Part IV: Toxic substances
In this part of the guide, the term “toxic substance” is used to refer to a biological, chemical or physical agent (or a combination of such agents) whose presence or use (or intended use) in the workplace may endanger the health or safety of a worker. This part also describes additional regulatory requirements relating to hazardous materials and requirements related to hazardous physical agents.
Part IV of the Occupational Health and Safety Act (OHSA or “the Act”) deals with toxic substances and has two purposes: to ensure that worker exposure to toxic substances is controlled, and to ensure that toxic substances in the workplace are clearly identified and that workers receive enough information about them to be able to use, handle, store, and dispose of them safely.
The OHSA also sets out a process for the general public to access information about toxic substances used by regulated employers in their workplaces.
The control of toxic substances
There are several ways that worker exposure to toxic substances can be controlled under the OHSA.
Regulations for designated substances
The OHSA enables the Lieutenant Governor in Council (LGIC) to prescribe a toxic substance as a “designated substance”, and to prohibit, regulate, restrict, limit or control its use, handling and removal in regulated workplaces.
Designation is typically reserved for substances known to be particularly hazardous to the health and safety of workers.
Eleven substances have been prescribed as designated substances in one regulation under the Act (O. Reg. 490/09, Designated Substances), including asbestos, lead, mercury and arsenic. The regulation prescribes the maximum amount of the designated substances that workers can be exposed to in a given time period and the ways to both control and assess the substances in the workplace. There is also a specific regulation relating to the designated substance asbestos on construction projects, buildings and repair operations (O. Reg. 278/05 - Designated Substance - Asbestos on Construction Projects and in Buildings and Repair Operations) as well as a guide to the regulation.
Regulation for control of exposure to biological or chemical agents
The OHSA enables the LGIC to regulate or prohibit the atmospheric conditions to which a worker may be exposed in the workplace. Regulation 833: Control of Exposure to Biological or Chemical Agents, Regulation 833, sets occupational exposure limits (OELs) for over 725 biological and chemical agents.
“Section 33” order
Where a Director of the Ministry of Labour, Immigration, Training and Skills Development (MLITSD) is of the opinion that a toxic substance used or intended to be used in the workplace is likely to endanger the health and safety of a worker, section 33 of the OHSA requires the Director of the MLITSD to issue an order to the employer. The order must state that the use, intended use, presence or manner of use be prohibited, limited or restricted as specified, or subject to conditions regarding administrative control, work practices, engineering controls and time limits for compliance [subsection 33(1)]. Section 33 orders do not apply to designated substances [subsection 33(11)].
What happens when a section 33 order is issued?
The employer must comply with the order.
The employer must also:
- give a copy of the order to the joint health and safety committee (JHSC), or health and safety representative and trade union, if any
- post in a conspicuous place a copy of the order in the workplace where it is most likely to come to the attention of the workers who may be affected by the use, presence, or intended use of the toxic substance [subsection 33(3)].
Can an employer appeal a section 33 order?
Yes. Within 14 days of the order being made the employer, a worker, or a trade union may appeal a s. 33 order by giving written notice to the Minister of Labour, Immigration, Training and Skills Development [subsection 33(4)].
The Minister may decide the appeal himself or herself or may appoint a person to determine the appeal on his or her behalf [subsection 33(5)]. There is no further appeal of this decision under the OHSA. The Minister or the appointed person has the power to suspend the operation of the order until a decision on the appeal has been made [subsection 33(9)]. He or she can also affirm or rescind the order of the Director or make a new order [subsection 33(7)].
The OHSA specifies the relevant factors the Director must consider when making an order under section 33 and by the Minister or person appointed by the Minister when determining an appeal [subsection 33(8)].
The right to know about hazardous materials
One of the three basic rights that the OHSA gives to all workers is the right to know about hazards they may be exposed to on the job. Compliance with the OHSA and WHMIS Regulation is necessary to fulfill the workers’ right to know about hazardous materials in the workplace. In 1988, the OHSA was amended as part of the Canada-wide implementation of the Workplace Hazardous Materials Information System (WHMIS),ensuring employers and workers receive consistent and comprehensive health and safety information about the hazardous products they may be exposed to at work.
The main purpose of the federal WHMIS legislation is to require suppliers of hazardous products that are intended for use, handling or storage in a workplace, to classify those products and provide health and safety information about them to their customers. The main purpose of provincial and territorial WHMIS legislation is generally to require employers to obtain health and safety information about hazardous products from their suppliers (labels and safety data sheets), and to use that information to provide worker education.
