Medicines in water bodies: a glimpse into the complexity of environmental sustainability

This thesis investigates a critical aspect of healthcare sustainability: the presence and potential impact of medicines in the aquatic environment. Medicines primarily enter water bodies through human consumption, where they can have detrimental effects on flora and fauna, including facilitating the spread of antimicrobial resistance and impairing fish reproduction. This thesis, in Chapter 1, acknowledges the progress in integrating this issue into the broader framework of rational medicine use and emphasizes the importance of a unified definition to pave the way for practical interventions. Subsequently, actions that various stakeholders can adopt to prevent or mitigate the presence of medicines in water bodies are presented. However, without reliable data and quantitative measures of the risks posed by medicines, identifying effective intervention strategies remains challenging. To this end, Chapter 2 presents the current gold standard for quantifying the presence of medicines in water bodies, that is water sampling, and highlights the effort to compile such data from the published literature. Chapter 3 explores the application of existing methods for estimating water concentrations, emphasizing their limitations and how my research seeks to address them. This chapter covers advancements in spatial and temporal modelling that current methods overlook. Spatial modelling is illustrated through examples from existing literature and my study in Lombardia (Italy), while temporal modelling is discussed through time series analysis of wastewater concentrations in North Netherlands during my time at the University of Groningen. Chapter 4 focuses on the creation of a shared repository for effect measures, specifically Predicted No Effect Concentrations. Chapter 5 combines these data to derive risk estimates for medicines using both measured and predicted concentrations. Finally, Chapter 6 addresses the need for quantitative data on the effectiveness of mitigation measures. A simulation study is proposed to evaluate the feasibility of switching antidepressant prescriptions from high-risk to low-risk substances.