The agricultural production of food and animal feed on an economically competitive basis requires an ever-increasing application of pesticides. “Pesticide” is a general term that includes a variety of chemical and biological products to eliminate or control pests, such as fungi, insects, rodents, and weeds (fungicides, insecticides, rodenticides, and herbicides, respectively). In the European Union (EU), approximately 320,000 tons of active substances are sold every year, which accounts for one quarter of the world market [1]. Residues in fruits and vegetables, cereals, processed baby food, and foodstuffs of animal origin are controlled through a system of statutory maximum residue limits (MRLs), which are defined as “The maximum concentration of pesticide residue (expressed as mg residue/kg commodity likely to occur in or on food commodities and animal feeds after the use of pesticides according to good agricultural practice” [2]. MRLs vary ordinarily within the range 0.0008–50 mg/kg [3], and they are typically between 0.01 and 10 mg/kg for the adult population. Lower values of MRLs are set for baby food: The EU specified a MRL of 0.010 mg/kg [4]; the lowest levels are set for particular special residues [5].