Occurrence and effects of pharmaceuticals in estuaries

Pharmaceuticals have been identified as emerging contaminants of concern due to their widespread occurrence in the aquatic environment and potential to be biologically active, yet the implications of their presence in the environment is not fully known. There is a plethora of pharmaceuticals commercially available making it unfeasible to carry out detailed investigations on all of these compounds, and prioritisation schemes can provide a useful tool to determine how best to direct resources. Different prioritisation schemes were carried out on the fifty most prescribed drugs in the UK, and their results were compared in order to assess the efficacy of these schemes. Many failed to accurately identify these risks, but a holistic approach using more than one method to generate a priority list of compounds, may provide better protection for the environment. To date, most monitoring and ecotoxicological studies have focused on pharmaceuticals in freshwater, and there is less understanding of their occurrence and effects in estuaries. In order to gain insight into their spatio-temporal patterns, five pharmaceuticals were monitored in the Humber Estuary every other month for twelve months. Patterns in their spatial and temporal occurrence were related to source points, consumption patterns and environmental conditions. Eleven further estuaries were monitored to give an overall picture of pharmaceutical pollution in the UK. The Humber Estuary contained highest levels of pharmaceuticals and concentrations of ibuprofen were the highest measured globally. Finally, ragworms (Hediste diversicolor) were exposed to diclofenac and metformin in a controlled experimental exposure, and the expression of selected target genes, ATP synthase and c-amp activated protein kinase was measured. Highest levels of metformin (1 µg l-1) were found to significantly increase expression of ATP synthase, indicating that this drug induces environmental stress in H. diversicolor. Overall, this body of research has further contributed to the knowledge of pharmaceuticals as emerging contaminants in estuaries, and information on the occurrence, current levels and biological effects of the drugs studied may be of interest to regulators in their management decisions for such environments.