Designated substances

In Ontario, designated substances are materials that cause severe health impairment from exposure or repeated exposure. The following are designated substances in Ontario:

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

The health effects are generally one or more of the following:

  • Cancer
  • Strong allergic reactions
  • Liver and lung disorders
  • Nervous system damage

An assessment is required if any of these substances are present and if there is a risk a worker could be exposed. Employers in Ontario must assess the use of these materials even if they are adequately controlled as there is potential for the worker to be exposed if the control breaks down or fails.

The assessment involves examining the “cradle to grave” use of the material. This means following the material from when it enters the facility to when it is disposed of and determining how an individual or group of individuals may be exposed. If in any instance a worker's health may be affected, a control program is required. Consider the following information when determining if control programs are required.

Control program not required (worker health not affected)

  • If the substance is present in the working environment, but because of the amount used or the physical state in which it is present, it is not possible for a worker's health to be affected by exposure.
  • If workers are exposed and some engineering controls exist, but the health of a worker is not likely to be affected because the risk to health would be minimal even if the engineering controls failed.

Control program is required (worker health may be affected) 

  • If there are no controls in place.
  • If the current controls are adequate but may fail or deteriorate.
  • If existing controls are not adequate.
  • If occupational exposure monitoring results indicate potential exposure of workers.
  • If there have been reports of previous health effects from one or more of these substances.

Safety Office contacts

  • For any construction-related exposure, such as maintenance, renovation, or construction of an area, contact Robert Mullins at extension 30190. At the University of Waterloo, the assessments are based on the material and type of exposure.
  • For any use of a designated substance in a laboratory or office as a result of research work, contact Dhananjai Borwankar at extension 36268.