Proposed Re-evaluation Decision PRVD2022-01, Trinexapac-ethyl and Its Associated End-use Products

Pest Management Regulatory Agency
25 January 2022
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2022-1E-PDF (PDF version)

Table of contents

• Proposed re-evaluation decision for trinexapac-ethyl and associated end-use products
• Proposed re-evaluation decision for trinexapac-ethyl
• Risk mitigation measures
• International context
• Next steps
• Other information
• Additional scientific information

Proposed re-evaluation decision for trinexapac-ethyl 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. Health Canada applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Trinexapac-ethyl is a plant growth regulator that inhibits the biosynthesis of gibberellin, a phytohormone that promotes growth of various plant organs. By inhibiting gibberellin, trinexapac-ethyl treatment reduces the size of leaves and stems. Trinexapac-ethyl is used on turf grown on commercial sod farms and golf courses to reduce the frequency of mowing and the amount of grass clippings. It also manages the growth of perennial ryegrass grown for seeds to reduce lodging and thus, improve seed yield and quality. Currently registered products containing trinexapac-ethyl can be found in the online Pesticide Label Search and in Appendix I of PRVD2022-01.

This document (Proposed Re-evaluation Decision PRVD2022-01, Trinexapac-ethyl and Its Associated End-use Products) presents the proposed re-evaluation decision for trinexapac-ethyl, including the 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 trinexapac-ethyl that are registered in Canada are subject to this proposed re-evaluation decision. PRVD2022-01 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 re-evaluation decision will be published after taking into consideration the comments and information received during the consultation period.

Proposed re-evaluation decision for trinexapac-ethyl

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 trinexapac-ethyl and associated end-use products registered for sale and use in Canada with additional risk mitigation measures.

With respect to human health, dietary risks were shown to be acceptable when trinexapac-ethyl is used according to current conditions of registration. Occupational and postapplication risks were shown to be acceptable when trinexapac-ethyl is used according to proposed conditions of registration, which includes new mitigation measures such as updated restricted-entry interval (REI), adding the standard drift mitigation label statement, and updating the personal protective equipment (PPE) label statements to reflect current standards.

The risks to the environment were shown to be acceptable when trinexapac-ethyl is used according to proposed conditions of registration, which includes new mitigation measures such as additional precautionary label statements and a 1 meter spray buffer zone to protect terrestrial non-target plants and freshwater aquatic habitats.

Trinexapac-ethyl has value as a plant growth regulator, in managing turf growth on golf courses and sod farms by reducing the frequency of mowing and the amount of grass clippings. It also reduces lodging in perennial ryegrass grown for seed.

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 revised/updated label statements and/or mitigation measures, as a result of the re-evaluation of trinexapac-ethyl, are summarized below. Refer to Appendix VII of PRVD2022-01 for details.

Human health

The following risk-reduction measures are proposed:

To protect mixer/loader/applicators:

• For use on perennial ryegrass grown for seed, require closed mixing/loading systems and closed cab groundboom application when handling more than 70 kg a.i./day.
• For all uses, update PPE label statements to reflect current standards.

To protect workers entering treated sites:

• For use on perennial ryegrass grown for seed, require an REI of 10 days for all postapplication activities.
• For use on sod farm, require an REI of 12 hours for all postapplication activities.
• For use on golf courses, restrict entry until residues have dried.

To protect/prevent bystander exposure:

• Prohibit the use of trinexapac-ethyl golf course treatment products from being used on turf in other residential areas (which includes lawns, gardens, parks, playing fields, cemeteries and schools).
• Add standard drift statement.

Environment

To protect terrestrial non-target plants and freshwater aquatic habitats, the following risk-reduction measures are proposed:

• A buffer zone of 1 meter is proposed for the protection of terrestrial non-target plants and freshwater aquatic habitats.
• Update Environmental precautions (spray drift) and disposal label statements to protect terrestrial non-target plants and freshwater aquatic habitats to reflect current standards.

International context

Trinexapac-ethyl is currently acceptable for use in other Organisation for Economic Co-operation and Development (OECD) member countries, including the European Union, Australia, and the United States. No decision by an OECD member country to prohibit all uses of trinexapac-ethyl 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 PRVD2022-01 for details on specific products impacted by this proposed decision.

Other information

The relevant confidential test data on which the proposed decision is based (in the References section of PRVD2022-01) are available for public inspection, upon application, in Health Canada’s Reading Room. For more information, please contact Health Canada’s Pest Management Information Service.

Additional scientific information

No additional scientific data are required at this time.