ABSTRACT
INTRODUCTION Trace quantities of human pharmaceuticals or their metabolites have been identified in many countries in various aquatic environments including sewage treatment plant (STP) effluents, surface waters, seawaters, groundwater, and some drinking waters (1). Of particular concern is the potential for contamination of fresh water, which is a highly finite resource. As most of the water on our planet is salty, only 3% is fresh and only around a third of this is accessible for human use, the remainder being frozen in glaciers and permanent snow (2). Advances in environmental analysis have enabled the detection of increasingly low levels of drug residues and evidence of their widespread distribution, particularly in treated wastewater and surface water (1), could be a cause for concern mainly in respect of possible effects on aquatic organisms (3). On the other hand, drug residues may well be present at concentrations significantly below those that cause adverse effects in aquatic environments (4,5). Consequently, regulatory approaches in dealing with pharmaceuticals in the environment have assumed that, unless there is evidence to the contrary for a particular therapeutic class, adverse effects are unlikely unless a threshold concentration is exceeded, and that environmental testing is required only when this threshold is crossed.
