Fate of progesterone and norgestrel in anaerobic/anoxic/oxic (A/A/O) process: Insights from biotransformation and mass flow

Norgestrel shows androgenic properties and triggers reproductive neuroendocrine toxicity in the testes of Pacific oysters (Crassostrea gigas)

Norgestrel (NGT), a prevalent progestin in the aquatic environment, can pose risks to vertebrates even at very low concentrations (<1 ng/L). Nevertheless, the understanding of NGT's effects on invertebrates is limited. Therefore, through histology and multi-omics, we explored the toxic effects of NGT (0, 10, and 1000 ng/L) on Pacific oysters Crassostrea gigas testes over 21 days. NGT accumulated in the testes and exhibited androgenic characteristics. Furthermore, transcriptomic sequencing revealed that differentially expressed genes were significantly enriched in the neurotransmitter ligand-receptor signaling pathway. A significant decrease in G protein-coupled receptors (GPCRs) and Calmodulin/ Calmodulin -dependent protein kinase gene expression was identified as the potential mechanism preventing hyperphosphorylation and G protein overactivation. Notably, the 1000 ng/L group showed clear Cytochrome P450/glutathione-s-transferase detoxification characteristics. Metabolomics analysis indicated that small peptides and organic acids were the most abundant differential metabolites, accounting for 26.96 %. The positive correlation between neuroendocrine related metabolites and several important G protein-coupled receptor genes, as revealed by correlation analysis, might play a major role in regulating NGT toxicity. In conclusion, NGT affects the reproductive neuroendocrine system in the C. gigas testis and triggers detoxification mechanisms. These findings provide new targets and a theoretical basis for environmental progestin toxicity and ecological risk assessment.

FT-GNN Tool for Bridging HRMS Features and Bioactivity: Uncovering Unidentified Estrogen Receptor Agonists in Sewage

Identifying primary estrogen receptor (ER) agonists in municipal sewage is essential for ensuring the health of aquatic environments. Given the complex and variable chemical composition of sewage, the predominant ER agonists remain unclear. High-resolution mass spectrometry (HRMS)-based models have been developed to predict compound bioactivity in complex matrices, but further optimization is needed to effectively bridge HRMS features with ER agonists. To address this challenge, an FT-GNN (fragmentation tree-based graph neural network) model was proposed. Given limited data and class imbalance, data augmentation was performed using model predictions within the applicability domain (AD) and oversampling technique (OTE). Model development results demonstrated that integrating the FT-GNN with data augmentation improved the balanced accuracy (bACC) value by 6%-31%. The developed model, with a high bACC to identify more true ER agonists, efficiently classified tens of thousands of unidentified HRMS features in sewage, reducing postprocessing workload in nontargeted screening. Analysis of ER agonist transformation during sewage treatment revealed the anaerobic stage as key to both their removal and formation. Estrogenic effect balance analysis suggests that α-E2 and 9,11-didehydroestriol may be two previously overlooked key ER agonists. Collectively, the development and application of the FT-GNN model are crucial advancements toward credible tracking and efficient control of estrogenic risks in water.

Effect-based analysis of endocrine effects in surface and ground water with focus on progestagenicity using Arxula yeast-based reporter gene assays

The use of effect-based methods in water monitoring for identifying risks to aquatic organisms and human health is important for aiding regulatory decisions. In the past decades, the database on monitoring, especially in surface waters, has grown as this aquatic environment is openly exposed to various contamination sources. With regard to endocrine disruption, estrogenic and androgenic effects have been primarily investigated. Here, yeast-based bioassays emerged as potent tools, offering sensitivity to environmentally relevant concentrations and high robustness. The objectives of this study were to investigate further endocrine endpoints and extend the monitoring to ground waters. The inclusion of progestagenic effects is crucial due to their multifaceted roles in various functions of organisms. Hence, three different Arxula-yeast hormone screens (estrogen, androgen, and progesterone receptors) were applied, revealing simultaneous exposure to diverse endocrine effects in surface and ground water matrices. Although effect profiles in surface waters showed mainly activation of hormone receptors, in-ground water samples inhibitory effects clearly predominate. Although toxicological thresholds are not yet legally binding, they are essential for effective regulatory measures and risk management to ensure the good ecological status of aquatic ecosystems. The results were compared with effect-based trigger values for ecological as well as human risk assessment depending on the sample matrix, none of which were exceeded.

