Proposed special review decision PSRD2026-01, Proposed special review decision for 4-Chloro-2-Methylphenoxyacetic Acid and its associated end-use products

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• Health Canada
• Healthy Environments and Consumer Safety Branch
• Pesticides Regulatory Directorate
• 29 May 2026
• ISSN: 2561-6366 (PDF version)
• Catalogue number: H113-30/2026-1E-PDF (PDF version)

Summary

Table of contents

• Proposed special review decision for 4-Chloro-2-Methylphenoxyacetic Acid and associated end-use products
• Proposed special review decision for MCPA
• Risk mitigation measures
  • Human health
• Next steps
• Other information

Proposed special review decision for 4-Chloro-2-Methylphenoxyacetic Acid and associated end-use products

Under the authority of the Pest Control Products Act, pesticides are regulated by Health Canada on behalf of the Minister of Health. The Pest Control Products Act prescribes both the pre-market and post-market assessment (re-evaluations and special reviews) of pesticides to determine the acceptability or continued acceptability of human health and environmental risks, and acceptable value of a pesticide in Canada. Unlike a re-evaluation, a special review is triggered only under certain circumstances, as described in section 17 of the Pest Control Products Act, and the intent of a special review is to address specifically the identified aspect(s) of concern. The special review approach is described in the PMRA Guidance Document: Approach to Special Reviews of Pesticides.

Health Canada evaluates the aspect(s) of concern that prompted the special review in accordance with subsection 18(4) of the Pest Control Products Act. The internationally accepted science-based approach is used for the assessment of the aspect(s) of concern, similar to all other scientific assessments (for example, new product registrations, re-evaluations).

Pursuant to subsection 17(1) of the Pest Control Products Act, Health Canada initiated a special review of all registered pest control products containing 2-methyl-4-chlorophenoxyacetic acid (MCPA present as acid) including MCPA present as amine salts (diethanolamine, dimethylamine, or mixed amines), MCPA present as esters, and MCPA present as potassium or sodium salts. Throughout this document, these forms are collectively referred to as MCPA. The initiation of this special review was based on the review of toxicology studies submitted under the Incident Reporting Program. The identified aspect of concern is:

• Potential inhalation occupational (mixing/loading/applying) and residential risk from the use of MCPA based on the current conditions of use.

Pursuant to subsection 18(4) of the Pest Control Products Act, Health Canada has evaluated the aspects of concern that prompted the special review of pest control products containing MCPA, which are relevant to human health.

MCPA is a phenoxy herbicide used to selectively control broadleaf weeds in forests and woodlots (use-site category 4), terrestrial non-food and non-feed seed and fibre crops (use-site category 7), terrestrial feed/food crops (use-site category 13,14), non-agricultural industrial and residential pest management for non-food sites (use-site category 16), and turf (use-site category 30). All currently registered products containing MCPA have been considered in this special review and are listed in Appendix I of the full version of Proposed Special Review Decision PSRD2026-01, Proposed Special Review Decision for 4-Chloro-2-Methylphenoxyacetic Acid and Its Associated End-use Products.

This document (PSRD2026-01) presents the proposed special review decision for MCPA, including the proposed amendments (risk mitigation measures) to protect human health, as well as the science evaluation on which the proposed decision is based.

All products containing MCPA that are registered in Canada are subject to this proposed special review decision. This document is subject to a 45-day public consultation period,^{Footnote 1} during which the public (including the pesticide manufacturers and stakeholders) may submit written comments and additional information to Pesticides Regulatory Directorate Publications Section. The final special review decision will be published after taking into consideration the comments received during the consultation period that are directly related to the assessment of the aspect of concern for this proposed special review decision.

Proposed special review decision for MCPA

Health Canada, under the authority of the Pest Control Products Act has conducted an evaluation of available scientific information related to the aspect of concern for human health in accordance with subsection 18(4) of the Pest Control Products Act. Based on the evaluation of the aspect of concern, Health Canada is proposing for public consultation, pursuant to section 28 of the Pest Control Products Act, the continued registration of MCPA and associated end-use products registered for sale and use in Canada under section 21 of the Pest Control Products Act.

The assessment of the aspect of concern from this special review indicate that risks to human health for MCPA are considered to be acceptable provided that proposed label amendments are implemented. The proposed additional mitigation measures are summarized below, and details are outlined in Appendix V of PSRD2026-01.

Risk mitigation measures

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 and must be followed by law. The proposed label amendments including revised/updated label statements and/or mitigation measures, as a result of the special review of MCPA, are summarized below. Refer to Appendix V of PSRD2026-01 for details.

Human health

Risk mitigation:

To protect workers from inhalation exposure, the following risk-reduction measures are proposed:

• Agricultural sites (use-site category 7, 13, 14)
  • Groundboom application:
    • Additional respiratory protection during application of more than 250 kg acid equivalent of MCPA per day.
    • If using closed cab, additional inhalation mitigation is not required.
• Terrestrial non-food and non-feed sites (use-site category 16)
  • Groundboom application:
    • Additional respiratory protection during application of more than 76 kg acid equivalent of MCPA per day.
    • If using closed cab, additional inhalation mitigation is not required.
  • Aerial application:
    • Additional respiratory protection during mixing and loading or use a closed mix/load system.
  • Handheld equipment (mechanically pressurized handgun, manually pressurized handwand or backpack):
    • Additional respiratory protection during mixing, loading and application.

Label improvements to meet current standards:

• Addition of standard drift statement:
  • "Apply only when the potential for drift beyond the area to be treated is minimal. Take into consideration wind speed, wind direction, temperature inversions, application equipment, and sprayer settings."
• Addition of standard restricted-entry interval statements:
  • For crop areas (use-site category 4,7,13,14):
    • "DO NOT enter or allow worker entry into treated areas during the restricted-entry interval (REI) of 12 hours."
  • For non-crop areas (use-site category 16):
    • "DO NOT enter or allow worker entry into treated areas until sprays have dried."
  • For golf courses (use-site category 30):
    • "DO NOT enter or allow entry into treated areas until sprays have dried."
  • For residential areas (use-site category 30):
    • "DO NOT enter or allow people or pets to enter into treated areas until sprays have dried."

Next steps

Health Canada will accept written comments on this proposal up to 45 days from the date of publication of PSRD2026-01. Comments on the proposed decision can be submitted during the consultation period to Health Canada through Pesticides Regulatory Directorate Publications, or the Public Engagement Portal (Public Engagement Forms - Consultation Comment). For more information or if you have questions, contact the Pesticides Information Service.

Before making a special review decision on MCPA under section 21 of the Pest Control Products Act, the comments received during the consultation period will be taken into consideration in preparation of the final special review decision document. A science-based approach will be applied in making a final decision on MCPA. In accordance with subsection 28(5) of the Pest Control Products Act, Health Canada will then publish a final special review decision document, which will include the decision, the reasons for it, a summary of the comments received during the consultation period that are directly related to the assessment of the aspect of concern for this proposed special review decision, and Health Canada's response to these comments.

Refer to Appendix I of PSRD2026-01 for details on specific products impacted by this proposed decision.

Other information

The relevant confidential test data on which the proposed decision is based (see References Section of PSRD2026-01) are available for public inspection, upon application, in Pesticide Regulatory Directorate's Reading Room. For more information, please contact the Pesticides Information Service.