Designated Substances

In Ontario a number of hazardous materials are specially regulated and require special steps to be taken for storage and handling. This page has a list of these materials and what you need to do while using or handling these materials.

The following substances are specially regulated in Ontario:

  • Acylonitrile
  • Arsenic
  • Asbestos
  • Benzene
  • Coke Oven Emissions
  • Ethylene Oxide
  • Isocyanates
  • Mercury
  • Lead
  • Silic
  • Vinyl Chloride           

If you use any of these materials, please notify Occupational Health & Safety (OHS) by completing an Inventory Form (Excel). Send the completed form to Anne Marie McCusker via e-mail. You must also ensure that you are familiar with the legislated requirements.

Western's Designated Substances Program

When a designated substance is present in the workplace, the Occupational Health and Safety Act requires the employer to review the work methods and assess the likelihood of worker exposure. When there is likelihood of worker exposure, a control program must be instituted that includes engineering controls, work practices, hygiene practices, training record keeping and medical surveillance, if applicable.

Additional steps such as air monitoring and health assessments may be required by OHS and Workplace Health.

If you have any other questions contact Anne Marie McCusker.


  • Asbestos on Construction Projects and in Buildings and Repair Operations - O.Reg 278/05
  • Designated Substances – Reg 490/09

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