Determination of endocrine disrupting chemicals in surface water and industrial wastewater from Beijing, China

Confirmation of the steroid hormone receptor-mediated endocrine disrupting potential of fenvalerate following the Organization for Economic Cooperation and Development test guidelines, and its estrogen receptor α-dependent effects on lipid accumulation

In this study, we focused on confirming the steroid hormone receptor-mediated endocrine-disrupting potential of the pyrethroid insecticide fenvalerate and unraveling the underlying mechanisms. Therefore, we assessed estrogen receptor-α (ERα)- and androgen receptor (AR)-mediated responses in vitro using a hormone response element-dependent transcription activation assay with a luciferase reporter following the Organization for Economic Cooperation and Development (OECD) test guidelines. We observed that fenvalerate acted as estrogen by inducing the translocation of cytosolic ERα to the nucleus via ERα dimerization, whereas it exhibited no AR-mediated androgen response element-dependent luciferase activity. Furthermore, we confirmed that fenvalerate-induced activation of ERα caused lipid accumulation, promoted in a fenvalerate-dependent manner in 3 T3-L1 adipocytes. Moreover, fenvalerate-induced lipid accumulation was inhibited in the presence of an ERα-selective antagonist, whereas it remained unaffected in the presence of a glucocorticoid receptor (GR)-specific inhibitor. In addition, fenvalerate was found to stimulate the expression of transcription factors that promote lipid accumulation in 3 T1-L1 adipocytes, and co-treatment with an ERα-selective antagonist suppressed adipogenic/ lipogenic transcription factors at both mRNA and protein levels. These findings suggest that fenvalerate exposure may lead to lipid accumulation by interfering with ERα activation-dependent processes, thus causing an ERα-mediated endocrine-disrupting effect.

Bifenthrin induces changes in clinical poisoning symptoms, oxidative stress, DNA damage, histological characteristics, and transcriptome in Chinese giant salamander (Andrias davidianus) larvae

Bifenthrin (BF) is a broad-spectrum insecticide that has gained widespread use due to its high effectiveness. However, there is limited research on the potential toxic effects of bifenthrin pollution on amphibians. This study aimed to investigate the 50 % lethal concentration (LC50) and safety concentration of Chinese giant salamanders (CGS) exposed to BF (at 0, 6.25,12.5,25 and 50 μg/L BF) for 96 h. Subsequently, CGS were exposed to BF (at 0, 0.04, and 4 μg/L BF) for one week to investigate its toxic effects. Clinical poisoning symptoms, liver pathology, oxidative stress factors, DNA damage, and transcriptome differences were observed and analyzed. The results indicate that exposure to BF at 4 μg/L significantly decreased the adenosine-triphosphate (ATP), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) contents in the brain, liver, and kidney of CGS. Additionally, the study found that the malondialdehyde (MDA), reactive oxygen species (ROS), and 8-hydroxydeoxyguanosine (8-OHdG) contents were increased. The liver tissue exhibited significant inflammatory reactions and structural malformations. RNA-seq analysis of the liver showed that BF caused abnormal antioxidant indices of CGS. This affected molecular function genes such as catalytic activity, ATP-dependent activity, metabolic processes, signaling and immune system processes, behavior, and detoxification, which were significantly upregulated, resulting in the differential genes significantly enriched in the calcium signaling pathway, PPARα signaling pathway and NF-kB signaling pathway. The results suggest that BF induces the abnormal production of free radicals, which overwhelms the body's self-defense system, leading to varying degrees of oxidative stress. This can result in oxidative damage, DNA damage, abnormal lipid metabolism, autoimmune diseases, clinical poisoning symptoms, and tissue inflammation. This work provides a theoretical basis for the rational application of bifenthrin and environmental risk assessment, as well as scientific guidance for the conservation of amphibian populations.

Co-exposure to polystyrene microplastics and cypermethrin enhanced the effects on hepatic phospholipid metabolism and gut microbes in adult zebrafish

Microplastics (MPs) can absorb environmental pollutants from the aquatic environment to cause mixed toxicity, which has received widespread attention. However, studies on the joint effects of MPs and insecticides are limited. As one of the most widely used pyrethroids, there was a large amount of residual cypermethrin (CYP) in water due to insufficient decomposition. Here, adult female zebrafish were exposed to MPs, CYP, and their mixtures for 21 days, respectively. After exposures, the MPs and CYP caused tissue damage to the liver. Hepatic triglyceride (TG) level increased significantly after MPs + CYP exposure, and the expression of genes about glycolipids metabolism was significantly altered. Furthermore, metabolome results suggested that MPs + CYP exposure resulted in increased content of some glycerophospholipid, affecting phospholipid metabolism-related pathways. In addition, through 16 s rDNA sequencing, it was found that MPs + CYP led to significant changes in the proportion of dominant phyla. Interestingly, Cetobacterium which increased in CYP and the co-exposure group was positively correlated with most lipid metabolites. Our results suggested that co-exposure to MPs and CYP enhanced the disturbances in hepatic phospholipid metabolism by affecting the gut microbial composition, while these changes were not observed in separate treatment groups. These results emphasized the importance of studying the joint toxicity of MPs and insecticides.

