Proposed Maximum Residue Limit PMRL2022-15, Quizalofop-ethyl
Pest Management Regulatory Agency
29 July 2022
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2022-15E-PDF (PDF version)
Purpose of consultation
Maximum residue limit (MRLs)Footnote 1 are being proposed for the pesticide quizalofop-ethyl,Footnote 2 as part of the following applications for Canadian use, under submission numbers 2019-6145, 2019-6146, and 2020-1244.
Under the authority of the Pest Control Products Act, Health Canada's Pest Management Regulatory Agency (PMRA) is proposing acceptability to establish new MRLs on pome fruits, stone fruits, and small fruits vine climbing (except fuzzy kiwifruit). This is based upon the requested applications to add various new commodities to the product label of Assure II Herbicide containing technical grade quizalofop-p-ethyl, for the control of labelled grassy weeds. The specific uses approved in Canada are detailed on this product label, Pest Control Products Act Registration Number 25462.
The evaluation of these quizalofop-p-ethyl applications indicated that the end-use product has value, and the human health and environmental risks associated with the new uses are acceptable. Dietary risks from the consumption of foods listed in Table 1 were shown to be acceptable when quizalofop-p-ethyl is used according to the supported label directions. Therefore, foods containing residues resulting from these uses are safe to eat, and MRLs are being proposed as a result of these assessments. A summary of the field trial data used to support the proposed MRLs can be found in Appendix I.
Dietary health assessment
In assessing the risk of a pesticide, Health Canada combines information on pesticide toxicity with information on the degree and duration of dietary exposure to the pesticide residue from food. The risk assessment process involves four distinct steps:
- Identifying the toxicology hazards posed by the pesticide;
- Determining the "acceptable dietary level" for Canadians (including all vulnerable populations), which is protective of adverse health effects;
- Estimating human dietary exposure to the pesticide from all applicable sources (domestic and imported commodities); and
- Characterizing health risk by comparing the estimated human dietary exposure to the acceptable dietary level.
Before registering a pesticide for food use in Canada, Health Canada must determine the quantity of residues that could 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 (Steps 3 and 4 above). If estimated human exposure is less than or equal to the acceptable level (developed in Step 2 above), Health Canada concludes that consuming residues resulting from use according to approved label directions is not a health concern. The proposed MRL is then subject to consultation to legally specify it as an MRL. An MRL applies to the identified raw agricultural food commodity as well as to any processed food product that contains it, except for certain instances where different MRLs are specified for the raw agricultural commodity and its processed product(s).
Residues of the resolved isomer quizalofop-p-ethyl are covered by MRLs established for quizalofop-ethyl, the unresolved isomeric mixture. Consultation on the proposed MRLs for quizalofop-ethyl is being conducted via this document. Health Canada invites the public to submit written comments on the proposed MRLs for quizalofop-ethyl in accordance with the process outlined in the Next steps section of this document.
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, to be added to the MRLs already established for quizalofop-ethyl, are summarized in Table 1.
|Common name||Residue definition||MRL (ppm)Table 1 Footnote 1||Food commodity|
quinoxalinyl)oxy]phenoxy]propanoate, including the acid metabolites of (RS)2-[4-(6-
acid, all expressed as quizalofop-ethyl
|0.1||Pome fruits (crop group 11-09), stone fruits (crop group 12-09), small fruits vine climbing, except fuzzy kiwifruit (crop subgroup 13-07F)|
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 MRLs proposed for quizalofop-ethyl in Canada are the same as corresponding American tolerances as listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there are no Codex MRLsFootnote 3 listed for quizalofop-ethyl in or on any commodity on the Codex Alimentarius Pesticide Index webpage.
Health Canada invites the public to submit written comments on the proposed MRLs for quizalofop-ethyl up to 75 days from the date of publication of this document. Please forward your comments to Publications. Health Canada will consider all comments received and a science-based approach will be applied in 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.
Summary of field trial data used to support the proposed maximum residue limits
Residue data for quizalofop-p-ethyl on apples, pears, cherries, peaches, plums and grapes were submitted to support the use of Assure II Herbicide on crops within crop group 11-09 (pome fruits), crop group 12-09 (stone fruits) and crop subgroup 13-07F (small fruits vine climbing, except fuzzy kiwifruit). In addition, a processing study in treated apples, plums and grapes were reviewed to determine the potential for concentration of residues of quizalofop-p-ethyl in processed commodities.
Dietary risk assessment results
Studies in laboratory animals showed no acute health effects. Consequently, a single dose of quizalofop-ethyl is not likely to cause acute health effects in the general population (including infants and children).
Chronic (non-cancer and cancer) dietary (food plus drinking water) intake estimates indicated that the general population and all population subgroups are exposed to less than 53% of the acceptable daily intake, and therefore there are no health concerns.
Maximum residue limits
The recommendation for maximum residue limits (MRLs) for quizalofop-ethyl 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 for pome fruits, stone fruits, and small fruits vine climbing (except fuzzy kiwifruit).
|Commodity||Application method/Total application rate (g a.i./ha)Footnote 1||Preharvest interval (days)||Lowest average field trial residues
|Highest average field trial residues
|Experimental processing factor|
|Apples||Banded ground/ 178–196||13–15||<0.10||<0.10||No quantifiable residues observed at exaggerated rates|
|Pears||Banded ground/ 184–190||13–15||<0.10||<0.10||Not applicable|
|Cherries||Banded ground/ 183–193||8–15||<0.10||<0.10||Not applicable|
|Peaches||Banded ground/ 184–191||12–16||<0.10||<0.10||Not applicable|
|Plums||Banded ground/ 180–193||13–15||<0.10||<0.10||No quantifiable residues observed at exaggerated rates|
|Grapes||Banded ground/ 75–81||6–15||<0.10||<0.10||No quantifiable residues observed at exaggerated rates|
Following the review of all available data, the MRLs proposed in Table 1 are recommended to cover residues of quizalofop-ethyl. Dietary risks from exposure to residues of quizalofop-ethyl in these crop commodities at the proposed MRLs were shown to be acceptable for the general population and all subpopulations, including infants, children, adults and seniors. Thus the foods that contain residues as listed in Table 1 are considered safe to eat.
|3049862||2018, Quizalofop: Magnitude of the Residue on Apple, DACO: 7.3,7.4.1, 7.4.5|
|3049863||2018, Quizalofop: Magnitude of the Residue on Pear, DACO: 7.4.1|
|3049874||2017, Quizalofop: Magnitude of the Residue on Peach, DACO: 7.3,7.4.1|
|3049875||2017, Quizalofop: Magnitude of the Residue on Plum, DACO: 7.3,7.4.1, 7.4.5|
|3049876||2017, Quizalofop: Magnitude of the Residue on Cherry, DACO: 7.3,7.4.1|
|3108713||2012, Final Report: Quizalofop: Magnitude of the residue on Grape, DACO: 7.3,7.4.1,7.4.5|
- Footnote 1
A maximum residue limit (MRL) is the maximum amount of residue that may remain in or on food when a pesticide is used according to label directions.
- Footnote 2
Quizalofop-ethyl is the unresolved isomeric mixture (containing R and S-enantiomers) of the technical grade active quizalofop-p-ethyl (which contains the R-enantiomer only). As both quizalofop-ethyl and quizalofop-p-ethyl contain the pesticidally-active R-enantiomer, residues of quizalofop-p-ethyl will be covered by MRLs established for quizalofop-ethyl.
- Footnote 3
The Codex Alimentarius Commission is an international organization under the auspices of the United Nations that develops international food standards, including MRLs.
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