Designated Substances

A “designated substance” is defined in the Occupational Health and Safety Act as “a biological, chemical or physical agent or combination of thereof prescribed as a designated substance to which the exposure of a worker is prohibited, regulated, limited or controlled.”

The following are designated substances:

  • Acrylonitrile
  • Arsenic
  • Asbestos
  • Benzene
  • Coke oven emissions
  • Ethylene oxide
  • Isocyanates
  • Lead
  • Mercury
  • Silica
  • Vinyl chloride

When a designated substance is present in the workplace, other than a construction project, the Occupational Health and Safety Act requires that the employer review the use of these materials to assess the likelihood of worker exposure. The review determines the potential for the worker to be exposed if the controls break down or fail and whether the health of a worker may be affected by exposure to the substance. This assessment must take a cradle to grave approach and identify all processes involved with the substance from the moment it enters the lab until it is disposed of. 

If any of these substances are present in the workplace and the likelihood of worker exposure exists, then an assessment is required to be completed by the supervisor or principal investigator. In the case of ethylene oxide, an assessment must be completed regardless of whether there is a likelihood of worker. If an assessment determines that there is a likelihood of worker exposure, a control program must be put into place. 

The applicable Joint Health and Safety Committee must be consulted and can make recommendations regarding the assessment that the employer carries out on the exposure or likelihood of exposure of a worker to a designated substance in the workplace. 

If there is a chance in the workplace or work process that could result in a significant difference in the exposure of a worker to a designated substance, than a reassessment shall be completed.

Documentation of the designated substance assessment must be kept by the Supervisor/PI and be made readily available within the workspace for as long as the designated substance is in their possession.

If you have any questions about the requirements for designated substances in a laboratory or workshop setting as part of research work, contact Tyler MacDonald

Designated substances must be identified and inventoried prior to the start of any renovation or construction work. If work on a project is tendered, the person issuing the tender must include this information with the rest of the tender documentation to ensure that all prospective bidders are aware of the presence of these designated substances. 

Before an owner can enter a binding contract with a constructor to work on a site where there are designated substances, the owner must ensure that the constructor has a copy of the list of designated substances. The constructor must then ensure that any prospective contractor or subcontractor also receive a copy of the list before entering a binding contractor for work on the project.

If an owner fails to comply with these requirements, they are liable to a constructor and every contactor and subcontractor who suffers any loss or damages as a result of the presence of designated substances that were not included in the list that the owner ought reasonable to have known of. A contractor who fails to comply with these requirements is similarly liable for any loss or damages suffered by a contractor or general contractor. 

If you have any questions about the requirements for designated substances in a construction setting (ex: maintenance, renovation work etc.), contact Tyler MacDonald