Ten-month comprehensive assessment of steroid hormones in the tributaries of Baiyun District, Guangzhou City, China: Spatiotemporal dynamics, source attribution, and environmental implications

The occurrence of steroid hormones in small river ecosystems raises environmental alarms due to their limited dilution capacity, heightened susceptibility to diverse pollution sources, and their substantial contribution to the contamination of larger river systems. Here, we investigated the occurrence of 40 steroid hormones over 10 months in 10 first-order tributaries (n = 250) of Guangzhou City, China. The observed concentrations of Σsteroid hormones ranged from 30.5 to 450 ng/L (mean: 55.6 ± 35.4 ng/L). No substantial variation in steroid hormone concentrations was observed between the flood and dry seasons, reflecting an intricate balance of dilution dynamics, agricultural runoff, and wastewater releases. Further correlation analysis underscored wastewater discharge as a consistent source of steroid hormone occurrence, with spikes coinciding with concurrent fertilizer application and rainfall intervals. Steroid hormone concentrations displayed significant spatial variations. Correlation analyses connected steroid hormone levels to nutrients in tributaries and agricultural ditch water and land usage, highlighting the joint effect of runoff and various wastewater types on steroid hormone distribution. Interestingly, steroid hormone levels displayed minimal variation along the tributaries, suggesting uniform and continuous pollution sources. Source attribution analysis revealed that 51.7 % of steroid hormones originated from untreated domestic wastewater, followed by treated wastewater, livestock wastewater, and runoff. Notably, 92.0 % of the sampling sites registered at least one steroid hormone level exceeding the risk quotient threshold of 1, indicating widespread ecological hazards. Our research emphasizes the persistent and stable nature of steroid hormone-related risks across seasons and along the tributaries, highlighting the imperative for vigilant monitoring. We further advocate for intensified surveillance efforts during pivotal periods (e.g., fertilization periods and low rainfall intervals), to better address these environmental challenges.

Tracing contaminants of emerging concern and their transformations in the whole treatment process of a municipal wastewater treatment plant using nontarget screening and molecular networking strategies

This study employed nontarget screening with high-resolution mass spectrometry and molecular network strategy to characterize the occurrence and tranformation of contaminants of emerging concern (CECs) through a wastewater treatment plant in Guangzhou. We detected 70,631 compounds in positive mode and 14,423 in negative mode in influent, from which 94.5 % of these compounds were successfully eliminated after treatment. Among them, 510 chemicals were identified, with pharmaceuticals being the largest category excluding natural products, accounting for 146 compounds. And 29 CECs were semiquantified with concentrations ranging from 2.80 ng/L (Fluconazole) to 10,351 ng/L (Nicotine). The removal efficiency varied: 60 compounds were easily removable (>90 % removal), 17 were partially removable (40-90 % removal), and 44 were non-degradable (<40 % removal). Additionally, we tentatively identified transformation products (TPs) of CECs using a molecular network analysis, revealing over 20,000 compound pairs sharing common fragments, with 191 compounds potentially linked to 47 level 1 compounds, suggesting their role as TPs of CECs. These findings illuminated the actual treatment efficiency of wastewater treatment plants for CECs and the potential TPs, offering valuable insights for future improvements in wastewater management practices.

The fate and transport of neonicotinoid insecticides and their metabolites through municipal wastewater treatment plants in South China

Neonicotinoid insecticides (NEOs) have gained widespread usage as the most prevalent class of insecticides globally and are frequently detected in the environment, posing potential risks to biodiversity and human health. Wastewater discharged from wastewater treatment plants (WWTPs) is a substantial source of environmental NEOs. However, research tracking NEO variations in different treatment units at the WWTPs after being treated by the treatment processes remains limited. Therefore, this study aimed to comprehensively investigate the fate of nine parent NEOs (p-NEOs) and five metabolites in two municipal WWTPs using distinct treatment processes. The mean concentrations of ∑NEOs in influent (effluent) for the UNITANK, anaerobic-anoxic-oxic (A2/O), and cyclic activated sludge system (CASS) processes were 189 ng/L (195 ng/L), 173 ng/L (177 ng/L), and 123 ng/L (138 ng/L), respectively. Dinotefuran, imidacloprid, thiamethoxam, acetamiprid, and clothianidin were the most abundant p-NEOs in the WWTPs. Conventional wastewater treatment processes were ineffective in removing NEOs from wastewater (-4.91% to -12.1%), particularly major p-NEOs. Moreover, the behavior of the NEOs in various treatment units was investigated. The results showed that biodegradation and sludge adsorption were the primary mechanisms responsible for eliminating NEO. An anoxic or anaerobic treatment unit can improve the removal efficiency of NEOs during biological treatment. However, the terminal treatment unit (chlorination disinfection tank) did not facilitate the removal of most of the NEOs. The estimated total amount of NEOs released from WWTPs to receiving waters in the Pearl River of South China totaled approximately 6.90-42.6 g/d. These findings provide new insights into the efficiency of different treatment processes for removing NEOs in current wastewater treatment systems.

