Proposed Maximum Residue Limit PMRL2017-18, Nicosulfuron

Pest Management Regulatory Agency
24 May 2017
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2017-18E-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 nicosulfuron on sorghum to permit the import and sale of foods containing such residues.
Nicosulfuron is a 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 nicosulfuron 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 nicosulfuron 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 nicosulfuron, is as follows.

Table 1 - Proposed Maximum Residue Limit for Nicosulfuron
Common Name Residue Definition MRL (ppm)Table 1 footnote 1 Food Commodity
Nicosulfuron 2[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide 0.8 Sorghum
Table 1 footnote 1

ppm = parts per million


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 nicosulfuron in Canada is the same as corresponding American tolerance as listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there are no Codex MRLsFootnote 1.2listed for nicosulfuron in or on any commodity on the Codex Alimentarius Pesticide Residues in Food and Feed webpage.

Next Steps

The PMRA invites the public to submit written comments on the proposed MRL for nicosulfuron 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 nicosulfuron in ALS-tolerant sorghum were submitted to support the maximum residue limit on imported sorghum. In addition, a processing study in treated sorghum was reviewed and a processing study in treated field corn was reassessed to determine the potential for concentration of residues of nicosulfuron into processed commodities.

Maximum Residue Limits

The recommendation for a maximum residue limit (MRL) for nicosulfuron was based upon the residues observed in  the crop treated according to label directions  in the exporting country, and the guidance provided in the OECD MRL Calculator. Table A1 summarizes the residue data used to calculate the proposed MRL for imported sorghum.

Table A1 - Summary of Field Trial and Processing Data Used to Support MRL
Commodity Application Method/ Total Application Rate
(g a.i./ha)Table 2 footnote 1.1
Preharvest Interval (days) Lowest Average Field Trial Residues
Highest Average Field Trial Residues
Experimental Processing Factor
Sorghum, grain Foliar broadcast/
69-118 0.016 0.45 0.6×
(AGF)Table 2 footnote 2
Table 2 footnote 1

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


Table 2 footnote 2

AGF = aspirated grain fractions


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