Uptake of pharmaceuticals into benthic invertebrates

The occurrence, fate and, uptake of active pharmaceutical ingredients (APIs) in the environment has received increasing attention from the scientific community. Research investigating the uptake of APIs into invertebrates is still limited specifically for benthic invertebrates. Therefore, the research presented in this thesis, evaluated the fate of pharmaceuticals in sediment and their uptake into the sediment-dwelling worm Lumbriculus variegatus. The experiments in the different chapters were conducted in order to explore the influence of compound physicochemical properties and sediment characteristics on the uptake of ionisable pharmaceuticals into the lumbricids. An initial evaluation of Quantitative Structure Actvity Relationships for bioconcentration was performed using existing representative fish and invertebrate bioconcentration data to elucidate whether these models were suitable for predicting the uptake of ionisable chemicals and what properties are essential in predicting the ionisable chemical uptake. Laboratory experiments were performed to measure the uptake of four APIs into the worms via water-only exposure at different pH values. For the bases, the bioconcentration factor (BCF) increased with the increase of the water pH. The opposite was observed for the acidic diclofenac (higher uptake at lower pH). The sorption behaviour of three APIs in four types of sediments was also evaluated. Sorption coefficients revealed that the sorption behaviour of the weak basic compounds was driven by the organic content, whereas, the sorption behaviour of diclofenac was driven by the pH. The influence of sediment properties on the uptake of the ionisable APIs into sediment-dwelling lumbricids was investigated for three APIs on two sediment types. With these experiments, we demonstrated differences in bioaccumulation of the two basic APIs and one acid into L. variegatus and how uptake varies across two sediments possessing diverse properties. In conclusion, our experimental findings produced knowledge on the fate and the uptake of ionisable pharmaceuticals in the water-sediment compartment.