Veterinary drugs are used in dairy cattle management mainly for therapy and prophylaxis of diseases, which chemicals may leave residues in milk. Human exposure and the unintentional consumption of residues of drugs can lead to side effects and development of resistant bacteria, representing a considerable concern to consumer health. This paper presents the occurrence of residues of veterinary drugs in milk from 2009 to 2011 in Brazil, monitored by the Official Program for Analysis of Residues of Veterinary Drugs in Foods of Animal Origin. A total of 961 samples were collected in the retail and evaluated for the main β-lactams, tetracyclines, amphenicol, aminoglycosides, quinolones, sulfonamides and avermectins. Residues of veterinary drugs did not exceed maximum residue limit (MRL); although, there is a considerable use of critically/highly important antimicrobials and avermectins in dairy cows, especially quinolones and tetracyclines. Doxycycline (9%) and abamectin (1.6%) were detected, even though these substances are not intended to be used in milk producing animals for human consumption. Norfloxacin (15%) was observed; although, there are no MRL established, consequently, no residue level should have been detected. No residues of streptomycin, chloramphenicol and β-lactams were confirmed. Milk in Brazil contains low levels of veterinary drugs so that toxicological risk regarding milk consumption could not be considered as a public health concern. However, due to the nature of the samples, which correspond to milk from several farms, it could occur a dilution effect. The absence of MRL established for norfloxacin prevents suitable interpretation of the findings and makes tough the control of these chemical residues in food. Detection of some antimicrobials and avermectins may be linked to extra-label use or noncompliance withdrawal periods suggesting that good veterinary practices are not being followed, since residues of unauthorized drugs have been detected.
maximum residue limit; milk monitoring; toxicological risk; veterinary drugs