Re-evaluation Decision RVD2019-02, Chlorimuron-ethyl and Its Associated End-use Products

Pest Management Regulatory Agency
22 February 2019
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2019-2E-PDF (PDF version)

Table of Contents

Re-evaluation Decision

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 current health and environmental safety 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.

Chlorimuron-ethyl is a commercial herbicide registered for use on soybeans in Eastern Canada for the control of broadleaf weeds. Currently registered products containing chlorimuron-ethyl are listed in Appendix I.

The regulatory approach for the re-evaluation of chlorimuron-ethyl was first presented in the Proposed Re-evaluation Decision PRVD2018-14, Chlorimuron-ethyl and Its Associated End-use Products.Footnote 1 PRVD2018-14 proposed continued registration provided that proposed risk mitigation measures are implemented. Health Canada did not receive any comments during the consultation period.

This document presents the final regulatory decisionFootnote 2 for the re-evaluation of chlorimuron-ethyl, including the required risk mitigation measures to protect human health and the environment. All products containing chlorimuron-ethyl that are registered in Canada are subject to this re-evaluation decision.

Outcome of Science Evaluation

Dietary risks from food and drinking water have been shown to be acceptable when products containing chlorimuron-ethyl are used according to label directions. Canadian maximum residue limits for chlorimuron-ethyl are currently specified for soybeans and no changes are required.

Occupational risks to handlers and postapplication risks have been shown to be acceptable when chlorimuron-ethyl is used according to label directions. To protect workers entering treated sites a restricted-entry interval of 12 hours is required for agricultural uses.

The environmental risks associated with the use of chlorimuron-ethyl and its related end-use products are acceptable when products are used according to the revised label directions, which include advisory statements and spray buffer zones.

Regulatory Decision for Chlorimuron-ethyl

Health Canada has completed the re-evaluation of chlorimuron-ethyl. Under the authority of the Pest Control Products Act, Health Canada has determined that continued registration of products containing chlorimuron-ethyl is acceptable. An evaluation of available scientific information found that uses of chlorimuron-ethyl products meet current standards for protection of human health and the environment when used according to the conditions of registration, which include required amendments to label directions. Label amendments, as summarized below and listed in Appendix II, are required for all technical and end-use product(s). No additional data are requested.

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.

Human Health

To protect workers, those entering treated areas and bystanders from occupational exposure, the following risk-reduction measures are required for continued registration of chlorimuron-ethyl in Canada:

  • To protect workers entering treated sites a standard restricted-entry interval (REI) of 12 hours is required for agricultural uses.
  • To protect bystanders, a standard statement is proposed indicating to apply only when the potential for drift is minimal to areas of human habitation or areas of human activity such as houses, cottages, schools and recreational areas.


  • Updated spray buffer zones ranging from 1 to 20 meters to mitigate the impact on sensitive non-target terrestrial and aquatic habitats.
  • Standard environmental precautionary label statements to protect non-target terrestrial plants and freshwater plants and algae.
  • An advisory label statement regarding run-off.

Next Steps

To comply with this decision, the required mitigation measures must be implemented on all product labels sold by registrants no later than 24 months after the publication date of this decision document.

Other Information

Any person may file a notice of objectionFootnote 3 regarding this decision on chlorimuron-ethyl within 60 days from the date of publication of this Re-evaluation Decision. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the Pesticides section of the website (Request a Reconsideration of Decision) or contact the PMRA’s Pest Management Information Service.

Appendix I  Registered Chlorimuron-ethyl Products in Canada

Table 1  Registered Chlorimuron-ethyl Products in CanadaTable 1 footnote 1
Registation Number Marketing Class Registrant Product Name Formulation Type Active Ingredient
25433 Commercial Production Agriscience Canada Company Classic 25 DF Herbicide Wettable Granules Chlorimuron-ethyl 25%
25784 Reliance STS Toss-N-Go Herbicide
  • Chlorimuron-ethyl: 21%
  • Thifensulfuron methyl: 12%
29416 Classic Grande Herbicide 25%
30803 SB-01 Herbicide
  • Chlorimuron-ethyl: 5.14%
  • Flumioxazin: 40.59%
31494 Guardian plus WDG Herbicide
  • Chlorimuron-ethyl: 5.14%
  • Flumioxazin: 40.59%
32086 DuPont SB-02 Herbicide
  • Chlorimuron-ethyl: 1.54%
  • Metribuzin 70.4%
32649 SB-03 Herbicide
  • Chlorimuron-ethyl: 6.62%
  • Imazethapyr 55.15%
30475 Nufarm Agriculture Inc. Nufarm Chaperone Herbicide Water Dispersible Granules Chlorimuron-ethyl 25%
25539 Manufacturing Concentrate Production Agriscience Canada Company Chlorimuron Ethyl 25 DF Manufacturing Concentrate Wettable Granules Chlorimuron-ethyl 25%
25432 Technical Grade Active Chlorimuron Ethyl Technical Herbicide Solid Chlorimuron-ethyl 97.80%
29924 Nufarm Agriculture Inc. Nufarm Chlorimuron-Ethyl Technical Solid Chlorimuron-ethyl 96%
Table 1 footnote 1

as of 7 January 2019, excluding discontinued products or products with a submission for discontinuation

