The adverse effects caused by the exposure to anthropogenic chemicals released into the aquatic environment were reported in various species. Due to their negative impact, the use of some of these chemicals was banned or their emission controlled. Nevertheless, new contaminants are continuously released and the undesirable effects are still unknown. Some pharmaceuticals and illicit drugs (PID) have been recognized as contaminants of emerging concern. Knowledge of the impact of these compounds, their metabolites and transformation products in living organisms is scarce but crucial for an accurate risk assessment and for the implementation of new directives and policies. Besides, most PID are chiral and enantiomers may differ in their biological responses. Thus, the aim of this project is to evaluate the ecotoxicological effects of the enantiomers of several PID as well as to investigate their enantioselective biodegradation and occurrence in aquatic matrices.