ABSTRACT
The use of antibiotics or other medications is common in modern agriculture because animals are held together in dense populations where the potential for disease outbreak is high. Drugs can be used therapeutically, to cure existing disease, or prophylatically, to minimize the potential for disease threat across a population. Often, however, they are used subtherapeutically as growth promotants to increase feed conversion. The possibility of drug residues remaining in the edible product and the potential human health problems associated with exposure to these residues is a concern because of the widespread drug use in food animals. The actual public health significance of drug use in animal agriculture and of their residues in food of animal origin is an area of much debate. Recently the National Research Council convened a group to evaluate the benefits and risks of using drugs in the animal food industry (National Research Council, 1999). They identified antimicrobial resistance of disease-causing bacteria as the most serious risk associated with the continued use of drugs in food animals. Animals fed low (subtherapeutic) levels of antibiotics may develop bacterial infections that evolve to be impervious to these drugs. Humans may be exposed to these bacterial populations in the environment or during preparation or consumption of food. A task force consisting of several U.S. government agencies has formulated a public health plan to combat antimicrobial resistance, including ways to limit the spread of drug resistance due to agricultural applications (Center for Disease Control, 2001). In addition, some animal drugs may cause an immediate adverse reaction, such as allergic response, in susceptible human populations. Therefore, it is important to regulate the improper use of animal drugs by monitoring animal tissues or the resulting food products for drug residues.