Biotransformation of cyproterone acetate, drospirenone, and megestrol acetate in agricultural soils: Kinetics, microbial community dynamics, transformation products, and mechanisms

The occurrence of biologically active synthetic progestins in agricultural soils is of growing concern due to their potential to disrupt the endocrine function of aquatic fish in nearby surface waters. This study investigated the biotransformation outcomes of cyproterone acetate (CPA), drospirenone (DRO), and megestrol acetate (MGA) in four agricultural soils. The biotransformation data were fitted to a first-order decay model (R2 = 0.93-0.99), with half-lives and first-order decay coefficients ranging from 76.2-217 h and 9.10 × 10-3-3.20 × 10-3 (h-1), respectively. Abundant biotransformation products (TPs) were generated during incubation, with the number and yields varying across the four soils. 1,2-Dehydrogenation was the main transformation pathway of DRO in the four soils (yields of 32.3-214 %). Similarly, 1,2-dehydrogenation was the most relevant transformation pathway of MGA in the four soils (yields of 21.8-417 %). C3 reduction was the major transformation pathway of CPA in soils B, C, and D (yields of 114-245 %). Hydrogenation (yield of 133 %) and hydroxylation (yield of 21.0 %) were the second major transformation pathway of CPA in soil B and C, respectively. In particular, several TPs exhibited progestogenic and antimineralocorticoid activity, as well as genotoxicity. The high-throughput sequencing indicated that interactions between microorganisms and soil properties may affect biotransformation. Spearman correlation and bidirectional network correlation analysis further revealed that soil properties can directly interfere with the soil sorption capacity for the progestins, thus affecting biotransformation. In particular, soil properties can also limit or promote biotransformation and the formation of TPs (i.e., biotransformation pathways) by affecting the relative abundances of relevant microorganisms. The results of this study indicate that the ecotoxicity of synthetic progestins and related TPs can vary across soils and that the assessment of environmental risks associated with these compounds requires special consideration of both soil properties and microbial communities.

Deleterious effect of gestagens from wastewater effluent on fish reproduction in aquatic environment: A review

Gestagens are common pollutants accumulated in the aquatic ecosystem. Gestagens are comprised of natural gestagens (i.e. progesterone) and synthetic gestagens (i.e. progestins). The major contributors of gestagens in the environment are paper plant mill effluent, wastewater treatment plants, discharge from pharmaceutical manufacturing, and livestock farming. Gestagens present in the aquatic environment interact with progesterone receptors and other steroid hormone receptors, negatively influencing fish reproduction, development, and behavior. In fish, the gonadotropin induces 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) production, an important steroid hormone involved in gametogenesis. DHP interacts with the membrane progestin receptor (mPR), which regulates sperm motility and oocyte maturation. Gestagens also interfere with the hypothalamic-pituitary-gonadal (HPG) axis, which results in altered hormone levels in fish. Moreover, recent studies showed that even at low concentrations exposure to gestagens can have detrimental effects on fish reproduction, including reduced egg production, masculinization, feminization in males, and altered sex ratio, raising concerns about their impact on the fish population. This review highlights the hormonal regulation of sperm motility, oocyte maturation, the concentration of environmental gestagens in the aquatic environment, and their detrimental effects on fish reproduction. However, the long-term and combined impacts of multiple gestagens, including their interactions with other pollutants on fish populations and ecosystems are not well understood. The lack of standardized regulations and monitoring protocols for gestagens pollution in wastewater effluent hampers effective control and management. Nonetheless, advancements in analytical techniques and biomonitoring methods provide potential solutions by enabling better detection and quantification of gestagens in aquatic ecosystems.