Curcumin protects against fenvalerate-induced neurotoxicity in zebrafish (Danio rerio) larvae through inhibition of oxidative stress

Fenvalerate (FEN), a typical type II pyrethroid pesticide, is widely used in agriculture. FEN has been detected in the environment and human body. However, the neurotoxicity of FEN has not been well elucidated. This study aimed to explore the mechanisms underlying FEN-induced neurotoxicity using the zebrafish (Danio rerio) model. We also investigated whether curcumin (CUR), a polyphenol antioxidant that exhibits neuroprotective properties, can prevent FEN-induced neurotoxicity. Here, zebrafish embryos were exposed to 0, 3.5, 7 and 14 μg/L of FEN from 4 to 96 h post fertilization (hpf) and neurotoxicity was assessed. Our results showed that FEN decreased the survival rate, heart rate, body length and spontaneous movement, and increased malformation rate. FEN caused neurobehavioral alterations, including decreased swimming distance and velocity, movement time and clockwise rotation times. FEN also suppressed neurogenesis in transgenic HuC:egfp zebrafish, reduced cholinesterase activity and downregulated the expression of neurodevelopment related genes (elavl3, gfap, gap43 and mbp). In addition, FEN enhanced oxidative stress via excessive reactive oxygen species and antioxidant enzyme inhibition, then triggered apoptosis by upregulation of apoptotic genes (p53, bcl-2, bax and caspase 3). These adverse outcomes were alleviated by CUR, indicating that CUR mitigated FEN-induced neurotoxicity by inhibiting oxidative stress. Overall, this study revealed that CUR ameliorated FEN-induced neurotoxicity via its antioxidant, indicating a promising protection of CUR against environmental pollutant-induced developmental anomalies.

Atrazine decontamination by a newly screened psychrotroph Paenarthrobacter sp. KN0901 in an aquatic system: Metabolic pathway, kinetics, and hydroponics experiment

Atrazine residues running off the fields and entering water resources are a major threat to food security and the ecosystem. In this study, a psychrotrophic functional strain named KN0901 to remove atrazine residues was screened. KN0901 could degrade 30 mg·L^-1 atrazine in 4 days at 15ºC with 10⁵ CFU·mL^-1 incubation. The phylogenetic results showed KN0901 belonged to Paenarthrobacter sp. PCR results showed that the functional genes consist of trzN, atzB, and atzC, suggesting atrazine was transformed to cyanuric acid by KN0901. KN0901 could degrade atrazine without adding exogenous carbon and nitrogen sources. What's more, KN0901 could tolerate extreme low temperature (5ºC) and high atrazine concentration (100 mg·L^-1). When growth and degradation curves were compared, the results indicated the length of lag time showed significant correlation to atrazine degradation rate. The hydroponic experiments showed that the toxicity of atrazine was significantly reduced with KN0901 treatment. The study provided an effective, economic, and eco-friendly bioremediation measure to address atrazine contamination.

Environmentally relevant concentrations of fenvalerate induces immunotoxicity and reduces pathogen resistance in Chinese rare minnow (Gobiocypris rarus)

Fenvalerate is a broadly used type II pyrethroid with a potential toxic effect in fish. However, information on the immunotoxicity of fenvalerate in fish is scarce. Here, to discover the immunotoxicity of fenvalerate and its underlying mechanism in fish, adult Chinese rare minnow was exposed to fenvalerate at 0, 0.3, 1, and 3 μg/L for 28 days and then subjected to Pseudomonas fluorescens (P. fluorescens) challenge. Fenvalerate induced significant pathological changes, with disintegration of cell boundaries in the intestine, epithelial hyperplasia in gills, and vacuolation of hepatocytes at 3 μg/L treatment. Additionally, the pathological characteristics were more serious during P. fluorescens infection after fenvalerate exposure. A significant increase in neutrophil counts was observed after 3 μg/L fenvalerate exposure for 28 days (p < 0.05), whereas significantly increased monocyte and neutrophil counts and greatly decreased lymphocyte counts were detected at 24 h post-injection (hpi) with P. fluorescens (p < 0.05). Furthermore, obvious decreases in LYS, IgM, ALP, and C3 levels were detected in plasma after 3 μg/L fenvalerate exposure for 28 days, which was consistent with the results at 24 and 48 hpi. Notably, fish exposed to fenvalerate suppressed the transcription of TLR-NF-κB signaling pathway-relevant genes in response to P. fluorescens, accompanied by high mortalities and bacterial loads. Therefore, our results demonstrate that fenvalerate at environmentally relevant concentrations caused immunotoxicity in fish. This study highlights the importance of considering the combined effects of chemicals and pathogens to refine our ability to predict the effects of environmental contaminants on aquatic organisms.

circRNA-based biomarker candidates for acute cypermethrin and chlorpyrifos toxication in the brain of Zebrafish (Danio rerio)

