Maximum residue limit means the maximum concentration of residues (expressed as μg marker residue per kg of edible wet tissue or product) which may be accepted by the Community to be legally permitted or recognised as acceptable in food. It is based on the type and amount of residue considered to be without any toxicological hazard for human health as expressed by the ADI. An MRL cannot be set in the absence of an ADI.
When establishing MRLs for feed additives, consideration is also given to residues that come from other sources (e.g., food of plant origin). Furthermore, the MRL may be reduced to be consistent with the conditions of use of feed additives and to the extent that practical analytical methods are available.
Where appropriate, individual MRLs (expressed as mg marker residue per kg of edible natural tissue or product) shall be set for different tissues or products of the target animal species. The individual MRLs in different tissues or products shall reflect the depletion kinetics and the variability of the residue levels within those tissues/products in the animal species intended for use. Variability shall normally be reflected by using the 95 % confidence limit of the mean. If the confidence limit cannot be calculated due to a low number of samples, variability is expressed by taking the highest individual value instead.
Studies concerning the Maximum Residue Limits of coccidiostats and histomonostats must be carried out following the appropriate rules in force for veterinary medicinal products (Volume 8 ‘The rules governing medicinal products in European Union — Notice to applicants and guidelines. Veterinary medicinal products. Establishment of maximum residue limits (MRLs) for residues of veterinary medicinal products in foodstuffs of animal origin’. October 2005).
The studies to establish maximum residue limits for additive categories other than coccidiostats and histomonostats, where necessary, shall be provided according to this Annex.
To determine the consumer exposure to the total residues (as calculated under 3.2.3.3.), the proposed MRLs for the different tissues or products shall take into account the ratio of marker residue to total residue (Table 2).
Definitions used in deriving an MRL
| i-j | Individual tissues/products (liver, kidney, muscle, skin + fat, milk, eggs, honey) at different times |
| MRLi-j | Maximum residue limit in tissues/products (mg marker substance kg-1) |
| Qti-j | Daily human consumption of individual tissues/products (kg) set by Table 1 or its refinement |
| TRCi-j | Total residue concentration in individual tissues/products (mg kg-1) |
| MRCi-j | Marker residue concentration in individual tissues/products (mg kg-1) |
| RMTRi-j | Ratio MRCi-j to TRCi-j for individual tissues/products |
| DITRi-j | Dietary intake for individual tissues/products calculated from total residues (mg) DITRi-j = Qti-j x TRCi-j |
| DITRMRLi-j | Dietary intake calculated from MRLs (mg) of individual tissues/products DITRMRLi-j = Qti-j x MRLi-j x RMTRi- j -1 |
The measured values for TRC and MRC shall be inserted as appropriate in the template shown in Table 3, and the other values calculated. Where a full data set is not available because values fall below the limit of detection (LOD), an extrapolation of RMTR may be acceptable.
Deriving an MRL can only be performed if the sum of the individual DITRs is below the ADI. If the ADI is exceeded, an alternative would be to use data from a longer withdrawal time or lower dosages. A first proposal for an MRL can be obtained using the MRC value as a guide and taking into consideration the LOQ of the analytical method. The sum of the DITRMRL obtained from the proposed MRLs must be below the ADI and close to the sum of the individual DITRs. If the ADI is exceeded, then a lower MRL shall be proposed and the comparison repeated.
For certain additives, residues could arise below the MRL values in milk, eggs or meat which could nonetheless interfere with food quality in particular food processing procedures. For such additives, it may be appropriate to consider a ‘maximum (food product) processing compatible residue’ (MPCR) in addition to establishing MRL values.