Proposed Maximum Residue Limit PMRL2024-09, Metsulfuron-methyl

Pest Management Regulatory Agency
30 May 2024
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2024-9E-PDF (PDF version)

Purpose of consultation

A maximum residue limit (MRL)^{Footnote 1} is being proposed for the pesticide metsulfuron-methyl, as part of the following application for Canadian use, under submission number 2022-2090.

Under the authority of the Pest Control Products Act, Health Canada’s Pest Management Regulatory Agency (PMRA) is proposing acceptability of the requested application to add the new commodity of oats to the product label of Express PRO Herbicide, containing technical grade metsulfuron-methyl and tribenuron-methyl, to control or suppress certain weeds. The specific uses approved in Canada are detailed on this product label, Pest Control Products Act Registration Number 29212.

The evaluation of this metsulfuron-methyl and tribenuron-methyl application indicated that the end-use product has value, and the human health and environmental risks associated with the new use are acceptable. Dietary risks from the consumption of the food listed in Table 1 were shown to be acceptable when metsulfuron-methyl is used according to the supported label directions. Therefore, the food containing residues resulting from this use is safe to eat, and an MRL is being proposed as a result of this assessment. A summary of the field trial data used to support the proposed MRL 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:

1. Identifying the toxicology hazards posed by the pesticide;
2. Determining the “acceptable dietary level” for Canadians (including all vulnerable populations), which is protective of adverse health effects;
3. Estimating human dietary exposure to the pesticide from all applicable sources (domestic and imported commodities); and
4. 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).

Consultation on the proposed MRL for metsulfuron-methyl is being conducted via this document. An MRL is currently established for tribenuron-methyl on oats at 0.05 ppm, accordingly a separate PMRL action is not required. Health Canada invites the public to submit written comments on the proposed MRL for metsulfuron-methyl 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 MRL is also being conducted internationally by notifying the World Trade Organization, as coordinated by the Canada’s Notification Authority and Enquiry Point.

Proposed MRL

The proposed MRL, to be added to the MRLs already established for metsulfuron-methyl, is summarized in Table 1.

Table 1 Proposed maximum residue limit for metsulfuron-methyl

Common name	Residue definition	MRL (ppm)Table 1 Footnote 1	Food commodity
Metsulfuron-methyl	methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoate, including the metabolite methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl] 4-hydroxybenzoate	0.1	Oats
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 are no tolerances in the United States (U.S.) for metsulfuron-methyl in or on the petitioned commodities listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide, nor are there Codex MRLs^{Footnote 2} listed for metsulfuron-methyl in or on any commodity on the Codex Alimentarius Pesticide Index webpage.

Next steps

Health Canada invites the public to submit written comments on the proposed MRL for metsulfuron-methyl up to 75 days from the date of publication of this document (by 13  August 2024). 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 MRL. Comments received will be addressed in a response to comments document found in Pesticides and pest management consultations. 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, barley, sorghum and oats were reassessed in the framework of this petition.

Dietary risk assessment results

Studies in laboratory animals showed no acute health effects relevant to dietary exposure. Consequently, a single dose of metsulfuron-methyl is not likely to cause acute health effects in the general population (including infants and children).

Chronic dietary (food plus drinking water) intake estimates indicated that the general population and all population subgroups are exposed to less than 4% of the acceptable daily intake, and therefore there are no health concerns.

Maximum residue limit

The recommendation for the MRL for metsulfuron-methyl was based upon the re-assessed Canadian and U.S. field trial data in representative cereal grain crops (barley, wheats, sorghum) as well as in oats, and the guidance provided in the OECD MRL Calculator. Residues in all trials were less than the limits of quantitation (LOQ), where the LOQs ranged from 0.02 ppm to 0.1 ppm, depending on the analytical method. An MRL to cover residues of metsulfuron-methyl and the metabolite 4-hydroxy metsulfuron-methyl in/on oats of 0.1 ppm is thus proposed. Residues did not concentrate in processed commodities, and are, therefore, covered under the proposed MRL for the raw agricultural commodity (RAC).

Following the review of all available data, the MRL proposed in Table 1 is recommended in order to cover residues of metsulfuron-methyl and the metabolite 4-hydroxy metsulfuron-methyl. Dietary risks from exposure to residues of metsulfuron-methyl in this commodity at the proposed MRL were shown to be acceptable for the general population and all subpopulations, including infants, children, adults and seniors. Thus, the food that contains residues as listed in Table 1 is considered safe to eat.

References

None

Footnotes