Modeling the use and end-of-life phase of pharmaceuticals in support of a life cycle inventory analysis – Case study on different antibiotics in Germany

Abstract

More focused measurements on antibiotics in the environment enable a more accurate assessment of potential risks to human health and ecosystems. Therefore, antibiotics are ranked as highly relevant with efforts to monitor and systematically map them (e.g., German Antibiotic Resistance Strategy, European Antimicrobial Resistance Surveillance Network, Global Antimicrobial Resistance Surveillance System). Due to limited life cycle analysis data, a recently developed life cycle inventory model to assess the use and end-of-life phase of pharmaceuticals in Germany is applied and reviewed for antibiotics, representatively for amoxicillin, ciprofloxacin and clarithromycin. Necessary data are collected from experimental research, publications by official agencies and data fact sheets by pharmaceutical companies, among others. To evaluate the model's accuracy and prediction potential, the results are compared to literature findings. The model predicts the emission pathway via the sewage treatment effluent to be the primary route ranging from 39.5% (clarithromycin) to 67% (amoxicillin). Accumulation in the sewage sludge is relevant for ciprofloxacin (24.3%) whereas clarithromycin shows the highest biodegradability (15.8%). Gaseous emissions are not predicted. Modeling of metabolites is not reliable because of major data gaps regarding the chemical structure and coherent physicochemical properties. The results highlight that currently neglected transformation processes (especially hydrolysis) need to be implemented prospectively to reclassify the gained results. Investigation of other software than SimpleTreat 4.0 should be done to display the fate of substances in sewage treatment plants more precisely. Also, more experimental, and scientifically assured data are needed to confirm the ratio of the antibiotics' pathways.