Proposed Maximum Residue Limit PMRL2014-84, Maleic Hydrazide

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Pest Management Regulatory Agency
27 November 2014
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2014-84E-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 dry bulb shallots to the product label of Royal MH-30 Xtra, containing technical grade maleic hydrazide, is acceptable. The specific uses approved in Canada are detailed on the label of Royal MH-30 Xtra, Pest Control Products Act Registration Number 29607.

The evaluation of this maleic hydrazide application indicated that the end-use product has merit and 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 specified 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 maleic hydrazide 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  Standards Council of Canada.

The proposed MRLs, to be added to the MRLs already established for maleic hydrazide, are as follows.

Table 1 Proposed Maximum Residue Limit for Maleic hydrazide
Common Name Residue Definition MRL (ppm)Table 1 footnote 1 Food Commodity

Table 1 footnotes

Table 1 footnote 1

ppm = parts per million

Return to table 1 footnote 1 referrer

Maleic hydrazide 1,2-dihydro-3,6-pyridazinedione 15 Bulb Onion Subgroup (Crop Subgroup 3-07A)

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

Table 2 compares the MRLs proposed for maleic hydrazide in Canada with corresponding American tolerances and Codex MRLs.Footnote 1 American tolerances are listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. A listing of established Codex MRLs is available on the Codex Alimentarius Pesticide Residues in Food website, by pesticide or commodity.

Table 2 Comparison of Canadian MRLs, American Tolerances and Codex MRLs (where different)
Food Commodity Canadian MRL (ppm) American Tolerance
Codex MRL
Shallot bulb 15 Not established 15
Garlic 15 Not established 15
Daylilies, fritillaria bulbs, great headed garlic, serpent garlic, lilies, Chinese onions, pearl onions, potato onions 15 Not established Not established

Next Steps

The PMRA invites the public to submit written comments on the proposed MRLs for maleic hydrazide 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 on file for dry bulb onions from field trials conducted in the United States were reassessed in the framework of this petition to support the domestic use of Royal MH-30 Xtra on dry bulb shallots. Maleic hydrazide was applied to dry bulb onions, the representative crop for Crop Subgroup 3-07A, at the proposed rate and the crop was harvested according to label directions.

Maximum Residue Limit

The recommendation for a maximum residue limit (MRL) for maleic hydrazide in/on crops within Crop Subgroup 3-07A was based upon the crop field trial data for dry bulb onions and the guidance provided in the  OECD MRL Calculator. Table A1 summarizes the residue data used to calculate the proposed MRL for crops in the Bulb Onion Subgroup (Crop Subgroup 3-07A).

Table A1 Summary of Field Trial and Processing Data Used to Support the MRL
Commodity Application Method/
Total Application Rate
(kg a.i./ha)Table a1 footnote 1
Preharvest Interval
Minimum Residues (ppm) Maximum Residues (ppm)

Table a1 footnotes

Table a1 footnote 1

kg a.i./ha = kilograms of active ingredient per hectare

Return to table a1 footnote 1 referrer

Dry bulb onion Foliar application using ground equipment / 2.24 10-11 0.48 7.44

Following the review of all available data, the MRL as proposed in Table 1 is recommended to cover residues of maleic hydrazide. Residues of maleic hydrazide in/on Crop Subgroup 3-07A 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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