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Ribavirin (RBV), which is extensively used to treat viral diseases such as COVID-19, is considered one of the major emerging contaminants due to its long-term existence and health risk in the aqueous environmental system. However, research on effective removal of RBV still remains insufficient. In this study, we investigated the RBV degradation kinetics and mechanism in UV/chlorine/Fe(II) process. The degradation rate constant kobs-RBV of RBV was 2.52 × 10−4 s−1 in UV/chlorine/Fe(II) process, which increased by 1.6 times and 1.3 times than that in chlorine alone and UV/chlorine process, respectively. Notably, trace amount Fe(II) promoted RBV degradation in UV/chlorine system through Fe2+/Fe3+ cycles, enhancing the yield of reactive species such as HO· and certain species reactive chlorine radicals (RCS). The contributions of HO· and RCS toward RBV degradation were 53.91% and 16.11%, respectively. Specifically, Cl·, ClO·, and Cl2·− were responsible for 8.59%, 2.69%, and 4.83% of RBV removal. The RBV degradation pathway indicated that the reactive species preferentially attacked the amide moiety of RBV, which cleaved the ether bond and the hydroxyl group. The toxicity evaluation of RBV degradation products elucidated that UV/chlorine/Fe(II) process was beneficial for RBV detoxification. [ABSTRACT FROM AUTHOR]

Fungal diseases cause substantial loss to agricultural crops, affecting both quantities and quality. Although several methods are used for preventing disease incidence, fungicides remain crucial for higher yields and better quality. But in the past, the efficacy of several fungicides has decreased due to increased cases of fungicide resistant. In our pursuit of new effective fungicides, we synthesised a series of twenty 2-Indazol-1-yl-chromen-4-one derivatives (6a- 6t). The characterization of synthesized compounds was performed by several spectroscopic methods including Infrared, Nuclear Magnetic Resonance (¹H and 13C) and HRMS. Out of 20 synthesised compounds, 19 (6b- 6t) were found to be novel. All synthesised indazolylchromones showed very good antifungal activity against Sclerotium rolfsii and Fusarium oxysporum. Among the tested compounds, 6t and 6f exhibited very good fungicidal activity against S. rolfsii with an ED50 of 10.10 mg L-1 and 16.18 mg L[sup -1], respectively. In case of Fusarium oxysporum compound 6f displayed good' activity with an ED50 value of 27.82 mg L-1. Molecular docking study was done to predict the binding sites of most active compounds, 6t and 6f with Cytochrome P450 14alpha -sterol demethylase (CYP51) enzyme using molsoft software. The acute toxicity predictions the of synthesized compounds for fish (LC50,96 Hr), daphnid (LC50, 48 Hr) and green algae (EC50, 96Hr) and the chronic toxicity predictions (ChV) were assessed using Ecological Structure Activity Relationship (ECOSAR) model. As per ECOSAR prediction, all the chemicals are inside AD and not missing predictions. [ABSTRACT FROM AUTHOR]

Fungal diseases cause substantial loss to agricultural crops, affecting both quantities and quality. Although several methods are used for preventing disease incidence, fungicides remain crucial for higher yields and better quality. But in the past, the efficacy of several fungicides has decreased due to increased cases of fungicide resistant. In our pursuit of new effective fungicides, we synthesised a series of twenty 2-Indazol-1-yl-chromen-4-one derivatives (6a- 6t). The characterization of synthesized compounds was performed by several spectroscopic methods including Infrared, Nuclear Magnetic Resonance (1H and 13C) and HRMS. Out of 20 synthesised compounds, 19 (6b- 6t) were found to be novel. All synthesised indazolylchromones showed very good antifungal activity against Sclerotium rolfsii and Fusarium oxysporum. Among the tested compounds, 6t and 6f exhibited very good fungicidal activity against S. rolfsii with an ED50 of 10.10 mg L-1 and 16.18 mg L-1, respectively. In case of Fusarium oxysporum compound 6f displayed good’ activity with an ED50 value of 27.82 mg L-1. Molecular docking study was done to predict the binding sites of most active compounds, 6t and 6f with Cytochrome P450 14alpha -sterol demethylase (CYP51) enzyme using molsoft software. The acute toxicity predictions the of synthesized compounds for fish (LC50,96 Hr), daphnid (LC50, 48 Hr) and green algae (EC50, 96Hr) and the chronic toxicity predictions (ChV) were assessed using Ecological Structure Activity Relationship (ECOSAR) model. As per ECOSAR prediction, all the chemicals are inside AD and not missing predictions.

Empirical and in silico data on the aquatic ecotoxicology of 2697 organic chemicals were collected in order to compile a dataset for assessing the predictive power of current Quantitative Structure Activity Relationship (QSAR) models and software platforms. This document presents the dataset and the data pipeline for its creation. Empirical data were collected from the US EPA ECOTOX Knowledgebase (ECOTOX) and the EFSA (European Food Safety Authority) report “Completion of data entry of pesticide ecotoxicology Tier 1 study endpoints in a XML schema – database”. Only data for OECD recommended algae, daphnia and fish species were retained. QSAR toxicity predictions were calculated for each chemical and each of six endpoints using ECOSAR, VEGA and the Toxicity Estimation Software Tool (T.E.S.T.) platforms. Finally, the dataset was amended with SMILES, InChIKey, pKa and logP collected from webchem and PubChem.

Pyriclobenzuron 11 PBU – pyriclobenzuron.(PBU) is a novel molluscicide developed to control Pomacea canaliculate, and little information on its environmental fate has been published. In this study, the photolysis of PBU in an aqueous environment was simulated using a xenon lamp. Results showed that the photolysis of PBU in water followed first-order kinetics, exhibiting a t0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 22 PPs – photolysis products.(PPs) were detected by HPLC-UV and identified by UPLC-Q/TOF MS, which were formed via the hydroxylation and photocatalytic hydro-dehalogenation of PBU, respectively. The initial relative abundance of photolysis product 1 33 PP-1 – photolysis product 1.(PP-1) in Milli-Q water was 1.55 times higher than that in river water. PP-1 was detected at 26.5 % and 76.8 % of the maximum relative abundance in the river water and Milli-Q water after 720 h, respectively. Photolysis product 2 44 PP-2 – photolysis product 2.(PP-2) was stable in water because of its weak hydrophilicity. The PP-2 detected after 720 h in Milli-Q water and river water was 93.7 % and 93.5 % of the maximum relative abundance, respectively. Finally, ECOSAR software was used to evaluate the acute aquatic toxicity of PBU and its PPs, revealing that the PPs had lower toxicity levels to non-target aquatic organisms.

This study explores the photocatalytic transformation of the antiviral drug abacavir employing different advanced oxidation processes (AOPs) such as UV/TiO2, UV/MOF/H2O2, UV/MOF/S2O82−, UV/Fe2+/H2O2, and UV/Fe2+/S2O82−. All processes appear to be effective in eliminating abacavir within a few minutes, while the evolution profile of the basic transformation product, descyclopropyl-abacavir (TP-247) was also monitored. Moreover, the implementation of the most efficient technologies towards the removal of abacavir in different matrices such as wastewater effluent and leachate was also assessed, revealing that the organic matter present or the inorganic constituents can retard the whole process. Four major transformation products were detected, and their time-evolution profiles were recorded in all studied matrices, revealing that different transformation pathways dominate in each matrix. Finally, the prediction of the toxicity of the major TPs employing ECOSAR software was conducted and showed that only hydroxylation can play a detoxification role in the treated solution. [ABSTRACT FROM AUTHOR]

The fungicides imazalil, penconazole and tebuconazole have been added to the 3rd EU watchlist due to their persistence and hazard to the environment. In vitro ecotoxicity studies against organisms such as Daphnia magna and Danio rerio have indicated the harmfulness. To prevent penetration of these substances into the aquatic environment, advanced cleaning stages are being tested for wastewater treatment plants, including ultraviolet radiation. Yet, the exposure of the compounds may result in transformation products whose ecotoxicity determination proves difficult due to the lack of reference standards. Alleviation comes from in silico methods such as quantitative structure activity relationship (QSAR) analysis and the determination of time-depended ecotoxicity equivalents (ETE) which combines chemical kinetics of the photoinduced degradation process and in silico predicted ecotoxicity of the transformation products. QSAR analysis was used to predict the ecotoxicity of the transformation products whose structures were elucidated with the help of high-resolution multifragmentation mass spectrometry. Predicted values were compared to the results of in vitro ecotoxicity assays from previous studies and found in agreement. All photoinduced products were described as subsequent or subsequent follow-up reaction products. Time-independent ETEs revealed that the degradation of the fungicide itself had the greatest effect on the ecotoxicity of the irradiated solution, as photoinduced transformation products were found of significantly lower amount in irradiated solution and of lesser ecotoxicological hazard than the fungicide. The method may help estimating the conditions needed for application of UV irradiation in an advanced purification step in wastewater treatment plants.

