Pharmaceuticals in groundwater
Pharmaceuticals and their metabolites occur in groundwater at around 15% of the monitoring sites throughout Switzerland. Groundwater resources in unconsolidated aquifers next to rivers are the most affected. The pharmaceuticals enter rivers and streams via sewers and sewage treatment plants, and finally infiltrate into groundwater.
According to the Waters Protection Ordinance (WPO), groundwater should generally contain no persistent synthetic substances. Primarily detected in groundwater are pharmaceuticals and radio-opaque substances used in human medicine. However, the concentrations are in most cases below 0.1 micrograms per litre (μg/l).
The three active substances most frequently detected in groundwater are the antiepileptic drug lamotrigine, the antibiotic drug sulfamethoxazole and the contrast agent amidotrizoic acid. Pharmaceuticals are mainly found at monitoring sites situated in catchment areas where watercourses carrying wastewater infiltrate into groundwater.