ABSTRACT
Pharmaceuticals are used extensively in both human and veterinary medicine. Many are excreted in the feces and urine as the nonmetabolized parent compound and, consequently, may be present in municipal biosolids and livestock manure. Because biosolids and manure are valuable sources of nutrients for crop growth, the use of these materials as a fertilizer is widespread in many agricultural areas. Consequently, use of biosolids and manure as fertilizer may be a potential source of pharmaceutical contamination of surface and ground water via surface runoff and leaching, respectively. Other sources of water contamination by pharmaceuticals include municipal sewage discharge, aquaculture, and inappropriate disposal1 (Figure 8.1). Some pharmaceuticals detected in environmental waters are known to exhibit hormonal activity with the potential to disrupt normal endocrine function.2 There is also concern that the presence of veterinary antimicrobials in environmental waters may accelerate the development of antimicrobial-resistant bacteria. While there is no clear evidence that the transfer of antimicrobial resistance and that the selection for resistant microbial agents occur at antimicrobial concentrations found in the environment, the spread of resistant bacteria and resistance genes by use of biosolids and manure on the agricultural landscape is not yet fully understood. Thus, in recent years, concern over the impact, fate, and transport of both human and veterinary pharmaceuticals entering the environment has gained much attention.3 In Canada, water quality has become an important issue with the public both in terms of safety of drinking water and in terms of protecting and conserving aquatic ecosystems.
