Organophosphorus flame retardants (PFRs) are contaminants of emerging concern which have been detected globally. However, little information on PFRs in the Arctic freshwater environment is currently ...available. In this study, both hydrophilic and hydrophobic PFRs in the water and sediment of four areas (town, surroundings, coastal marine water, and glacier melt runoff) near Ny-Ålesund Svalbard were investigated by time-integrated passive sampling (water) and grab sampling (sediment). Seven kinds of PFRs were found in the Arctic waters with individual freely dissolved concentrations from 0.007 ng L−1 to 355 ng L−1, and the concentrations of chlorinated PFRs were 3–4 orders of magnitude higher than those of non-chlorinated PFRs. The distribution of different PFRs in freshwater showed significant spatial differences among the different areas, and the town was found to have most kinds of PFRs and highest PFRs concentrations. The sources and transport of different kinds of PFRs were explored based on a spatial overlay analysis of the contaminant distributions, environmental conditions, and PFR applications. As a result, human settlements, industrial activities, atmospheric deposition, and transportation in Ny-Ålesund were proposed to be related to the pollution of different PFRs at Ny-Ålesund. The PFRs in the inshore marine water were found to be affected by both local ship contamination and ocean current transport. Furthermore, nine PFRs were detected in the sediments of Ny-Ålesund. Accumulation of different PFRs in the Arctic sediment was found to be dominated by their physico-chemical properties (polarity).
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•Organophosphorus flame retardants (PFRs) were found in Arctic freshwater environment.•Two kinds of passive sampler were coupled to monitor twelve PFRs in the water.•Sources and transport of PFRs in the Arctic aquatic environment were explored.•Chlorinated PFRs pollution at Ny-Ålesund may be related to atmospheric transport.•Accumulation of PFRs in the sediment was dominated by their chemical polarities.
The distribution, sources, and transport of PFRs in the water and sediment of different areas near Ny-Ålesund, Svalbard, the Arctic, were studied.
An increasing number of studies have indicated that environmental contamination with chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) has been underestimated. However, insufficient available ...toxicological information on Cl-PAHs makes evaluating their risks to health challenging. Two in vitro bioassays were used in the present study to characterize the aryl hydrocarbon receptor (AhR) activity and DNA-damaging effects of 22 low-molecular-weight PAHs and their Cl-PAHs by using the EROD assay in rat hepatoma (H4IIE) cells and the SOS/umu test (S. typhimurium TA1535/pSK1002). Compared with their parent PAHs, most of the Cl-PAHs enhanced AhR-mediated activity in the EROD assay. 1,3,6,8-Tetrachloro-pyrene (1,3,6,8-Tetracl-Py) induced the greatest potency of EROD activity (83.1%-TCDD-max) and its single point ReP was 6.64 × 10−6. Compared with their parent PAHs, several Cl-PAHs showed significant DNA-damaging effects in the SOS/umu test with the addition of S9, and the toxic equivalency of benzoapyrene (TEQBaP) was calculated for them. 9-Chloroanthracene (9-Ant) and 5,6-Dichloroacenaphthene (5,6-Dicl-Ace) had relatively high TEQBaP (0.62 and 0.54, respectively). However, only 1,3,6,8-Tetracl-Py elicited strong DNA-damaging effects in the absence of S9. The degree of chlorination, the position of chlorine substitutions, and the structure of parent PAHs influenced the potency of low-molecular-weight PAHs with regard to their AhR activity and DNA-damaging effects. More concern should be raised for these environmentally relevant pollutants.
•Cl-PAHs had more potent AhR activity and DNA-damaging effects than their parent PAHs.•2,5-Dicl-Fl, 2,7-Dicl-Fl and 1,3,6,8-tetracl-Py induced strong EROD activity.•Degree of chlorination and the position of chlorine influence the AhR activity and DNA-damaging effects.
