Ten years of monitoring pharmaceuticals and pesticides in the aquatic environment nearby a solid-waste treatment plant: Historical data, trends and risk assessment

The emission of contaminants of emerging concern (CECs) from wastewater treatment plants has been extensively studied; however, less attention has been paid to municipal solid waste treatment plants (MSWTPs), which can also be a potential source for CECs into surface water (SW) and groundwater (GW) ecosystems. In this work, the environmental impact of a MSWTP located in the province of Castelló, Spain, was studied along a period of ten years (from 2012 to 2022). A total of 173 water samples (including SW and GW) collected from the surrounding of this plant were monitored for 93 compounds (pharmaceuticals and pesticides) by using liquid chromatography coupled to tandem mass spectrometry with triple quadrupole. This study reveals the presence of several pharmaceuticals (e.g. primidone, gabapentin, azithromycin, clarithromycin, tramadol), particularly in GW samples collected near areas related to composting and storage of biostabilized material. The presence of antibiotic residues in GW raises concerns about the potential development of antimicrobial resistance. In addition, agricultural activities in the study area emerge as potential contributor to GW pollution by pesticides, as the MSWTP is located in an important agricultural area where citrus is the predominant crop. Some compounds that are currently prohibited for agricultural use (e.g. atrazine, simazine, chlorpyrifos) were also found, which highlights the importance of continuing their monitoring to assess their long-term environmental impacts. Several pesticide and pharmaceutical compounds exceeded the threshold values established by the EU groundwater directive. Therefore, a hazard assessment for GW ecosystems and for humans drinking contaminated GW resources was conducted. Our data indicated that some organophosphate insecticides (i.e., chlorpyrifos, carbofuran, pyridaphention) may pose high risks for groundwater crustaceans, while the risks for the human population were considered to be very low.