Bioconcentration factors (BCFs) are markers of chemical substance accumulation in organisms, and they play a significant role in determining the environmental risk of various chemicals. Experiments to obtain BCFs are expensive and time-consuming; therefore, it is better to estimate BCF early in the chemical development process. The current research aims to evaluate the ecotoxicity potential of 122 pharmaceuticals and identify possible important structural attributes using BCF as the determining feature against a group of fish species. We have calculated the theoretical 2D descriptors from the OCHEM platform and SiRMS descriptor calculating software. The regression-based quantitative structure–property relationship (QSPR) modeling was used to identify the chemical features responsible for acute fish bioconcentration. Multiple models with the “intelligent consensus” algorithm were employed for the regression-based approach improving the predictive ability of the models. To ensure the robustness and interpretability of the developed models, rigorous validation was performed employing various statistical internal and external validation metrics. From the developed models, it can be specified that the presence of large lipophilic and electronegative moieties greatly enhances the bioaccumulative potential of pharmaceuticals, whereas the hydrophilic characteristics have shown a negative impact on BCF. Furthermore, the developed models were employed to screen the DrugBank database (https://go.drugbank.com/) for assessing the BCF properties of the entire database. The evidence acquired from the modeled descriptors might be used for aquatic risk assessment in the future, with the added benefit of providing an early caution of their probable negative impact on aquatic ecosystems for regulatory purposes.

In this study, the acute toxicity effects of a fluorescent xanthene dye, Rhodamine B (RhB), widely used in textile, paper, and leather industries was investigated on a freshwater microalgae Chlorella vulgaris. The acute toxicity of RhB on C. vulgaris was determined by examining the growth, cell morphology, pigment production, protein content, and the activities of oxidative stress enzymes. Based on the results of the toxicity study of 24–96 h, the median inhibitory concentration (IC50) values ranged from 69.94 to 31.29 mg L−1. The growth of C. vulgaris was conspicuously inhibited by RhB exposure, and the cell surfaces appeared to be seriously shrunk in SEM analysis. The growth of C. vulgaris was hindered after exposure to graded concentrations (10–50 mg L−1) of RhB. A significant reduction in growth rate, pigment synthesis (chlorophyll a, chlorophyll b, and carotenoid), and protein content was recorded in a dose-dependent manner. After 96 h exposure of C. vulgaris to 50 mg L−1 RhB, chlorophyll a, chlorophyll b, carotenoids, and protein contents were reduced by 71.59, 74.90, 65.84, and 74.20%, respectively. The activities of the antioxidant enzymes peroxidase (POD), and catalase (CAT) also increased markedly in the presence of RhB. A notable effect was observed on oxidative enzymes catalase and peroxidase, indicating that oxidative stress may be the primary factor in the inhibition of growth and pigment synthesis. Consequently, the experimental acute toxicity data were compared to the QSAR prediction made by the ECOSAR programme. Results showed that the experimental acute toxicity values were 67.74-fold lower than the ECOSAR predicted values. The study provides convincing evidence for the metabolic disruption in the ubiquitous microalgae C. vulgaris due to the RhB dye toxicity. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMX) is a typical antibiotic in the world, which is frequently detected in the aquatic environment. The current study was aimed to investigate the SMX degradation in secondary treated wastewater using potassium Ferrate [Fe(VI)]. The effects of various experimental conditions, EDTA and phosphate as chelating agents, and toxicity assessment were also considered. Secondary treated effluent was spiked with predefined SMX concentrations, and after desired reaction time with Fe(VI), residual SMX was measured using HPLC. Results indicated that SMX degradation by Fe(VI) was favored under acidic condition, where 90% of SMX degradation was achieved after 120 min. Fe(VI) and SMX reaction obeyed first-order kinetic; meantime, the SMX degradation rate under pH 3 was 7.6 times higher than pH 7. The presence of phosphate (Na2HPO4) and EDTA declined SMX degradation, while Fe (III) effect was contradictory. In addition to promising demolition, 10% TOC removal was achieved. Eighteen major intermediates were identified using LC-MS/MS and the degradation pathways were suggested. Transformation products (TPs) were formed due to hydroxylation, bond cleavage, transformation after bond cleavage, and oxidation reactions. The ECOSAR analysis showed that some of the SMX oxidation products were toxic to aquatic organisms (fish, daphnia and green algae). [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment. Unlike other persistent chemicals, PFAS are highly soluble in water and tend to partition to surface and groundwater rather than soil and sediment. While numerous studies have evaluated the potential ecological effects of certain PFAS, there remain data gaps, especially for newer PFAS. Consequently, this study evaluated a high-throughput in silico approach for a screening-level risk assessment of PFAS in aquatic species. We focused on two well-studied PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), to provide a better context to our estimates. The Ecological Structural Activity Relationships (ECOSAR) program was used to estimate acute and chronic toxicity thresholds for fish, Daphnid, mysid, and green algae. The Exposure and Fate Assessment Screening Tool (E-FAST) model was used to derive estimated environmental concentrations (EECs) in surface water following hypothetical discharges from wastewater treatment plants (WWTPs). The predicted toxicity thresholds and EECs were compared to reported values. Subsequently, risk quotients (RQs) were calculated. We showed that (1) the acute toxicity thresholds for PFOA and PFOS were typically lower (i.e., more conservative) than reported values, whereas chronic toxicity thresholds were typically in the range of reported values, (2) the EECs were in the range of reported environmental concentrations in most cases, and (3) the acute and chronic RQs were mostly below the levels of concern. Additionally, the study highlighted that even for the well-studied PFOA and PFOS, there were still data gaps with regards to ecotoxicity in certain aquatic species as well as environmental concentrations for certain water bodies.

This study explores the photocatalytic transformation of the antiviral drug abacavir employing different advanced oxidation processes (AOPs) such as UV/TiO2, UV/MOF/H2O2, UV/MOF/S2O82−, UV/Fe2+/H2O2, and UV/Fe2+/S2O82−. All processes appear to be effective in eliminating abacavir within a few minutes, while the evolution profile of the basic transformation product, descyclopropyl-abacavir (TP-247) was also monitored. Moreover, the implementation of the most efficient technologies towards the removal of abacavir in different matrices such as wastewater effluent and leachate was also assessed, revealing that the organic matter present or the inorganic constituents can retard the whole process. Four major transformation products were detected, and their time-evolution profiles were recorded in all studied matrices, revealing that different transformation pathways dominate in each matrix. Finally, the prediction of the toxicity of the major TPs employing ECOSAR software was conducted and showed that only hydroxylation can play a detoxification role in the treated solution.