Aryl phosphorus-containing flame retardants (aryl-PFRs) have been frequently detected with increasingly used worldwide as one of alternatives for brominated flame retardants. However, information on ...their adverse effects on human health and ecosystem is insufficient, with limited study on their molecular mode of action in vitro. In this study, the cytotoxicity, DNA damage, mitochondrial impairment and the involved molecular mechanisms of certain frequently detectable aryl-PFRs, including 2-ethylhexyldiphenyl phosphate (EHDPP), methyl diphenyl phosphate (MDPP), bisphenol-A bis (diphenyl phosphate) (BDP), isodecyl diphenyl phosphate (IDPP), cresyl diphenyl phosphate (CDP) and the structurally similar and widely used organophosphorus pesticide chlorpyrifos (CPF), were evaluated in A549 cells using high-content screening (HCS) system. Aryl-PFRs showed different lethal concentration 50 (LC50) values ranging from 97.94 to 546.85 μM in A549 cells using CCK-8 assay. EHDPP, IDPP, CDP, MDPP and CPF demonstrated an ability to induce DNA damage, evidenced by increased DNA content and S phase-reducing cell cycle arrest effect using fluorophore dye cocktail assay. Additionally, the selected aryl-PFRs induced mitochondrial impairment by the increasing mitochondrial mass and decreasing mitochondrial membrane potential. Moreover, BDP, MDPP, and CDP, which contain short alkyl chains showed their potential oxidative stress with intracellular ROS and mitochondrial superoxide overproduction from an initially relatively low concentration. Additionally, based on the promotion of firefly luminescence in p53-transfected A549 cells, p53 activation was found to be involved in aryl-PFRs-induced DNA damage. Further real-time PCR results showed that all selected aryl-PFRs triggered p53/p21/gadd45β-, and p53/p21/mdm2-mediated cell cycle pathways, and the p53/bax mediated apoptosis pathway to induce DNA damage and cytotoxic effects. These results suggest that aryl-PFRs (e.g., BDP, MDPP, CDP) cause oxidative stress-mediated DNA damage and mitochondrial impairment, and p53-dependent pathway was involved in the aryl-PFRs-induced DNA damage and cell cycle arrest. In conclusion, this study improves the understanding of PFRs-induced adverse outcomes and the involved molecular mechanism.
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•The cytotoxicity, DNA damage, and mitochondrial impairment induced by aryl-PFRs were evaluated.•Aryl-PFRs induced oxidative stress-mediated DNA and mitochondrial damage.•EHDP, IDPP, CDP, MDPP and CPF exerted S phase cell ratio-reducing effects.•p53 pathway activation is an underlying mechanism of the induced DNA damage.•Cytotoxicity was evidenced by the upregulation of the p53/bax-mediated apoptosis pathway.
It has been recognized that ecological risk assessment based on traditional endpoints of toxicity are unable to provide adequate protection because some chemicals may affect reproductive fitness of ...aquatic organisms at much lower concentrations. In this paper, predicted no effect concentrations (PNECs) for 4-nonylphenol (NP) were derived based either on endpoints of survival, development, and growth or on some nonlethal biomarkers of reproduction, biochemical and molecular biology data. The PNECs derived from reproductive lesion ranged from 0.12 to 0.60 μg NP L–1, which was significantly lower than those derived from other endpoints. An assessment of ecological risks posed by NP to aquatic organisms in surface waters of China was conducted based on concentration levels of NP in 16 surface waters of 4 major river basins and PNECs derived from reproductive fitness by a tiered ecological risk assessment (ERA). The results showed that 14.2% and 76.5% of surface waters in China may have ecological risks resulting from reproductive fitness if the thresholds of protection for aquatic organisms were set up as 5% (HC5) and 1% (HC1), respectively. The risks were significantly greatest in the Yangtze River Basin than in other major river basins. In comparison with the risks assessed based on traditional endpoints, such as lethality, for those chemicals causing adverse effects on reproduction due to modulation of endocrine function, to be protective of ecosystem structure and function, lesser PNECs, based on sublethal effects of reproduction, were appropriate.
As the typical aryl-organophosphate flame retardants (OPFRs), triphenyl phosphate (TPhP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were reported to be estrogen disruptors. However, estrogen ...receptor α (ERα) binding experiments could not explain their biological effects. In this study, their action on ERα, G protein-coupled estrogen receptor (GPER) and the synthesis of 17β-estradiol (E2) were investigated using in vitro assays and molecular docking. The results showed that TPhP acted as an ERα agonist and recruited steroid receptor co-activator 1 (SRC1) and 3 (SRC3), which was found for the first time. Unlike TPhP, TDCIPP acted as an ERα antagonist. However, both TPhP and TDCIPP activated the estrogen pathway by GPER in SKBR3 cells which were lack of ERα. Although molecular docking results revealed that both TPhP and TDCIPP could dock into ERα and GPER, their substituent groups and combination mode might affect the receptor activation. In addition, by using estrogen biosynthesis assay in H295R cells, both of TPhP and TDCIPP were found to promote E2 synthesis and E2/T ratio involving their different alteration on levels of progesterone, testosterone and estrone, and expression of various key genes. Our data proposed estrogen-disrupting mechanism frameworks of TPhP and TDCIPP. Moreover, our results will contribute to future construction of adverse outcome pathway (AOP) framework of endocrine disruptors.
•TPhP acted as an ERα agonist, while TDCIPP acted as an ERα antagonist.•First evidence on TPhP-ERα recruiting SRC1 and SRC3.•TPhP and TDCIPP activated the GPER-mediated cAMP pathway.•The substituent groups of TPhP and TDCIPP might affect the estrogen receptors activation.•TPhP and TDCIPP promoted E2 synthesis by different effects on various key enzymes.