Canada has adopted international standards for classifying hazardous materials and providing information on labels and safety data sheets. These standards are part of the Globally Harmonized System for the Classification and Labelling of Chemicals (GHS) that was generally phased in across Canada. The original WHMIS requirements are generally referred to as WHMIS 1988 and the new ones are called WHMIS 2015.
Implementation of the system was generally phased in across Canada between February 2015 and December 2018. Amendments have been made to applicable sections of the Ontario Occupational Health and Safety Act and to Regulation 860: Workplace Hazardous Materials Information System (WHMIS) to transition to WHMIS 2015. Effective December 1, 2018, employers subject to Regulation 860 should be in compliance with WHMIS 2015.
Refer to the Ontario government website for an electronic copy of the regulation, Reg. 860: Workplace Hazardous Materials Information System (WHMIS).
While the OHSA uses the term “hazardous materials,” the term “hazardous products” is used in Regulation 860 (WHMIS) to align with language in the federal WHMIS legislation. Regulation 860 designates all hazardous products as hazardous materials for the purposes of the OHSA so that provisions in the OHSA related to “hazardous materials” apply.
Employer’s responsibilities concerning hazardous materials
In addition to general employer duties under the OHSA, an employer has specific duties in the OHSA relating to hazardous materials, including the duty to:
- identify hazardous materials in the prescribed manner, e.g., labels [clause 37(1)(a), OHSA]
- obtain or prepare (as may be prescribed) current Safety Data Sheets (SDSs) for all hazardous materials in the workplace [clause 37(1)(b), OHSA]
- ensure workers who are exposed or likely to be exposed to hazardous materials and hazardous physical agents receive, and that the workers participate in, prescribed instruction and training [subsection 42(1), OHSA]
- assess all biological and chemical agents that the employer produces for its own use to determine if they are hazardous materials [subsection 39(1), OHSA, and section 3, WHMIS Regulation]
Prescribed information related to hazardous materials are set out in Regulation 860 (WHMIS), which includes more detailed requirements related to worker education, labelling and safety data sheets, among other things.
References to the WHMIS Regulation in this guide pertains to Ontario Regulation 860: Workplace Hazardous Materials Information System (WHMIS).
Employers are required to ensure that hazardous materials are not handled, used or stored at a workplace unless the prescribed requirements relating to identification, SDSs and worker instruction and training are met [subsection 37(3) of the OHSA].
Where an employer is unable to obtain a required label or SDS after making reasonable efforts to do so, he or she is required to notify a Director of the MLITSD, in writing [subsection 37(4) of the OHSA].
In general, the WHMIS Regulation applies to hazardous products at a workplace and does not include hazardous products being transported or handled according to the requirements in the Dangerous Goods Transportation Act (Ontario) or the federal Transportation of Dangerous Goods Act, 1992. If a hazardous product is repackaged (assembled, labelled or re-labelled), processed or used, WHMIS requirements may apply. For further details, refer to the relevant legislation.
Identifying hazardous materials
The employer must ensure that all hazardous materials in the workplace are identified in the prescribed manner and must obtain or prepare, as prescribed, a current SDS for all hazardous materials present in the workplace [clauses 37(1)(a) and (b) of the OHSA].
The employer shall ensure that the SDS is in English and any other prescribed languages [clause 37(1)(c) of the OHSA].
No one is permitted to remove or deface the identification of a hazardous material, including a label or a safety data sheet [subsection 37(1) of the OHSA].
An employer must make certain that a hazardous material is not used, handled or stored at a workplace unless the prescribed requirements regarding identification, SDSs and worker instruction and training are met [subsection 37(3), of the OHSA].
In many situations, the supplier label is the worker’s first warning on a hazardous product. Employers who buy the hazardous product should understand the obligations of suppliers who sell it to them. Under WHMIS, employers must ensure that hazardous products received from suppliers are labelled with supplier labels and employers must obtain the supplier SDS.
Suppliers must also provide new data about hazardous products to employers in certain circumstances. Where an employer receives such new data, the employer must, as soon as practicable, attach the new information to every relevant supplier label and update the supplier SDS [subsections 8(5) and 17(2), WHMIS Regulation]. Supplier labels and supplier SDS must also be in English and French, separately or together.