Wastewater release in an urban wetland in Mexico City entails discharging complex mixtures of hundreds of chemical substances into the aquatic system. Therefore, in order to identify the most important contaminants, a GC–MS screening method coupled with deconvolution software was used. LC50 values from ECOSAR and Toxic Units were obtained to identify the organic pollutants-of-concern and to pinpoint the most ecotoxic sites. The results showed that, even though the area has intensive farming, agrochemicals are not of concern. Industrial and domestic groups make up from about 30%–66% of the pollutants for all sites. Of the 189 identified substances, 17 were detected 44% of the time and the Toxic Unit showed that terbutol, coprostanol, and hexadecane were capable of generating considerable adverse effects on the aquatic ecosystem. Total Toxic Units for each site exhibited a decreasing trend as they distanced from the urban and agricultural area. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes such as thermal plasma activation and UV-C/H 2 O 2 treatment are considered as applications for the degradation of pharmaceutical residues in wastewater complementary to conventional wastewater treatment. It is supposed that direct oxidative treatment can lower the toxicity of hospital sewage water (HSW). The aim of this study was to predict the ecotoxicity for three aquatic species before and after oxidative treatment of 10 quantified pharmaceuticals in hospital sewage water. With the application of oxidative chemistry, pharmaceuticals are degraded into transformation products before reaching complete mineralization. To estimate the potential ecotoxicity for fish, Daphnia and green algae ECOSAR quantitative structure-activity relationship software was used. Structure information from pristine pharmaceuticals and their oxidative transformation products were calculated separately and in a mixture computed to determine the risk quotient (RQ). Calculated mixture toxicities for 10 compounds found in untreated HSW resulted in moderate-high RQ predictions for all three aquatic species. Compared to untreated HSW, 30-min treatment with thermal plasma activation or UV-C/H 2 O 2 resulted in lowered RQs. For the expected transformation products originating from fluoxetine, cyclophosphamide and acetaminophen increased RQs were predicted. Prolongation of thermal plasma oxidation up to 120 min predicted low-moderate toxicity in all target species. It is anticipated that further degradation of oxidative transformation products will end in less toxic aliphatic and carboxylic acid products. Predicted RQs after UV-C/H 2 O 2 treatment turned out to be still moderate-high. In conclusion, in silico extrapolation of experimental findings can provide useful predicted estimates of mixture toxicity. However due to the complex composition of wastewater this in silico approach is a first step to screen for ecotoxicity. It is recommendable to confirm these predictions with ecotoxic bioassays. [Display omitted] • Advanced oxidation processes can be applied to degrade pharmaceutical residues. • Moderate to high toxicity was predicted for untreated hospital sewage water (HSW). • Ecotoxicity of oxidatively treated HSW was estimated using ECOSAR software. • Thermal plasma and UV-C/H 2 O 2 oxidation result in reduced estimated risk quotients. • In silico toxicity predictions are useful to inform laboratory testing strategies. [ABSTRACT FROM AUTHOR]

The toxicity of endocrinologically active pharmaceuticals finasteride (FIN) and melengestrol acetate (MGA) was assessed in freshwater mussels, including acute (48 h) aqueous tests with glochidia from Lampsilis siliquoidea, sub-chronic (14 days) sediment tests with gravid female Lampsilis fasciola, and chronic (28 days) sediment tests with juvenile L. siliquoidea, and in chronic (42 days) sediment tests with the amphipod Hyalella azteca and the mayfly Hexagenia spp. Finasteride was not toxic in acute aqueous tests with L. siliquoidea glochidia (up to 23 mg/L), whereas significant toxicity to survival and burial ability was detected in chronic sediment tests with juvenile L. siliquoidea (chronic value (ChV, the geometric mean of LOEC and NOEC) = 58 mg/kg (1 mg/L)). Amphipods (survival, growth, reproduction, and sex ratio) and mayflies (growth) were similarly sensitive (ChV = 58 mg/kg (1 mg/L)). Melengestrol acetate was acutely toxic to L. siliquoidea glochidia at 4 mg/L in aqueous tests; in sediment tests, mayflies were the most sensitive species, with significant growth effects observed at 37 mg/kg (0.25 mg/L) (ChV = 21 mg/kg (0.1 mg/L)). Exposure to sublethal concentrations of FIN and MGA had no effect on the (luring and filtering) behaviour of gravid L. fasciola, or the viability of their brooding glochidia. Based on the limited number of measured environmental concentrations of both chemicals, and their projected concentrations, no direct effects are expected by these compounds individually on the invertebrates tested. However, organisms are exposed to contaminant mixtures in the aquatic environment, and thus, the effects of FIN and MGA as components of these mixtures require further investigation. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes (AOPs) using various energy sources and oxidants to produce reactive oxygen species are widely used for the destruction of recalcitrant water contaminants. The current study is about the degradation of two emerging pollutants—salicylic acid (SA) and methyl paraben (MP)—by high-frequency ultrasonication followed by identification of the oxidation byproducts and modeling of the reaction mechanisms using the density functional theory (DFT). The study also encompasses prediction of the aquatic toxicity and potential risk of the identified byproducts to some aquatic organisms bussing the ECOSAR (Ecological Structure Activity Relationships) protocol. It was found that the degradation of both compounds was governed by •OH attack and the pathways consisted of a cascade of reactions. The rate determining steps were decarboxylation (~ 60 kcal mol−1) and bond breakage reactions (~ 80 kcal mol−1), which were triggered by the stability of the reaction byproducts and overcome by the applied reaction conditions. Estimated values of the acute toxicities showed that only few of the byproducts were harmful to aquatic organisms, implying the environmental friendliness of the experimental method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co–Cu@g-C 3 N 4 /PMS system exhibited excellent performance for many pollutants removal. • Quenching and EPR analysis indicated both SO 4 − and 1O 2 were the dominant ROS. • Fukui index was calculated to elucidate the possible degradation pathways. • ECOSAR analysis indicated the ecotoxicity of most products was lower than SMX. Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have shown great potential for recalcitrant contaminants removal in wastewater treatment. Herein, we report the efficient activation of PMS by bimetallic oxides (cobalt and copper) co-doped graphitic carbon nitride (Co–Cu@g-C 3 N 4) for removal of sulfamethoxazole (SMX). The morphology and chemical composition of the fresh and used Co–Cu@g-C 3 N 4 were characterized by TEM, SEM, XRD, BET, and XPS. Nearly complete removal of SMX (50 mg/L) was observed in the presence of 50 mg/L Co–Cu@g-C 3 N 4 , 0.5 mmol/L PMS within 20 min at neutral pH with a degradation rate of 0.137 min−1. Moreover, the Co–Cu@g-C 3 N 4 catalyst enabled more than 90 % removal of various typical pollutants within 20 min, including sulfapyridine, rhodamine B, acridine red, and malachite green, with rate constants of 0.083, 0.130, 0.096, and 0.160 min−1, respectively. Quenching experiments and electron paramagnetic resonance (EPR) analysis demonstrated that sulfate radical (SO 4 −) and singlet oxygen (1O 2) were collectively responsible for SMX degradation. The efficient activation of PMS by Co–Cu@g-C 3 N 4 was ascribed to the continuous conversion of Co(Ⅲ) to Co(Ⅱ) and Cu(I) to Cu(ⅠI), and the presence of oxygen vacancy (O V) on the catalyst. The Co–Cu@g-C 3 N 4 /PMS system exhibited superior durability and maintained high efficiency in real water samples. Finally, theoretical calculations of Fukui index were performed to determine the possible degradation pathways of SMX, and the ecotoxicity of the degradation products was evaluated by the ECOSAR program. This study significantly advances the understanding of the reaction between PMS and bimetallic oxides catalysts, as well facilitates the development and application of PMS-based AOPs in wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeBDC-NH 2 , is used as a dual functional catalyst for activating PDS to degrade BMI. • FeBDC-NH 2 shows more visible-light enhancement than FeBDC for activating PDS. • FeBDC-NH 2 can lead to a significantly lower Ea of BMI degradation than reported values. • DFT calculation is performed to elucidate degradation process of BMI by FeBDC-NH 2. • Eco-toxicity of BMI degradation intermediates is evaluated to study implication. Ionic liquids (ILs) are increasingly adopted in various applications, leading to their release into the water environment, where they pose potential threats to ecology in view of toxicities. In order to remove 1-n-Butyl-3-Methylimidazolium (BMI) chloride, a well-known model IL, from water, urgent and crucial techniques are needed. Peroxydisulfate (PDS) activated by heterogeneous catalysts is useful for BMI degradation; nonetheless, heterogeneously activated PDS has been utilized in very few studies. A Fe-based metal–organic framework, Fe-2-aminobenzene-1,4-dicarboxylic acid (FeBDC-NH 2), is suggested here for serving as an activator because of its Fe sites, high surface areas, porosities, and visible-light responsive photocatalytic activity. The structure–property relationship of FeBDC-NH 2 in PDS activation is compared to that of Fe-Benzene-1,4-dicarboxylic acid (FeBDC), and both are found to activate PDS to degrade BMI. FeBDC-NH 2 , however, significantly accelerated BMI degradation when exposed to visible light. Compared to activation energies reported by other oxidation approaches, the activation energy of BMI degradation is considerably lower. Through theoretical DFT calculations, the mechanism and pathway of BMI degradation by FeBDC-NH 2 /PDS are examined. The eco-toxicities of BMI degradation intermediates are researched to understand the impact of BMI degradation on the environment. These analyses show that the toxicities of BMI are effectively reduced by FeBDC-NH 2 -activated PDS under light irradiation and that the final derivatives of BMI produced during the degradation process are non-harmful in terms of both acute and chronic toxicities. [ABSTRACT FROM AUTHOR]

