Navigating Designated Hazardous Substances in the Workplace
- 5 min read
- November 19, 2025
Workplace safety is of paramount importance, especially when dealing with hazardous materials such as designated substances. In Ontario, stringent regulations are in place to safeguard the health and well-being of workers. Designated substances, also known as hazardous materials, can pose significant risks to human health. In this comprehensive article, we will explore what designated substances are, the potential health hazards they pose, the legal obligations of employers, risk assessment strategies, control measures, and the importance of training when dealing with designated substances in an Ontario workplace.
Understanding Designated Substances
Designated substances, as defined by the Ontario Occupational Health and Safety Act (OHSA), are materials and chemicals known to have harmful health effects when exposed to them. These substances can vary widely and include asbestos, lead, mercury, arsenic, benzene, and more. They are categorized into three primary groups:
Designated Substance Regulations (DSRs):
These substances are explicitly listed in the DSRs, and employers are required to adhere to specific and stringent regulations for their management and control.
Hazardous Substances:
While not explicitly listed in the DSRs, these substances still pose significant threats to health and safety. Employers have a general duty to protect workers from exposure to these substances.
Biological or Chemical Agents:
This category includes biological agents like bacteria and viruses, as well as other chemical agents that may pose health risks to individuals. Click here to read a guide about designated substances in the workplace.
Health Risks Associated with Designated Substances
Designated substances can pose severe health risks to individuals exposed to them. Understanding these risks is crucial to appreciate the importance of proper management and control. Here are some common designated substances and the health risks associated with them:
Asbestos
Prolonged inhalation of asbestos fibers can lead to severe lung diseases, such as asbestosis and mesothelioma.
Lead
Exposure to lead can result in neurological issues, kidney damage, and reproductive system problems.
Mercury
Mercury exposure is known to cause neurological disorders, kidney damage, and other serious health complications.
Arsenic
Prolonged exposure to arsenic has been linked to skin, lung, bladder, and kidney cancer.
Benzene
Benzene exposure can lead to leukemia and other blood-related diseases.
Legal Obligations in Ontario
Employers in Ontario have a legal obligation to ensure the protection of their employees from the potential health risks associated with designated substances. The OHSA is the cornerstone of occupational health and safety regulation in the province, and it encompasses several regulations concerning designated substances. Here are some key aspects of the legal obligations related to designated substances in Ontario:
The Designated Substance Regulations (DSRs):
These regulations specify stringent requirements for managing and controlling specific hazardous substances, including asbestos, lead, and mercury.
Occupational Health and Safety Awareness and Training Regulation
Employers are mandated to provide employees with information and training on workplace hazards, including designated substances.
Written Health and Safety Policy and Program
Employers must establish a written health and safety policy and program that addresses the control and management of designated substances in the workplace. Read 4S Consulting’s article to learn why a good health and safety program is important for your company.
General Duty
The OHSA establishes a general duty on employers to protect workers from hazardous substances, including designated substances not explicitly mentioned in the DSRs.
Risk Assessment
To effectively manage designated substances in the workplace, a thorough risk assessment is vital. This process helps employers understand the potential risks associated with specific substances and allows them to implement appropriate control measures. A risk assessment typically involves the following steps:
Identification of Designated Substances
Create a comprehensive list of all designated substances present in the workplace. This can be done by referencing safety data sheets, prior assessments, or consulting experts.
Hazard Evaluation
Evaluate the level of risk associated with each designated substance, considering factors like concentration, exposure duration, and frequency.
Exposure Assessment
Assess potential worker exposure by examining work processes, employee tasks, and the existing control measures.
Risk Characterization
Combine the hazard and exposure assessments to determine the overall risk for each designated substance.
Control Measures
Develop and implement control measures based on the risk characterization, aimed at minimizing or eliminating worker exposure to designated substances.
Based on the type of workplace or business, some designated substance regulations do not apply. Visit the Summary Chart of Application to see which designated substance regulations are not required in your workplace. Learn more about factors that cause health and safety hazards.
Control Measures for Designated Substances
Effective control measures are the foundation of preventing worker exposure to designated substances. Employers must take proactive steps to minimize health risks. Here are some key control measures:
Substitution
When feasible, replace designated substances with safer alternatives to eliminate or reduce health risks.
Engineering Controls
Implement engineering controls, such as ventilation systems and containment, to reduce exposure levels.
Administrative Controls
Develop and enforce workplace policies and procedures that reduce exposure risks. These can include training, signage, and work schedules.
Personal Protective Equipment (PPE)
Provide appropriate PPE such as respirators, gloves, and protective clothing to workers as a last line of defense.
Monitoring
Regularly assess and monitor exposure levels to ensure that control measures remain effective.
Medical Surveillance
Implement medical surveillance programs to track workers' health and identify potential exposure-related health issues.
Emergency Response Plans
Develop and communicate emergency response plans for accidents or incidents involving designated substances.
Training and Education
Proper training and education are critical components of managing designated substances in the workplace. Employers must ensure that all workers are adequately informed about the risks associated with these substances and understand how to protect themselves. Training should cover:
- Identification and awareness of designated substances present in the workplace.
- Proper handling and storage procedures for these substances.
- Correct usage of personal protective equipment (PPE).
- Emergency response protocols in case of accidental exposure.
- Reporting procedures for incidents or near-misses related to designated substances.
Conclusion
In Ontario, workplace safety is a fundamental commitment, and the management of designated substances plays a significant role in achieving this goal. Employers have a legal obligation to protect workers from the potential health risks associated with these substances. Understanding the specific risks, conducting thorough risk assessments, implementing control measures, and providing proper training are essential steps in ensuring the safety and well-being of workers.
Effective management of designated substances not only prevents workplace injuries and illnesses but also fosters a safer and more productive working environment in Ontario. Employers and employees must work together to minimize the risks associated with these hazardous materials, ultimately contributing to a safer and healthier workplace for all.
