Proposed Maximum Residue Limit PMRL2020-34, Triallate

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Pest Management Regulatory Agency
20 October 2020
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2020-34E-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 the new use on annual canarygrass to the product label of Avadex Microactiv Herbicide, containing technical grade triallate, is acceptable. The specific uses approved in Canada are detailed on the label of Avadex Microactiv Herbicide, Pest Control Products Act Registration Number 25112.

The evaluation of this triallate application indicated that the end-use product has 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 MRL for triallate 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 triallate, is as follows.

Table 1 Proposed maximum residue limit for triallate

Common name
Residue definition MRL (ppm)Footnote 1 Food commodity
Triallate S-(2,3,3-trichloro-2-propen-1-yl) N,N-bis(1-methylethyl)carbamothioate, including the metabolite 2-propene-1-sulfonic acid, 2,3,3-trichloro- 0.05 Annual canarygrass 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 triallate in Canada with corresponding American tolerance and Codex MRLFootnote 1. American tolerances are listed inthe Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there are no Codex MRLs listed for triallate in or on any commodity on the Codex Alimentarius Pesticide Index webpage.

Table 2 Comparison of Canadian MRL, American Tolerance and Codex MRL (where different)

Food commodity
Canadian MRL
(ppm)
American Tolerance
(ppm)
Codex MRL
(ppm)
Annual canarygrass 0.05 Not Established Not Established

Next steps

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

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

Maximum residue limit

The recommendation for maximum residue limit (MRL) for triallate 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 MRL for triallate.

Table A1 Summary of field trial and processing data used to support the MRL

Commodity
Application method/ Total application rate
(kg a.i./ha)Footnote 1
Preharvest interval (days) Lowest average field trial residues
(ppm)
Highest average field trial residues
(ppm)
Experimental processing factor
Wheat grain Pre-plant soil incorporation/ 1.7 36–312 <0.02 <0.04 Triallate: No quantifiable residues observed

TCPSAFootnote 2:
Wheat bran: 3.0×
Wheat shorts: 2.3×
Wheat flour: 0.3×
Barley grain Pre-plant soil incorporation/ 1.7 110–113 <0.02 <0.02 TriallateFootnote 3: No quantifiable residues observed

TCPSAFootnote 2,Footnote 3:
Barley bran: 3.0×
Barley flour: 0.3×

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

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