Aquatic ecosystems throughout the world are exposed to an increasing pressure from various anthropogenic sources that release large variety of potentially harmful synthetic organic contaminants, including pharmaceutically active compounds. Most of the environmental studies of pharmaceuticals are focused mainly on the determination of parent compounds and encompass only one environmental compartment. Such simplified approach often underestimates the ecotoxicological relevance of a contaminant class, either by neglecting the contribution of its transformation products or by overlooking some critical mechanisms that may pose a threat to the environmental safety and human health. As opposed to that, this project aims at demonstrating the importance of the comprehensive assessment of aquatic contaminants, based on the study of two important groups of pharmaceuticals, macrolide antibiotics (MAs) and opioid analgesics (OAs), by including their main transformation products (TPs) and addressing the issue of physico-chemical partitioning in the exposure assessment.
The project work plan envisages development of dedicated class-specific methods for the concurrent quantitative analysis of the target contaminants and their known TPs using liquid chromatography- tandem mass spectrometry (LC/MS/MS), while identification of unknown TPs will be performed using LC coupled to high-resolution mass spectrometry employing time-of-flight (TOF) mass analyzer. The transformation processes of selected contaminant classes will be systematically studied in laboratory-controlled conditions with a special emphasis on biotransformation and ozonation. The biotransformation experiments will be performed using well-characterised mixed microbial communities isolated from contaminated natural habitats. The transformation studies will encompass the determination of dissipation kinetics of the parent compounds as well as identification of TPs. Possible ecotoxicological importance of the transformation processes will be evaluated using a combination of exposure-driven and effect-driven approaches. Finally, the project envisages verification of the relative importance of TPs in real systems, including wastewater treatment plants and ambient surface waters.