Providing Safety Data Sheets (SDSs)
The employer has a duty to either obtain or prepare current SDSs for all hazardous materials present in the workplace [clause 37(1)(b)].
The employer is required to update the SDS as soon as it is practicable, but not later than 90 days after significant new data about the hazardous product becomes available to the employer [subsection 18(3), WHMIS Regulation].
The employer may store hazardous product received from a supplier without a label, without obtaining a supplier SDS, and without conducting a program of worker education about it, only while the employer is actively seeking the supplier label and SDS from the supplier for the hazardous product [subsection 5(1), WHMIS Regulation]. This is not intended to be a method allowing for permanent storage without proper labelling, etc.
The employer may also store employer-produced hazardous products without applying a label or using other identification, without an SDS and without conducting a program of worker education while the employer is actively seeking information required to produce the workplace label and an SDS [subsection 5(2), WHMIS Regulation]. If, after making reasonable efforts, the employer is unable to obtain an SDS or label, the employer must notify a Director of the MLITSD in writing [subsection 37(4) of the OHSA].
Similar to requirements for the label, where the employer produces the hazardous product at the workplace, the employer is required to prepare an SDS that meets the federal WHMIS requirements under the Canadian Hazardous Products Regulations for an SDS [subsection 18(1), WHMIS Regulation].
Upon request of the parties noted below, an employer who produces a hazardous product in a workplace is required to disclose as quickly as possible under the circumstances, the source of any toxicological data used by the employer to prepare an SDS. The parties that can request the employer to disclose the source of toxicological data include an inspector, a worker at the workplace, a member of the JHSC, a health and safety representative or, where there is no JHSC or health and safety representative, a worker representative [section 25, WHMIS Regulation].The employer may withhold confidential business information (e.g. a valid trade secret) in certain circumstances.
For the purposes of clause 25 (2) (b) of the OHSA, in a medical emergency, an employer is required to provide information, including confidential business information, upon request, to a medical professional for the purpose of diagnosis or treatment [section 24, WHMIS Regulation].
No workplace label, identification or SDS is required for a fugitive emission, or for a hazardous product that exists only as an intermediate and undergoes further reaction within a process or reaction vessel, e.g., a volatile organic compound such as benzene at a chemical plant escaping due to leakage from a valve [subsection 1(2), WHMIS Regulation].).
The employer is required to make copies of current SDSs available to:
- to the JHSC or to the health and safety representative, if any
- the relevant medical officer of health of the health unit in which the workplace is located if requested or prescribed
- the local fire department if requested or prescribed
- a Director of the Ministry ofLabour, Immigration, Training and Skills Development if requested or prescribed [subsection 38(1) of the OHSA].
Employers must also make a copy of SDSs readily available to those workers that may be exposed to the hazardous material to which the SDS relates [subsection 38(1)]. An electronic version of an SDS is considered a copy [subsection 38].
Wider distribution of safety data sheets is discussed later in this chapter, in the section “Public access to Safety Data Sheets.”
The employer is permitted to make safety data sheets (SDSs) available to workers by means of a computer terminal, if the employer,
- takes all reasonable steps to keep the computer terminal in working order
- provides a paper copy of the SDS if requested by a worker, and
- provides training on how to access computer-stored data sheets, to all workers working with or in proximity to controlled products, and to members of the JHSC or a health and safety representative.
The employer has a specific duty to provide prescribed instruction and training to workers who are exposed or likely to be exposed to a hazardous material or hazardous physical agent on the job [subsection 42(1) of the OHSA]. Employers are further required to ensure that workers participate in any prescribed instruction/training. This is in addition to the general employer duty to provide information, instruction and supervision to workers to protect their health and safety in clause 25(2)(a) of the OHSA.
In addition, the employer must consult the JHSC, or health and safety representative, if any, in developing and implementing prescribed instruction and training for workers exposed or likely to be exposed to a hazardous material or hazardous physical agent. [subsection 42(2) of the OHSA].
The employer must inform the workers who work with or who may be exposed in the course of his or her work to a hazardous product received from a supplier about all the hazard information received from the supplier about the hazardous product, as well as further hazard information that the employer is aware of or ought to be aware of regarding the storage, use and handling of the product [subsection 6(1), WHMIS Regulation]. In general, this refers to the information provided on supplier labels and safety data sheets, but it can also include other information such as letters from the supplier in response to inquiries from the employer.
