Re-evaluation Note REV2026-02, Triazole pesticides – Cumulative health risk scoping assessment, problem formulation and planned approach of analysis

Health Canada
Healthy Environments and Consumer Safety Branch
Pesticides Regulatory Directorate
1 June 2026
ISSN: 1925-0649 (PDF version)
Catalogue number: H113-5/2026-2E-PDF (PDF version)

Summary

Triazole pesticides – Cumulative health risk scoping assessment, problem formulation and planned approach of analysis

In Canada, the cumulative health risk assessment of active ingredients belonging to the triazole class of pesticides, as described in SPN2018-02, Cumulative Health Risk Assessment Framework, was initiated in October 2024.

Under the authority of section 16 of the Pest Control Products Act, the Canadian registrants of 13 triazole pesticides were notified of the initiation of the cumulative risk assessment (CRA) of this class of compounds. Following notification, the registrants indicated support for all uses included on the labels of the end-use products for 13 of the 13 triazole pesticides registered in Canada at the time of initiation. This CRA includes 13 triazole pesticides that are registered in Canada: difenoconazole, flutriafol, ipconazole, mefentrifluconazole, metconazole, myclobutanil, paclobutrazol, propiconazole, prothioconazole, tebuconazole, tetraconazole, triticonazole and uniconazole-p. In addition to the triazole pesticides registered in Canada, using the decision tree included in Appendix II of the full version of REV2026-02, residues of 8 other triazole pesticides may be present on imported food commodities, namely bitertanol, cyproconazole, epoxiconazole, fenbuconazole, flusilazole, penconazole, triadimefon, and triadimenol. These triazole pesticides will also be considered in the CRA.

Common metabolites of the triazole pesticides include 1,2,4-triazole, triazole alanine, triazole acetic acid, triazole lactic acid (triazole hydroxy propionic acid) and are typically referred to as triazole-derivative metabolites (TDMs). The CRA will also consider assessment of TDMs in conjunction with the CRA for the parent triazole pesticides.

As outlined in SPN2018-02, cumulative risk assessments are aimed at evaluating human health risks associated with co-exposure to two or more pesticides that have a common mechanism of toxicity, based on available information. It may consist of a quantitative or qualitative cumulative risk assessment or result in a determination that a cumulative risk assessment is not required, for example, in situations that do not involve co-exposures.

A quantitative approach will be used in this CRA to assess risk from major exposure pathways, routes, and uses of triazole pesticides. This will include deterministic and/or probabilistic assessments, as required. The results of this complex analysis must be interpreted with a full understanding of the assumptions made and the uncertainties introduced as a result of these assumptions. Qualitative assessments will also be used to assess risk from minor exposure pathways, routes, and uses of triazole pesticides.

The process Health Canada undertook to identify available evidence relating to a common mechanism of toxicity for the triazole pesticides, their co-exposure and their potential to result in a material contribution to non-occupational (dietary and residential) exposure, in order to define the cumulative assessment group (CAG), is outlined in the appendices.

A scoping assessment is included in Appendix I of REV2026-02; a decision tree is included in Appendix II of REV2026-02; and the planned approach for analysis of the triazole CRA is included in Appendix III of REV2026-02.

Scoping Assessment: The anticipated exposure scenarios resulting from the uses of each of the 13 triazole pesticides registered in Canada are provided in Appendix I, Table 1 of REV2026-02. Additional triazole pesticides that could be present on imported food commodities are listed in Appendix I, Table 2 of REV2026-02. The decision tree used by Health Canada to determine which of these active ingredients would be included (quantitatively or qualitatively), or excluded, from the dietary exposure cumulative assessment is presented in Appendix II of REV2026-02. This 4-step process was used to categorize the 24 triazole pesticides that are listed in Appendix I, Table 2 of REV2026-02 into the three categories described below:

• Triazole pesticides not registered in Canada that will be quantitatively included in the cumulative assessment (7 triazoles),
• Triazole pesticides not registered in Canada and determined to be minor contributors to overall cumulative exposure to triazole pesticides and will be considered qualitatively in the cumulative assessment (1 triazole), and
• Triazole pesticides not registered in Canada that will be excluded from the cumulative assessment as their food residues are not relevant to dietary exposure based on the available Canadian food supply (16 triazoles).

Problem Formulation and CRA Analysis: The planned approach for analysing the triazoles CRA is presented in Appendix III, Table 1 of REV2026-02 to clearly identify and describe the problem formulation elements that will be considered in the triazole CRA, and to summarize the key information that will be used to support Health Canada’s assessment.