Proposal to amend the List of Maximum Residue Limits (MRLs) for veterinary drugs in foods - Proposed MRL 2013-2

Notice to the reader:

The online consultation is now closed.

Date: June 10, 2013
Project Number: Proposed MRLs 2013-2
Description: Proposed MRLs for ractopamine in cattle, swine and turkey tissues

Notice is hereby given that the Director General, Veterinary Drugs Directorate, Health Canada, on behalf of the Minister of Health, pursuant to sections 30.3(1) to 30.5(1) of the Food and Drugs Act, proposes to amend the List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods. These proposed MRLs for veterinary drugs in foods, referenced below, are approved for public consultation as part of the  Marketing Authorization for Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods.

 MRLs for ractopamine in swine tissues were previously published for consultation in Canada Gazette I and were also available as administrative MRLs on the Health Canada website. However, these MRLs were not yet finalized due to ongoing discussions at the international level (see  Canada Gazette II). The proposed MRLs for cattle and turkey tissues were also pre-consulted and available on the Health Canada website. In this proposal, MRLs for ractopamine in some tissues of cattle and swine are slightly revised compared to those previously published. These revisions are made to harmonize the proposed MRLs with the recently adopted MRLs for ractopamine by the Codex Alimentarius Commission.

Interested persons may make representations with respect to the proposed MRLs within 75 days after the date of publication of this notice. All such representations must cite this document and the date of publication of this notice, and be addressed to the undersigned.

To comply with Canada's international trade obligations, consultation on the proposed MRLs is also being conducted internationally by notifying the World Trade Organization.

After the period of consultation is complete, and the issues noted in the consultation have been appropriately addressed by Health Canada, the proposed MRLs will be included in the List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods with a Final Notice to Amend the List of MRLs for Veterinary Drugs in Foods and the effective implementation date.

Daniel Chaput
Director General

Veterinary Drugs Directorate
Health Products and Foods Branch, Health Canada
Holland Cross Complex
11 Holland Avenue,
Ground Floor, Suite 14,
Ottawa, Ontario K1A 0K9
Fax: 613-954-5694

I. Proposed MRLs

The List will be amended by inserting MRLs for ractopamine as follows:

Proposed MRLs
Column I Veterinary Drug Column II
Name of the Substance for Drug Analysis Purposes
Column III
Column IV
Maximum Residue Limits p.p.m.
Ractopamine Ractopamine free base Kidney of cattle 0.09
Liver of cattle 0.04
Muscle of cattle 0.01
Kidney of swine 0.09
Liver of swine 0.04
Muscle of swine 0.01
Liver of turkeys 0.2
Muscle of turkeys 0.03

Summary of Maximum Residue Limit (MRL) Scientific Assessment


Under the Canadian Food and Drug Regulations all veterinary drugs must be authorized by Health Canada prior to their sale and administration to prevent and treat diseases, or as a production aid, in animals. Some drugs are only permitted in certain species not intended to be used for foods while others are used in food-producing animals. When a drug is approved for use in a food- producing animal, residues of drugs could remain in tissues or products of treated animals. Health Canada sets acceptable limits of residues of veterinary drugs in food commodities called maximum residue limits (MRLs). MRLs are the maximum concentrations of residues, expressed in parts per million (ppm) on a fresh weight basis, in edible tissues or products of food-producing animals as a result of the treatment of those animals with veterinary drugs, which are  recognized as safe by Health Canada. An MRL is based on the type and amount of residue considered to pose no adverse health effects if ingested daily by humans over a lifetime.

According to sections 30.3(1) to 30.5(1) of the Food and Drugs Act, the Minister of Health publishes the List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods on the Health Canada website through incorporation by reference. The proposed amendment establishes safe limits for residues of various drugs in foods originating from animals treated with these particular drugs. These veterinary drugs are an important tool in the production of healthy animals which are destined for use as food. The amendments would permit the regulated sale of food containing residues of veterinary drugs up to the specified levels (MRLs) as a result of use of these drugs in food-producing animals. These amendments benefit both industry and the consumer by reducing potential losses in production, increasing quality of products, improving availability of certain foods, and supporting the trade of safe and high quality products derived from animals.

