memory, insomnia 
  • Loss of appetite, loss of weight 
  • Kidney damage

Skin contact with mercury can cause sensitization (skin allergy) without necessarily resulting in acute poisoning. 

In pregnant women, mercury can threaten the health of the fœtus, because it can cross the placental barrier.

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When to Consult

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Protection and prevention

To prevent mercury poisoning at the source: 

  • Replace mercury by a less toxic product. 
  • Use instruments that do not contain mercury (e.g., electronic thermometers).
  • Change production processes (e.g., closed circuit manufacturing).
  • Handle mercury-containing substances under a hood to draw off the vapours.

To prevent mercury poisoning in the work environment:

  • Make sure that the walls and floor are smooth and non-porous, because mercury tends to break up into smaller and smaller beads as it is shaken and can get trapped in grooves or porous joints in the floor. 
  • Use work surfaces that are smooth, free of joints and equipped with a lip to trap any mercury that might be spilled. 
  • Avoid overheating the premises because higher temperatures cause mercury to evaporate faster. 
  • Avoid burning or trashing/flushing mercury-tainted waste that would contaminate the environment. 
  • Do not pour mercury down a sink, because the mercury will build up in the S-pipe and continue to give off toxic vapours every time hot water flows in the pipe. 
  • Dispose of mercury and waste in accordance with hazardous waste and environmental protection regulations. 
  • Store mercury in closed, unbreakable containers. 
  • Keep a register of the use of mercury and the quantities kept on the premises so that any losses can been detected and investigated. 
  • Organize work in a way that exposes the fewest people possible. 
  • Wear the appropriate type of gloves when handling mercury. 
  • Wear respiratory protection (mask), if appropriate. 
  • Follow hygiene and prevention instructions.
  • Do not keep food and do not eat or smoke in any place where mercury is handled. 
  • Wash your hands before leaving places where mercury is handled, and before eating, drinking or smoking. 
  • Wear work clothes that are separate from the clothes you wear outside of work. 
  • Change rooms should be separate from work areas and there should be separate lockers for street clothes and work clothes. 
  • Do not take soiled clothing or articles home to avoid exposing your family to mercury. 
  • Wash work clothes separately. 

All mercury that escapes in a room must be recovered quickly according to a pre-established procedure. 

  • There must be an established recovery and decontamination procedure  (ask your employer or the person responsible for health and safety). 
  • Isolate the site where a mercury spill has occurred and restrict access to authorized people only. 
  • Do not use a broom or ordinary vacuum cleaner.
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Risk factors

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Help and Resources

If a worker is indisposed by mercury vapours: take the victim out into fresh air and call the Québec Poison Centre at 1-800-463-5060 or 911.

For more information, contact the CLSC occupational health team in your region.

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People at Risk

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Dernière mise à jour le : 2019.06.11