Modeling risk dynamics of contaminants of emerging concern in a temperate-region wastewater effluent-dominated stream

Abstract

Wastewater effluent-dominated streams are becoming increasingly common worldwide, including in temperate regions, with potential impacts on ecological systems and drinking water sources. We recently quantified the occurrence/ spatiotemporal dynamics of...

Metformin Contamination in Global Waters: Biotic and Abiotic Transformation, Byproduct Generation and Toxicity, and Evaluation as a Pharmaceutical Indicator

“…Four biological TPs, i.e., GU, MBG, 2,4-DAT, and 2,4-AMT, have been reported in influents and effluents of WWTPs and surface water, among which GU has the highest detection concentration. ,, In general, an increasing trend for GU was found from influents (0.04–5.4 μg/L) to effluents (9.2–28 μg/L) in WWTPs from Germany and China, which corresponded to the reduced levels of metformin from influents to effluents (Figure A). , In the same study, MBG was detected at much lower concentrations (41–380 ng/L and 35–122 ng/L in the influents and effluents, respectively), which is consistent with MBG being the intermediate of metformin transformation to GU with a low proportion (0.12%) in the final product profile of the laboratory tests using aerobic activated sludge . In addition, the signals of 2,4-DAT and 2,4-AMT were observed to increase from influents to effluents, but no quantitative data were available owing to the lack of analytical standards .…”

“…Once excreted from the human body, metformin tends to stay in the aqueous phases instead of getting retained by soil or undergoing sedimentation because of its high water solubility (1000 g/L) and low octanol–water partition coefficient (log K ow , – 2.64) (calculated by EPI Suite v 4.1 software). Metformin has been ubiquitously detected in global aquatic systems in over 91 countries, mostly including in wastewater influents/effluents, surface water, and stormwater, as well as even in groundwater and drinking water in six studies, ,,,,− with the concentration level spanning 7 orders of magnitude from 0.2 ng/L to 1180 μg/L (Figure ,Text S1 and Table S1). With the growing diabetic population and related prescription items, metformin levels in environmental waters have been found to increase over time.…”

“…The ecosystem risk levels (RQ < 0.01, no significant risk; 0.01 < RQ < 0.1, low risk; 0.1 < RQ < 1, medium risk; RQ > 1, high risk) can be extrapolated using the measured environmental concentration divided by its predicted no-effect concentration which is obtained from the ratio of half-maximal lethal concentration (LC 50 ) or EC 50 to the assessment factor (Table S6). ,, The RQ results show different risk levels of metformin, GU, MBG, and NCDC to species in three trophic levels (Table S6). Metformin at the highest concentration of 1180 μg/L in the surface water of Lagos, Nigeria, results in risks to various species, with risk levels increasing from fish (RQ < 0.1) to daphnia (RQ = 0.88) and algae (RQ = 2.31).…”

“…Likewise, GU leads to increasing RQ values from fish (0.09) to algae (0.62) and daphnia (5.55) when exposed to its highest concentration of 222 μg/L in the Erpe River, Germany, indicating a higher risk of GU than metformin even with its lower detected concentrations. In addition, long-term exposure to metformin (RQ = 1.18, P. promelas ) or GU (RQ = 1.39, D. magna ) may pose a high risk to aquatic biota. In comparison, the RQ results indicate that MBG and NCDC exert no threat to aquatic species (all RQs < 0.01) because of their low concentrations in surface water.…”

RNA-seq reveals potential gene biomarkers in fathead minnows (Pimephales promelas) for exposure to treated wastewater effluent

“…Sampling methods, quality assurance/quality control (QA/QC), and analysis are fully described in a prior publication. 42…”