Drug Residues in Foods of Animal Origin and Their Impact on Human Health: Review

The safety of human food is threatened by various agents including pathogenic microorganisms, and antimicrobial agents. Antibiotics are natural products of a micro-organism, or similar semi-synthetic products that inhibit the growth or destroy microorganisms. Residues of veterinary medicines are defined as pharmacologically active substances, principles, or degradation products and their metabolites, which remain in foodstuffs obtained from animals that have been administered the veterinary medicine. The most common causes for the presence of antibiotic residues in food of animal origin are violation of withdrawal periods, overdosing of antibiotics and use of inaccurate routes of administration of drugs. Drug residues concentrations vary from tissue to tissue and are generally observed to be higher in tissues of storage such as body fat or in organs that actively metabolize and excrete them. Probably the most common way milk is contaminated by penicillin is through intra-mammary infusion of the drug in the treatment of mastitis. The presence of antibiotics or their metabolites in food is potentially hazardous to health as it may cause allergic reactions in people and antibiotic resistance in pathogenic microorganisms. Some antibiotics like streptomycin, neomycin and gentamicin has been reported to cause damage to the kidney and to hearing. Allergic reaction to the human body mostly resulted from β -Lactam antibiotics. Anaphylactic reactions are reported to result from consumption of beef or pork containing penicillin. Drugs in which their residues induce cancer in humans or consumers are: nitrofurans, nitroimdazoles, etc. Antibiotics are invariably administered to dairy cattle, but their indiscriminate use, without adequate technical and veterinary control, can lead to a series of negative consequences at all levels of the dairy productive chain. Many antibacterial and anticoccidial drugs are licensed for use in poultry for treatment of enteric and respiratory disease. Potential adverse effects of drugs that appear as residues in food animals are: carcinogenic, allergic, toxic, neurologic disorder and microbiological effects.