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Rice crab co-culture is a new integrated farming model in China. The application of triazole plant growth regulators (PRGs) is often used as an advantageous option to combat rice lodging. However, there is still a gap regarding the toxicity of these PRGs on the growth and development of the Chinese mitten crab (Eriocheir sinensis, E. sinensis). Here the effect of triazoles (paclobutrazol and uniconazole) on the molting mechanism of E. sinensis was investigated. Monitoring of regulatory genes associated with molting showed that the two PRGs were found to inhibit the expression of ecdysteroid hormone (EH), ecdysteroid receptors gene (EcR), and retinoid X receptors gene (RXR) and induce secretion of molt-inhibiting hormone (MIH) gene. In addition, the activities of chitinase (CHIA) and N-acetyl-β- d -aminoglucosidase (β-NAGase) were also inhibited by exposure to PRGs. Exposure to PRGs also elevated the mRNA expression of the growth-related myostatin gene (MSTN). These results revealed that there is a long-term risk of exposure to triazoles PRGs that may inhibit molting and affect normal development and immune system of E. sinensis. [Display omitted] • Effects of triazole plant growth regulators (RPGs) on E. sinensis were researched. • Paclobutrazol and uniconazole were not significantly acutely toxic to E. sinensis. • Triazole RPGs show endocrine disruptive ability in inhibiting molting in E. sinensis. [ABSTRACT FROM AUTHOR]

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Background: A number of predictive models for aquatic toxicity are available, however, the accuracy and extent of easy to use of these in silico tools in risk assessment still need further studied. This study evaluated the performance of seven in silico tools to daphnia and fish: ECOSAR, T.E.S.T., Danish QSAR Database, VEGA, KATE, Read Across and Trent Analysis. 37 Priority Controlled Chemicals in China (PCCs) and 92 New Chemicals (NCs) were used as validation dataset. Results: In the quantitative evaluation to PCCs with the criteria of 10-fold difference between experimental value and estimated value, the accuracies of VEGA is the highest among all of the models, both in prediction of daphnia and fish acute toxicity, with accuracies of 100% and 90% after considering AD, respectively. The performance of KATE, ECOSAR and T.E.S.T. is similar, with accuracies are slightly lower than VEGA. The accuracy of Danish Q.D. is the lowest among the above tools with which QSAR is the main mechanism. The performance of Read Across and Trent Analysis is lowest among all of the tested in silico tools. The predictive ability of models to NCs was lower than that of PCCs possibly because never appeared in training set of the models, and ECOSAR perform best than other in silico tools. Conclusion: QSAR based in silico tools had the greater prediction accuracy than category approach (Read Across and Trent Analysis) in predicting the acute toxicity of daphnia and fish. Category approach (Read Across and Trent Analysis) requires expert knowledge to be utilized effectively. ECOSAR performs well in both PCCs and NCs, and the application shoud be promoted in both risk assessment and priority activities. We suggest that distribution of multiple data and water solubility should be considered when developing in silico models. Both more intelligent in silico tools and testing are necessary to identify hazards of Chemicals. [ABSTRACT FROM AUTHOR]

