Maximum Residue Limit

Pesticide residues on crops are monitored through the use of Maximum Residue Limits (MRL), which are based on the analysis of the quantity of a given chemical remaining on food product samples. The MRL is usually determined by repeated (on the order of 10) field trials, where the crop has been treated according to good agricultural practice (GAP) and an appropriate pre harvest interval or withholding period has elapsed. For many pesticides this is set at the Limit of Determination (LOD) – since only major pesticides have been evaluated and understanding of Acceptable daily intake (ADI) is incomplete (i.e. producers or public bodies have not submitted MRL data – often because these were not required in the past). LOD can be considered a measure of presence/absence, but certain residues may not be quantifiable at very low levels. For this reason the limit of quantification (LOQ) is often used instead of the LOD. As a rule of thumb the LOQ is approximately two times the LOD. For substances that are not included in any of the annexes in EU regulations, a default MRL of 0.01 mg/kg normally applies.