Abstract In the present work, quantitative structure-activity relationship (QSAR) models have been developed for ecotoxicity of pharmaceuticals on four different aquatic species namely Pseudokirchneriella subcapitata , Daphnia magna , Oncorhynchus mykiss and Pimephales promelas using genetic algorithm (GA) for feature selection followed by Partial Least Squares regression technique according to the Organization for Economic Co-operation and Development (OECD) guidelines. Double cross-validation methodology was employed for selecting suitable models. Only 2D descriptors were used for capturing chemical information and model building, whereas validation of the models was performed by considering various stringent internal and external validation metrics. Interestingly, models could be developed even without using any LogP terms in contrary to the usual dependence of toxicity on lipophilicity. However, the current manuscript proposes highly robust and more predictive models employing computed logP descriptors. The applicability domain study was performed in order to set a predefined chemical zone of applicability for the obtained QSAR models, and the test compounds falling outside the domain were not taken for further analysis while making a prioritized list. An additional comparison was made with ECOSAR, an online expert system for toxicity prediction of organic pollutants, in order to prove predictability of the obtained models. The obtained robust consensus models were utilized to predict the toxicity of a large dataset of approximately 9300 drug-like molecules in order to prioritize the existing drug-like substances in accordance to their acute predicted aquatic toxicities following a scaling technique. Finally, prioritized lists of 500 most toxic chemicals obtained by respective consensus models and those predicted from ECOSAR tool have been reported. Highlights • This work proposes robust QSAR models for aquatic toxicity of pharmaceuticals. • Consensus modeling improves predictive performance of models. • Comparison of predictive performance is made with the ECOSAR tool. • Ranking and prioritization of pharmaceuticals from DrugBank database are performed. [ABSTRACT FROM AUTHOR]

Assisted wet deposition methods to localize the active phase metal on the carrier surface and prevent atomic aggregation during conventional heat treatment are strongly preferred. Herein, single-atom cobalt catalysts (SA-Co-PCN) with different metal-central content were target-prepared using a combination of impregnation and secondary annealing on polymerized carbon nitride (PCN) through reticular confinement. Fitting the coordination configuration of the Co-N pathway within the first coordination shell according to quantitative EXAFS indicated that the ligancy of Co-N was 4. The removal efficiency of representative micropollutants in the SA-Co-PCN/PMS system achieved 100% within 15 min. The outstanding degradation properties of micropollutants were ascribed to the SA-Co-PCN boosts PMS to a 1O 2 -dominated system. Moreover, the effects of substituents on the degradation behavior and ecotoxicology of sulfonamides (SAs) in PMS-activated systems were investigated in depth. The combination of DFT theoretical calculations and LC-MS further confirmed that the similar electron-rich sites on the SAs molecules allowed for commonality in the degradation pathway. Both S-N bond and C-S bond fragments became the initial attack and cleavage sites in the series of SAs. Ecotoxicity predictions indicated that most intermediates of SAs exhibited lower acute and chronic toxicity, especially acute toxicity, than the parent compounds. Assisted wet deposition to localize the active phase metal on the carrier surface allows easy target formation of single-atom cobalt catalysts (SA-Co-PCN), which could boost PMS to a 1O 2 -dominated system for efficient oxidation of typical micropollutants. The degradation behavior and ecotoxicology of sulfonamides in the SA-Co-PCN/PMS system were investigated in depth, revealing that most intermediates of sulfonamides exhibited lower acute and chronic toxicity, especially acute toxicity, than the parent compounds. This work provides a strategy for the development of facilely prepared single-atom catalysts and contributes to the development and application potential of PMS advanced oxidation technology for water pollution control. [Display omitted] • Targeted preparation of SA-Co-PCN can activate PMS efficiently. • PCN improved performance relatively less with initial Co atom addition above 8 wt%. • The K obs of SAs were SDZ, SIX, SMT and SMX in descending order. • Both S-N bond and C-S bond cleavage were the commonalities of SAs degradation pathway. • The toxicity of SAs degradation products was significantly reduced. [ABSTRACT FROM AUTHOR]

Pyriclobenzuron 1 1 PBU – pyriclobenzuron. (PBU) is a novel molluscicide developed to control Pomacea canaliculate , and little information on its environmental fate has been published. In this study, the photolysis of PBU in an aqueous environment was simulated using a xenon lamp. Results showed that the photolysis of PBU in water followed first-order kinetics, exhibiting a t 0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 2 2 PPs – photolysis products. (PPs) were detected by HPLC-UV and identified by UPLC-Q/TOF MS, which were formed via the hydroxylation and photocatalytic hydro-dehalogenation of PBU, respectively. The initial relative abundance of photolysis product 1 3 3 PP-1 – photolysis product 1. (PP-1) in Milli-Q water was 1.55 times higher than that in river water. PP-1 was detected at 26.5 % and 76.8 % of the maximum relative abundance in the river water and Milli-Q water after 720 h, respectively. Photolysis product 2 4 4 PP-2 – photolysis product 2. (PP-2) was stable in water because of its weak hydrophilicity. The PP-2 detected after 720 h in Milli-Q water and river water was 93.7 % and 93.5 % of the maximum relative abundance, respectively. Finally, ECOSAR software was used to evaluate the acute aquatic toxicity of PBU and its PPs, revealing that the PPs had lower toxicity levels to non-target aquatic organisms. [Display omitted] • Photolysis t 0.5 values of PBU in two aqueous environments were 95.1 h and 83.6 h. • The photolysis pathways of PBU were hydroxylation and hydro-dehalogenation. • PP-2 was more stable than PP-1 in aqueous environments. • ECOSAR predicted that aquatic toxicity of PPs was lower than that of PBU. [ABSTRACT FROM AUTHOR]

Empirical and in silico data on the aquatic ecotoxicology of 2697 organic chemicals were collected in order to compile a dataset for assessing the predictive power of current Quantitative Structure Activity Relationship (QSAR) models and software platforms. This document presents the dataset and the data pipeline for its creation. Empirical data were collected from the US EPA ECOTOX Knowledgebase (ECOTOX) and the EFSA (European Food Safety Authority) report "Completion of data entry of pesticide ecotoxicology Tier 1 study endpoints in a XML schema - database". Only data for OECD recommended algae, daphnia and fish species were retained. QSAR toxicity predictions were calculated for each chemical and each of six endpoints using ECOSAR, VEGA and the Toxicity Estimation Software Tool (T.E.S.T.) platforms. Finally, the dataset was amended with SMILES, InChIKey, pKa and logP collected from webchem and PubChem., (© 2023 The Authors.)

