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Plastics are invading nearly all ecosystems on earth, acting as emerging repositories for toxic organic pollutants and thereby imposing substantial threats to ecological integrity. The colonization of plastics by microorganisms, forming the plastisphere, has garnered attention due to its potential influence on biogeochemical cycles. However, the capability of plastisphere microorganisms to attenuate organohalide pollutants remains to be evaluated. This study revealed that the plastisphere, collected from coastal ecosystems, harbors unique microbiomes, while the natural accumulation of organohalide pollutants on plastics may favor the proliferation of organohalide-respiring bacteria (OHRB). Laboratory tests further elucidated the high potential of plastisphere microbiota to reductively dehalogenate a variety of organohalide pollutants. Notably, over 70% tested plastisphere completely debrominated tetrabromobisphenol A (TBBPA) and polybrominated diphenyl ethers (PBDEs) to nonhalogenated products, whereas polychlorinated biphenyls (PCBs) were converted to lower congeners under anaerobic conditions. Dehalococcoides , Dehalogenimonas , and novel Dehalococcoidia populations might contribute to the observed dehalogenation based on their growth during incubation and positive correlations with the quantity of halogens removed. Intriguingly, large fractions of these OHRB populations were identified in a lack of the currently known TBBPA/PBDEs/PCBs reductive dehalogenase (RDase) genes, suggesting the presence of novel RDase genes. Microbial community analyses identified organohalides as a crucial factor in determining the composition, diversity, interaction, and assembly of microbes derived from the plastisphere. Collectively, this study underscores the overlooked roles of the plastisphere in the natural attenuation of persistent organohalide pollutants and sheds light on the unignorable impacts of organohalide compounds on the microbial ecology of the plastisphere.

Novel brominated flame retardants (NBFRs) have been developed as replacements for legacy brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). The prevalence of NBFRs in aquatic environments has initiated intense concerns that they resemble to BFRs. To comprehensively elucidate the fate of NBFRs in aquatic environments, this review summarizes the physico-chemical properties, distribution, bioaccumulation, and fates in aquatic environments. 1,2-bis(2,3,4,5,6-pentabromophenyl) ethane (DBDPE) as the major substitute for PBDEs is the primary NBFR. The release from industrial point sources such as e-waste recycling stations is the dominant way for NBFRs to enter the environment, which results in significant differences in the regional distribution of NBFRs. Sediment is the major sink of NBFRs attributed to the high hydrophobicity. Significantly, there is no decreasing trend of NBFRs concentrations, while PBDEs achieved the peak value in 1970-2000 and decreased gradually. The bioaccumulation of NBFRs is reported in both field studies and laboratory studies, which is regulated by the active area, lipid contents, trophic level of aquatic organisms, and the log K OW of NBFRs. The biotransformation of NBFRs showed similar metabolism patterns to that of BFRs, including debromination, hydroxylation, methoxylation, hydrolysis, and glycosylation. In addition, NBFRs show great potential in trophic magnification along the aquatic food chain, which could pose a higher risk to high trophic-level species. The passive uptake by roots dominates the plant uptake of NBFRs, followed by acropetal and basipetal bidirectional transportation between roots and leaves in plants. This review will provide the support to understand the current pollution characteristics of NBFRs and highlight perspectives for future research., Competing Interests: Declaration of competing interest We declare that we have no financial or personal relationships with other people or organizations that can inappropriately influence our work. There is no professional or other personal interest of any nature or kind in any product, service, and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The study assessed persistent organic pollutants (POPs) in Caretta caretta turtles along Turkish coasts, analyzing bioaccumulation in accessible organs and discerning sex-related differences. Ten adult turtles (5 males, 5 females) from Mugla province were sampled post-mortem. Various tissues were analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry. DDT distribution showed no sex-based difference, with concentrations highest in fat tissue followed by liver, kidney, muscle, spleen, and heart. Male PCB concentrations ranked highest in fat, followed by kidney, liver, spleen, muscle, and heart, while females showed a similar trend. PAH concentrations were highest in fat for both sexes, followed by various organs. Limited PBDE concentrations hindered comprehensive evaluation. Overall, C. caretta act as effective bioindicators for monitoring environmental pollution, with certain POPs exhibiting sex and organ-based variations., 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 © 2024 Elsevier Ltd. All rights reserved.)

