Fate and Distribution of Steroid Drugs and Conjugates in Wastewater Treatment Plants and River:Application of LC-HRMS based suspect screening

Steroid drugs(SDs) have emerged as significant environmental pollutants due to their strong bioactivity and potential to disrupt endocrine systems. In this study, the occurrence of steroid drugs and their conjugates was investigated in wastewater treatment plants and natural river waters. A total of 57 steroid compounds, including parent drugs and conjugated forms, were screened using a suspect screening approach based on liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Sampling was conducted in the Nakdong River around the Daegu and Busan regions of South Korea, as well as five wastewater treatment plants in 5 different regions.Among the screened compounds, testosterone sulfate and nandrolone acetate were identified with high confidence and were frequently detected in influent samples, exhibiting strong signal intensities. These compounds were effectively removed during the wastewater treatment processes, particularly after the bioreactor and nitrification-denitrification stages. However, no high-confidence detections were observed in river water samples, suggesting that these substances were either effectively removed or diluted to concentrations below the detection limit. This study demonstrates the effectiveness of LC-HRMS-based suspect screening for tracking steroid contaminants in aquatic environments. It also underscores the importance of monitoring not only parent steroid drugs but also their conjugated and potentially bioactive metabolites to fully assess environmental risks.