In order to determine MRLs, scientists at Health Canada conduct extensive reviews on the toxicity, metabolism and residue depletion data submitted by manufacturers, assess the risks and benefits of the use of the drug and the acceptability of the resulting levels of residues of the drugs that are found in food products. Only when there is sufficient evidence to demonstrate that the residues found will not pose undue risks to consumers can the drug be permitted for administration to food-producing animals and the related food products sold in Canada. The MRLs apply to foods produced domestically or imported into Canada.

Scientific Rationale

Health Canada reviewed extensive toxicological studies (such as short term toxicity studies in rats, mice and monkeys; long term toxicity and carcinogenicity studies in rats, mice and monkeys; reproductive toxicity studies in rats and swine; and in-vitro and in-vivo genotoxicity studies) on ractopamine submitted by the drug manufacturer. Additionally, studies investigating cardiac effects of ractopamine in dogs, monkeys and humans were reviewed. The pharmacokinetics and biotransformation of ractopamine in humans and animals were comparable; orally administered ractopamine was extensively and rapidly absorbed and eliminated. Ractopamine was shown to have pharmacological effects on cardiovascular system, and the pharmacological endpoint was significantly lower than the no-observed effect levels derived from chronic studies. Health Canada considered that data from patients with congestive heart failure (sensitive human population) for the hemodynamic effects of RR isomer of ractopamine (the most active isomer) to be the most appropriate endpoint for establishing the acceptable daily intake (ADI). Using a safety factor of 10 (to account for individual variation), Health Canada established an ADI of 1.4 µg/kg bw for ractopamine. Data on the metabolism and residue depletion of ractopamine in cattle, swine and turkeys were also reviewed to establish the proposed MRLs.

As discussed above, the administrative MRLs for ractopamine were previously available on the Health Canada website and those proposed in this consultation are highlighted below. Health Canada has determined that these revisions will have no negative impact on food safety or on the approved conditions of use of the drug in these species.  Residue compliance for the proposed MRLs has been monitored and confirmed by the Canadian Food Inspection Agency (CFIA).

II. Administrative MRLs and Proposed MRLs for ractopamine

Proposed MRLs for ractopamine
Foods Administrative MRLs (p.p.m.) for ractopamine previously published on Health Canada website Proposed MRLs (p.p.m.) for ractopamine in this notice
Kidney of cattle 0.1 0.09
Liver of cattle 0.04 0.04
Muscle of cattle 0.01 0.01
Kidney of swine 0.14 0.09
Liver of swine 0.12 0.04
Muscle of swine 0.01 0.01
Liver of turkeys 0.2 0.2
Muscle of turkeys 0.03 0.03

Other considerations

The MRLs proposed for ractopamine in cattle and swine in this consultation are harmonized with levels established by the Joint Food and Agriculture Organization of the United Nations/World Health Organization Food Standards Programme - Codex Alimentarius Commission. Consequently, it is not anticipated that the MRLs listed in the proposed amendments would have an adverse impact on Canada's international trade activities. It is noted that the proposed MRLs are slightly lower than that established by the United States Food and Drug Administration. Consequently, no anticipated trade issues to export Canadian products to the United States are envisaged at this time.

Complete harmonization with trading partners or international organizations is desirable, although it may not always be possible for various reasons (e.g., differences in consumption patterns, testing methodologies, climate, and animal husbandry practices). Greater harmonization of food standards continues to be a priority for Health Canada and MRLs will be harmonized with those of our trading partners or Codex whenever possible provided that there are no health and safety concerns.

Implementation, enforcement and service standards

The CFIA enforces compliance with the MRLs published in the List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods. Compliance is monitored by the ongoing domestic and import inspection programs conducted by the CFIA. If levels of drug residues in excess of these limits are found in food products derived from food-producing animals intended for human consumption, the product will be considered "adulterated" in accordance with sections 4(a) and 4(d) of the Food and Drugs Act. The CFIA Food and Drugs Act to take compliance action, when it finds violative residues. The CFIA regulatory activities help to maintain consumer and market confidence in Canada's food supply.

The implementation date for the proposed MRLs will be announced at a later date, but will not be less than 6 months from the date of this publication.

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