Workbook for Designated Substance Assessments
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366-BPV-01-IMOT © 2024, Workplace Safety & Prevention Services (WSPS)
1 877 494 WSPS (9777) | 905 614 1400 | WSPS.CA
SECTION I: INTRODUCTION
PURPOSE OF THIS WORKBOOK
This workbook can assist you in carrying out your responsibilities required under the law to complete a
written assessment of the exposure or likelihood of exposure of a worker to a designated substance in the
workplace, and determine if a control program is required.
Under the Occupational Health and Safety Act certain toxic substances are classified as Designated
Substances and the employer must comply with Regulation 490/09 Designated Substances. Where this
regulation applies to a workplace, the employer must conduct an assessment to determine whether the
health of a worker may be affected by exposure to the substance.
This workbook will help you to decide if the Designated Substances Regulation applies to your
workplace; where it does, the workbook will also help you complete the required written assessment of
the likelihood of exposure of a worker to the designated substance.
The Ministry of Labour, Immigration, Training and Skills Development (MLITSD) also has A Guide to
Designated Substances in the Workplace to help you understand what you are required to do to limit the
risks of exposure to these harmful substances.
This method can also be applied to the assessment of other toxic substance that are not currently
designated. Once an assessment has been made, you will be better able to identify the appropriate controls.
At the present time, the following 11 substances have been designated:
1. acrylonitrile
2. arsenic
3. asbestos
4. benzene
5. coke oven emissions
6. ethylene oxide
7. isocyanates
8. lead
9. mercury
10. silica
11. vinyl chloride
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