A refined approach to estimate exposure for use in calculating the Maximum Residue Limit of veterinary drugs

Maximum Residue Limits (MRLs) are standards that represent the maximum residue concentration expected to be found if a veterinary drug is administered according to good practice in the use of veterinary drugs (GVP). MRLs are established only where the exposure to residues in food resulting from particular use patterns of the veterinary drug pass a public health risk assessment. The current model diet as used by major regulators overstates mean consumption of food for populations when compared to results from food surveys of actual consumption. Exposure to residues is overestimated when calculating long-term (chronic) exposure using the model diet leading to the risk to consumers being overstated. Additionally the model diet underestimates the size of large portions eaten by the group of consumers that eat large quantities of a particular food in a single meal potentially leading to understating of risks associated with exposure to residues of drugs that produce an adverse effect after a single exposure. A revision of dietary consumption figures is proposed that will better match the consumption figures used in point-estimates of dietary exposure to the timeframe for consumption that is relevant to the reference dose.

► We examine exposure calculations used in setting MRLs for residues of veterinary drugs in food. ► We propose new methodology including revised food consumption figures. ► The new methodology reflects advances in exposure assessment and standard setting. ► It increases consistency with approaches used for pesticides, contaminants, and food additives.