Proposed special review decision PSRD2025-01, Proposed special review decision of dicamba and its associated end-use products (revised)

Pest Management Regulatory Agency
Published: 17 September 2025
Revised: 8 October 2025
ISSN: 2561-636 (PDF version)
Catalogue number: H113-30/2025-1E-PDF (PDF version)

Summary

If you would like to comment, please request the full consultation document.

To obtain a full copy of Proposed Special Review Decision PSRD2025-01, Proposed Special Review Decision of Dicamba and Its Associated End-use Products please contact our publications office.

Should you require further information please contact the Pest Management Information Service.

Document history (revision/update)

Updated	Update/Rationale:
8 October 2025	Health Canada became aware of formatting errors in the tables for the proposed updates to spray buffer zones. As a result, the spray buffer zone tables in Appendix II have been updated.
17 September 2025	Initial publication

Table of contents

• Proposed special review decision for dicamba and associated end-use products
• Proposed special review decision for dicamba
• Risk mitigation measures
• Next steps
• Other information

Proposed special review decision for dicamba and associated end-use products

Under the authority of the Pest Control Products Act, pesticides are regulated by Health Canada’s Pest Management Regulatory Agency (PMRA) 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. Dicamba is also under re-evaluation, where aspects related to human health, environment and value will be assessed.

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 and 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 dicamba, as applicable, based on the preliminary analysis of incident reports, as well as a new non-target plant toxicity study submitted through the Incident Reporting program (IRP). Since the initiation of the special review, the scope was expanded in 2022 and 2024 under subsection 17(7) of the Pest Control Products Act. The identified aspect of concern for the special review is:

• Risk to non-target terrestrial plants from the use of dicamba products (Over-The-Top and non-Over-The-Top).

For this special review, the registered uses of dicamba included Over-The-Top (OTT) uses and Non-Over-The-Top (Non-OTT) uses. Over-The-Top (OTT) uses of dicamba are defined as the registered uses of commercial dicamba products in DT field corn and in DT soybean. Non-Over-The-Top (Non-OTT) uses of dicamba are defined as all registered uses of commercial dicamba products except registered uses in DT field corn and DT soybean. All currently registered commercial-class products containing dicamba and their associated uses have been considered in this special review. Domestic-class dicamba products were determined to be out of scope as increased incidents were associated with commercial uses. Currently registered pest control products containing dicamba with OTT and non-OTT uses are listed in Appendix I of the full version of the Proposed Special Review Decision PSRD2025-01, Proposed Special Review Decision of Dicamba and Its Associated End-use Products.

Pursuant to subsection 18(4) of the Pest Control Products Act, Health Canada has evaluated the aspect of concern that prompted the special review of pest control products containing dicamba, which is relevant to the environment. To assess the aspect of concern, Health Canada considered the information that prompted the special review and other relevant information currently available, including information from international regulatory authorities such as the United States Environmental Protection Agency (USEPA) and Australian Pesticides and Veterinary Medicines Authority (APVMA). New non-target plant toxicity studies received by the PMRA indicated increased risk to non-target terrestrial plants and warranted re-consideration of this risk from OTT and non-OTT outdoor uses.

Dicamba is a selective systemic herbicide that is absorbed through leaves, roots, and stems and moves throughout the plant. Dicamba belongs to the benzoic acid chemical family. Classified as a Group 4 herbicide, dicamba mimics the natural plant hormone indole-3-acetic acid (also known as synthetic auxin) and produces an “auxin overload”, thereby causing susceptible plants to be injured and controlled. Dicamba OTT and non-OTT use are registered for the control of broadleaf weeds in dicamba-tolerant (DT) soybean, DT and non-DT field corn, other non-DT cereal crops, lowbush blueberries, grasses, turf, lawns, fallow, stubble, and non-agricultural areas (such as, roadsides, hydro, pipeline and railway rights-of-way, airports, military bases, wasteland, and turf).

The forms of dicamba registered in Canada include: dicamba acid, sodium (Na) salt of dicamba, potassium (K) salt of dicamba, dimethylamine (DMA) salt of dicamba, diglycolamine salt (DGA) salt of dicamba, N,N-Bis(3-aminopropyl)methylamine (BAPMA) salt of dicamba, isopropylamine (IPA) salt of dicamba, monoethanolamine (MEA) salt of dicamba, diethanolamine (DEA) salt of dicamba and N-(2-aminoethyl)-1,2-ethanediamine salt (DETA) salt of dicamba. End-use products are only formulated as a salt form of dicamba. Not all forms of dicamba registered in Canada have associated end-use products.

This document (PSRD2025-01) presents the proposed special review decision for dicamba, including the proposed amendments (risk mitigation measures) to protect the environment, as well as the science evaluation on which the proposed decision is based. PSRD2025-01 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 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 dicamba

Health Canada, under the authority of the Pest Control Products Act has conducted an evaluation of available relevant scientific information related to the aspect of concern for the environment 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 most uses of dicamba and associated end-use products registered for sale and use in Canada under section 21 of the Pest Control Products Act. Certain uses are proposed for cancellation.

The assessment of the aspect of concern from this special review indicated that risks to the environment for the following commercial uses of dicamba are considered to be acceptable provided that proposed label amendments are implemented:

• All non-OTT uses (such as, non-DT cereal crops, lowbush blueberries, and non-agricultural areas)
• OTT uses in DT field corn
• OTT uses in DT soybean excluding seed production

However, the following uses of dicamba are proposed for cancellation since risks to the environment are not shown to be acceptable when used according to the current conditions of registration, or when additional mitigation is considered:

• Seed production of DT soybeans

The proposed additional mitigation measures are summarized, and details are outlined in the Appendix II and Section 1.4: Risk mitigation measures of PSRD2025-01.

Risk mitigation measures

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment , and to ensure the product has acceptable value which 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 dicamba, are summarized below. Refer to Appendix II and Section 1.4: Risk mitigation measures of PSRD2025-01 for details.

Environment

Commercial-class dicamba products with OTT and Non-OTT uses.

To improve understanding of the risk of dicamba volatilization:

• Proposed best management practice statement regarding temperature: 
• “Due to potential for increased volatility and off-target movement of dicamba at higher temperatures, which could result in adverse effects on non-target terrestrial plants, avoid application when temperatures exceed 25°C.” 

To mitigate the risks from spray drift:

• Updated spray buffer zones are proposed to protect terrestrial habitats, range proposed for field sprayer: 1–115 m and proposed for aerial: 45–800 m.

Commercial-class dicamba products with OTT uses

To mitigate risks from volatilization:

• Proposed reduction in the maximum height of DT field corn crop from 76 cm to 50 cm for post-emergence applications.
• Proposed a single pre-plant or pre-emergence application in DT soybean.
• Proposed cancellation of the use for DT soybean seed production. 

Next steps

Health Canada will accept written comments on this proposal up to 90 days from the date of publication of PSRD2025-01 (“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 Forms - Consultation Comment). For more information or if you have questions, contact the PMRA’s Pest Management Information Service.

Before making a special review decision on dicamba 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 dicamba. 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 on the proposed special review decision during the consultation period that are directly related to the assessment of the aspect(s) of concern for this proposed special review decision, and Health Canada’s response to these comments.

Refer to Appendix I of PSRD2025-01 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 PSRD2025-01) are available for public inspection, upon application, in PMRA’s Reading Room. For more information, please contact the Pest Management Information Service.