Chemicals, Dangerous Goods, and Hazardous Substances

Dental workers come into contact with mercury daily. Amalgam used during tooth reconstruction is a mixture of silver and mercury. The mercury is in the form of liquid metal, finely dispersed, throughout the silver. Dental workers can have severe health effects due to overexposure.

The symptoms of overexposure to mercury are irrational, excitable, indecisive and depressed behaviours as well as fatigue, weakness, headaches, memory loss, insomnia, tremors, poor digestion, eyesight and urinary track issues. Unborn children are also at risk because mercury can pass through the placenta.

Prevention

Workers can protect themselves from overexposure by:

1. Preventing absorption through the skin.

• Wear medical gloves licensed by Health Canada.
• Use sealed premixed, disposable capsules of amalgam preparation.
• Avoid the squeeze cloth technique as it requires too much handling and unprotected hands may receive a high dose of mercury.
• Avoid skin contact when cleaning the traps of suction equipment.

2. Preventing mercury from being inhaled.

• Keep mercury away from hot surfaces, as an increase in temperature causes a rapid increase in mercury vapour.
• Avoid accumulation of amalgam debris by routine cleaning of operatory drawers, amalgam mixers, and chairs.  Carpet in the operatory is not recommended as it is almost impossible to remove spilled mercury or amalgam fragments from them.
• Store unused amalgam under liquid to minimize vapour release (e.g,, mineral oil or glycerin).
• Wear dust masks to prevent inhaling fragments.
• Do not overlook the vacuum cleaner as a potential source of exposure. If a household style vacuum cleaner is used, the bag should be changed frequently.

3. Prevent ingestion.

• Avoid eating in areas of possible contamination.
• Wash your hands before eating.
• Store food away from the work area.

How to handle spills

Equipment and procedures should be in place to handle clean ups. Visible droplets can be removed by a suction probe or mercury vacuum.  If a spill gets into floor cracks or under baseboards, there are commercial products that will change mercury to a less hazardous form that can be cleaned up easily with water.  Equal parts of lime and flowers of sulphur made into a paste with water and left for 24 hours on the spill area will produce the same effect. 

If spills occur frequently, special mercury vacuum cleaners are available that will eliminate vapour from the exhausted air.  Porous surfaces such as carpets and furnishings are the hardest to clean up.  Cleaning methods will likely be ineffective and may discolour or ruin the surface.

Safe Work and Emergency Procedures

Respiratory Devices

Monitoring

Employers are responsible to protect their workers from the hazards associated with handling chemical and biological substances.

Most workers will handle or be exposed to chemical or biological substances during their employment.   

Those who work in chemical laboratories, chemical production and other chemical processes will handle chemicals daily.  Less frequently, other workers may be required to handle common trade name products that contain chemicals such as paints, adhesives, photographic developers, and cleaners.

Safely handling biological substances or products containing biological substances is common in careers like food processing, sewage work, laboratories, agriculture and health care, to name a few.

Sometimes workers do not use, produce or handle chemical and biological substances directly, but are exposed to them when the substances are released into the workplace (for example, from equipment or processes such as welding, oil-drilling and servicing, sawing or grinding).

Cytotoxic drugs include any drug that inhibits or prevents the function of cells. Cytotoxic drugs include drugs used to treat cancer and, in some cases, to treat certain skin conditions (e.g., psoriasis).