Information Note – Cumulative health risk assessment operational planning framework

Health Canada's Pest Management Regulatory Agency
19 December 2025

Table of contents

• Background
• Status of cumulative health risk assessments

Background

The purpose of this document is to inform registrants, pesticide regulatory officials and the Canadian public of the ongoing and planned cumulative health risk assessment work by Health Canada's Pest Management Regulatory Agency (PMRA).

Health Canada regulates pesticides in Canada, with the primary objective of protecting the health of Canadians and the environment. A pesticide product may only be sold or used in Canada if it has been registered or otherwise authorized under the authority of the Pest Control Products Act (the Act). Health Canada uses a rigorous science-based risk assessment approach to ensure that the product meets health and environmental protection standards and has value.^{Footnote 1}

The Act requires Health Canada to consider available information on potential cumulative health effects of pest control products that have a common mechanism of toxicity. This is described in the Cumulative Health Risk Assessment Framework (SPN2018-02)^{Footnote 2} as the human health risks associated with co-exposures to two or more pesticides that cause a toxic effect(s) by the same, or essentially the same, sequence of major biochemical events (that is, a common mechanism of toxicity). Concurrent exposure to relevant pesticides, including common metabolites that share the common mechanism of toxicity, from dietary (food and drinking water), residential and other non-occupational exposures are assessed to determine the potential for cumulative effects, based on the likelihood that people may be exposed to more than one of these pesticides, including metabolites, at the same time. These assessments may consist of a qualitative, semi-quantitative or quantitative cumulative risk assessment, or result in a determination that a cumulative risk assessment is not required.

The framework and specific methodology that Health Canada uses for assessing the cumulative health effects of pesticides that have a common mechanism of toxicity is described in SPN2018-02. This framework includes a step-wise approach to identify pesticides that belong to a common mechanism group, including criteria for initial grouping and considerations for refining a common mechanism group.

Based on the definitions reported in SPN2018-02 for cumulative and aggregate risk, neither of these approaches corresponds to assessing risk to a common metabolite generated by several pesticidal active ingredients. A health risk assessment for a common metabolite produced by more than one active ingredient (for example, the environmental degradate trifluoroacetic acid (TFA)), where the mechanism of toxicity of the metabolite is not the same as the one from the parent active ingredients, does not meet the definition of cumulative assessment. Also, the risk assessment is conducted for a single chemical, the common metabolite. Therefore, although such assessments were considered under the cumulative assessment framework in the past, Health Canada will conduct health risk assessments for a common metabolite independently from the cumulative health risk assessments.

Status of cumulative health risk assessments

This plan includes identified pesticide groups where the active ingredient is registered in Canada or has established Canadian maximum residue limits (MRLs) on imported food commodities that may require cumulative health risk assessments (CRA).

• Table 1 identifies pesticide groups for which a CRA is under review or in the initial planning stage.
• Table 2 identifies pesticide groups for which a CRA has been completed.
• Table 3 identifies active ingredients for which a CRA was not required during the most recent reviews.
• Table 4 identifies common metabolite risk assessments that are currently under the initial planning stage. In the past, these assessments were considered under the cumulative risk assessment framework, and will now be conducted separately.

Pesticides Since 2018, each new pesticide evaluation—pre-market or post-market—has systematically considered the need for a CRA. Health Canada will continue to assess the potential for co-exposures to pesticide products with common mechanisms of toxicity to determine new and updated cumulative assessment groups and associated active ingredients.

This operational planning framework will be updated as needed. Health Canada will maintain transparency regarding active ingredients included in cumulative assessment groups, as defined in SPN2018-02, and will communicate any changes to that determination resulting from regulatory decisions. These groups may evolve throughout a product's lifecycle as new information becomes available and risk characterization evolves. Information on the announcements of new cumulative health risk assessments, including relevant documents such as notices for new initiations or scoping assessments, will be included and made available through the Public Registry.

Table 1 Planned cumulative health risk assessments

The following list of pesticides groups were identified as having or potentially having a common mechanism of toxicity, and for which CRAs are either currently under review or in the initial planning stage (listed out in alphabetical order). For some of the groups for which CRAs are in the planning stage, further work is needed to confirm that the pesticide group shares a common mechanism of toxicity, and if so, which active ingredients would be included in the CRA.

Table 2 Completed cumulative health risk assessments

The following list of pesticides groups were identified to have a common mechanism of toxicity, for which cumulative health risk assessments were conducted. These risk assessments will be updated as new information becomes available or new uses are added.

Table 3 Active ingredients for which cumulative health risk assessments are not required

In the most recent review of the following registered active ingredients, it was determined that a cumulative health risk assessment was not required for at least one of the following reasons:

1. Due to no common mechanism of toxicity identified with other pesticides, or
2. Due to no potential for non-occupational exposure based on the registered use pattern of the pesticide, or
3. Due to the inherently low toxicity concern of several non-conventional active ingredients, including metabolite(s).

As new submissions for registration are received or new information becomes available, the need for a cumulative health risk assessment will be revisited.

Table 4 Planned health risk assessments of common metabolites

The following common metabolites generated from multiple pesticidal sources, that do not share the common mechanism of toxicity with the parent active ingredients, have been identified to require separate health risk assessments. These assessments are currently under the initial planning stage. In the past, this type of risk assessment was considered under the cumulative assessment framework, however moving forward, will be conducted separately.