Proposed maximum residue limit PMRL2019-42, Clopyralid

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Pest Management Regulatory Agency
19 December 2019
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2019-42E-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 a new use on pome fruits to the product label of Lontrel 360 Herbicide, containing technical grade clopyralid, is acceptable. The specific use approved in Canada is detailed on the label of Lontrel 360 Herbicide, Pest Control Products Act Registration Number 23545.

The evaluation of this clopyralid application indicated that the end-use product has value and the human health and environmental risks associated with the new use 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 MRL for clopyralid is being conducted via this document (see Next steps). A summary of the field trial data used to support the proposed MRL can be found in Appendix I.

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

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

Table 1: proposed maximum residue limit for Clopyralid
Common name Residue definition MRL (ppm)Tablenote 1 Food commodity
Clopyralid 3,6-dichloro-2-pyridinecarboxylic acid 0.05 Pome fruits (crop group 11-09)


Tablenote 1

ppm = parts per million

Return to tablenote 1 referrer

MRLs are proposed for each commodity included in the listed crop grouping in accordance with the Residue Chemistry Crop Groups webpage in the Pesticides section of the website.

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

The MRL proposed for clopyralid in Canada is the same as the corresponding American tolerance as listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there is no Codex MRLFootnote 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 MRL 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 MRL. Comments received will be addressed in a separate document linked to this PMRL. The established MRL will be legally in effect as of the date that it is entered into the Maximum Residue Limit Database.

Appendix I

Summary of field trial data used to support the proposed maximum residue limit

Residue data for clopyralid in pears were submitted to support the domestic use of Lontrel 360 Herbicide on pome fruits. In addition, previously reviewed residue data from field trials conducted in/on apples and pears were reassessed in the framework of this petition. A processing study in treated apples was also reassessed to determine the potential for concentration of residues of clopyralid into processed commodities.

Maximum residue limit

The recommendation for a maximum residue limit (MRL) for clopyralid was based upon the submitted field trial data, and the guidance provided in the OECD MRL Calculator. Table A1 summarizes the residue data used to calculate the proposed MRL for pome fruits.

Table A1: summary of field trial and processing data used to support the MRL
Commodity Application method/Total application rate
(g a.i./ha)Table A1 note 1
Preharvest interval (days) Lowest average field trial residues
Highest average field trial residues
Experimental processing factor
Apples Application to the ground/
23-32 <0.05 <0.05 Apple juice: 1.0x
Pears Application to the ground/
23-30 <0.05 0.07 Not required

Table A1 notes

Table A1 note 1

g a.i./ha = grams of active ingredient per hectare

Return to table A1 note 1 referrer

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


Footnote 1

The Codex Alimentarius Commission is an international organization under the auspices of the United Nations that develops international food standards, including MRLs.

Return to footnote 1 referrer

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