Bromophenols has been proven to synthesize hydroxylated polybrominated diphenyl ethers (OH-PBDEs), which may pose additional environmental and health risks in the process of bioremediation. In this study, the removal of 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) and the biosynthetic of OH-PBDEs by Prorocentrum donghaiense were explored. The removal efficiencies of 2,4-DBP and 2,4,6-TBP ranged from 32.71% to 76.89% and 31.15%-78.12%, respectively. Low concentrations of 2,4-DBP stimulated algal growth, while high concentrations were inhibitory. Furthermore, exposure to 10.00 mg L -1 2,4-DBP resulted in the detection of 2'-hydroxy-2,3',4,5'-tetrabromodiphenyl ether (2'-OH-BDE-68) within P. donghaiense. In contrast, increasing concentrations of 2,4,6-TBP considerably inhibited P. donghaiense growth, with 4'-hydroxy-2,3',4,5',6-pentabromodiphenyl ether (4'-OH-BDE-121) detected within P. donghaiense under 5.00 mg L -1 2,4,6-TBP. Metabolomic analysis further revealed that the synthesized OH-PBDEs exhibited higher toxicity than their precursors and identified the oxidative coupling as a key biosynthetic mechanism. These findings confirm the capacity of P. donghaiense to remove bromophenols and biosynthesize OH-PBDEs from bromophenols, offering valuable insights into formulating algal bioremediation to mitigate bromophenol contamination., 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 © 2024 Elsevier Ltd. All rights reserved.)

The contamination status on persistent organic pollutants (POPs) in the Croatian terrestrial ecosystem was investigated by analyzing two classes of contaminants in adipose tissue of male European brown bear (Ursus arctos, N = 27) collected in 2021 and 2022. In addition to seven indicator polychlorinated biphenyls (PCBs), for the first time seven polybrominated diphenyl ethers (PBDEs) were analyzed in terrestrial species from this region. Sum of mass fractions detected in adipose tissue ranged from 0.011 to 0.463 ng g -1 lipid weight (lw) for the PBDEs, and from 0.652 to 30.17 ng g -1 lw for PCBs, with two orders of magnitude difference in the median value for these two groups of POPs (PBDEs: 0.022 ng g -1 lw; PCBs: 2.307 ng g -1 lw). PCBs dominated over PBDEs with a share of over 94 % of the total mass fractions of both groups of analyzed POPs. Results of the comparison of the PCB levels in the adipose tissue of brown bears reported here and in previous investigation from this region showed decrease in PCB-28, but increase of PCB-118 and PCB-180, while other congeners seemed to have reached a steady-state level in the environment over a ten-year period. Among the compounds analyzed in this study, BDE-47, PCB-153 and PCB-180 were the dominant congeners. Somewhat higher sum of PCBs was measured in April compared to October, although not statistically significant, indicating possible impact of winter hibernation causing concentration of lipophilic compounds due to body fat loss. Revealed POP levels in brown bears are consistent with the data on the low contamination of the Croatian terrestrial ecosystem in general., 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 © 2024 Elsevier Ltd. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) in soils posed potential risks to crop growth and food safety due to their prevalence and persistence. PBDEs were capable of being absorbed and accumulated into crops, impacting their growth, whereas the interference on metabolic components and nutritional composition deserves further elucidation. This study integrated a combined non-targeted and targeted metabolomics method to explore the influences of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) and decabromodiphenyl ether (BDE-209) on the metabolic responses of rice (Oryza sativa). Metabolic pathways, which were associated with sugars, organic acids, and amino acids, were significantly disturbed under PBDE stresses. Particularly, 75% of the marked altered pathways belonged to amino acid metabolism, with alanine/aspartate/glutamate metabolism being commonly enhanced. The degradation of aspartic acid promoted the formation of downstream amino acids, among which the levels of lysine, methionine, isoleucine, and asparagine were increased by 1.31-3.15 folds compared to the control. Thus, the antioxidant capacity in rice plants was enhanced, particularly through the significant promotion of ascorbic acid-glutathione (AsA-GSH) cycle in rice leaves. The amino acids were promoted to resist reactive oxygen species (ROS) efficiently, thus were deficient for nutrient storage. When exposed to 4 μmol/kg PBDEs, the contents of amino acids and proteins in grains decreased by 9.1-32.1% and 8.6-34.8%, respectively. In particular, glutelin level was decreased by 5.6-41.2%, resulting in a decline in nutritional quality. This study demonstrated that PBDEs deteriorated the protein nutrition in rice grains by affecting amino acid metabolism, providing a new perspective for evaluating the ecological risks of PBDEs and securing agricultural products., 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 © 2024. Published by Elsevier Ltd.)