ABSTRACT The rough scad, Trachurus lathami Nichols, 1920, is a small pelagic species distributed along the West Atlantic coast. It is most abundant in the Southern Brazil (28°30’-34°S) and in the Southeastern Brazilian Bight (SEBB, 22°-28°30’S). The rough scad is fished by purse seines, which main target is the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879). Age and growth are vital to understand the life cycle of a species, to fishery management and ecosystem modeling. This study aimed to assess the age and growth of T. lathami, to identify its age structure in the SEBB, and to evaluate what causes the wide differences among Trachurus species in terms of body size and growth parameters. Data available on T. lathami was attained between 2008 and 2010 from surveys at SEBB. A total of 278 whole otoliths of T. lathami, total length between 27 mm and 208 mm, were analyzed and compared with the only other source of otolith data, from 1975. Three blind readings were performed and assessed using traditional methods to study fish age and growth. Zero up to eight rings were found, each ring corresponding to one year in the life of an individual of this species. The von Bertalanffy growth model parameters were L∞ = 211.90 mm and K = 0.319 year-1. The results of the analyses have shown similarities between 1975 and 2008-2010, indicating that the otolith development, the growth pattern and the age structure remained stable. T. lathami is the smallest species of Trachurus and it has the highest growth rates among them. This is probably related to the different temperatures where larvae/juvenile and adult grow, to the absence of a strong fishing pressure and to decadal population variability.

The rough scad, Trachurus lathami Nichols, 1920, is a small pelagic species distributed along the West Atlantic coast. It is most abundant in the Southern Brazil (28°30'-34°S) and in the Southeastern Brazilian Bight (SEBB, 22°-28°30'S). The rough scad is fished by purse seines, which main target is the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879). Age and growth are vital to understand the life cycle of a species, to fishery management and ecosystem modeling. This study aimed to assess the age and growth of T. lathami, to identify its age structure in the SEBB, and to evaluate what causes the wide differences among Trachurus species in terms of body size and growth parameters. Data available on T. lathami was attained between 2008 and 2010 from surveys at SEBB. A total of 278 whole otoliths of T. lathami, total length between 27 mm and 208 mm, were analyzed and compared with the only other source of otolith data, from 1975. Three blind readings were performed and assessed using traditional methods to study fish age and growth. Zero up to eight rings were found, each ring corresponding to one year in the life of an individual of this species. The von Bertalanffy growth model parameters were L∞ = 211.90 mm and K = 0.319 year-1. The results of the analyses have shown similarities between 1975 and 2008-2010, indicating that the otolith development, the growth pattern and the age structure remained stable. T. lathami is the smallest species of Trachurus and it has the highest growth rates among them. This is probably related to the different temperatures where larvae/juvenile and adult grow, to the absence of a strong fishing pressure and to decadal population variability. [ABSTRACT FROM AUTHOR]

Aromatic amines (anilines and related derivates) are an important class of environmental pollutants that can be released to the aquatic environment as industrial effluents or as breakdown products of pesticides and dyes. The toxicity of aniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline and 3,5-dichloroaniline towards a multitrophic test battery comprised of bacteria Aliivibrio fischeri (formerly Vibrio fischeri), a ciliated protozoan Tetrahymena thermophila and two crustaceans (Daphnia magna and Thamnocephalus platyurus) were investigated. Under the applied test conditions, the toxicity of the anilines notably varied among the test species. The bacteria and protozoa were much less sensitive towards the anilines than the crustaceans: EC50 values 13–403 mg L-1 versus 0.13–15.2 mg L-1. No general tendency between toxicity and the chemical structure of the anilines (the degree of chloro-substitution and the position of the chloro-substituents) was found in the case of all the tested aquatic species. The replacement of the artificial test medium (ATM) by the river water remarkably decreased the toxicity of anilines to crustaceans but not to protozoa. This research is part of the EU 6th Framework Integrated Project OSIRIS, in which ecotoxicogenomic studies of anilines (e.g., for Daphnia magna) will also be performed that may help to clarify the mechanisms of toxicity of different anilines.

Bioconcentration factors (BCFs) are markers of chemical substance accumulation in organisms, and they play a significant role in determining the environmental risk of various chemicals. Experiments to obtain BCFs are expensive and time-consuming; therefore, it is better to estimate BCF early in the chemical development process. The current research aims to evaluate the ecotoxicity potential of 122 pharmaceuticals and identify possible important structural attributes using BCF as the determining feature against a group of fish species. We have calculated the theoretical 2D descriptors from the OCHEM platform and SiRMS descriptor calculating software. The regression-based quantitative structure–property relationship (QSPR) modeling was used to identify the chemical features responsible for acute fish bioconcentration. Multiple models with the "intelligent consensus" algorithm were employed for the regression-based approach improving the predictive ability of the models. To ensure the robustness and interpretability of the developed models, rigorous validation was performed employing various statistical internal and external validation metrics. From the developed models, it can be specified that the presence of large lipophilic and electronegative moieties greatly enhances the bioaccumulative potential of pharmaceuticals, whereas the hydrophilic characteristics have shown a negative impact on BCF. Furthermore, the developed models were employed to screen the DrugBank database (https://go.drugbank.com/) for assessing the BCF properties of the entire database. The evidence acquired from the modeled descriptors might be used for aquatic risk assessment in the future, with the added benefit of providing an early caution of their probable negative impact on aquatic ecosystems for regulatory purposes. [ABSTRACT FROM AUTHOR]

The spatial distribution of small pelagic fishes off the Southeastern Brazilian coastal area (22°-29°S) was investigated over six periods, from 1995 to 2010, in the context of the Program "Prospection and Assessment of the Biomass of the Sardine, Sardinella brasiliensis" in order to provide data about their pattern of distribution and biomass. A checklist of the species collected is presented herein with data on geographic position and depth of captures. Such information is intended to be a reference about the fauna that occupied the region in the period under investigation, and allow future comparisons about the resilience of the local fauna, i.e., the detection of future changes caused by environmental factors or human activities. Sampling was conducted during hydroacoustic surveys with mid water trawling plus a few purse seine operations between 10 m and 100 m depth. A total of 86 species were collected.

[Display omitted] • Red mud was used as an iron precursor for preparation of Fe0-biochar (RMIS 1:1). • Efficient removal of sulfadiazine (SDZ) was achieved by RMIS 1:1 /PDS system. • The intermediates of SDZ in RMIS 1:1 /PDS system have less eco-toxicity. • RMIS 1:1 /PDS was able to treat practical pharmaceutical wastewater. • RMIS 1:1 /PDS was more cost-effective than other advanced oxidation processes. Zerovalent iron (Fe0)-based biochar (Fe0-BC) has attracted wide attention in activating persulfate to eliminate antibiotics. In this study, the waste red mud (RM) was successfully used as an iron precursor to prepare Fe0-BC (RMIS 1:1) via co-pyrolysis strategy, which was confirmed with remarkable capacity in peroxydisulfate (PDS) activation. The removal efficiency of sulfadiazine (SDZ) was 99.7% in RMIS 1:1 /PDS system in 20 min, with k obs of 0.3001 min−1. Both free radicals (SO 4 −, OH, and O 2 −) and non-free radicals (1O 2) were responsible for SDZ degradation, in which the SO 4 − and O 2 − played the dominant roles. Four SDZ degradation pathways were provided according to the intermediates identified by Q-TOF-MS. Furthermore, the ECOSAR prediction implied that the intermediates have less eco-toxicity than SDZ. Compared with PDS concentration and RMIS 1:1 dosage, the initial SDZ concentration had stronger effect on its degradation. Co-existed Cl− slightly improved SDZ degradation rate, while other anions (NO 3 –/SO 4 2−/HCO 3 –/CO 3 2–) and humic acid exhibited different levels of inhibition on SDZ removal. Moreover, RMIS 1:1 /PDS maintained acceptable degradation ability for practical pharmaceutical wastewater. The electrical energy per mass of SDZ was about 2.24 kWh/(g·SDZ) by RMIS 1:1 /PDS, lower than that produced in any other advanced oxidation processes that have been reported so far. In summary, this study reported a green strategy for Fe0-BC preparation from RM, which was valuable for both waste resource recycling and environmental remediation. [ABSTRACT FROM AUTHOR]

