Veterinary Medicines and the Environment
Veterinary medicines are often used in circumstances where they may enter the natural environment in significant quantities, for example through the use of ectoparasiticides in animals or by direct discharge of spent sheep dip into rivers. However, the mass medication of farm animals with other drugs including antimicrobials and endectocides may also result in environmental contamination, largely through elimination in urine and faeces. These drugs may add to the burden of contamination caused by human medicines, which usually arise in the environment from elimination in urine and faeces followed by entry into the sewerage systems. These sources of pollution present a dilemma as the only certain way to prevent environmental contamination is to prevent the use of medicines, something which is not considered to be acceptable in human or veterinary medicine. To make matters worse, the adverse effects of environmental contamination with medicinal products are not at all clear. However, some agents may be toxic to animals and plants, while others may act as endocrine disrupting chemicals.