The pollution of various brominated flame retardants (BFRs) is concurrence, while their environmental fate and toxicology in water-sediment-submerged plant systems remain unclear. In this study, Vallisneria natans plants were co-exposed to 2,3,4,5,6-pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ether (BDE209), and decabromodiphenyl ethane (DBDPE). The ∑BFRs concentration in the root was 2.15 times higher than that in the shoot. Vallisneria natans accumulated more BTBPE and HBB in 0.2, 1, and 5 mg/kg treatments, while they accumulated more DBDPE and BDE209 in 25 and 50 mg/kg treatments. The bioaccumulation factors in the shoot and root were 1.08-96.95 and 0.04-0.70, respectively. BFRs in sediments had a more pronounced effect on bioaccumulation levels than BFRs in water, and biotranslocation was another potential influence factor. The SOD activity, POD activity, and MDA content were significantly increased under co-exposure. The DBDPE separate exposure impacted the metabolism of substances and energy, inhibited mismatch repair, and disrupted ribosomal functions in Vallisneria natans. However, DBDPE enhanced their photosynthesis by upregulating the expression level of genes related to the light reaction. This study provides a broader understanding of the bioaccumulation and toxicity of BFRs in submerged plants, shedding light on the scientific management of products containing BFRs., 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 © 2024 Elsevier B.V. All rights reserved.)

Persistent organic pollutants (POPs), such as polychlorinated diphenyls (PCBs) and brominated diphenyl ethers (PBDEs), are ubiquitous in the pet cat's living environment and are ingested through dietary intake and environmental exposure such as house dust. Cats are known to be susceptible to chronic kidney disease (CKD) and exposure to POPs may be associated with CKD. However, no studies have been conducted on the renal accumulation and health effects of POPs in cats. The objective of this study was to elucidate the accumulation of PCBs, PBDEs, and organochlorine pesticides (OCPs) in the kidneys of domestic cats and discuss their potential impact on feline health. We report here that cats specifically accumulate POPs in their kidneys. Tissue samples were collected from the kidneys, livers, and muscles of cats and the concentrations of POPs in these tissues were analyzed in this study. The results showed that these compounds accumulated significantly higher in the kidney compared to other tissues. In addition, the ability to accumulate in the kidney was higher in cats than in other animals, suggesting that cats have a unique pattern of POPs accumulation in their kidneys, which is thought to occur because cats store a significant number of lipid droplets in the proximal tubules of the kidneys. This unique feature suggests that lipophilic POPs may accumulate in these lipid droplets during the excretory process. Accumulation of certain POPs in the kidneys causes necrosis and sloughing of renal tubular epithelial cells, which may be associated with CKD, a common disease in cats. This study provides valuable insight into understanding the renal accumulation and risk of POPs in cats and provides essential knowledge for developing strategies to protect the health and welfare of domestic cats., 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 © 2024 Elsevier B.V. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants, easily enter the environment, thus posing environmental and health risks. Iron materials play a key role during the migration and transformation of PBDEs. This article reviews the processes and mechanisms of adsorption, degradation, and biological uptake and transformation of PBDEs affected by iron materials in the environment. Iron materials can effectively adsorb PBDEs through hydrophobic interactions, π-π interactions, hydrogen/halogen bonds, electrostatic interactions, coordination interactions, and pore filling interactions. In addition, they are beneficial for the photodegradation, reduction debromination, and advanced oxidation degradation and debromination of PBDEs. The iron material-microorganism coupling technology affects the uptake and transformation of PBDEs. In addition, iron materials can reduce the uptake of PBDEs in plants, affecting their bioavailability. The species, concentration, and size of iron materials affect plant physiology. Overall, iron materials play a bidirectional role in the biological uptake and transformation of PBDEs. It is necessary to strengthen the positive role of iron materials in reducing the environmental and health risks caused by PBDEs. This article provides innovative ideas for the rational use of iron materials in controlling the migration and transformation of PBDEs in the environment., 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 © 2024 Elsevier B.V. All rights reserved.)

