Management of Macrolide Antibiotics (Erythromycin, Clarithromycin and Azithromycin) in the Environment: A Case Study of Environmental Pollution in Lithuania

Of all the antibiotics used today for human treatment in the world, macrolide antibiotics-erythromycin, clarithromycin and azithromycin-stand out the most for misuse, and they were included as high-risk substances in the monitoring Watch List of Regulation 2018/840/EU. The aim of the present research was to investigate the level of target human pharmaceuticals' prevalence in the environment by the substance flow analysis (SFA) approach and to determine the potential risks of the antibiotics for the environment. The target for the environmental investigations was Lithuania. For SFA, 2021 consumption input data were used, and such key processes as the consumption rate, disposal and distribution of pharmaceuticals in the environment were analyzed. The analysis revealed that the largest part of pharmaceutical contaminants (80.1%) enters wastewater treatment plants. The risk quotient approach was based on the determination of predicted environmental concentrations (PECs), measured environmental concentrations (MECs) and their ratio to the predicted no-effect environmental concentrations (PNECs). The analysis revealed that clarithromycin causes a high potential risk for the aquatic environment in effluents from the wastewater treatment plants (WWTP); PEC/PNEC > 7. For azithromycin and erythromycin, the estimated PEC values were between 0.1 and 1. Clarithromycin concentration in the effluents of two target WWTPs showed a significant risk quotient (MEC/PNEC) of higher than 7. Recommendations on how to reduce the release of pharmaceutical residues into the environment have been proposed in the framework of the environmental management system.