Europe’s grey water footprint of human pharmaceuticals

Human pharmaceuticals have been detected in surface waters around the globe (Wilkinson et al. 2022), posing risk to ecosystems (Bouzas‐Monroy et al. 2022; Fent et al. 2006) as well as to human exposure through e.g. swimming (Duarte et al. 2022), entering drinking water (Zanni et al. 2025) or the food chain (Sleight et al. 2023). While the presence of pharmaceuticals in Europe has been proven through measurements widely (compared to other global regions) (Dusi et al. 2019), spatially explicit modelling approaches – including historical development of pharmaceutical pollution - rarely exist. This study addresses this shortcoming by presenting the grey water footprint and related water pollution levels of selected human pharmaceuticals across Europe from 1990-2019.

The grey water footprint is a volumetric indicator for water pollution, defined as the ratio of pollutant load to the maximum allowed concentration. For this study, the load was determined based on pharmaceutical sales data, human excretion rates and waste water treatment removal rates (Wöhler et al. 2020). Respective data was acquired through public sources and scientific literature. Both, spatial and temporal gaps were addressed by inter-and extrapolation and assumptions. For the maximum allowed concentration, EU’s WFD water quality standards and literature values are used. Resulting grey water footprints are compared to the available runoff to indicate water pollution levels (WPL) per (sub)catchment.

The results present the first Europe-wide grey water footprint analysis over a timespan of three decades. WPLs make an interpretation of the severity of pollution possible, indicating temporal trends and geographical hotspots.

References

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Duarte, Daniel J., Rik Oldenkamp, and Ad M. J. Ragas. 2022. “Human Health Risk Assessment of Pharmaceuticals in the European Vecht River.” Integrated Environmental Assessment and Management 18 (6): 1639–54. https://doi.org/10.1002/ieam.4588.

Dusi, E., M. Rybicki, and D. Jungmann. 2019. The Database “Pharmaceuticals in the Environment” - Update and New Analysis. German Environment Agency (UBA).

Fent, Karl, Anna A. Weston, and Daniel Caminada. 2006. “Ecotoxicology of Human Pharmaceuticals.” Aquatic Toxicology 76 (2): 122–59. https://doi.org/10.1016/j.aquatox.2005.09.009.

Sleight, Harriet, Alistair B. A. Boxall, and Sylvia Toet. 2023. “Uptake of Pharmaceuticals by Crops: A Systematic Review and Meta-Analysis.” Environmental Toxicology and Chemistry 42 (10): 2091–104. https://doi.org/10.1002/etc.5700.

Wilkinson, John L., Alistair B. A. Boxall, Dana W. Kolpin, et al. 2022. “Pharmaceutical Pollution of the World’s Rivers.” Proceedings of the National Academy of Sciences 119 (8): e2113947119. https://doi.org/doi:10.1073/pnas.2113947119.

Wöhler, Lara, Gunnar Niebaum, Maarten Krol, and Arjen Y. Hoekstra. 2020. “The Grey Water Footprint of Human and Veterinary Pharmaceuticals.” Water Research X 7 (May): 100044. https://doi.org/10.1016/j.wroa.2020.100044.

Zanni, Stefano, Vincenzo Cammalleri, Ludovica D’Agostino, Carmela Protano, and Matteo Vitali. 2025. “Occurrence of Pharmaceutical Residues in Drinking Water: A Systematic Review.” Environmental Science and Pollution Research 32 (16): 10436–63. https://doi.org/10.1007/s11356-024-34544-8.