Proposed Maximum Residue Limit PMRL2019-40, Clopyralid

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Pest Management Regulatory Agency
12 December 2019
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2019-40E-PDF (PDF version)

Under the authority of the Pest Control Products Act, Health Canada’s Pest Management Regulatory Agency (PMRA) has concluded that the addition of new uses on annual canarygrass to the product labels of Curtail M Herbicide and XRM-5171 Herbicide, containing technical grade clopyralid and MCPA, is acceptable. The specific uses approved in Canada are detailed on the labels of Curtail M Herbicide and XRM-5171 Herbicide, Pest Control Products Act Registration Numbers 30914 and 22764, respectively.

The evaluation of these clopyralid applications indicated that the end-use products have value and the human health and environmental risks associated with the new uses are acceptable.

Before registering a pesticide for food use in Canada, the PMRA must determine the quantity of residues that are likely to remain in or on the food when the pesticide is used according to label directions and that such residues will not be a concern to human health. This quantity is then legally established as a maximum residue limit (MRL). An MRL applies to the identified raw agricultural food commodity as well as to any processed food product that contains it, except where separate MRLs are specified for the raw agricultural commodity and a processed product made from it.

Consultation on the proposed MRLs for clopyralid is being conducted via this document (see Next Steps). MRL consultation for the other active ingredient, MCPA, present in Curtail M Herbicide and XRM-5171 Herbicide, is being conducted under a separate action. A summary of the field trial data used to support the proposed MRLs can be found in Appendix I.

To comply with Canada’s international trade obligations, consultation on the proposed MRLs is also being conducted internationally by notifying the World Trade Organization, as coordinated by the Canada’s Notification Authority and Enquiry Point.

The proposed MRLs, to be added to the MRLs already established for clopyralid, are as follows.

Table 1 Proposed Maximum Residue Limits for Clopyralid
Common Name Residue Definition MRL (ppm)Footnote 1 Food Commodity
Clopyralid 3,6-dichloro-2-pyridinecarboxylic acid 7.0 Annual canarygrass bran
3.0 Annual canarygrass seeds
Footnote 1

ppm = parts per million

Return to footnote 1 referrer

MRLs established in Canada may be found using the Maximum Residue Limit Database on the Maximum Residue Limits for Pesticides webpage. The database allows users to search for established MRLs, regulated under the Pest Control Products Act, both for pesticides or for food commodities.

International Situation and Trade Implications

Currently there are no American tolerances for clopyralid on annual canarygrass seeds or bran listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide, nor are there Codex MRLsFootnote 1 listed for clopyralid in or on any commodity on the Codex Alimentarius Pesticide Index webpage.

Next Steps

The PMRA invites the public to submit written comments on the proposed MRLs for clopyralid up to 75 days from the date of publication of this document. Please forward your comments to Publications. The PMRA will consider all comments received before making a final decision on the proposed MRLs. Comments received will be addressed in a separate document linked to this PMRL. The established MRLs will be legally in effect as of the date that they are entered into the Maximum Residue Limit Database.

Appendix I

Summary of Field Trial Data Used to Support the Proposed Maximum Residue Limits

Previously reviewed residue data from field trials conducted in/on wheat and barley were reassessed in the framework of this petition. In addition, processing studies in treated wheat and barley were also reassessed to determine the potential for concentration of residues of clopyralid into processed commodities.

Maximum Residue Limits

The recommendation for maximum residue limits (MRLs) for clopyralid was based upon the field trial data on file, and the guidance provided in the OECD MRL Calculator. Table A1 summarizes the residue data used to calculate the proposed MRLs for annual canarygrass.

Table A1 Summary of Field Trial and Processing Data Used to Support the MRLs
Commodity Application Method/ Total Application Rate
(g a.e./ha)Footnote 1
Preharvest Interval (days) Lowest Average Field Trial Residues
Highest Average Field Trial Residues
Experimental Processing Factor
Wheat grain Foliar ground application/
41-70 0.19 1.1 Wheat bran: 3.4×
Wheat flour:
Barley grain Foliar ground application/
35-92 1.1 2.0 No concentration in processed fractions
Footnote 1

g a.e./ha = grams of acid equivalents per hectare

Return to footnote 1 referrer

Following the review of all available data, MRLs as proposed in Table 1 are recommended to cover residues of clopyralid. Residues of clopyralid in these crop commodities at the proposed MRLs will not pose an unacceptable risk to any segment of the population, including infants, children, adults and seniors.

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