Pharmaceuticals (antibiotics and hormones)
Veterinary pharmaceuticals can be used to promote growth, fight disease, or provide other therapeutic goals. USEPA estimates that between 60 and 80 percent of all livestock and poultry receive some type of antibiotic during their life (USEPA, 2003a). Almost all antibiotics and other pharmaceuticals given are eventually excreted in urine and bile either unchanged or in metabolite form. The release of antibiotics to the environment may contribute to the emergence of strains of pathogens that are more resistant to antibiotics (USEPA, 2003a). Drug residues in animal food products are also of potential concern for adverse impacts on human health.
Hormones are used to increase growth and productivity in the dairy, beef, and poultry industries. Such hormones can include estrogens, estradiol, progesterone, and testosterone, as well as their synthetic counterparts. Some hormones are known or suspected of interfering with the endocrine system of various species, including humans, and can affect the reproductive biology of fish and aquatic vertebrates species. Although steroids and other hormones adsorb to soil and sediment, they are often sufficiently mobile to impact water quality and have been reported in surface and groundwater following cattle manure and poultry litter land application (Shore et al., 1993). Hormones have also been detected in wastewater samples from dairy farms and aquaculture (Kolodziej et al., 2004).
- USGS studies of pharmaceuticals in animal wastes - the data from these studies demonstrate that veterinary pharmaceuticals are excreted and frequently occur at detectable levels ranging from ppb to ppm concentrations in liquid and solid waste.
- USGS 1999-2000 National Reconnaissance - detected a variety of pharmaceuticals and hormones in US surface waters downstream of areas with intense livestock production. The measured concentrations were generally low and rarely exceeded drinking water guidelines, health advisories, or aquatic-life criteria (Kolpin et al., 2002).
- USGS website on pharmaceuticals and other emerging contaminants in the environment.