Proposed Maximum Residue Limit PMRL2016-23, Metaldehyde

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Pest Management Regulatory Agency
25 May 2016
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2016-23E-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 new uses on cabbage, lettuce, CSG8-09A, CSG13-07A, and CSG13-07G to the product label of Deadline M-Ps, containing technical grade metaldehyde, is acceptable. The specific uses approved in Canada are detailed on the label of Deadline M-Ps, Pest Control Products Act Registration Number 26650.

The evaluation of this metaldehyde 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 MRLs for metaldehyde is being conducted via this document (see Next Steps, the last section of this document). 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 MRLs is also being conducted internationally by notifying the World Trade Organization, as coordinated by the Canada’s Notification Authority and Enquiry Point.

The proposed MRLs are as follows.

Table 1: Proposed Maximum Residue Limits for Metaldehyde
Common Name Residue Definition MRL
(ppm)Table 1 footnote 1
Food Commodity
Metaldehyde 2,4,6,8-tetramethyl-1,3,5,7-tetroxocane 1.5 Leaf lettuce
1.0 Cabbage
0.15 Caneberries (Crop Subgroup 13-07A), low growing berries (Crop Subgroup 13-07G), head lettuce
0.09 Tomatoes (Crop Subgroup 8-09A)
Table 1 footnote 1

ppm = parts per million

Return to table 1 footnote 1 referrer

MRLs are proposed for each commodity included in the listed crop groupings in accordance with the Residue Chemistry Crop Groups webpage in the Pesticides and Pest Management section of Health Canada’s 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

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 MRLs proposed for metaldehyde in Canada with corresponding American tolerances. American tolerances are listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there are no Codex MRLsFootnote 1 listed for metaldehyde in or on any commodity on the Codex Alimentarius Pesticide Residues in Food webpage.

Table 2: Comparison of Canadian MRLs and American Tolerances
Food Commodity Canadian MRL
American Tolerance
Caneberries (Crop Subgroup 13-07A) 0.15 0.15 (CSG 13-07A)
Cabbage 1.0 2.5 (CG5)
Head lettuce 0.15 1.73 (lettuce)
Leaf lettuce 1.5 1.73 (lettuce)
Low growing berries
(Crop Subgroup 13-07G)
0.15 6.25 (CSG 13-07G)
Tomatoes (Crop Subgroup 8-09A) 0.09 0.24 (CSG 8-10A)

Next Steps

The PMRA invites the public to submit written comments on the proposed MRLs for metaldehyde 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 MRLs. Comments received will be addressed in a separate document linked to this PMRL. The established MRLs will be legally in effect as of the date that they are entered into the Maximum Residue Limit Database.

Appendix I

Summary of Field Trial Data Used to Support the Proposed Maximum Residue Limits

Residue data for metaldehyde were submitted to support the domestic use of Deadline M-Ps on blackberries/raspberries, cabbage, lettuce, strawberries, and tomatoes. In addition, a processing study in treated tomatoes was reviewed to determine the potential for concentration of residues of metaldehyde into processed commodities.

Maximum Residue Limits

The recommendation for maximum residue limits (MRLs) for metaldehyde 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 MRLs.

Table A1: Summary of Field Trial and Processing Data Used to Support MRLs
Commodity Application Method/ Total Application Rate
(kg ai/ha)Table A1 footnote 1
Preharvest Interval
Lowest Average Field Trial Residues
Highest Average Field Trial Residues
Experimental Processing Factor
Caneberries (CSG13-07A): Blackberries/Raspberries Soil treatment/4.78 0 <0.05 0.055 N/A
Cabbage Soil treatment/3.36 19-21 <0.05 0.488 N/A
Head lettuce Soil treatment/3.36 3 <0.05 0.076 N/A
Leaf lettuce Soil treatment/3.36 3 <0.05 0.603 N/A
Low growing berries (CSG13-07G): Strawberries Soil treatment/6.72 8 <0.05 0.084 N/A
Tomatoes (CSG8-09A): Tomatoes Soil treatment/3.36 9-11 <0.05 0.082 Paste: 0.9-fold
Purée: 0.9-fold
Table A1 footnote 1

kg ai/ha = kilograms of active ingredient per hectare

Return to table A1 footnote 1 referrer

Following the review of all available data, MRLs as proposed in Table 1 are recommended to cover residues of metaldehyde. Residues of metaldehyde in these crop commodities 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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