Circular RNAs (circRNAs) are a new class of non-endogenous coding RNA and an area with a lot of research interest and activity. Cypermethrin and chlorpyrifos have been shown to cause serious toxicological damage in the brain of fish and other non-target organisms. However, circRNAs associated with acute brain toxicity caused by cypermethrin and chlorpyrifos have not been studied yet. In this study, circRNAs were identified and characterized using RNA-seq in Zebrafish brains exposed to acute cypermethrin and chlorpyrifos toxicity. A total of 10,375 circRNAs were detected. It was determined that 6 circRNAs were up-regulated, 10 circRNAs were down-regulated in CYP brain samples compared to controls. In addition, it was found that 57 circRNAs are up-regulated and 3 circRNAs down-regulated in CPF brain samples compared to controls. Moreover, 62 circRNAs were down-regulated in the CYP samples, when CYP and CPF samples were compared. However, up-regulated circRNA could not be detected. It was revealed that the detected circRNAs specifically regulated the MAPK signaling pathway, endocytosis mechanism, apoptosis, and p53 signaling pathway. This study, which was conducted for the first time in terms of the subject of the study, could bring a different perspective, especially to pesticide toxicity studies.

Bioaugmentation of Atrazine-Contaminated Soil With Paenarthrobacter sp. Strain AT-5 and Its Effect on the Soil Microbiome

Atrazine, a triazine herbicide, is widely used around the world. The residue of atrazine due to its application in the fore-rotating crop maize has caused phytotoxicity to the following crop sweet potato in China. Bioaugmentation of atrazine-contaminated soil with atrazine-degrading strains is considered as the most potential method to remove atrazine from soil. Nevertheless, the feasibility of bioaugmentation and its effect on soil microbiome still need investigation. In this study, Paenarthrobacter sp. AT-5, an atrazine-degrading strain, was inoculated into agricultural soils contaminated with atrazine to investigate the bioaugmentation process and the reassembly of the soil microbiome. It was found that 95.9% of 5 mg kg⁻¹ atrazine was removed from the soils when inoculated with strain AT-5 with 7 days, and the phytotoxicity of sweet potato caused by atrazine was significantly alleviated. qRT-PCR analysis revealed that the inoculated strain AT-5 survived well in the soils and maintained a relatively high abundance. The inoculation of strain AT-5 significantly affected the community structure of the soil microbiome, and the abundances of bacteria associated with atrazine degradation were improved.

Profiles and risk assessment of legacy and current use pesticides in urban rivers in Beijing, China

Pesticides in the environment can pose serious risks to aquatic ecosystems. This study focused on the existence of 27 pesticides, including 13 pesticides regulated by the Stockholm Convention as persistent organic pollutants (POPs) and 14 commonly used pesticides in three urban rivers in Beijing that receive effluents from three municipal wastewater treatment plants (MWTPs). Among the 27 pesticides, 12 were detected at least once over a period of 4 seasons. Atrazine, aldrin and dieldrin were universally found in the three rivers, with the highest concentrations being 311, 163 and 23.3 ng/L, respectively. HCHs, DDTs, heptachlor and endosulfan, which are POPs, were detected at lower concentrations (ND-16.7 ng/L). Most of the insecticides and some of the herbicides in the rivers originated from MWTP effluents. The risk assessment results showed that aldrin posed medium risk (0.1 ≤ RQ < 1) to fish, and atrazine exhibited medium risk to both fish and algae. Despite the implementation of the Stockholm Convention and the upgrades of MWTPs emitting ozone, high loads of aldrin, atrazine and dieldrin were discharged to the rivers. Efforts should be devoted to identifying POP pesticide sources and upgrading MWTPs with other technologies to ensure the ecological safety of rivers.

Characterization, genome functional analysis, and detoxification of atrazine by Arthrobacter sp. C2

Residual injury of atrazine to the succeeding crops has been frequently reported. It is necessary to find a solution for the detoxification of atrazine contaminated soil. A high-efficient bacterial strain Arthrobacter sp. C2 for atrazine degradation was isolated in this study. The genomic information of the isolate C2, and its degradation characteristics and potential application in detoxification of atrazine contaminated soil were investigated. The results indicated that the isolate C2 genome contained 4,305,216 bp nucleotides, three plasmids, and 4705 coding genes. The degradation rates of atrazine at levels of 1, 10, 100 mg/L by the isolate C2 were 0.34, 1.94, 18.64 mg/L/d, respectively. The optimum temperature and pH for the isolate C2 to degrade atrazine were 30 °C and 7.0-9.0. Based on the metabolites detected by UPLC-TOF-MS/MS and genome annotation of the isolate C2, a common metabolic pathway of atrazine was proposed as that atrazine is firstly dechlorinated into hydroxyatrazine, and subsequently to N-isopropylammelide via dealkylation, and ultimately deaminated to cyanuric acid. Introduction of the isolate C2 into soil can enhance degradation of atrazine and thus eliminate the toxic effect of this herbicide on wheat growth. Our results indicate that the strain C2 could be a potential bioresource for bioremediation of atrazine contaminated soil.

