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O. Reg. 490/09: Designated Substances

Facilities that use designated substances in their process must undertake an assessment to ensure workers are not adversely exposed. This requires a review of a facility’s MSDS library to identify if a designated substance is used. A site visit is usually required to gather information about the process and potential routes of exposure. In some cases air monitoring to determine a workers exposure is necessary. A final report is produced detailing the process, results from air monitoring, and if there is need for a control program.


In Ontario there are eleven designated substances:

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