Public health is a major concern globally, owing to the presence of industrial dyes in the effluent. Nanoparticles with green synthesis are an enthralling research field with various applications. This study deals with investigating the photocatalytic potential of Fe-oxide nanoparticles (FeO-NPs) for the degradation of methylene blue dye and their potential biomedical investigations. Biosynthesis using Anthemis tomentosa flower extract showed to be an effective method for the synthesis of FeO-NPs. The freshly prepared FeO-NPs were characterized through UV/Vis spectroscopy showing clear peak at 318 nm. The prepared FeO-NPs were of smaller size and spherical shape having large surface area and porosity with no aggregations. The FeO-NPs were characterized using XRD, FTIR, HRTEM, SEM and EDX. The HRTEM results showed that the particle size of FeO-NPs was 60–90 nm. The antimicrobial properties of FeO-NPs were investigated against two bacterial Staphylococcus aureus 13 (±0.8) and Klebsiella pneumoniae 6(±0.6) and three fungal species Aspergillus Niger, Aspergillus flavus, and Aspergillus fumigatus exhibiting a maximum reduction of 57% 47% and 50%, respectively. Moreover, FeO-NPs exhibited high antioxidant properties evaluated against ascorbic acid. Overall, this study showed high photocatalytic, antimicrobial, and antioxidant properties of FeO-NPs owing to their small size and large surface area. However, the ecotoxicity study of methylene blue degradation products showed potential toxicity to aquatic organisms. • Biosynthesis of FeNanoparticles. • Characterizations of FeONPs. • Photocatalytic behavior of FeONPs. • Biomedical screening of FeONPs. • ECOSAR study of Methylene Blue. [ABSTRACT FROM AUTHOR]

The metal–organic frameworks (MOF)-based photocatalytic treatment of lincomycin employing Basolite F300 as catalyst in the presence of two oxidants (H 2 O 2 , S 2 O 8 2-) was investigated. Both processes led to the elimination of lincomycin within 120 min of treatment. The oxidant's addition has an enhancing effect on the process, possibly from heterogeneous Fenton-type reactions. The concentration effect (0–300 mg/L) of the oxidants was explored, and the optimum amount achieving the highest degradation rate proved to be 100 mg/L for both oxidants. In total, 39 transformation products were identified out of which 24 are proposed for the first time, while the main transformation pathways were hydroxylation, S-oxidation, desulfurization, pyranose ring opening, and cleavage of the C-N bond. For an integrated evaluation of the process, toxicity measurements of the treated solution were performed by a bioassay using D.Magna. Toxicity was more pronounced in the first stages of treatment, implying synergistic effects between the formed intermediate transformation products (TPs), while notable toxicity reduction was achieved at the end of the process. Ecological structure-activity relationship (ECOSAR) predictions revealed the formation of many non-toxic TPs with hydroxylation being the key to the detoxification of the formed compounds. [Display omitted] • Complete degradation of lincomycin within 120 min of treatment. • Oxidant's addition plays a dominant role leading to Fenton-type reactions. • Thirty-nine transformation products are identified. • A notable toxicity reduction is achieved at the end of the process. • ECOSAR predictions reveal the formation of many non-toxic TPs. [ABSTRACT FROM AUTHOR]

Hydroxyl radicals (·OH) are strong oxidants that can degrade organic pollutants in advanced oxidation processes (AOPs). The mechanisms, kinetics, and toxicity assessment of the ·OH-initiated oxidative degradation of the phenolic preservative, methylparaben (MPB), were systematically investigated using a computational approach, as the supplementary information for experimental data. Results showed that MPB can be initially attacked by ·OH via OH-addition and H-abstraction routes. Among these routes, the ·OH addition to the C atom at the ortho-position of phenolic hydroxyl group was the most significant route. However, the methyl-H-abstraction route also cannot be neglected. Further, the formed transient intermediates, OH-adduct (·MPB-OH1) and dehydrogenated radical (·MPB(-H)α), could be easily transformed to several stable degradation products in the presence of O2 and ·OH. To better understand the potential toxicity of MPB and its products to aquatic organisms, both acute and chronic toxicities were assessed computationally at three trophic levels. Both MPB and its products, particularly the OH-addition products, are harmful to aquatic organisms. Therefore, the application of AOPs to remove MPB should be carefully performed for safe water treatment. [ABSTRACT FROM AUTHOR]

Coal tar wastewater is hard to degrade by traditional methods because of its toxic pollutant constituents and high concentration of aromatic hydrocarbons, especially phenolic substances. A new type of hydrophobic benzacetone modified PbO 2 anode (BA-PbO 2 electrodes) was used for the electrocatalytic treatment of coal tar wastewater in a continuous cycle reactor. The surface morphology, structure, valences of elements, hydrophobicity, hydroxyl radical (·OH) produced capacity, electrochemical properties and stability of BA-PbO 2 electrodes were characterized by SEM (scanning electron microscopy), XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), contact angle, a fluorescence probe test, an electrochemical workstation and accelerated life test, respectively. The BA-PbO 2 electrodes exhibited a compact structure and finely dispersed crystallize size of 4.6 nm. The optimum degradation conditions of coal tar wastewater were as follows: current density of 90 mA cm−2, electrode gap of 1 cm and temperature at 25 °C with flow velocity of 80 L h−1. The chemical oxygen demand (COD) removal efficiency reached 92.39% after 240 min of degradation under the optimized conditions and the after-treatment COD value was 379.51 mg L−1 which was lower than the centralized emission standard (less than 400 mg L−1). These findings demonstrated the feasibility and efficiency of electrocatalytically degrading coal tar wastewater by BA-PbO 2 electrodes. The possible mechanism and pathway for phenol a specific pollutant in coal tar wastewater were investigated by quantum chemistry calculations (Multiwfn) and gas chromatography-mass spectrometry (GC-MS). The toxicity of each intermediate was predicted by the ECOSAR program. [Display omitted] • A novel hydrophobic PbO 2 electrode was fabricated and characterized. • BA-PbO 2 electrode effectively remove phenol from actual coal tar wastewater. • Degradation pathways and ecotoxicity were revealed systematically. • Fukui functions and dual descriptor were calculated to predict reactive sites. • A novel continuous cycle reactor was used in the degradation system. [ABSTRACT FROM AUTHOR]

Highlights: [•] A reliable QSAR is proposed to predict fish LC50 of organic solvents. [•] Solvents are described both by physicochemical and quantum theoretical descriptors. [•] Log P, LUMO, dielectric constant and surface tension were selected in the QSAR. [Copyright &y& Elsevier]

