Proposed Maximum Residue Limit PMRL2025-21, Isocycloseram

• Pest Management Regulatory Agency
• 9 October 2025
• ISSN: 1925-0843 (PDF version)
• Catalogue number: H113-24/2025-21E-PDF (PDF version)

Table of contents

• Purpose of consultation
• Dietary health assessment
• Proposed MRLs
• International situation and trade implications
• How to get involved

Purpose of consultation

Maximum residue limit(s) (MRLs)^{Footnote 1} are being proposed for the pesticide isocycloseram as part of the following applications for Canadian use, under submission numbers 2021-3038; 2021-3045; 2021-3048.

Under the authority of the Pest Control Products Act, Health Canada's Pest Management Regulatory Agency (PMRA) is proposing acceptability of the uses requested under the above-noted applications to register the technical grade isocycloseram and the end-use products A22241ST (containing isocycloseram only) and A23128 ST (containing isocycloseram, difenoconazole, sedaxane, metalaxyl-M and fludioxonil) for new uses on barley, oats, rye, triticale and wheat (spring/durum, winter) in Canada, to control or suppress various insects and seed- and soil-borne diseases, as seed treatments.

The evaluation of these isocycloseram applications indicated that the end-use products have value, and the human health and environmental risks associated with their proposed uses are acceptable. Details regarding these applications can be found in Proposed Registration Decision PRD2025-11, Isocycloseram, VANECTO COCKROACH GEL BAIT, EQUENTO and A23128 ST [Isocycloseram Technical and Associated End-use Products, posted to the Pesticides and pest management portion of Canada.ca on 9 October 2025. Dietary risks from the consumption of foods listed in Table 1 were shown to be acceptable when isocycloseram 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 this assessment.

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 (step 3 and step 4). If estimated human exposure is less than or equal to the acceptable level (developed in step 2), 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 MRLs for isocycloseram is being conducted via PMRL2025-21 and PRD2025-11. MRLs are currently established for fludioxonil, difenoconazole, metalaxyl-M and sedaxane on barley, oats, rye, wheat and triticale, accordingly, separate PMRL actions are not required. Health Canada invites the public to submit written comments on the proposed MRLs for isocycloseram in accordance with the process outlined in the How to get involved Section of PMRL2025-21, and with the process outlined in PRD2025-11.

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 Canada's Notification Authority and Enquiry Point.

Proposed MRLs

The proposed MRLs for isocycloseram are summarized in Table 1.

MRLs established in Canada may be found using the Maximum Residue Limit Database on the Maximum residue limits, human health, and food safety 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

Isocycloseram is a new active ingredient that is concurrently being registered in Canada and the United States (U.S.). The MRLs proposed for isocycloseram in Canada are the same as corresponding tolerances to be promulgated in the United States, except for certain livestock commodities, in accordance with Table 2, for which differences in MRLs/tolerances may be due to different livestock feed items and practices.

Once established, the U.S. tolerances for isocycloseram will be listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide.

A listing of established Codex MRLs^{Footnote 2} is available on the Codex Alimentarius Pesticide Index webpage, by pesticide or commodity.

How to get involved

Health Canada invites the public to submit written comments on the proposed MRLs for isocycloseram up to 75 days from the date of publication of PMRL2025-21 (9 October 2025). Please forward your comments to the Pest Management Regulatory Agency Publications Section. 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 response to comments document found in Pesticides and pest management consultations. The established MRLs will be legally in effect as of the date that they are entered into the Maximum Residue Limit Database.