Molecular mechanism of reproductive toxicity induced by beta-cypermethrin in zebrafish

Beta-cypermethrin, a type II synthetic pyrethroid insecticide, is widely used in pest control. Several studies have demonstrated that beta-cypermethrin can affect the reproductive system of mammals. However, there is still a scarcity of information about the reproductive toxicity to fish induced by beta-cypermethrin and its molecular mechanism. Therefore, this study was conducted to address this scientific question, in which the adult zebrafish were exposed to 0 (blank control), 0 (acetone solvent control), 0.1, 0.5, and 2.5 μg/L of beta-cypermethrin for 21 days. A decrease in cumulative egg production of zebrafish was observed, indicating that beta-cypermethrin had a negative impact on reproductive capacity of zebrafish. Regarding the histomorphological analysis of gonads, the delay of gonadal development was observed after exposure for 21 days. In addition, significant changes in plasma 17β-estradiol (E2) and testosterone (T) were found in zebrafish. Further exploration showed that the transcription levels of hypothalamic-pituitary-gonadal (HPG) axis-related genes were remarkably changed, which corresponded well with the alterations of hormone levels. These results demonstrated that beta-cypermethrin might have an adverse effect on the reproduction system of zebrafish through delaying gonadal development, disturbing sex hormone secretion, and affecting HPG axis gene expression. This study suggests that beta-cypermethrin poses a potential threat to the reproduction of fish populations, and the toxicity assessment of beta-cypermethrin plays a vital role in the environmental risk assessment of pesticides.

Three-dimensional Co/Ni bimetallic organic frameworks for high-efficient catalytic ozonation of atrazine: Mechanism, effect parameters, and degradation pathways analysis

Herein, the potential of bimetallic MOFs in catalytic ozonation was investigated for the first time. Three novel ozonation catalysts, i.e. cobalt-based, nickel-based and cobalt/nickel-based metal-organic frameworks (Co-MOF, Ni-MOF and Co/Ni-MOF), were synthesized, characterized by XRD, SEM, N₂ sorption-desorption isotherms, FTIR and XPS, and applied in catalytic ozonation for atrazine removal. It was found that the catalysts showed outstanding performance in the catalytic ozonation, especially Co/Ni-MOF which was attributed to multiple metal sites, higher coordination unsaturation, metal centers with larger electron density, and better efficiency in electron transfer than its single-metal counterparts. Under specific experimental conditions, 47.8%, 67.0%, 75.5%, and 93.9% of atrazine were removed after adsorption and degradation in the ozonation system without catalyst, and the catalytic ozonation systems with Co-MOF, Ni-MOF and Co/Ni-MOF, respectively. Higher removal rates could be achieved by growing initial pH, increasing oxidant dosage and reducing pollutant concentration, while an excess of Co/Ni-MOF was not favorable for the catalytic ozonation. Surface hydroxyl groups and acid sites were considered as the critical catalytic sites on Co/Ni-MOF. From the results of EPR tests, O₂·^-, ¹O₂ and ·OH were ascertained as the main reactive species in the degradation. It was suspected that O₂·^- and H₂O₂ played important roles in the formation of ·OH and the cycle of Co(II)/Co(III) and Ni(II)/Ni(III). Additionally, Co/Ni-MOF displayed good stability and reusability in cycling experiments, ascribed to the enhancement of the porosity and pore hydrophobicity. Finally, based on MS/MS analysis at different reaction times, major degradation pathways for atrazine were proposed.

Screening anti-predator behaviour in fish larvae exposed to environmental pollutants

Predation is one of the main sources of mortality for fish larvae. During evolution, they have developed different anti-predator behaviours, as the vibrational-evoked startle response and its habituation, for promoting survival to predator's strikes. Whereas these two behaviours can be altered by the exposure to some neurotoxicants, it is currently unknown if the exposure to environmentally relevant concentration (ERC) of neurotoxic pollutants could impair them. In this study thirty neurotoxic environmental pollutants from nine chemical groups, including: herbicides; carbamate, organophosphate (OP), organochlorine (OC), neonicotinoid and pyrethroid insecticides; toxins; metal and non-metal elements, have been screened at two concentrations, including one environmental relevant concentration (ERC), for adverse effects on anti-predator behaviours by using the Vibrational Startle Response Assay on zebrafish larvae. Significant effects over anti-predator responses were equally observed in both exposure concentrations. Focusing on the ERC scenario, it was found that the startle response was the less affected behaviour, where ten pollutants from all chemical groups except for organochlorine, neonicotinoid and pyrethroids, altered this response. Interestingly, organic and inorganic pollutants showed opposite effects on this response: whereas all organic pollutants decreased the startle response, the three remaining inorganic pollutants increased it. On the other hand, more pollutants affected habituation of the startle response of the larvae, where thirteen of the pollutants from all groups, except for herbicides, altered this behaviour at ERC, generally resulting in a faster habituation except for one OP and one marine toxin, which were able to delay this response. Ultimately, only one chemical from the OP, toxin, metal and non-metal element groups altered both the startle response and its habituation at both ERC and WSC. These results emphasize the environmental risk of the current levels of some neurotoxicants present in our aquatic ecosystems, as they are high enough to impair essential anti-predator behaviours in fish larvae.

