Risk-based and hazard-based approaches to pesticide assessment

Hazard and risk

A hazard is something that has the potential to cause harm. A risk is the likelihood of a hazard causing harm. Risk mitigation measures are methods used to decrease the risk, which decreases the chance of harm from a hazard.

For example: A bear in the woods is a hazard. Hiking in bear country is a risk. Making noise, hiking with a group, and sticking to marked trails are risk mitigation measures.

Health Canada’s approach to pesticide assessment

Health Canada plays a crucial role in the regulation of pesticides in Canada. Like many chemicals, pesticides can be harmful if not used properly. That is why their use must be carefully managed to protect human health, public safety, and the environment.

Health Canada uses a scientific, risk-based approach to make decisions on pesticides. Because of the difference between risk-based and hazard-based approaches, regulatory bodies in different countries may reach different conclusions about the same pesticide.

Risk-based approach

The risk-based approach focuses on assessing, understanding, and reducing the risks associated with pesticide use. This approach looks at how likely it is that something bad will happen, and how serious the harm could be. To lower risks, Health Canada puts risk mitigation measures in place to make the use of a pesticide safe. If the risks cannot be managed safely, the pesticide will not be approved for sale or use in Canada.

Health Canada uses a well-defined, internationally recognized framework for risk assessment and risk management in its decision-making that involves four steps:

Identify: Determine potential health and environmental concerns (hazards).
Assess: Evaluate the likelihood and potential impact of harm (risk).
Manage: Implement strategies to reduce or control the risks (mitigation).
Monitor: Continuously check to make sure the risk-management measures are working.

A risk-based approach is flexible and can be adjusted as new scientific information becomes available. This approach helps ensure that important pesticides remain available for farming, forestry, industry, and public health, while making sure the risks of using them can be managed.

Hazard-based approach

A hazard-based approach focuses on the hazardous properties (built-in dangers) of substances that exist no matter how or where it’s used, and regardless of exposure conditions. It identifies and regulates substances based solely on their potential to cause harm.

This approach involves:

Hazard Identification: Recognizing substances with harmful properties.
Regulation: Applying precautionary measures to control or ban hazardous substances.

A hazard-based approach focuses on the properties of a substance, rather than the context of its use. It often assumes that any exposure should be avoided. This approach may be suitable in certain regulatory contexts or where precaution is the upmost priority. However, it can limit the use of substances that could offer important benefits when used safely.

Comparison between the two approaches

Both risk-based and hazard-based approaches aim to protect human health and the environment, but they take different paths to get there. A hazard-based approach focuses solely on the potential dangers of a pesticide and often assumes any exposure should be avoided. A risk-based approach looks at how a pesticide is used and whether safeguards can make it safe to use.

In a risk-based approach, regulators examine real-world conditions, like how people might encounter a pesticide (such as eating, touching, or breathing it in), how much of it, and how often. This is called exposure. Scientific data is used to determine if the pesticide can be used in a way that still protects health and the environment against potential harm, and rules and restrictions are set to make that possible. This means decisions are based not just on the hazard itself, but also on whether the risk can be responsibly managed.

Examples

Example 1: Hiking in a Canadian National Park

To bring back our previous example:

Imagine you are deciding where to vacation next summer with your friends and you’re considering a hiking trip in one of Canada’s beautiful National Parks. You know that the hike you are considering is in bear country. You and your friends have identified bears as a hazard.

If you take a hazard-based approach: you may conclude that the hazard must be entirely avoided and decide on some other type of vacation.

If you take a risk-based approach you can evaluate your risk of hiking in woods known to be inhabited by bears. You can research how likely you are to come across a bear in that area at that time of year to help you and the group better understand the risk. You can commit to making noise, hiking with a group, and only using officially marked paths and trails to mitigate the risk of encountering bears. You can also decide to monitor the frequency of bear sightings and interactions leading up to your vacation so you can adjust your risk management (mitigation) measures or change your plans. You may conclude that it is safe to enjoy the hiking trip after all because you understand the risk and the risk mitigation and monitoring measures you need to take.

Example 2: Using “Pestatrix” in agriculture

Let’s consider a hypothetical example involving farming.

Imagine two farmers in two different countries, Jack and Jill, thinking about how to manage weeds in their fields. One option they’ve heard of is to use pestatrix, an effective herbicide known to be highly toxic if not handled properly. Pestatrix is identified as a hazard.

Jack lives in a country that uses a hazard-based approach in pesticide regulation. Scientists use available hazard data and clear criteria to identify potential hazards. The regulator has decided that because pestatrix is inherently dangerous, it should not be used at all and be banned due to its toxicity.

Jill lives in a country where the pesticide regulator takes a risk-based approach. Scientists rely on modern, internationally recognized science to guide decisions. They analyze data from water and food testing, published research, and global best practices. They determine how pestatrix is used and how exposure can be controlled using risk mitigation measures. In Jill’s country, only trained and licensed applicators can use pestatrix, and they must wear protective gear and follow safety protocols when they do. Pestatrix can only be used at certain times of year, and not within specific distances to sensitive habitats. The regulator in Jill’s country continues to monitor new data and scientific evidence. They will adjust the rules around pestatrix if needed. This approach involves understanding the risk (how likely harm is under specific conditions) and taking steps to monitor and manage that risk through regulation, training, and oversight.

In Jill’s case, the regulator allows access to a pesticide that helps her grow safe, high-quality food for people in her country and for export around the world. Since Jill knows that pestatrix has been carefully reviewed by scientists and she has received training on proper application of that pesticide, she feels confident in her ability to use the product safely while managing weeds in her field effectively. This gives Jill a tool she needs to keep her farm productive and competitive and support a safe and secure food supply.

Why this matters

Recognising the difference between risk-based and hazard-based approaches is key to understanding how pesticides are regulated in Canada.

Health Canada’s risk-based approach is used by many reliable regulators worldwide, relies on all available science, and uses risk management measures to protect people and the environment. This approach gives farmers the tools they need to grow safe food for people in Canada and around the world. It also supports other sectors that rely on pesticides, such as public health and forestry.

By focusing on how pesticides are used, incorporating emerging science, and managing risks responsibly, we help ensure an adaptable, strong and sustainable future.

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2026-06-16

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Risk-based and hazard-based approaches to pesticide assessment

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