Proposed Re-evaluation Decision PRVD2021-02, Isoxaflutole and Its Associated End-use Products

Pest Management Regulatory Agency
29 January 2021
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2021-2E-PDF (PDF version)

Table of contents

• Proposed re-evaluation decision for isoxaflutole and associated end-use products
• Proposed re-evaluation decision for isoxaflutole
• International context
• Next steps
• Additional scientific information

Proposed re-evaluation decision for isoxaflutole and associated end-use products

Under the authority of the Pest Control Products Act, all registered pesticides must be re-evaluated by Health Canada’s Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet current health and environmental standards and continue to have value. The re-evaluation considers data and information from pesticide manufacturers, published scientific reports and other regulatory agencies, as well as comments received during public consultations. Health Canada applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Isoxaflutole is a broad spectrum herbicide registered for use in field corn and soybeans in Eastern Canada and British Columbia and for use in seed corn in Eastern Canada only. Currently registered products containing isoxaflutole can be found in the Pesticide Label Search and in Appendix I or PRVD2021-02.

This document (Proposed Re-evaluation Decision PRVD2021-02, Isoxaflutole and Its Associated End-use Products) presents the proposed re-evaluation decision for isoxaflutole, including the proposed 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 isoxaflutole that are registered in Canada are subject to this proposed re-evaluation decision. PRVD2021-02 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 and information received during the consultation period.

Proposed re-evaluation decision for isoxaflutole

Under the authority of the Pest Control Products Act and based on an evaluation of available scientific information, Health Canada is proposing continued registration of all uses of isoxaflutole and associated end-use products registered for sale and use in Canada.

The human health risk assessment indicated that, dietary and occupational (mixing/loading/application, and postapplication) risks were shown to be acceptable when isoxaflutole is used according to proposed conditions of registration which includes a new mitigation measure of a restricted-entry interval. Statements to update labels based on current policies and language are proposed. To meet current labelling standards and to reduce bystander exposure, an updated spray drift advisory label statement is proposed for all end-use products.

The environmental risk assessment found that potential risks to the environment from isoxaflutole were shown to be acceptable when used according to the proposed conditions of registration, which includes new mitigation measures such as precautionary label statements and spray buffer zones.

Isoxaflutole has value as an herbicide due to its broad-spectrum of activity, ability to manage certain resistant weeds, and as a resistance management tool.

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 must be followed by law. The proposed label amendments including any updated label statements as a result of the re-evaluation of isoxaflutole, are summarized below. Refer to Appendix VII of PRVD2021-02 for details. 

Human Health

Label improvements:

As a result of the re-evaluation of isoxaflutole, Health Canada is proposing additional revisions to the isoxaflutole labels to update label statements to current policies and language.
To protect bystanders, a statement indicating to apply only when the potential for drift to areas of human habitation or areas of human activity such as houses, cottages, schools and recreational areas is minimal is proposed.

Risk mitigation:

To protect workers entering treated sites, a restricted-entry interval (REI) of 12 hours is proposed.

Environment

Risk mitigation:

To protect the environment, the following risk mitigation measures are proposed:

• Standard label statements to inform users of the potential toxic effects of isoxaflutole to aquatic organisms and terrestrial plants.
• Spray buffer zones for the protection of aquatic and terrestrial habitats.
• A leaching advisory statement.
• Precautionary label statements to reduce the potential for runoff of isoxaflutole to adjacent aquatic habitats for sites with characteristics that may be conducive to runoff and when heavy rain is forecast.

Value

Risk mitigation:

A warning statement of potential adverse effects on sugar beet crops from carryover of isoxaflutole.

International context

Isoxaflutole is currently acceptable for use in other Organisation for Economic Co-operation and Development (OECD) member countries, including the United States, the European Union and Australia. As of 15 October 2020, no decision by an OECD member country to prohibit all uses of isoxaflutole for health or environmental reasons has been identified.

Next steps

Upon publication of this proposed re-evaluation decision, the public, including the registrants and stakeholders are encouraged to submit additional information that could be used to refine risk assessments during the 90-day public consultation period.
All comments received during the 90-day public consultation period will be taken into consideration in preparation of re-evaluation decision document,^{Footnote 2} which could result in revised risk mitigation measures. The re-evaluation decision document will include the final re-evaluation decision, the reasons for it and a summary of comments received on the proposed re-evaluation decision with Health Canada’s responses.

Refer to Appendix I of PRVD2021-02 for details on specific products impacted by this proposed decision.

Additional scientific information

No additional scientific data are required at this time.