Fenvalerate triggers Parkinson-like symptom during zebrafish development through initiation of autophagy and p38 MAPK/mTOR signaling pathway

Fenvalerate (FEN), one of the most used synthetic pyrethroids, has the potential to interfere with human neural function. However, far too little attention was paid to the mechanism of FEN-induced neurotoxicity. Thus we exposed zebrafish to FEN from 4 to 120 h post fertilization (hpf), and analyzed the morphology and behavior of zebrafish. Our results showed that FEN decreased the survival rate of zebrafish, with increased malformation rates and abnormal behaviors. Furthermore, we found typical parkinson-like symptoms in FEN-exposed zebrafish with increases in parkinson's disease (PD), ubiquitin, and Lewy bodies-relevant genes. We also observed the loss of dopaminergic neurons in both FEN-exposed zebrafish and PC12 cells, which were all associated with PD-like symptoms. Besides, FEN activated autophagy by the enhanced expressions of p-mTOR, and LC3-II but the reduction of p62. Further, FEN initially activated p-p38 MAPK followed by p-mTOR, which triggered the transcription of genes responsible for autophagy process and prompted the Lewy bodies neuron generation leading to the PD-like symptoms. This process was inhibited by both 3-methyladenine (3-MA, an autophagy inhibitor) and SB203580 (a p38 MAPK selective inhibitor) in zebrafish and PC12 cells. These results suggest that FEN might cause parkinson-like symptom during zebrafish development through induction of autophagy and activation of p38 MAPK/mTOR signaling pathway. The study revealed the potential mechanism of FEN-induced neurotoxicity and should give new insights into a significant environmental risk factor of developing parkinson's disease.

The synthetic pyrethroid deltamethrin impairs zebrafish (Danio rerio) swim bladder development

Deltamethrin (DM) is a widely used insecticide and reveals neural, cardiovascular and reproductive toxicity to various aquatic organisms. It has been known that DM negatively affects motion of zebrafish (Danio rerio). However, little is known in relation to the impacts of DM on development of swim bladder, which is a key organ for motion. In the present study, zebrafish embryos were exposed to 20 and 40 µg/L DM. The changes of swim bladder morphology were observed and transcription levels of key genes were compared between DM treatments and the control. The results showed that DM treatments significantly blocked the formation of progenitor and tissue layers in swim bladder of zebrafish embryos, leading to failed inflation of swim bladder. Compared with the control, the key genes (pbx1, foxA3, mnx1, has2, anxa5b, hprt1l and elovl1a) responsible for swim bladder development also showed decreased levels in response to DM treatments, suggesting that DM might specifically affect swim bladder development. Moreover, transcription levels of genes in the Wnt (wnt5b, tcf3a, wnt1, wnt9b, fzd1, fzd3 and fzd5) and Hedgehog (ihhb, ptc1 and ptc2) signaling pathways all decreased significantly in response to DM treatments, compared with the control. Considering the importance of Wnt and Hedgehog pathways in development of swim bladder, these results suggested that DM might affect swim bladder development through inhibiting the Wnt and Hedgehog pathways. Overall, the present study reported that swim bladder might be a potential target organ of DM toxicity in zebrafish, which contributed more information to the evaluation of DM's environmental risks.

Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data

Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre- and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.

Enhanced degradation of atrazine by nanoscale LaFe1-xCuxO3-δ perovskite activated peroxymonosulfate: Performance and mechanism

Cu-doped LaFeO₃ perovskite (LaFe_1-xCu_xO_3-δ, LFC_x) synthesized using a sol-gel method was introduced in the heterogeneous activation of peroxymonosulfate (PMS) for atrazine degradation. The obtained LFC_x catalysts were characterized by several technologies and the results showed that Cu was incorporated into the perovskites lattice successfully. In addition, the introduction of Cu resulted in the mixed valence state of Fe(III)/Fe(II) and Cu(II)/Cu(I) in perovskite structure. LaFe_0.8Cu_0.2O_3-δ (LFC_0.2) exhibited excellent catalytic activity and stability towards the degradation of atrazine. Atrazine (23 μM) was removed completely within 60 min in the presence of 0.5 g/L catalyst and 0.5 mM PMS. The efficient degradation was obtained when the initial pH ranged from 2 to 10. Sulfate radicals (SO₄^•-) and hydroxyl radicals (HO^•) generated during activation process were determined as the main reactive species based on the electron spin resonance (ESR) studies and radical quenching experiments. The enhanced catalytic activity derived from the lower valence state of Fe and Cu as well as the synergetic effect between them. A surface catalyzed-redox cycle between Fe(III)/Fe(II) and Cu(II)/Cu(I), along with surface hydroxyl groups (-OH), were all responsible for the decomposition of PMS. The oxygen vacancies could promote the chemical bonding with PMS and enhance the reactivity of Fe and Cu. The 12 transformation products were determined by LC-MS and the degradation mechanisms were further proposed, which involved five different pathways. The perovskite that possesses bimetallic active sites can be a promising catalyst for PMS activation towards the degradation of persistent organic pollutants with high-efficiency.