The environmental risks of environmental estrogens (EEs) are often assessed via the same mode of action in the concentration addition (CA) model, neglecting the complex combined mechanisms at the ...genetic level. In this study, the cell proliferation effects of estrone, 17α-ethinylestradiol, 17β-estradiol, estriol, diethylstilbestrol, estradiol valerate, bisphenol A, 4-tert-octylphenol and 4-nonylphenol were determined individually using the CCK-8 method, and the proliferation effects of a multicomponent mixture of estrogenic chemicals mixed at equipotent concentrations using a fixed-ratio design were studied using estrogen-sensitive MCF-7 cells. Furthermore, transcription factors related to cell proliferation were analyzed using RT-PCR assays to explore the potential molecular mechanisms related to the estrogenic proliferative effects. The results showed that the estrogenic chemicals act together in an additive mode, and the combined proliferative effects could be predicted more accurately by the response addition model than the CA model with regard to their adverse outcomes. Furthermore, different signaling pathways were involved depending on the different mixtures. The RT-PCR analyses showed that different estrogens have distinct avidities and preferences for different estrogen receptors at the gene level. Furthermore, the results indicated that estrogenic mixtures increased ERα, PIK3CA, GPER, and PTEN levels and reduced Akt1 level to display combined estrogenicity. These findings indicated that the potential combined environmental risks were greater than those found in some specific assessment procedures based on a similar mode of action due to the diversity of environmental pollutions and their multiple unknown modes of action. Thus, more efforts are needed for mode-of-action-driven analyses at the molecular level. Furthermore, to more accurately predict and assess the individual responses in vivo from the cellular effects in vitro, more parameters and correction factors should be taken into consideration in the addition model.
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•Dose-response concentration of single and combined effects of nine selected environmental estrogens (EEs) were evaluated.•RA model were more suitable than CA model for predicting the environmental risks of EEs at environmentally relevant concentrations.•Different estrogens have distinct avidities and preferences for different estrogen receptors.•EEs showed combined effects by increasing PIK3CA, GPER, and PTEN levels and reducing Akt1 level in the PI3K/AKT pathway.
Accurate rainfall prediction remains a challenging problem because of the high volatility and complicated essence of atmospheric data. This study proposed a hybrid model (DSP) that combines the ...advantages of discrete wavelet transform (DWT), support vector regression (SVR), and Prophet to forecast rainfall data. First, the rainfall time series is decomposed into high-frequency and low-frequency subseries using discrete wavelet transform (DWT). The SVR and Prophet models are then used to predict high-frequency and low-frequency subsequences, respectively. Finally, the predicted rainfall is determined by summing the predicted values of each subsequence. A case study in China is conducted from 1 January 2014 to 30 June 2016. The results show that the DSP model provides excellent prediction, with RMSE, MAE, and R2 values of 6.17, 3.3, and 0.75, respectively. The DSP model yields higher prediction accuracy than the three baseline models considered, with the prediction accuracy ranking as follows: DSP > SSP > Prophet > SVR. In addition, the DSP model is quite stable and can achieve good results when applied to rainfall data from various climate types, with RMSEs ranging from 1.24 to 7.31, MAEs ranging from 0.52 to 6.14, and R2 values ranging from 0.62 to 0.75. The proposed model may provide a novel approach for rainfall forecasting and is readily adaptable to other time series predictions.
This study was conducted to explore the exposure potential of Chinese residents to PBBs, PBDEs, and PCBs in e-waste disassembly sites in Zhejiang province. The contents of 23 PBB congeners, 12 PBDE ...congeners, and 27 PCB congeners in hair and in their potential sources, including soil and e-waste, were measured via GC-MS. The levels of PHAHs in the three subfamilies (i.e., the PBBs, PBDEs, and PCBs) were all considerably higher (
P
<
0.05) in hair samples collected from the disassembly sites than from the control site. The highest levels of PBBs (57.77 ng g
−
1
dw), PBDEs (29.64 ng g
−
1
dw), and PCBs (181.99 ng g
−
1
dw) in hair were all found in those from the disassembly site Xinqiu, which are respectively 2, 2, and 10 times more than those observed in hair from the control site Yandang. Among the three subfamilies of PHAHs, PCBs were the most predominant pollutants detected. PBBs, which have very limited information available in China, can be detected at a comparable level with PBDEs in these samples in the study. Therefore, these observations suggested that more attention should be given over the potential for environmental or occupational exposure to PHAHs present in e-waste. By and large, the PHAH levels measured in the hair samples were consistent with those detected in the soil. Hair analysis could thus be a valid screening tool for assessing human PHAHs exposure in and around e-waste disassembly sites.
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