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.

Estimation methods for Maximum Residue Limits for pesticides.

Maximum Residue Limits (MRLs) are standards that represent the maximum residue concentration expected to be found if a pesticide is applied according to good agricultural practice (GAP). MRLs are established only where the residues in food resulting from particular use patterns of the pesticide pass the public health risk assessment. Foodstuffs are monitored for MRL compliance and MRL exceedance can have economic and trade consequences. There is a trade-off when deciding on values for MRLs. The aim is to establish MRLs at levels that are high enough to prevent chance exceedance but not so high that misuse will not be detected. Small data sets typically available for estimating MRLs present problems for establishing consistent values. A review of MRL estimation methods is presented together with an assessment of the various methods.

A review of the effect of different application rates on pesticide residue levels in supervised residue trials.

Residue trial data reported by the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) have been reviewed to establish whether or not the resulting residues in harvested commodities are proportional to the pesticide application rate used on the crop. Numerous sets of trials were identified where the only parameter varied was application rate or spray concentration. Analysis of this database in terms of application rate, spray concentration, formulation type, preharvest interval, crop, pesticide, residue level and application type confirms that residues scale with application rate (proportionality principle). It is anticipated that use of the proportionality principle by regulators and those interested in evaluating pesticide residue data will improve pesticide risk assessment.