Spatiotemporal distributions of Cu, Zn, metribuzin, atrazine, and their transformation products in the surface water of a small plain stream in eastern China

The intensive use of fertilizers and pesticides in agriculture has led to widespread nonpoint source pollution in surface waterbodies. In this work, the occurrence and distribution of nonpoint source metals (Cu and Zn) and herbicides (metribuzin; atrazine; and its degradates, including desethyl atrazine (DEA), desisoproylatrazine (DIA), and deethyldeisopropylatrazine (DEDIA)) in the surface water of the Baima River, which is located in a region noted for its intense agricultural activities, were investigated during a high water period in August and a low water period in October. The results showed that the heavy metals and herbicides investigated were detected frequently in the surface water of the river during the two periods. The average concentrations of Cu during the high water period and low water period were 9.3 (0-20.7) and 8.7 (0-15.55) μg/L, and the average concentrations of Zn during the two periods were 11.4 (6.65-22.15) and 10.6 (7.55-15.15) μg/L, respectively. The concentrations of atrazine were higher than those of metribuzin, which ranged from 0.07 to 1.12 μg/L during the high water period and 0.01-0.74 μg/L during the low water period. The total concentrations of atrazine and its transformation products in 60.00% of the samples during the high water period exceeded the maximum contaminant level (MCL) of 3 μg/L for the drinking water criteria in the USA, and 33.33% of the samples exceeded the MCL during the low water period. The spatial and temporal distributions of nonpoint source pollutants along the Baima River were influenced by land use and hydrogeomorphic settings. The ecotoxicological risk assessment indicated that atrazine and DIA have moderate risks to aquatic environment in Baima River.

Enhanced Fe(III)-mediated Fenton oxidation of atrazine in the presence of functionalized multi-walled carbon nanotubes

In this study we reported that the presence of functionalized multi-walled carbon nanotubes (FCNT-H) would greatly enhance the degradation of atrazine (ATZ), a model contaminant, in the Fe(III)-mediated Fenton-like system. Efficient ATZ degradation (>90%) was achieved within 30 min in the presence of 20 mg.L^-1 FCNT-H, 2.0 mg.L^-1 Fe(III), and 170 mg.L^-1 H₂O₂, whereas negligible ATZ degradation occurred in FCNT-H free system. The structure and surface chemistry of FCNT-H and other CNTs were well characterized. The formed active species were determined based on ESR analysis, and the mass balance of Fe species during the reaction was monitored. In particular, a new method based on ferrozine complexation was proposed to track the formed Fe(II). The results indicated that ATZ was mainly degraded by the generated hydroxyl radical (HO·), and Fe(III)/Fe(II) cycling was still the rate-limiting step. Besides a small fraction of Fe(III) reduced by FCNT-H, a new pathway was revealed for fast reduction of most Fe(III), i.e., reaction of FCNT-H-Fe(III) complexes with H₂O₂. Comparison of different CNTs-mediated Fe(III)/H₂O₂ systems indicated that such enhanced effect of CNTs mainly resulted from the surface carboxyl group instead of hydroxyl and carbonyl group. Combined with X-ray photoelectron spectroscopy (XPS) analysis, the electron density migration from Fe(III) to FCNT-H possibly resulted in the fast reduction of FCNT-H-Fe(III) complexes by H₂O₂. This study enables better understanding the enhanced Fe(III)-mediated Fenton-like reaction in the presence of MWCNTs and thus, will shed new light on how to develop more efficient similar Fenton systems via Fe(III) complexation.

Effect of titanium dioxide nanoparticles on the bioavailability and neurotoxicity of cypermethrin in zebrafish larvae

In aquatic environment, the presence of nanoparticles (NPs) has been reported to modify the bioavailability and toxicity of the organic toxicants. Nevertheless, the combined toxicity of NPs and the pesticides that were used world-widely still remains unclear. Cypermethrin (CYP), a synthetic pyrethroid insecticide, is commonly used for controlling agricultural and indoor pests. Therefore, the effects of titanium dioxide NPs (nTiO₂) on CYP bioconcentration and its effects on the neuronal development in zebrafish were investigated in our study. Zebrafish embryos (2- hour-post-fertilization, hpf) were exposed to CYP (0, 0.4, 2 and 10 μg/L) alone or co-exposed with nTiO₂ (1 mg/L) until 120-hpf. nTiO₂ is taken up by zebrafish larvae and also it can adsorb CYP. The zebrafish body burdens of CYP was observed and CYP uptake was increased by nTiO₂, indicating that the nTiO₂ could accelerate the bioaccumulation of CYP in larvae. Co-exposure of nTiO₂ and CYP induced the generation of reactive oxygen species. Exposure to CYP alone significantly decreased the mRNA expression of genes, including glial fibrillary acidic protein (gfap), α1-tubulin, myelin basic protein (mbp) and growth associated protein (gap-43). Besides, reductions of serotonin, dopamine and GABA concentrations were observed in zebrafish and the larval locomotion was significantly decreased in response to the lower level of the neurotransmitters. Moreover, co-exposure of nTiO₂ and CYP caused further significantly decreased in the locomotion activity, and enhanced the down-regulation of the mRNA expression of specific genes and the neurotransmitters levels. The results demonstrated that nTiO₂ increased CYP accumulation and enhanced CYP-induced developmental neurotoxicity in zebrafish.

