The notion of "maximal residue limit" (MRL) takes into account a combination of data of three different sources: toxicity studies in laboratory animals, tissular distribution of veterinary drugs in animal species producing food-stuffs and habits of consumption by human beings. The determination of MRL is intended to protect the consumer from any risk due to the possible presence of dangerous residues in food-stuffs such as meat, offal milk,. The present article intends to explain the notions of admissible daily intake, MRL and withdrawal time, and to show their consequences, taking into account their ever evolving political context.