Proposed Maximum Residue Limit PMRL2025-07, Linuron

Pest Management Regulatory Agency
17 June 2025
ISSN: 1925-0843 (PDF version)
Catalogue number: H113-24/2025-7E-PDF (PDF version)

Table of Contents

• Purpose of consultation
• Dietary health assessment
• Proposed MRL
• International situation and trade implications
• How to get involved
• Appendix I
• References

Purpose of consultation

A maximum residue limit (MRL)^{Footnote 1} is being proposed for the pesticide linuron, as part of the following application for Canadian use, submitted by Tessenderlo Kerley, Inc. under submission number 2024-1857.

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 re-instate the use on the commodity of celery to the product label of Lorox L Herbicide containing technical grade linuron, for the control of labelled broadleaf and grassy weeds as an early postemergent foliar use, since restricted-entry intervals (REIs) calculated as part of the most recent re-evaluation (RVD2020-10) that had been considered agronomically unfeasible at that time are now considered agronomically feasible by growers. In support, new food residue chemistry data, including crop field trial studies, were reviewed to determine the recommended MRL. The specific uses approved in Canada are detailed on this product label, Pest Control Products Act Registration Number 16279.

The evaluation of this linuron 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 food listed in Table 1 were shown to be acceptable when linuron is used according to the supported label directions. Therefore, foods containing residues resulting from this use are 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). 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 MRL for linuron is being conducted via this document. Health Canada invites the public to submit written comments on the proposed MRL for linuron in accordance with the process outlined in the How to get involved 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 for linuron is summarized in Table 1.

Table 1 Proposed maximum residue limit for linuron

Common name	Residue definition	MRL (ppm)Footnote 1	Food commodity
Linuron	N-(3,4-dichlorophenyl)-N-methoxy-N-methylurea, including metabolites that can be converted to the 3,4-dichloroaniline moiety (expressed as parent equivalents)	0.5	Celery

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

As per Table 2, the MRL proposed for linuron in Canada is the same as the corresponding tolerance in the United States (U.S) as listed in the Electronic Code of Federal Regulations, 40 CFR Part 180, by pesticide. Currently, there are no Codex MRLs^{Footnote 2} listed for linuron in or on any commodity on the Codex Alimentarius Pesticide Index webpage.

Table 2 Comparison of proposed Canadian MRL, U.S. tolerance and Codex MRL

Food commodity	Proposed Canadian MRL (ppm)	Established U.S. tolerance (ppm)	Established Codex MRL (ppm)
Celery	0.5	0.5	Not established

How to get involved

Health Canada invites the public to submit written comments on the proposed MRL for linuron up to 75 days from the date of publication of this document (by 31 August 2025). 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

Residue data for linuron were submitted to support the use of Lorox L Herbicide on celery. In addition, previously reviewed residue data from field trials conducted in/on celery were reassessed in the framework of this petition.

Dietary risk assessment results

Acute dietary (food plus drinking water) intake estimates indicated that the general population and all population subgroups are exposed to less than 37% of the acute reference dose, and therefore there are no health concerns.

Chronic dietary (food plus drinking water) intake estimates indicated that the general population and all population subgroups are exposed to less than 71% of the acceptable daily intake, and therefore there are no health concerns.

Maximum residue limit

The recommendation for a maximum residue limit (MRL) for linuron was based upon data on file and newly submitted field trial data, and the guidance provided in the OECD MRL Calculator. Table A1 summarizes the residue data for linuron, including the metabolites convertible to 3,4-dichloroaniline (parent equivalents), used to calculate the proposed MRL for celery.

Table A1 Summary of field trial data used to support the MRL

Commodity	Application method/Total application rate (kg a.i./ha)Footnote 1	Preharvest interval (days)	Lowest average field trial residuesFootnote 2 (ppm)	Highest average field trial residuesFootnote 2 (ppm)
Celery	Foliar/1.68–1.77	44–102	0.040	0.300

Following the review of all available data, the MRL proposed in Table 1 is recommended, in order to cover total residues of linuron, including the metabolites convertible to 3,4-dichloroaniline (parent equivalents). Dietary risks from exposure to total residues of linuron in this crop commodity at the proposed MRL was 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.

References

PMRA Number	Citation
3594909	2006, MAGNITUDE OF RESIDUES OF LINURON IN CELERY FOLLOWING APPLICATION OF LOROX(r) DF HERBICIDE AT MAXIMUM LABEL RATES - UNITED STATES LOCATIONS, SEASON 2005, DACO: 7.4.1,7.4.2
3594910	1988, Linuron Residue Study, Response to Special Review/Reregistration Guidance Document - EPA Case No. 47 (6-29-84), DACO: 7.4.1,7.4.2