If the employer produces the hazardous product in the workplace, the employer must inform the workers who work with or who may be exposed in the course of their work to the hazardous product about all hazard information of which the employer is aware, or ought to be aware regarding its storage, use and handling [subsection 6(2), WHMIS Regulation ].
Information that employers may wish to consider include:
- publications and computerized information available from the Canadian Centre for Occupational Health and Safety (CCOHS)
- publications available from industry or trade associations of which the employer is a member and from labour organization(s) representing workers at the workplace, and
- publications from the Ontario Ministry of Labour, Immigration, Training and Skills Development (MLITSD).
Employers must ensure that workers who work with or who may be exposed in the course of their work to a hazardous product are instructed in the following areas [subsection 7(1), WHMIS Regulation]:
- the information required on labels, and the purpose and significance of that information
- the information required on SDSs, the purpose and significance of that information
- procedures for the safe use, storage, handling and disposal of a hazardous product, including when a hazardous product is contained or transferred in a pipe, a piping system, a process vessel, a reaction vessel, or a tank car, a tank truck, an ore car, a conveyor belt or a similar conveyance
- procedures to be followed where fugitive emissions are present
- procedures to be followed in case of an emergency involving a hazardous product.
The employer must ensure that the program of worker education is developed and implemented for the employer’s workplace and is related to any other training, instruction and prevention programs at the workplace [subsection 7(2), WHMIS Regulation].
An employer shall ensure, so far as is reasonably practicable, that the program of worker instruction required by subsection 7(1) results in the workers being able to use the information to protect their health and safety [subsection 7(3), WHMIS Regulation].
Assessment for hazardous materials
The OHSA requires that, in prescribed circumstances, an employer assess all biological and chemical agents produced in the workplace for use in it, to determine if the agents are hazardous materials. This assessment must be in writing. A copy of the assessment must be made available in the workplace to allow examination by workers and provided to the JHSC or health and safety representative, if any, or to a worker selected by the workers to represent them if there is no JHSC or health and safety representative [section 39 of the OHSA].
Process for public access to Safety Data Sheets (SDSs)
The OHSA provides for the distribution of SDSs outside the workplace in certain circumstances. Specifically, upon request or where prescribed, the employer must provide the SDS to the following:
- the medical officer of health of the health unit where the workplace is located
- the local fire department
- a Director of the Ministry ofLabour, Immigration, Training and Skills Development [subsection 38(1)]
It is through the medical officer of health that the public has access to SDSs. Upon request by any person, the medical officer of health must ask an employer to provide a copy of a current SDS or must make available a copy of any SDS requested by the person in the medical officer of health’s possession [subsections 38(2) and (3)].
The medical officer of health is prohibited from disclosing the name of any person asking to see an SDS as described above [subsection 38(4)].
Confidential business information
The Occupational Health and Safety Act (OHSA or “the Act”) provides protection for certain types of confidential business information that are prescribed by regulation. Employers may file a claim for an exemption from disclosing information that is normally required on a label or SDS or the name of a toxicological study that was used by the employer to prepare a SDS on the basis that it is confidential business information [subsection 40(1), OHSA]. An employer that claims an exemption for confidential business information will have the claim determined by Health Canada, according to procedures set out in the federal HMIRA (Hazardous Materials Information Review Act) [subsection 40(3), OHSA]. Where a claim is successful, an employer is not required to disclose the confidential business information on a label or SDS but must include certain information about the exemption instead [sections 20 and 21, WHMIS Regulation]. The WHMIS Regulation sets out types of information for which an employer may claim an exemption [section 19, WHMIS Regulation].
A form for the request of an exemption can be obtained by sending an email to the following address:
Details regarding confidential business information and the application process is on the Government of Canada website.
MLTSD is responsible for enforcement of both the federal and Ontario WHMIS legislation. This is done so that employers and suppliers will not be subject to inspections by both federal and provincial inspectors. It means that MLTSD inspectors monitor compliance with the federal Hazardous Products Act (HPA), the Hazardous Products Regulations (HPR), as well as the OHSA, and the WHMIS Regulation.
Hazardous physical agents
Physical agents include noise, heat, cold, vibration and radiation. Hazardous physical agents are covered by the OHSA [section 41] and in circumstances where there are no specific requirements that address the use of potentially hazardous physical agents in the workplace, employers must take every precaution reasonable in the circumstances for the protection of workers [clause 25(2)(h)], in addition to other duties in the OHSA.
Content last reviewed May 2019.