Maximum Residue Limits (MRLs): what they are and why they matter

Canada’s reputation for safe food is unparalleled, thanks to all the people involved in the food business, from field to fork. Although pesticides are an important part of our farming, nobody wants them remaining in or on food that we consume in quantities that can affect our health. That is why all food products grown in and imported into Canada (whether organic or conventionally grown) are tested for pesticide residue. As harvest progresses, it is important to keep maximum residue limits (MRLs) in mind.

What is MRL?

To put it simply, MRL is the highest level of a pesticide residue legally tolerated in or on food or feed. Relevant authorities set MRLs from multiple scientific trials that determine the maximum amount of residue that could remain on the crop when a pesticide is applied according to the product’s label instructions. Then, using estimates of how much a person might consume in a day or a year, risks are calculated. In Canada, MRLs are set by Health Canada for each pesticide and crop combination (Health Canada’s database of MRLs can be found here). MRLs are set at levels far below the amount of pesticide residue that could cause health concerns, taking into account all of the population including infants, children, and pregnant women. The Canadian Food Inspection Agency takes enforcement actions if tested food products exceed MRLs. MRL exceedance also has trade consequences.

What is our part?

As growers, we must continue to use good agricultural and pest management practices throughout the cropping season to keep residues within limits. This includes following label recommendations for rate and timing of application of agricultural chemicals, as well as proper storage of the harvested product. Pay particular attention to the pre-harvest interval recommended for whatever product you are using, whether desiccants or late-season fungicides or insecticides.

It is also important to keep an eye on recent developments in international markets. For example, because of the current heightened level of focus on glyphosate, there is a push in some markets for a reduction of its MRL or its ban as a pre-harvest aid in certain crops like oats. This trend may continue and emphasizes the importance of following label instructions to ensure Canadian products comply with MRLs set by buyers and importing countries.


-Ikenna Mbakwe, PhD, PAg
Head of Research



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