Proposed Maximum Residue Limit PMRL2021-20, Dicamba

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Pest Management Regulatory Agency
29 June 2021
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2021-20E-PDF (PDF version)

Under the authority of the Pest Control Products Act, Health Canada's Pest Management Regulatory Agency (PMRA) is proposing to establish a maximum residue limit (MRL) for dicamba on undelinted cotton seeds to permit the import and sale of foods containing such residues.

Dicamba is an herbicide currently registered in Canada for use on various commodities.

The PMRA must determine the quantity of residues that are likely to remain in or on the imported food commodities when dicamba is used according to label directions in the exporting country, and that such residues will not be a concern to human health. This quantity is then legally established as an MRL on the corresponding imported commodity. 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 dicamba 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 Canada's Notification Authority and Enquiry Point.
The proposed MRL, to be added to the MRLs already established for dicamba, is as follows.

Table 1 Proposed maximum residue limits for dicamba
Common name Residue definition MRL
(ppm)Table 1 Footnote 1
Food commodity
Dicamba benzoic acid, 3,6-dichloro-2-methoxy including the metabolites benzoic acid, 3,6-dichloro-2-hydroxy- and benzoic acid, 2,5-dichloro-3-hydroxy-6-methoxy- (expressed in parent equivalents) 3.0 Undelinted cotton seeds

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

MRLs may vary from one country to another for a number of reasons, including differences in pesticide use patterns and the locations of the crop field trials used to generate residue chemistry data.

Table 2 compares the MRL proposed for dicamba in Canada with corresponding American tolerance and Codex MRL.Footnote 1American tolerances are listed inthe Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. A listing of established Codex MRLs is available on the Codex Alimentarius Pesticide Index webpage, by pesticide or commodity.

Table 2 Comparison of Canadian MRLs, American tolerances and Codex MRLs (where different)
Food commodity Canadian MRL
(ppm)
American Tolerance
(ppm)
Codex MRL
(ppm)
Undelinted cotton seeds 3.0 3.0

0.04

Next steps

The PMRA invites the public to submit written comments on the proposed MRL for dicamba 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 limits

Residue data comprising of metabolism, analytical method, and freezer storage stability data for dicamba in dicamba-tolerant cotton were submitted to support the maximum residue limit on imported cotton. In addition, a processing study in treated cotton was reviewed to determine the potential for concentration of residues of dicamba into processed commodities.

Maximum residue limits

The recommendation for a maximum residue limit (MRL) for dicamba was based upon the residues observed in crop commodities treated according to label directions in the exporting country, and the guidance provided in the OECD MRL Calculator. Table A1summarizes the residue data used to calculate the proposed MRL for imported cotton.

Table A1 Summary of field trial and processing data used to support the MRLs
Commodity Application method/Total application rate
(kg a.e./ha)Table A1 Footnote 1
Preharvest interval
(days)
Lowest average field trial residues
(ppm)
Highest average field trial residues
(ppm)
Experimental processing factor
Undelinted cotton seeds Foliar broadcast/2.2 49–105 <0.06 0.280 Refined cotton oil: <0.1×

Following the review of all available data, the MRL as proposed in Table 1 is recommended to cover residues of dicamba. Residues of dicamba in this imported crop commodity 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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