Return to Table 1 footnote 1 referrer

Appendix II  Label Amendments for Products Containing Chlorimuron-ethyl

The label amendments presented below do not include all label requirements for individual end-use products, such as first aid statements, disposal statements, precautionary statements and supplementary protective equipment. Information on labels of currently registered products should not be removed unless it contradicts the label statements provided below.

1. Front Panel of all Chlorimuron-ethyl Products:

On all chlorimuron-ethyl labels, replace “GUARANTEE” with “ACTIVE INGREDIENT.”

2. Technical Grade Products

Remove the following statement under the PRECAUTIONS:

“Do not contaminate any body of water.”

and add the following statement:

DO NOT discharge effluent containing this product into sewer systems, lakes, streams, ponds, estuaries, oceans or other waters.”

Before the section entitled STORAGE, remove:


and add the following title and the following statements:


  • TOXIC to freshwater vascular plants and algae
  • TOXIC to non-target terrestrial plants”

Remove the following statement under the “DISPOSAL AND DECONTAMINATION

“Canadian formulators of this technical should dispose of unwanted active and containers in accordance with municipal and provincial regulations. For information on disposal of unused, unwanted product, contact the manufacturer or the provincial regulatory agency. Contact the manufacturer and the provincial regulatory agency in the case of a spill, and for clean-up of spills.”

and add the following statement:

“Canadian manufacturers must dispose of unwanted active ingredients and containers in accordance with municipal or provincial regulations. For additional details and cleanup of spills, contact the manufacturer or the provincial regulatory agency.”

3. Commercial Class Products

Add to PRECAUTIONS section:

The following statements are required for all agricultural and commercial pesticide products:

DO NOT enter or allow worker entry into treated areas during the restricted-entry interval (REI) of 12 hours.

Apply only to agricultural crops when the potential for drift to areas of human habitation and human activity such as houses, cottages, schools and recreational areas is minimal. Take into consideration wind speed, wind direction, temperature inversions, applications equipment, and sprayer settings.

Gloves are not required during application within a closed cab.”


  • TOXIC to non-target terrestrial plants. Observe buffer zones specified under DIRECTIONS FOR USE.
  • TOXIC to freshwater plants and algae. Observe buffer zones specified under DIRECTIONS FOR USE.
  • To reduce runoff from treated areas into aquatic habitats:
  • Avoid application to areas with a moderate to steep slope, compacted soil or clay.
  • Avoid application when heavy rain is forecast.
  • Contamination of aquatic areas as a result of runoff may be reduced by including a vegetative strip between the treated area and the edge of the water body.”


The following statements are required for all agricultural and commercial pesticide products.

“As this product is not registered for the control of pests in aquatic systems, DO NOT use to control aquatic pests

DO NOT contaminate irrigation or drinking water supplies or aquatic habitats by cleaning of equipment or disposal of wastes.”

For field applications using conventional boom sprayers (agricultural or commercial products), the following statements are required:


Field sprayer application: DO NOT apply during periods of dead calm. Avoid application of this product when winds are gusty. DO NOT apply with spray dropletssmaller than the American Society of Agricultural Engineers (ASAE S572.1) medium classification. Boom height must be 60 cm or less above the crop or ground.

DO NOT apply by air.”

Buffer zones:

Spot treatments using hand-held equipment DO NOT require a buffer zone.

The buffer zones specified in the table below are required between the point of direct application and the closest downwind edge of sensitive terrestrial habitats (such as grasslands, forested areas, shelter belts, woodlots, hedgerows, riparian areas and shrublands) and sensitive freshwater habitats (such as lakes, rivers, sloughs, ponds, prairie potholes, creeks, marshes, streams, reservoirs and wetlands).

Buffer zones required:
Method of application Crop Buffer Zones (metres) Required for the Protection of:
Freshwater Habitat of Depths: Terrestrial Habitat:
Less than 1 m Greater than 1 m
Field sprayer Soybean 1 1 20

For tank mixes, consult the labels of the tank-mix partners and observe the largest (most restrictive) buffer zone of the products involved in the tank mixture and apply using the coarsest spray (ASAE) category indicated on the labels for those tank mix partners.

The buffer zones for this product, with the exception of the freshwater habitat, can be modified based on weather conditions and spray equipment configuration by accessing the Buffer Zone Calculator found on the Drift Mitigation page of the Pesticides section of

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