Persistent organic pollutants pose a great threat to amphibian populations, but information on the bioaccumulation of contaminants in amphibians remains scarce. To examine the tissue distribution and maternal transfer of organic halogenated pollutants (OHPs) in frogs, seven types of tissues from black-spotted frog (muscle, liver, kidney, stomach, intestine, heart, and egg) were collected from an e-waste-polluted area in South China. Among the seven frog tissues, median total OHP concentrations of 2.3 to 9.7 μg/g lipid weight were found (in 31 polychlorinated biphenyl [PCB] individuals and 15 polybrominated diphenyl ether [PBDE], dechlorane plus [syn-DP and anti-DP], bexabromobenzene [HBB], polybrominated biphenyl] PBB153 and -209], and decabromodiphenyl ethane [DBDPE] individuals). Sex-specific differences in contaminant concentration and compound compositions were observed among the frog tissues, and eggs had a significantly higher contaminant burden on the whole body of female frogs. In addition, a significant sex difference in the concentration ratios of other tissues to the liver was observed in most tissues except for muscle. These results suggest that egg production may involve the mobilization of other maternal tissues besides muscle, which resulted in the sex-specific distribution. Different parental tissues had similar maternal transfer mechanisms; factors other than lipophilicity (e.g., molecular size and proteinophilic characteristics) could influence the maternal transfer of OHPs in frogs. Environ Toxicol Chem 2024;43:1557-1568. © 2024 SETAC., (© 2024 SETAC.)

Studies on the occurrence of POPs and other persistent compounds in pristine areas are extremely valuable, as they offer insights on the long-range transportation of POPs and the occurrence of natural compound producers' areas. In this regard, this study aimed to report data of both anthropogenic (polychlorinated biphenyls, PCBs, and polybrominated diphenyl ethers, PBDEs) and natural (methoxylated PBDEs, MeO-BDEs) compounds in tissues of the black triggerfish, Melichthys niger (Tetraodontiformes, Balistidae), specimens (n = 30) sampled in 2018 during a scientific expedition conducted at Trindade Island. Concentrations of ∑ 28 PCBs ranged from 73 to 1052 ng g -1 lw in liver, 334 to 1981 ng g -1 lw in gonads, and 20 to 257 ng g -1 lw in muscle, with the predominance of PCB-180 in liver and PCB-52 in gonad and muscle. Concentrations of ∑ 7 PBDEs ranged from -1 lw in liver, -1 lw in muscle, and they were < LOD in gonads. The BDE-47 was the most representative congener detected in liver and muscle. Mean concentrations of ∑ 8 MeO-BDEs were 270 ng g -1 lw, 442 ng g -1 lw, and 70 ng g -1 lw in liver, gonad, and muscle, respectively. The 2-MeO-BDE-68 was the most representative congener among MeO-BDEs. The mobilization of lower chlorinated PCBs from liver to other tissues, with possible retention of higher chlorinated PCBs in liver, can be a factor of concern considering the chronic exposure of those fish. PBDEs and MeO-BDEs in fish from remote environments were reported in a low number of studies worldwide. Considering that remote sites face environmental pollution either directly by anthropogenic influence or by long-range transportation, more studies on the occurrence of persistent compounds in these environments are paramount, and it is fundamental to understand the dispersion and accumulation of POPs., 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 © 2024 Elsevier B.V. All rights reserved.)