Site-specific water quality criteria considering hydrochemical conditions are needed for zoning control of environmental risks. However, the differences in water quality parameters between regions have not been fully considered in the current research on water quality criteria and risk assessment of lead. In this study, lead concentration and total hardness (TH) data of surface water in 13 major river basins and 31 administrative regions in China were collected. Based on the normalization of the TH of the toxicity data, the short-term and long-term water quality criteria of lead in China's surface water in the specific TH condition (100 mg/L) were derived using the species sensitivity distribution method, which were 90.7 μg/L and 2.1 μg/L, respectively. Furthermore, this study provided general derivation formulas for the water quality criteria based on the TH of surface water and obtained the site-specific criteria for different regions/basins in China. On this basis, an ecological risk assessment considering the TH was proposed for the first time. The results showed that there was a clear risk of lead in the Pearl River Basin and the rivers in Zhejiang-Fujian. The southern coastal provinces were at an unacceptable risk level, although the lead concentrations in the surface water were medium; the opposite was true in northern China, which meant that a high concentration of lead did not necessarily pose a high ecological risk and about 25 % of the variation in the predicted risk can be explained by the TH in Monte Carlo simulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Tricyclazole is used as a common fungicide to control rice blast. However, studies on the toxicity of tricyclazole to crabs in the rice-crab co-culture system are still extremely rare. Here, the environmental dissipation of tricyclazole was monitored in this model, and the potential toxicity of tricyclazole to E. sinensis at environmental concentrations as well as the dietary risk was evaluated. The results showed that tricyclazole had no significant acute toxicity to E. sinensis (LC 50  > 100 mg/L), while it promoted body weight gain. Tricyclazole in the hepatopancreas had a higher persistent bioaccumulation risk than in the muscle. Tricyclazole suppressed the immune response of E. sinensis under prolonged exposure and there should be gender differences, with females being more sensitive. Lipid metabolism enzymes were also significantly inhibited. While tricyclazole stimulated males molting but prolonged molting duration, both molting and duration of females were also disturbed. The dietary risk assessment indicated that tricyclazole intake from current crab consumption was low risk. This evidence demonstrated that tricyclazole may have potential risks to individual development, nutritional quality, and economic value on E. sinensis and should be used with caution in rice-crab co-culture system whenever possible., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Linear alkylbenzene sulfonate (LAS) is a widely used anionic surfactant that exists as a mixture of various homologous structures in water environment. In the calculation of hazardous concentrations of LAS, cross-taxonomies toxicity estimation was often used instead of species-level-specific estimation for the normalization of toxicity data, which led to substantial uncertainties. In this study, combined quantitative structure–activity relationship (QSAR) and interspecific relationship estimation (ICE) models were developed to normalize the alkyl chain length of toxicity data and calculate the 5th percentile hazard concentrations (HC 5 s) of LAS. Using seven acute QSAR models based on measured data and 29 acute QSAR-ICE models derived from them, the acute HC 5 s of LAS were calculated as 2.09–3.67 mg/L. Furthermore, species- and family-level-specific QSAR and QSAR-ICE models were used to calculate chronic HC 5 s (0.19–0.38 mg/L). Additionally, the sensitivity of biological toxicity to the hydrophobicity of LAS, represented by the slope of the QSAR models, had a significant correlation with the taxa of the species. Further risk assessment based on chronic HC 5 s showed potential ecological risks in the Dianchi Lake basin and Haihe River basin in China, which should cause concern. [Display omitted] • The QSAR-ICE models were developed to calculate the HC 5 s of LAS. • Species- or family-level normalization was done to improve toxicity prediction. • SSDs and HC 5 s were generated to compare representative hazard assessment scenarios. • The ecological risk of LAS in major basins in China was assessed for the first time. [ABSTRACT FROM AUTHOR]

The widely used antidiabetic drug metformin has become an emerging contaminant of water systems. In a prior study, we demonstrated the marked mammalian toxicity of the disinfection-derived byproducts (DBPs) Y (yellow, C 4 H 6 ClN 5 ) and C (colorless, C 4 H 6 ClN 3 ), and here assess the distribution, formation, and ecotoxicity of these in Chinese urban water systems. A national tap water assessment showed that metformin and C concentrations were higher in large, dense urban areas and surface water sources than in sparsely populated areas and groundwater sources. Water types' analysis clearly showed that C derived from chlorination of metformin-contaminated water (up to 4308.5 ng/L) circulated from domestic water (0.7-9.7 ng/L) via sewage (2.3 ng/L in effluent) to surface water (0.6-3.5 ng/L). Simulated disinfection and aqueous stability results systematically showed rapid formation and 24 h stability of both byproducts, indicating high exposure odds for water users. Both byproducts showed clear but distinct toxic effects on the growth (72 h IC 50 , 0.6 mg/L for Y and 4.4 mg/L for C) and photosynthesis of the microalgae Pseudokirchneriella subcapitata at milligram levels. Combinedly, our work reveals that metformin byproducts have been disseminated to urban water cycle and contaminated tap water, increasing potential toxic risk for drinking water. Its outcomes provide a preliminary reference for future studies on the environmental fate and ecotoxicological effects of unintended DBPs formed in the chlorination of metformin-contaminated water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Phthalates (PAEs) are of wide concern because they are commonly used in various plastic products as plasticizers, and can found their way into the environment. However, their interaction with the environment and their toxicity in aquatic animals is still a matter of intense debate. In this review on PAEs in aquatic environments (lakes, rivers and seas), it is found that there is a large variety and abundance of PAEs in developing countries, and the total concentration of PAEs even exceeds 200 μg / L. The interaction between metabolic processes involved in the toxicity induced by various PAEs is summarized for the first time in the article. Exposure of PAEs can lead to activation of the detoxification system CYP450 and endocrine system receptors of aquatic animals, which in turn causes oxidative stress, metabolic disorders, endocrine disorders, and immunosuppression. Meanwhile, each system can activate / inhibit each other, causing genotoxicity and cell apoptosis, resulting in the growth and development of organisms being blocked. The mixed PAEs shows no cumulative toxicity changes to aquatic animals. For the combined pollution of other chemicals and PAEs, PAE can act as an agonist or antagonist, leading to combined toxicity in different directions. Phthalate monoesters (MPEs), the metabolites of PAEs, are also toxic to aquatic animals, however, the toxicity is weaker than the corresponding parent compounds. This review summarizes and analyzes the current ecotoxicological effects of PAEs on aquatic animals, and provides guidance for future research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)