Vertebrate testing under the European Union's regulation on Registration, Evaluation, Authorisation and Restriction of Chemical substances (REACH) is discouraged, and the use of alternative nontesting approaches such as quantitative structure-activity relationships (QSARs) is encouraged. However, robust QSARs predicting chronic ecotoxicity of organic compounds to fish are not available. The Ecological Structure Activity Relationships (ECOSAR) Class Program is a computerized predictive system that estimates the acute and chronic toxicity of organic compounds for several chemical classes based on their log octanol-water partition coefficient ( KOW). For those chemical classes for which chronic training data sets are lacking, acute to chronic ratios are used to predict chronic toxicity to aquatic organisms. Although ECOSAR reaches a high score against the Organisation for Economic Co-operation and Development (OECD) principles for QSAR validation, the chronic QSARs in ECOSAR are not fully compliant with OECD criteria in the framework of REACH or CLP (classification, labeling, and packaging) regulation. The objective of the present study was to develop a chronic ecotoxicity QSAR for fish for compounds acting via nonpolar and polar narcosis. These QSARs were built using a database of quality screened toxicity values, considering only chronic exposure durations and relevant end points. After statistical multivariate diagnostic analysis, literature-based, mechanistically relevant descriptors were selected to develop a multivariate regression model. Finally, these QSARs were tested for their acceptance for regulatory purposes and were found to be compliant with the OECD principles for the validation of a QSAR. Environ Toxicol Chem 2013;32:2217-2225. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Abstract: The thermal decomposition of Fenitrothion [phosphorothioic acid O,O-diethyl O-(3-methyl-4-nitrophenyl) ester] was investigated. Results obtained by different scale calorimetric techniques show that the thermal decomposition of Fenitrothion involves two main steps. Intermediate and final thermal degradation products formed during isothermal and adiabatic thermal decomposition experiments were identified. The eco-toxicological profile of the decomposition products was assessed experimentally and compared to results obtained with a predictive software (ECOSAR). A specific index was defined to assess the change in ecotoxicity profile of decomposition products with respect to the original compound. [Copyright &y& Elsevier]

This study concentrates on the external validation of an existing Quantitative Structure-Activity Relationship (QSAR) model widely used for long-term aquatic toxicity to fish. In the context of the REACH legislation, QSARs are used as an alternative for experimental data to achieve a complete environmental assessment without the need for animal testing. The predictivity of the model was evaluated in order to increase the reliability of the model. We assessed whether the model met all of the OECD principles. The model was adapted to become more robust, and predictions were made with an external validation set collected from several databases. For the internal validation of the QSAR, the r2, [image omitted] and [image omitted] were used as validation criteria, and for the external validation r2, [image omitted], h and the validation ratio were used. A few substances were classified as outliers and therefore the applicability domain of the QSAR had to be adjusted. The QSAR passed all validation criteria and met all the OECD principles for QSAR validation, and the long-term toxicity QSAR for fish can be applied with high certainty of a correct prediction within the limits of the inherent uncertainty of the model in cases where the substance falls within the applicability domain. [ABSTRACT FROM AUTHOR]

Abstract: Aquatic toxicity information is essential in environmental risk assessment to determine the potential hazards and risks of new and existing chemicals. Prediction and modelling techniques, such as quantitative structure activity relationships (QSAR) and species sensitivity distributions (SSDs), are applied to fill data gaps and to predict, assess and extrapolate the toxicity of chemicals. In this study, both techniques (i.e. the ECOSAR programme as QSAR tool and SSDs) were assessed for a set of polar narcotic structural analogues that differ in their degree of chloro-substitution (aniline, 4-chloroaniline, 3,5-dichloroaniline and 2,3,4-chloroaniline). The acute toxicity of these compounds was tested in one prokaryote species (Escherichia coli) and three eukaryote aquatic species (Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio). Consequently, the experimental acute toxicity data were compared to the QSAR predictions made by the ECOSAR programme and compared to the species sensitivity modelling results. Large interspecies differences in sensitivity were observed (D. magna > P. subcapitata > D. rerio > E. coli). 4-Chloroaniline acted as an outlier in P. subcapitata toxicity. Whereas in D. magna, toxicity decreased rather than increased with increasing log K ow of the test compounds. In general, large interchemical and interspecies differences in toxicity of these relatively simple chemical structures were observed. Moreover, this species variation could not entirely be characterized by the ECOSAR tool. SSD modelling is particularly focussed on species variations and emphasis is put on protecting those species that are most affected by chemical exposure. Compared to QSARs, SSDs offer broader perspectives regarding species sensitivity ranking, however, in this study they could only be applied for aniline and 4-chloroaniline. [Copyright &y& Elsevier]

Aromatic amines (anilines and related derivates) are an important class of environmental pollutants that can be released to the aquatic environment as industrial effluents or as breakdown products of pesticides and dyes. The toxicities of aniline, 2-chloroaniline, 3- chloroaniline, 4-chloroaniline and 3,5-dichloroaniline towards a multitrophic test battery comprised of bacteria Aliivibrio fischeri (formerly Vibrio fischeri), a ciliated protozoan Tetrahymena thermophila and two crustaceans (Daphnia magna and Thamnocephalus platyurus) were investigated. Under the applied test conditions, the toxicities of the anilines notably varied among the test species. The bacteria and protozoa were much less sensitive towards the anilines than the crustaceans: EC50 values 13-403 mg L-1 versus 0.13-15.2 mg L-1. No general tendency between toxicity and the chemical structure of the anilines (the degree of chloro-substitution and the position of the chloro-substituents) was found in the case of all the tested aquatic species. The replacement of the artificial test medium (ATM) by the river water remarkably decreased the toxicity of anilines to crustaceans but not to protozoa. This research is part of the EU 6th Framework Integrated Project OSIRIS, in which ecotoxicogenomic studies of anilines (e.g., for Daphnia magna) will also be performed that may help to clarify the mechanisms of toxicity of different anilines. [ABSTRACT FROM AUTHOR]

Abstract: Improvements in analytical techniques have led to an increased awareness of the presence of pharmaceuticals in the environment. Concern is now raised as to the potential adverse effects these compounds may have on non-target organisms, particularly under conditions of chronic exposure. There is a paucity of experimental ecotoxicity data available for pharmaceuticals, hence the use of in silico tools to predict toxicity is a pragmatic option. Previous studies have used the ECOSAR program to predict environmental toxicity of pharmaceuticals, however, these models were developed using industrial chemicals and the applicability of the models to predict effects of pharmaceuticals should be carefully considered. In this study ECOSAR was used to assign 364 diverse pharmaceuticals to recognised chemical classes and hence predict their aquatic toxicity. Confidence in the predictions was assessed in terms of whether the assigned class was realistically representative of the pharmaceutical in question. The correlation between experimentally determined toxicity values (where these were available) and those predicted by ECOSAR was investigated in terms of confidence in the prediction. ECOSAR was shown to make reasonable predictions for certain pharmaceuticals considered to be within the applicability domain of the models, but predictions were less reliable for compounds judged to fall outwith the domain of the models. This study is not critical of ECOSAR or the class based approach to predicting toxicity, but demonstrates the importance of using expert judgement to ascertain whether or not use of a particular model is appropriate when the specific chemistry of a query compound is considered. [Copyright &y& Elsevier]

Abstract: The new EU legislation for managing chemicals called REACH aims to fill in gaps in toxicity information that exist for the chemicals listed on the European Inventory of Existing Chemical Substances (EINECS). REACH advocates the use of alternatives to animal experimentation including, amongst others, (quantitative) structure–activity relationship models [(Q)SARs] to help fill in the toxicity data gaps. The aim of the present study was to provide a science-based estimate of the number of EINECS compounds that can be covered by (Q)SAR models for acute toxicity. Using the ECOSAR software, 54% of the 100196 EINECS chemicals were classified into 49 classes that can be potentially covered by (Q)SAR models. The largest proportion of the classified compounds (40% of the EINECS list) falls into the classes of non-polar and polar narcotics. Compounds that were not classified include, for example, fish oils, botanical and animal extracts, and crude oil distillates. With rapid improvements in analytical tools, the number of EINECS compounds for which toxicity evaluations may be based on (Q)SAR approaches may be extended by further developing the method recently developed for the safety assessment of natural flavor complexes used as ingredients in food. This method is based on identification of the individual components in a mixture, and judgment of the safety of these identified individual compounds using toxicity information on structurally similar congeners in the respective classes. Such (Q)SAR approaches may be applied to an additional 2938 EINECS compounds, representing botanical and animal extracts, leading to a total estimate of 57% of the EINECS compounds for which (Q)SAR-based approaches may assist in their safety assessment. It is concluded that, despite the fact that individual (Q)SARs may often each cover only a limited number, i.e. less than 1%, of the EINECS compounds, the potential for applying (Q)SAR approaches for safety assessment of EINECS compounds may prove to be significant. [Copyright &y& Elsevier]