Halogenated flame retardants in farmlands were observed to inhibit the growth of exposed crops. This study aimed to elucidate the mechanism of inhibition on rice by employing four representative polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). The exposure to these contaminants at 200 nM led to a decrease of 0.63-0.95 fold in rice below-ground biomass and 0.49-0.66 fold in yield, and a corresponding 4%-10% increase in soluble sugars in leaves. PBDEs and PCBs were found to significantly disrupt the synthesis, decomposition, and transport of sugars in leaves, the three pivotal determinants of crop growth. Notably, these compounds promoted a 1.41- to 7.60-fold upregulation of the triose phosphate translocator, significantly enhancing soluble sugar synthesis. Conversely, a 0.45-0.97 fold downregulation was observed for sucrose transporters, thus impeding the leaf-to-shoot efflux of soluble sugars. Furthermore, PBDEs and PCBs were favorably bound to fructose-1,6-bisphosphate aldolase (FBA), inducing its substrate-specific dysfunction in fructose-1,6-diphosphate decomposition (3%-14%). Overall, PBDE and PCB exposure promoted a notable intracellular accumulation of soluble sugars in rice leaves, a typical symptom of plant diabetes, since the intensified synthesis of soluble sugars in leaves and the repressed decomposition and transportation of soluble sugars to other storage organs, thus impeding crop growth. This study provided an insightful understanding of the toxic effects and molecular mechanisms of halogenated flame retardants, highlighting their role in abnormal sugar accumulation and growth inhibition in crops and offering vital information for the risk assessment and administration of these compounds to guarantee the safety of agricultural products., 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 © 2024. Published by Elsevier Ltd.)

Adipose tissue compromises one of the principal depots where brominated flame retardants (BFR) accumulate in vivo, yet whether BFR disturb thermogenic brown/beige adipocytes is still not referred to date. Herein, effects of BDE-99, a major congener of polybrominated diphenyl ethers (PBDEs) detected in humans, on brown/beige adipocytes were explored for the first time, aiming to provide new knowledge evaluating the obesogenic and metabolic disrupting effects of BFR. Our results firstly demonstrated that exposure to BDE-99 during the lineage commitment period significantly promoted C3H10T1/2 MSCs differentiating into brown/beige adipocytes, evidenced by the increase of brown/beige adipocyte marker UCP1, Cidea as well as mitochondrial membrane potential and basal respiration rate, which was similar to pharmacological PPARγ agonist rosiglitazone. Unexpectedly, the mitochondrial maximal respiration rate of BDE-99 stimulated brown/beige adipocytes was not synchronously enhanced and resulted in a significant reduction of mitochondrial spare respiration capacity (SRC) compared to control or rosiglitazone stimulated adipocytes, indicating a deficient energy-dissipating capacity of BDE-99 stimulated thermogenic adipocytes. Consistently with compromised mitochondrial SRC, lipidomic analysis further revealed that the lipids profile of mitochondria derived from BDE-99 stimulated brown/beige adipocytes were quite different from control or rosiglitazone stimulated cells. In detail, BDE-99 group contains more free fatty acid (FFA) and lyso-PE in mitochondria. In addition to energy metabolism, our results also demonstrated that BDE-99 stimulated brown/beige adipocytes were deficient in endocrine, which secreted more adverse adipokine named resistin, coinciding with comparable beneficial adipokine adiponectin compared with that of rosiglitazone. Taken together, our results showed for the first time that BDE-99 stimulated brown/beige adipocytes were aberrant in energy metabolism and endocrine, which strongly suggests that BDE-99 accumulated in human adipose tissue could interfere with brown/beige adipocytes to contribute to the occurrence of obesity and relevant metabolic disorders., 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 © 2024 Elsevier Ltd. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) are toxic to organisms with melatonin (MT) providing protection for tissues and cells against these. This study investigates the mechanism of damage of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and the cellular protection of MT on grass carp hepatocytes. Grass carp hepatocytes were exposed to 25 μmol/L BDE-47 and/or 40 μmol/L MT for 24 h before testing. Acridine orange/ethidium bromide (AO/EB) double fluorescence staining results showed that BDE-47 could induce cell apoptosis. The expression levels of the endoplasmic reticulum (ER) stress-related genes ire1, atf4, grp78, perk, and chop were also significantly up-regulated (P < 0.01). The levels of the apoptosis-related genes caspase3, bax, and caspase9 were significantly up-regulated (P < 0.0001), while the level of bcl-2 was significantly down-regulated (P < 0.01). Compared with the BDE-47 group, the BDE-47 + MT group showed reduced levels of ER and apoptosis of hepatocytes, while the expression of the ER stress-related genes ire1, atf4, grp78, perk, and chop and the apoptosis-related genes caspase3, bax, and caspase9 were down-regulated (P < 0.05), and the level of bcl-2 was up-regulated (P < 0.01). In conclusion, BDE-47 can activate ER and apoptosis in grass carp hepatocytes, while MT can reduce these responses., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Polybrominated diphenyl ethers (PBDEs) in soil and groundwater have garnered considerable attention owing to the significant bioaccumulation potential and toxicity. Currently, the coupling treatment method of nano zero-valent iron (nZVI) with dehalogenation microorganisms is a research hotspot in the field of PBDE degradation. In this study, various systems were established within anaerobic environments, including the nZVI-only system, microorganism-only system, and the nZVI + microorganisms system. The aim was to investigate the degradation pathway of BDE-209 and elucidate the degradation mechanism within the coupled system. The results indicated that the degradation efficiency of the coupled system was better than that of the nZVI-only or microorganism-only system. Two modified nZVI (carboxymethyl cellulose and polyacrylamide) were prepared to improve the coupling degradation efficiency. CMC-nZVI showed the highest stability, and the coupled system consisting of microorganisms and CMC-nZVI showed the best degradation effect among all of the systems in this study, reaching 89.53% within 30 days. Furthermore, 22 intermediate products were detected in the coupling systems. Notably, changing the inoculation time did not significantly improve the degradation effect. The expression changes of the two reductive dehalogenase genes, e.g. TceA and Vcr, reflected the stress response and self-recovery ability of the dehalogenating bacteria, indicating such genes can be used as biomarker for evaluating the degradation performance of the coupling system. These findings provide a better understanding about the mechanism of coupling debromination process and the direction for the optimization and on-site repair of coupled systems., 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 © 2023 Elsevier B.V. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) are persistent pollutants that may undergo microbial-mediated debromination in anoxic environments, where diverse anaerobic microbes such as methanogenic archaea co-exist. However, current understanding of the relations between PBDE pollution and methanogenic process is far from complete. To address this knowledge gap, a series of anaerobic soil microcosms were established. BDE-47 (2, 2', 4, 4'-tetrabromodiphenyl ether) was selected as a model pollutant, and electron donors were supplied to stimulate the activity of anaerobes. Debromination and methane production were monitored during the 12 weeks incubation, while obligate organohalide-respiring bacteria (OHRBs), methanogenic, and the total bacterial communities were examined at week 7 and 12. The results demonstrated slow debromination of BDE-47 in all microcosms, with considerable growth of Dehalococcoides and Dehalogenimonas over the incubation observed in most BDE-47 spiked treatments. In addition, the accumulation of intermediate metabolites positively correlated with the abundance of Dehalogenimonas at week 7, suggesting potential role of these OHRBs in debromination. Methanosarcinaceae were identified as the primary methanogenic archaea, and their abundance were correlated with the production of debrominated metabolites at week 7. Furthermore, it was observed for the first time that BDE-47 considerably enhanced methane production and increased the abundance of mcrA genes, highlighting the potential effects of PBDE pollution on climate change. This might be related to the inhibition of reductive N- and S-transforming microbes, as revealed by the quantitative microbial element cycling (QMEC) analysis. Overall, our findings shed light on the intricate interactions between PBDE and methanogenic processes, and contribute to a better understanding of the environmental fate and ecological implication of PBDE under anaerobic settings., 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 © 2023. Published by Elsevier B.V.)

