SinS - Abstract

Abstract Information :

Water and effluent quality monitoring methods in the UK are predominantly focused on organic matter (nitrogen, phosphorus levels) whereas pharmaceuticals and their transformation products (TPs) are not monitored routinely in river water. A European Commission report in 2020 details a shortlist of several anti-microbial pharmaceuticals in the next EU Water Framework Directive (WFD) “watch list” to be closely monitored in inland surface waters and to further the understanding of any effects. Antimicrobials such as sulfamethoxazole and clotrimazole are pharmaceuticals that are of particular concern. These compounds are increasingly being detected in surface water and soils across Europe and are toxic and mobile in the aquatic environment. High resolution analytical methods have been developed for in silico identification of active pharmaceutical ingredients (APIs) and their TPs but do not provide information about the mechanisms or pathways of transformation. This project aims to fill a research gap in the lack of predictive understanding of API transformation and degradation by determining the transformation rate of prioritised compounds and investigate their transformation pathways to gain a better understanding of their fate in river water. River water samples were collected from wastewater affected sites including River Wandle, Hogsmill River, Grand Union Canal, River Lea and River Brent. These rivers and sites were in proximity to major London treatment works and were analysed using a suspect screening workflow compared to a commercial library of 1,195 compounds. A total of 45 compounds were identified from the library with 7 parent compounds and 7 accompanying transformation products identified. Compounds of interest to be shortlisted were prioritised in terms of occurrence and by risk quotient which included carbamazepine, lamotrigine and venlafaxine (all medium risk). Predicted No Effect Concentration (PNEC) values for each of the detected compounds were found using the Norman Ecotoxicology Database. Although apixaban had the lowest PNEC value at 0.015 ng/L venlafaxine and carbamazepine had the second and third lowest values at 0.038 and 0.05 ng/L, respectively and are also currently monitored in the EU WFD “watch list”. Online predictive transformation tools including BioTransformer (BT) 3.0 and EAWAG-Biocatalysis/Biodegradation Database/Pathway Prediction System (EAWAG—BBD/PPS) were used to predict TPs for the most occurrent parent compounds found in river water samples - amisulpride, sulpiride and cetirizine had the most predicted TPs at 26, 23 and 17 respectively. Future analysis will look at targeted quantitative analysis on spiked river water and sterile artificial freshwater in aerated glass containers using LC-MS/MS to measure the amount of transformation of shortlisted pharmaceuticals in river water over time up to 6 months (using at least two environmentally relevant concentration levels of 200 and 2000 ng/L). Microbial analysis on these samples will also be conducted to observe what microbial communities may be involved in transformation and to what extent. The microbial and chemical data derived from these studies will be used to create a machine learning based model that can help predict the biotransformation of pharmaceuticals in river water.