The maximum residue limit has been set on the basis of information obtained on the safety of the substance and its residues in animal tissue. Other factors considered include the potential effects of the substance on microbes, and its dynamics in humans. This data is used to specify an acceptable daily intake (ADI) for humans, which is then used to specify the actual MRL. The MRL value is set at such a level that the intake of a medicinal substance in foods does not exceed the acceptable daily intake for humans.
Because the absorption, distribution, metabolism and secretion of different medicinal substances vary in different species, the MRL for one substance may be different for different species. If results reveal that the residues are not harmful for human health, it may be deemed that no MRL is required.
In the European Union, the maximum residue limits (MRL) of pharmacological substances are assessed by the Committee for Medicinal Products for Veterinary Use (CVMP) of the European Medicines Agency (EMA).