Proposed Maximum Residue Limit PMRL2019-43, Malathion

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Pest Management Regulatory Agency
19 December 2019
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2019-43E-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 annual canarygrass to the product label of Malathion 85E, containing technical grade malathion, is acceptable. The specific use approved in Canada is detailed on the label of Malathion 85E, Pest Control Products Act Registration Number 8372.

The evaluation of this malathion 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 malathion is being conducted via this document (see Next Steps). 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 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 malathion, is as follows.

Table 1 Proposed Maximum Residue Limit for Malathion
Common Name Residue Definition MRL (ppm)Table 1 Footnote 1 Food Commodity
Malathion diethyl 2-[(dimethoxyphosphinothioyl)thio]butanedioate 0.8 Annual canarygrass seeds
Table 1 Footnote 1

ppm = parts per million

Table 1 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 is no American tolerance for malathion on the petitioned commodity listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide, nor is there a Codex MRLFootnote 1 listed for malathion in or on the petitioned commodity on the Codex Alimentarius Pesticide Index webpage.

Next Steps

The PMRA invites the public to submit written comments on the proposed MRL for malathion 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 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 malathion into processed commodities.

Maximum Residue Limit

The recommendation for the maximum residue limit (MRL) for malathion 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 annual canarygrass seeds.

Table A1 Summary of Field Trial and Processing Data Used to Support the MRL
Commodity Application
(g a.e./ha)Footnote 1
Field Trial
Residues (ppm)
Field Trial
Residues (ppm)
Experimental Processing Factor
Wheat Foliar ground/ 4099–5700 14 <0.01 0.08 Wheat bran: 0.24×
Wheat flour: 0.14×
Foliar aerial/ 2027–2700 14 <0.01 0.50
Footnote 1

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

Return to footnote 1 referrer

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