Early life exposure of zebrafish (Danio rerio) to synthetic pyrethroids and their metabolites: a comparison of phenotypic and behavioral indicators and gene expression involved in the HPT axis and innate immune system

Ecotoxicological studies have revealed the association between synthetic pyrethroid (SP) exposure and aquatic toxicity in fish; however, research on the toxic effects of SP metabolites is still limited. In this study, the toxicity of two SPs (permethrin (PM) and β-cypermethrin (β-CP)) and their three metabolites (3-phenoxybenzoic alcohol (PBCOH), 3-phenoxybenzaldehyde (PBCHO), and 3-phenoxybenzoic acid (PBCOOH)) towards zebrafish embryos and larvae was evaluated. Both SPs and their metabolites exhibited significant developmental toxicities, caused abnormal vascular development, and changed locomotor activities in larvae. The alteration of gene expression involved in the thyroid system and the innate immune system indicated that SPs and their three metabolites have the potency to induce thyroid disruption and trigger an immune response. The results from the present study suggest that SP metabolites could induce multiple toxic responses similar to parent compounds, and their toxicity should be considered for improving the understanding of environmental risks of SPs.

Environmentally relevant levels of λ-cyhalothrin, fenvalerate, and permethrin cause developmental toxicity and disrupt endocrine system in zebrafish (Danio rerio) embryo

Synthetic pyrethroids (SPs) are one of the most widely used pesticides and frequently detected in the aquatic environment. Previous studies have shown that SPs posed high aquatic toxicity, but information on the developmental toxicity and endocrine disruption on zebrafish (Danio rerio) at environmentally relevant concentrations is limited. In this study, zebrafish embryos were employed to examine the adverse effects of λ-cyhalothrin (LCT), fenvalerate (FEN), and permethrin (PM) at 2.5, 10, 25, 125, 500 nM for 96 h. The results showed these 3 SPs caused dose-dependent mortality, malformation rate, and hatching rate. Thyroid hormone triiodothyronine (T₃) levels were significantly decreased after exposure to LCT and FEN. Quantitative real-time PCR analysis was then performed on a series of nuclear receptors (NRs) genes involved in the hypothalamic-pituitary-gonadal (HPG), hypothalamic-pituitary-thyroid (HPT), hypothalamic-pituitary-adrenocortical (HPA) axes, and oxidative-stress-related system. Our results showed that LCT, FEN, and PM downregulated AR expression while upregulated ER1 expression, and caused alteration to ER2a and ER2b expression. As for the expression of TRα and TRβ, they were both decreased following exposure to the 3 SPs. LCT and PM downregulated the MR expression and FEN induced MR expression. In addition, the expression of GR was increased after treating with LCT, while it was suppressed after exposure to FEN and PM. The 3 SPs also caused various alterations to the expression of genes including AhRs, PPARα, and PXR. These findings suggest that these 3 SPs may cause developmental toxicity to zebrafish larvae by disrupting endocrine signaling at environmentally relevant concentrations.

Acute exposure to synthetic pyrethroids causes bioconcentration and disruption of the hypothalamus-pituitary-thyroid axis in zebrafish embryos

Synthetic pyrethroids (SPs) have the potential to disrupt the thyroid endocrine system in mammals; however, little is known of the effects of SPs and underlying mechanisms in fish. In the current study, embryonic zebrafish were exposed to various concentrations (1, 3 and 10 μg/L) of bifenthrin (BF) or λ-cyhalothrin (λ-CH) until 72 h post fertilization, and body condition, bioaccumulation, thyroid hormone levels and transcription of related genes along the hypothalamus-pituitary-thyroid (HPT) axis examined. Body weight was significantly decreased in the λ-CH exposure groups, but not the BF exposure groups. BF and λ-CH markedly accumulated in the larvae, with concentrations ranging from 90.7 to 596.8 ng/g. In both exposure groups, alterations were observed in thyroxine (T4) and triiodothyronine (T3) levels. In addition, the majority of the HPT axis-related genes examined, including CRH, TSHβ, TTR, UGT1ab, Pax8, Dio2 and TRα, were significantly upregulated in the presence of BF. Compared to BF, λ-CH induced different transcriptional regulation patterns of the tested genes, in particular, significant stimulation of TTR, Pax8, Dio2 and TRα levels along with concomitant downregulation of Dio1. Molecular docking analyses revealed that at the atomic level, BF binds to thyroid hormone receptor (TRα) protein more potently than λ-CH, consequently affecting HPT axis signal transduction. In vitro and in silico experiments disclosed that during the early stages of zebrafish development, BF and λ-CH have the potential to disrupt thyroid endocrine system.

