A Maximum Residue Limit is a level of residue that could safely remain in the tissue or food product derived from a food-producing animal that has been treated with a veterinary drug. This residue is considered to pose no adverse health effects if ingested daily by humans over a lifetime.
MRLs are established only after Health Canada's Veterinary Drugs Directorate has conducted extensive reviews of data submitted by manufacturers and has determined that foods containing these veterinary drug residues up to the established levels are safe for human consumption. MRLs are established by using a scientific, multi-step, health risk assessment process that is internationally recognized.
Previously MRLs for Veterinary Drugs were published in Table III, Division 15 of the Food and Drug Regulations. The process whereby MRLs are added or updated to the "List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods" has recently been streamlined. On April 26, 2012, as part of Bill C-38, the Government of Canada brought forward two targeted changes to the Food and Drugs Act. The new tools, called "Marketing Authorizations" and "Incorporation by Reference", will reduce delays, cut red tape and make the food regulatory system more efficient and flexible. The amendments received Royal Assent on June 29, 2012, and have since come into force.
With the Marketing Authorization for Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods, any changes to the List will be made by updating and publishing an amended List on the Health Canada website, as opposed to requiring regulatory promulgations. However, the process or the rigour of the scientific assessment of safety to establish MRLs remains the same, and the stakeholders and the public will still be consulted on the proposed MRLs. This means that while keeping the same rigour of scientific assessments and maintaining the transparency through public consultations, food standards (e.g., MRLs) could be established in a much timelier and more efficient manner.
The current version of the MRLs is available on the List of Maximum Residue Limits (MRLs) for Veterinary Drugs in Foods. The List includes the following information: Column I (Veterinary Drug); Column II (Name of the Substance for Drug Analysis Purposes); Column III (Foods); and Column IV (Maximum Residue Limits p.p.m.). Note that the MRLs listed in Column IV are applicable to food derived from all production classes of species indicated in Column III, unless otherwise specified. For example, MRLs listed for edible tissues of “cattle” apply to tissues of adult cattle, as well as calves. MRLs for veterinary drugs listed for edible tissues of “cattle, other than calves to be processed for veal” are not applicable to tissues of veal calves. For that reason, calves that have been administered these drugs should not be processed for veal.
Upon completion of the scientific assessment of a Veterinary New Drug Submission, or reassessment of a previously approved drug, Health Canada will notify the public of its intent to amend the List via a Proposal to Amend the List of MRLs for Veterinary Drugs in Foods that will be posted on the Health Canada website for public consultation. Interested parties may provide comments on the proposal, and should new scientific or safety evidence be raised, amendments to the proposed values may be considered. After addressing the public comments, a Final Notice to Amend the List of MRLs for Veterinary Drugs in Foods will be posted on the Health Canada website and the proposed amendments will be formally incorporated to the List of MRLs for Veterinary Drugs in Foods.