Proposed re-evaluation decision PRVD2025-10, Iodosulfuron-methyl-sodium and its associated end-use product

Pest Management Regulatory Agency
30 October 2025
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2025-10E-PDF (PDF version)

Summary

Table of contents

• Proposed re-evaluation decision for iodosulfuron-methyl-sodium and its associated end-use product
• Proposed label amendments
• Next steps
• Other information
• Additional scientific information

Proposed re-evaluation decision for iodosulfuron-methyl-sodium and its associated end-use product

Under the authority of the Pest Control Products Act, all registered pesticides must be regularly re-evaluated by Health Canada’s Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet health and environmental safety standards and continue to have value. The re-evaluation considers data and information from various sources such as existing reviews, incident reports and other regulatory agencies. Health Canada applies internationally accepted risk assessment methods, risk management approaches and policies to all re-evaluations.

Iodosulfuron-methyl-sodium is a selective sulfonylurea herbicide. It inhibits the activity of acetolactate synthase (ALS), which is the key enzyme in the biosynthesis of the branch-chain amino acids, isoleucine, leucine and valine. Although the actual sequence of phytotoxic processes is unclear, plant death results from events occurring in response to inhibition of the ALS enzyme. Iodosulfuron-methyl-sodium is used to control a range of post-emergence grassy and broadleaf weeds in field corn. It is applied once a year by field sprayer. Currently, there is one technical active ingredient and one commercial class end-use product registered for use in Canada. Registered products can be found in the Pesticide Product Information Database and in Appendix I of the full version of Proposed Re-evaluation Decision PRVD2025-10, Iodosulfuron-methyl-sodium and Its associated end-use product.

This document (PRVD2025-10) presents the proposed re-evaluation decision for iodosulfuron-methyl-sodium, including any proposed amendments (risk mitigation measures) to protect human health and the environment, as well as the science evaluation on which the proposed decision is based. All products containing iodosulfuron-methyl-sodium that are registered in Canada are subject to this proposed re-evaluation decision. PRVD2025-10 is subject to a 90-day public consultation period,^{Footnote 1} during which the public (including the pesticide manufacturers and stakeholders) may submit written comments and additional information to PMRA Publications. The final re-evaluation decision will be published after taking into consideration the comments received during the consultation period that are directly related to this proposed re-evaluation decision.

Health Canada, under the authority of the Pest Control Products Act, has conducted all evaluations considered necessary with respect to the health and environmental risks and value of iodosulfuron-methyl-sodium based on available scientific information in accordance with subsection 16(6) of the Pest Control Products Act. Health Canada is proposing for public consultation, pursuant to section 28 of the Pest Control Products Act, the continued registration of iodosulfuron-methyl-sodium and associated end-use product registered for sale and use in Canada under section 21 of the Pest Control Products Act.

Iodosulfuron-methyl-sodium is a substance with both a contact and selective mode of action that has acceptable value in providing a pest management solution. Based on the current use pattern, potential risks to human health (occupational, dietary, residential and bystander) and the environment (aquatic and terrestrial organisms) are considered to be acceptable when products containing iodosulfuron-methyl-sodium are used according to proposed label amendments (Appendix II of PRVD2025-10).

Proposed label amendments

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health, the environment and ensure the product has acceptable value which must be followed by law. The proposed label amendments as a result of the re-evaluation of iodosulfuron-methyl-sodium are summarized below. Refer to Appendix II of PRVD2025-10 for details.

Human health

No label amendments are proposed.

Environment

Label amendments to meet current standards: update runoff statement and add leaching and storage statements.

Next steps

Upon publication of this proposed re-evaluation decision, the public, including the registrants and stakeholders are encouraged to submit comments during the 90-day public consultation period.

Health Canada will accept written comments on this proposal up to 90 days from the date of publication of PRVD2025-10 (“consultation period”). Comments on the proposed decision can be submitted during the consultation period to the PMRA through PMRA Publications, or the Public Engagement Portal (Public Engagement Portal forms – Consultation Comment). For more information or if you have questions, contact the PMRA’s Pest Management Information Service.

Before making a re-evaluation decision on iodosulfuron-methyl-sodium under section 21 of the Pest Control Products Act, the comments received during the consultation period that are directly related to this proposed decision, such as comments directed to the science evaluation, will be taken into consideration in preparation of the final re-evaluation decision document.

A science-based approach will be applied in making a final decision on iodosulfuron-methyl-sodium. In accordance with subsection 28(5) of the Pest Control Products Act, Health Canada will then publish a final re-evaluation decision document, which will include the decision,^{Footnote 2} the reasons for it, a summary of the comments received directly related to the proposed re-evaluation decision during the consultation period, and Health Canada’s response to these comments.

Refer to Appendix I of PRVD2025-10 for details on specific products impacted by this proposed decision.

Other information

The relevant confidential test data on which the proposed decision is based are available for public inspection, upon application, in Health Canada’s Reading Room. For more information, please contact the PMRA’s Pest Management Information Service.

Additional scientific information

No additional scientific data are being requested at this time.