Abstract: Chemical warfare agents (CWAs) have been disposed of in various fashions over the past decades. Significant amounts (∼11,000tonnes) have been dumped in the Baltic Sea east of the island Bornholm following the disarmament of Germany after World War II, causing concerns over potential environmental risks. Absence of risk based on assumptions of extremely low solubility of CWAs cannot alone dismiss these concerns. Existing and modelled fate and effects data were used in the analysis to assess the fish community risk level. The most realistic and also conservative assessment result is the scenario describing 70m water depth for the most realistic dump-site area with a focus on chronic toxicity, at 0–20cm above the sediment, yielding a total mixture toxic unit (TU) of 0.62. Triphenylarsine is the CWA with the highest realistic risk profile at 0.2TU for the fish community followed by Adamsite (0.17), Clark I (0.086) and Yperite (0.083) TU. Adamsite is more persistent and constitutes a potential risk for a longer period than triphenylarsine. The seawater volume potentially at risk is <4m above sediment and <58km down current of dump sites. Further risk assessment of dumped CWAs in the Baltic Sea is warranted. [Copyright &y& Elsevier]

The toxicity of SSRIs to algae/phytoplankton was investigated using the US EPA ECOSAR, acute single-species growth inhibition assays, species sensitivity distributions (SSDs), and an outdoor microcosm mixture experiment. Worst-case ECOSAR estimates of SSRI toxicity to algae ranged from 0. 73 to 13. 08mg/L. Sertraline was the most toxic SSRI tested in single-species growth inhibition assays followed by fluoxetine and fluvoxamine with worst-case 96-h IC10s of 4. 6, 31. 3, and 1662μg/L, respectively. HC5s of 2. 4, 3. 6, and 1100μg/L were estimated, respectively, for sertraline, fluoxetine, and fluvoxamine toxicity to algae-using SSDs. Microcosm phytoplankton structural endpoints were more sensitive than functional endpoints in the short term. However, in the long term, structural endpoints were resilient and functional endpoints remained impacted even after a period of recovery. The worst-case EC10 determined from the outdoor microcosm mixture toxicity to phytoplankton communities was 15. 2nM. Although SSRIs are toxic to algae, hazard quotients using worst-case PECs represent a margin of safety of 20 to phytoplankton. Although SSRIs do not appear to pose a hazard to primary production, this assessment is not protective of higher aquatic organisms and further research into the chronic toxicity to low levels of SSRIs to higher-level aquatic species is recommended. [Copyright &y& Elsevier]

At a recent workshop in Setubal (Portugal) principles were drafted to assess the suitability of (quantitative) structure-activity relationships ((Q)SARs) for assessing the hazards and risks of chemicals. In the present study we applied some of the Setubal principles to test the validity of three (Q)SAR expert systems and validate the results. These principles include a mechanistic basis, the availability of a training set and validation. ECOSAR, BIOWIN and DEREK for Windows have a mechanistic or empirical basis. ECOSAR has a training set for each QSAR. For half of the structural fragments the number of chemicals in the training set is > 4. Based on structural fragments and log Kow, ECOSAR uses linear regression to predict ecotoxicity. Validating ECOSAR for three 'valid' classes results in predictivity of a ≥ 64%. BIOWIN uses (non-)linear regressions to predict the probability of biodegradability based on fragments and molecular weight. It has a large training set and predicts non-ready biodegradability well. DEREK for Windows predictions are supported by a mechanistic rationale and literature references. The structural alerts in this program have been developed with a training set of positive and negative toxicity data. However, to support the prediction only a limited number of chemicals in the training set is presented to the user. DEREK for Windows predicts effects by 'if-then' reasoning. The program predicts best for mutagenicity and carcinogenicity. Each structural fragment in ECOSAR and DEREK for Windows needs to be evaluated and validated separately. [ABSTRACT FROM AUTHOR]

Four different classes of environmental concern are quantitatively and qualitatively assessed for environmental hazards; antibiotics (n = 226), antineoplastics (n = 81), cardiovascular (n = 272), and sex hormones (n = 92). These along with an ECOSAR scan of all pharmaceuticals (n = 2848) were then classified according to the OECD aquatic toxicity classification system. The predicted species susceptibility is: daphnid > fish > algae, and the predicted rank order of relative toxicity: sex hormones > cardiovascular = antibiotics > antineoplastics (Table 1). Generally, a relatively large proportion (1/3) of all pharmaceuticals are potentially very toxic to aquatic organisms (Table 2). The qualitative risk assessment ranking relative to probability and potential severity for human and environmental health effects is: antibiotics > sex hormones > cardiovascular > antineoplastics. (Q)SARs and pharmacodynamic information should be used to prioritize and steer experimental risk assessments of pharmaceuticals, and potentially, also be used in new drug discovery optimizing efficacy and in minimising environmental hazards of new products. Nuclear receptors are relatively well conserved in evolution. Currently, antibacterial resistance represents the most significant human health hazard, and potentially the largest non-target organism hazard is sex hormones acting as endocrine modulators in wildlife. Data for the individual compounds are accessible via . [Copyright &y& Elsevier]

The risks associated with occurrence of pharmaceuticals in water resources are mostly unknown. In the absence of extensive toxicological data, we scanned all the compounds observed in the environment for toxicological properties by (Quantitative) Structure Activity Relationship ((Q)SAR). The results of the probabilistic distribution of environmental and effect concentrations and hazard quotients (HQs) do not indicate significant acute risks prior to application of assessment factors. Compared with measured effect concentrations SAR predictions were more “sensitive” 80% of the time. The long-term effects of subtle and chronic changes, additive or synergistic effects and effects on other endpoints e.g. reproduction, behavior, metabolism, bacterial resistance etc. are still uncertain. (Q)SAR''s can be important prioritization tools for subsequent experimental risk assessment of pharmaceuticals in surface waters, due to the prevalent lack of ecotoxicological data. [Copyright &y& Elsevier]

ECOSAR and DEREKfW predictions for the (eco)toxicological effects of circa 70 substances were compared with experimental data for risk assessment purposes. These and other (quantitative) structure-activity relationships ((Q)SARs) programs will play an important role in future chemical policies, such as in the European Union and The Netherlands, to reduce animal testing and costs and to speed up the number of risk assessments for hazardous chemicals. The two programs, ECOSAR and DEREKfW, were selected because they are easy to use and transparent in their predictions. They predict to which chemical class a substance belongs and also predict some (eco)toxicological properties. ECOSAR categorised 87% of the chemicals correctly in chemical classes. With regard to predicting ecotoxicity, criteria were drawn up for the reliability of the QSARs provided by ECOSAR. Application of these criteria had the result that half of the regression lines from ECOSAR were considered unreliable beforehand. It turned out, however, that the "unreliable" regression lines predicted similar accurately as the "reliable" lines, although much less chemicals were available for validating the "unreliable" QSARs. The overall accurate prediction of toxicity by ECOSAR was 67%. DEREKfW categorised 90% of the chemicals correctly in chemical classes, while 10% of the structural fragments needed a more detailed description. The accuracy of prediction was around 60% for sensitisation, 75% for genotoxicity and carcinogenicity for a limited number of chemicals. Irritation and reproductive toxicity were predicted poorly. Finally, it should be stressed that regulators and industries need to agree on the acceptability criteria relating to false negative and false positive (Q)SAR predictions. This to prevent unnecessary animal testing when regulators do not sufficiently rely on (Q)SAR predictions or to prevent too much faith in (Q)SAR predictions which will then may cause an insufficient protection of man and the environment. Therefore, if the regulatory trend is that (Q)SARs have to be applied more and more systematically in the risk assessment process, their validity and the available tools have to be explored further. [ABSTRACT FROM AUTHOR]