The application of multiple pesticides over the last decades has resulted in their frequent and in some cases long-term presence in soils as complex mixtures. This work assessed the toxicity of realistic pesticide mixtures to the springtail Folsomia candida observed in 11 case study sites. Each mixture was composed of five pesticides (as active substances or metabolites), chosen based on their occurrence in soil and expected risk to soil invertebrates. Reproduction tests were conducted in natural agricultural soil, and the springtails were exposed to three concentrations of the selected pesticides: the median environmental concentration (MEC), the predicted environmental concentration (PEC), and five times PEC (5PEC). No significant effect was observed at MEC exposure in any case study sites; however, effects on reproduction, adult survival, and adult size were observed at PEC and 5PEC exposures in five case study sites. Risk quotients (RQs) of individual pesticides were calculated by dividing the exposure concentrations (MEC, PEC, and 5PEC) by the no observed effect concentration values from the literature, and the sum of the five pesticides was calculated as ∑RQ in each case study site. The toxicity at PEC exposure was higher than expected based on the ∑RQ in two case study sites, indicating a possible synergistic mixture effect. This work provides new information on the effects of realistic pesticide mixtures. Further research is required to clarify whether the current risk assessment of individual pesticides adequately protects soil species from exposure to multiple pesticide residues that may occur in even more complex mixtures.

• Keywords
• collembola, mixture toxicity, plant protection products, soil ecotoxicology, soil invertebrates,
• MeSH
• Arthropods * drug effects   MeSH
• Soil Pollutants * toxicity   MeSH
• Pesticides * toxicity   MeSH
• Reproduction drug effects   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Soil Pollutants * MeSH
• Pesticides * MeSH

The use of pharmaceuticals entails a significant risk of environmental contamination. Wastewater treatment plants (WWTPs) are considered to be the main contributors to contamination as they ineffectively eliminate these compounds from wastewater. Simultaneously, they produce solid waste, sludge, which often contains a variety of retained pollutants, including pharmaceuticals. Since sewage sludge is frequently applied to agricultural soil due to its rich nutrient content, pollutants are introduced into the environment in this way. Only a few studies have been carried out on the topic of the analysis of pharmaceuticals in sludge. Therefore, information on the occurrence of pharmaceuticals in sludge is limited. The present study employed quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis to establish a simple and reliable procedure for determining 16 pharmaceuticals (antibiotics, anticonvulsants, antidepressants and β-blockers) in sewage sludge. The method has been thoroughly validated, and parameters such as linear range, accuracy, precision, matrix effects and detection and quantification limits were assessed. Our method achieved low limits of quantification (0.5-9.0 µg kg-1) and satisfactory recoveries (51-101%). Forty sludge samples from different WWTPs across the Czech Republic were analysed. Fourteen compounds were detected and quantified in most samples, with antidepressants having the highest detection frequency and overall content. Sertraline, with a mean concentration of 521.0 µg kg-1, was notably prevalent alongside its metabolite norsertraline (mean concentration 204.9 µg kg-1). The antibiotic azithromycin was also found at higher levels (mean concentration 185.1 µg kg-1).

• Keywords
• LC–MS/MS, Micropollutants, Pharmaceuticals, QuEChERS, Sewage sludge,
• MeSH
• Water Pollutants, Chemical analysis   MeSH
• Chromatography, Liquid MeSH
• Liquid Chromatography-Mass Spectrometry MeSH
• Pharmaceutical Preparations analysis   MeSH
• Environmental Monitoring methods   MeSH
• Wastewater chemistry   MeSH
• Sewage * chemistry   MeSH
• Tandem Mass Spectrometry * MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Water Pollutants, Chemical MeSH
• Pharmaceutical Preparations MeSH
• Wastewater MeSH
• Sewage * MeSH