Global Assessment of Bisphenol A in the Environment: Review and Analysis of Its Occurrence and Bioaccumulation

Because bisphenol A (BPA) is a high production volume chemical, we examined over 500 peer-reviewed studies to understand its global distribution in effluent discharges, surface waters, sewage sludge, biosolids, sediments, soils, air, wildlife, and humans. Bisphenol A was largely reported from urban ecosystems in Asia, Europe, and North America; unfortunately, information was lacking from large geographic areas, megacities, and developing countries. When sufficient data were available, probabilistic hazard assessments were performed to understand global environmental quality concerns. Exceedances of Canadian Predicted No Effect Concentrations for aquatic life were >50% for effluents in Asia, Europe, and North America but as high as 80% for surface water reports from Asia. Similarly, maximum concentrations of BPA in sediments from Asia were higher than Europe. Concentrations of BPA in wildlife, mostly for fish, ranged from 0.2 to 13 000 ng/g. We observed 60% and 40% exceedences of median levels by the US Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey in Europe and Asia, respectively. These findings highlight the utility of coordinating global sensing of environmental contaminants efforts through integration of environmental monitoring and specimen banking to identify regions for implementation of more robust environmental assessment and management programs.

Monitoring endocrine disrupting compounds and estrogenic activity in tap water from Central Spain

The aims of this study are to investigate the presence of 30 substances known or thought to act as endocrine disrupting compounds in tap water from the main water supply areas for region of Madrid, to determine the total estrogenic activity of the samples analysed and to estimate the health risk for the population resulting from those compounds found at detectable concentrations. To this end, a one-off composite sampling was performed in August 2012 in which six tap water samples were collected from private residences in the drinking water supply network of the region of Madrid. A total of 14 of the 30 endocrine disruptors analysed were found at concentrations ranging from 0.3 to 165 ng/L. The organophosphorus flame retardants were detected at the highest concentrations followed by the plasticizer bisphenol A, alkylphenols, anticorrosion agents and preservatives. Tap water in the region of Madrid is contaminated with traces (ng/L) of compounds with endocrine disrupting properties. Although the concentrations of endocrine disrupting compounds obtained are too low to be able to confirm a public health risk, and no risk has been detected upon evaluation, it should be remembered that these compounds act at very low doses and that their effects may only appear in the long term.

Determination of levels of current drugs in hospital and urban wastewater

A rapid, sensitive and highly specific HPLC-MS/MS method with direct on-line preparation was applied for the determination of 20 common pharmaceuticals in hospital and urban wastewater. Median drug concentrations were quite similar in the majority of samples, cerca 1 μg L⁻¹ ranging from 0.06 to 2.67 μg L⁻¹ in both water. Pharmaceutical hospital contribution, below 1 %, was negligible, as compared to the huge amount in the municipal plant flow. Due to only partial elimination in the plant, hundreds of kilograms of harmful waste per year are discharged in the River Seine. Therefore, to reduce potential human and environmental exposure, a topic of major concern, an efficient drug treatment procedure should be used at the municipal plant stage in order to reduce urban wastewater pollution. The HPLC-MS/MS method could be a very useful tool to optimize the pharmaceutical wastewater treatment process.

Relevance of drinking water as a source of human exposure to bisphenol A

A comprehensive search of studies describing bisphenol A (BPA) concentrations in drinking water and source waters (i.e., surface water and groundwater) was conducted to evaluate the relevance of drinking water as a source of human exposure and risk. Data from 65 papers were evaluated from North America (31), Europe (17), and Asia (17). The fraction of drinking water measurements reported as less than the detection limit is high; 95%, 48%, and 41%, for North America, Europe, and Asia, respectively. The maximum quantified (in excess of the detection limit) BPA concentrations from North America, Europe, and Asia are 0.099 μg/l, 0.014 μg/l, and 0.317 μg/l. The highest quantified median and 95th percentile concentrations of BPA in Asian drinking water are 0.026 μg/l and 0.19 μg/l, while high detection limits restricted the determination of representative median and 95th percentile concentrations in North America and Europe. BPA in drinking water represents a minor component of overall human exposure, and compared with the lowest available oral toxicity benchmark of 16 μg/kg-bw/day (includes an uncertainty factor of 300) gives margins of safety >1100. Human biomonitoring data indicate that ingestion of drinking water represents <2.8% of the total intake of BPA.

Proteomic analysis of hepatic tissue in adult female zebrafish (Danio rerio) exposed to atrazine

Atrazine (ATZ), the most common herbicide, is a frequently observed contaminant in freshwater ecosystems. In the present study, two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization tandem time-of-flight-mass spectrometry, combined with histopathological analysis, were used to detect the hepatic damage in adult female zebrafish (Danio rerio) exposed to ATZ. More than 600 hepatic protein spots were detected in each gel with silver staining, and most of the proteins ranged from 20 to 70 kD and pH 4-9. Through comparison and analysis, 7 proteins were found to be upregulated>2-fold, whereas 6 protein spots were downregulated>2-fold after 10 and 1000 μg/l ATZ exposures for 14 days, which had caused histological effects in zebrafish livers. We found that these changed proteins were associated with a variety of cellular biological processes, such as response to oxidative stress, oncogenesis, etc. The results demonstrated that ATZ comprehensively influenced a variety of cellular and biological processes in zebrafish. The information presented in this study will be helpful in fully understanding the mechanism of the potential effects induced by ATZ in fish.