Antibiotic residues in final effluents of European wastewater treatment plants and their impact on the aquatic environment

Sara Rodríguez-Mozaz ,Thomas Jaeger,Damià Barceló,Christian Elpers,Sara Schubert,Isabel Henriques,Célia M Manaia,Marko Virta,Marta Llorca,Fiona Walsh,Erik Paulshus,Thomas Schwartz,Saulo Varela Della Giustina,Thomas U Berendonk,Katariina Pärnänen ,I Michael-Kordatou ,José Luis Martínez ,Thi Thuy ,Despo Fatta‐Kassinos ,Kristin O’sullivan ,Ivone Vaz‐Moreira

doi:10.1016/j.envint.2020.105733

Abstract

A comprehensive monitoring of a broad set of antibiotics in the final effluent of wastewater treatment plants (WWTPs) of 7 European countries (Portugal, Spain, Ireland, Cyprus, Germany, Finland, and Norway) was carried out in two consecutive years (2015 and 2016). This is the first study of this kind performed at an international level. Within the 53 antibiotics monitored 17 were detected at least once in the final effluent of the WWTPs, i.e.: ciprofloxacin, ofloxacin, enrofloxacin, orbifloxacin, azithromycin, clarithromycin, sulfapyridine, sulfamethoxazole, trimethoprim, nalidixic acid, pipemidic acid, oxolinic acid, cefalexin, clindamycin, metronidazole, ampicillin, and tetracycline. The countries exhibiting the highest effluent average concentrations of antibiotics were Ireland and the southern countries Portugal and Spain, whereas the northern countries (Norway, Finland and Germany) and Cyprus exhibited lower total concentration. The antibiotic occurrence data in the final effluents were used for the assessment of their impact on the aquatic environment. Both, environmental predicted no effect concentration (PNEC-ENVs) and the PNECs based on minimal inhibitory concentrations (PNEC-MICs) were considered for the evaluation of the impact on microbial communities in aquatic systems and on the evolution of antibiotic resistance, respectively. Based on this analysis, three compounds, ciprofloxacin, azithromycin and cefalexin are proposed as markers of antibiotic pollution, as they could occasionally pose a risk to the environment. Integrated studies like this are crucial to map the impact of antibiotic pollution and to provide the basis for designing water quality and environmental risk in regular water monitoring programs.

Highlights

A comprehensive monitoring of a broad set of antibiotics in the final effluent of wastewater treatment plants (WWTPs) of 7 European countries (Portugal, Spain, Ireland, Cyprus, Germany, Finland, and Norway) was carried out in two consecutive years (2015 and 2016)
The concentration values measured in our study are in agreement with those found in final effluents of other European WWTP, as reported by other authors (Johnson et al, 2017; Lindberg et al, 2005; Senta et al, 2013; Gracia-Lor et al, 2011; Birošová et al, 2014) and in particular by Carvalho and Santos in their review on the occurrence of antibiotics in wastewater and different environmental matrices (Carvalho and Santos 2016) and, most recently, in the report by the European Commission Joint Research Center (JRC) (Sanseverino et al, 2018) where concentrations in WWTP effluents for the majority of antibiotics were between 0.1 and 1 μg/L
Ciprofloxacin, azithromycin, and cefalexin were selected as markers of antibiotic pollution and are suggested to be used for widespread temporal and geographical characterization of environmental water or WWTP effluents

Summary

Introduction

A comprehensive monitoring of a broad set of antibiotics in the final effluent of wastewater treatment plants (WWTPs) of 7 European countries (Portugal, Spain, Ireland, Cyprus, Germany, Finland, and Norway) was carried out in two consecutive years (2015 and 2016). The current study was motivated by the need for water monitoring at an international level to acquire reliable and comparable analytical data concerning antibiotics occurrence With this aim, the final effluent of 13 WWTPs located in 7 European countries (Portugal, Spain, Ireland, Cyprus, Germany, Finland, and Norway) was sampled twice (early Spring and early Autumn) in two consecutive years (2015 and 2016) and was monitored for 53 antibiotic residues belonging to 10 different therapeutic classes. The specific objectives of the study were: (i) to provide an overview of the presence and concentration of antibiotics in final effluents of WWTPs located in different European countries; (ii) to assess geographical and temporal trends about the occurrence of these contaminants; (iii) to infer about the potential environmental and human health risk posed by antibiotic residues in final treated wastewater effluents; and (iv) to propose robust analytical tools and indicator compounds to be used in regular water-monitoring programs, making feasible the comparison of country-based studies

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