The Maximum residue limit is a value estimated for pesticides or veterinary drug residues in food. It is based on the assumption that good agricultural practice has been employed for the use of pesticides in farming, or good practice in the use of veterinary drugs. It is assumed that the product has been used in an appropriate manner and suitable withdrawal periods have been permitted. Since residues of pesticides and drugs may be broken down in tissue into various metabolites, MRLs are expressed either in terms of the amount of the parent compound remaining, or a metabolite that is representative of the residue of toxicological concern in the food. Estimates are usually made by comparing the acceptable daily intake (ADI) with a calculation of the total intake of the residue based on the MRLs and food intake data of these commodities for which MRLs have been established.