Molecular Characterization of Estrogen Receptor Agonists during Sewage Treatment Processes Using Effect-Directed Analysis Combined with High-Resolution Full-Scan Screening

Abstract

Endocrine-disrupting potential was evaluated during the sewage treatment process using in vitro bioassays. Aryl hydrocarbon receptor (AhR)-, androgen receptor (AR)-, glucocorticoid receptor (GR)-, and estrogen receptor (ER)-mediated activities were assessed over five steps of the treatment process. Bioassays of organic extracts showed that AhR, AR, and GR potencies tended to decrease through the sewage treatment process, whereas ER potencies did not significantly decrease. Bioassays on reverse-phase high-performance liquid chromatography fractions showed that F5 (log K OW 2.5–3.0) had great ER potencies. Full-scan screening of these fractions detected two novel ER agonists, arenobufagin and loratadine, which are used pharmaceuticals. These compounds accounted for 3.3–25% of the total ER potencies and 4% of the ER potencies in the final effluent. The well-known ER agonists, estrone and 17β-estradiol, accounted for 60 and 17% of the ER potencies in F5 of the influent and primary treatment, respectively. Fourier transform ion cyclotron resonance mass spectrometry analysis showed that various molecules were generated during the treatment process, especially CHO and CHOS (C: carbon, H: hydrogen, O: oxygen, and S: sulfur). This study documented that widely used pharmaceuticals are introduced into the aquatic environments without being removed during the sewage treatment process.

Effect-Directed Analysis Combined with Nontarget Screening to Identify Unmonitored Toxic Substances in the Environment

“…However, this step can be performed only on compounds for which standard materials are available. Such materials are frequently unavailable , or cannot be purchased due to their high cost or export/import restrictions . In such instances, in silico modeling and toxicity prediction databases can be utilized to predict the toxicological potencies of chemicals, providing insights into their toxicity mechanism, effective concentration (EC), and inhibitory concentration .…”

“…6,10 When the BEQ chem and BEQ bio are similar, the analyzed compounds account for most of the responses (Figure 2, Case 2). 11,30 For most environmental samples, the BEQ chem is much smaller than the BEQ bio (Figure 2, Case 3), indicating the presence of unknown toxic substances. 4,49 When the newly identified toxic substances explain a significant portion of the induced toxicity, EDA combined with NTS can be considered successful; when these compounds do not substantially increase the explanatory power, the major toxic substance has not been identified.…”

“…In recent years, the identification of novel toxic substances has been enabled due to the development of high-resolution mass spectrometry (HRMS) . Nontarget screening (NTS) aims to detect and identify all substances present in a sample and can be usefully applied in EDA to identify causative toxic substances in highly potent fractions. − The combined use of EDA and NTS addresses the limitations of performing only NTS, which lacks information on the potential toxicity of compounds in environmental samples. − ,− EDA combined with NTS has been applied successfully for the identification of unmonitored toxicants in sediment, wastewater, biota, etc. ,, This approach will help to expand the scope of analysis to include unknown substances, moving away from existing methods that rely solely on target chemical monitoring. , Furthermore, it is expected to facilitate the efficient incorporation of effect-based monitoring (EBM) into environmental monitoring programs. , The purpose of this paper is to describe the current status and limitations of EDA combined with NTS, with case studies of its successful application. In addition, we provide suggestions for the integration of EDA into future environmental monitoring programs and management policies.…”

“…Wastewater treatment plant (WWTP) effluent is a major point source of toxic substances in aquatic environments, and the identification of unmonitored toxicants is crucial. ,, Mijangos et al identified toxic substances in WWTP effluents that caused growth inhibition and skeletal malformation in sea urchin embryos. For fractions showing high toxicity, NTS was performed with the use of LC–HRMS.…”

“…4−6,10−12 EDA combined with NTS has been applied successfully for the identification of unmonitored toxicants in sediment, wastewater, biota, etc. 6,11,13 This approach will help to expand the scope of analysis to include unknown substances, moving away from existing methods that rely solely on target chemical monitoring. 14,15 Furthermore, it is expected to facilitate the efficient incorporation of effect-based monitoring (EBM) into environmental monitoring programs.…”