Decabromodiphenyl ether (BDE-209) is a widely used brominated flame retardant that can easily detach from materials and enter into feed and foodstuffs, posing a serious risk to human and animal health and food safety of animal origin. However, the immunotoxic effects of BDE-209 on the avian spleen and the exact mechanism of the toxicity remain unknown. Therefore, we established an experimental model of BDE-209-exposed chickens and a positive control model of cyclophosphamide-induced immunosuppression in vivo and treated MDCC-MSB-1 cells and chicken splenic primary lymphocytes with BDE-209 in vitro. The results showed that BDE-209 treatment caused morphological and structural abnormalities in the chicken spleens. Mechanistically, indicators related to oxidative stress, endoplasmic reticulum stress (ERS), autophagy, and apoptosis were significantly altered by BDE-209 exposure in both the spleen and lymphocytes, but the use of the N -acetylcysteine or the 4-phenylbutyric acid significantly reversed these changes. In addition, BDE-209 exposure decreased the spleen antimicrobial peptide and immunoglobulin gene expression. In conclusion, the present research revealed that BDE-209 exposure enhanced lymphocyte autophagy and apoptosis in chicken spleen via the ROS-mediated ERS pathway. This signaling cascade regulatory relationship not only opens up a new avenue for studying BDE-209 immunotoxicity but also provides important insights into preventing BDE-209 hazards to animal health.

As one of the typical brominated flame retardants, decabromodiphenyl ether (BDE-209) has been widely detected in environment. However, scarce information was available on BDE-209 phototransformation mechanisms in various media. In this study, compound-specific stable isotope analysis was first applied to investigate BDE-209 phototransformation in n-hexane, MeOH:H 2 O (v:v, 8:2), and simulated seawater by simulated sunlight. BDE-209 transformation followed pseudo-first-order kinetic, with degradation rate in the following of n-hexane (2.66 × 10 -3  min -1 ) > simulated seawater (1.83 × 10 -3  min -1 ) > MeOH:H 2 O (1.41 × 10 -3  min -1 ). Pronounced carbon isotope fractionation was first observed for BDE-209 phototransformation, with carbon isotope enrichment factors (ε C ) of -1.01 ± 0.14‰, -1.77 ± 0.26‰, -2.94 ± 0.38‰ in n-hexane, MeOH:H 2 O and simulated seawater, respectively. Combination analysis of products and stable carbon isotope, debromination with cleavage of C-Br bonds as rate-limiting step was the main mechanism for BDE-209 phototransformation in n-hexane, debromination and hydroxylation with cleavage of C-Br bonds as rate-limiting steps in MeOH:H 2 O, and debromination, hydroxylation and chlorination in simulated seawater. This present study confirmed that stable carbon isotope analysis was a robust method to discovery the underlying phototransformation mechanisms of BDE-209 in various solutions., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

From 2005 to 2019, three gadoid species, Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and saithe (Pollachius virens), were sampled approximately every third year in the northeastern part of the North Sea. Liver samples were analyzed to investigate levels and temporal trends of six groups of persistent organic pollutants (POPs): polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its degradation products, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), trans-nonachlor (TNC), and polybrominated diphenyl ethers (PBDEs). Some of the highest average concentrations were found in cod, the levels otherwise being similar between the three species and mostly below established threshold values. The levels of all the contaminants except HCB and TNC were higher than previously reported for cod and haddock in the Barents Sea. Significantly decreasing levels were found for Σ7PCBs, ΣDDTs, ΣHCHs and Σ15PBDEs in all three species, and for TNC in haddock and saithe, while there was no significant trend for TNC in cod. HCB levels increased significantly in cod and haddock and showed only a minor decrease in saithe. The observed time trends of legacy POPs demonstrate the persistence of some of the studied pollutants despite efforts to eliminate them from the marine environment., 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 © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The environmental presence of polybrominated diphenyl ethers (PBDEs) is ubiquitous due to their wide use as brominated flame retardants in industrial products. As a common congener of PBDEs, decabromodiphenyl ether (BDE-209) can pose a health risk to animals as well as humans. However, to date, few studies have explored BDE-209's toxic effects on the intestinal tract, and its relevant mechanism of toxicity has not been elucidated. In this study, adult male zebrafish were exposed to BDE-209 at 6 μg/L, 60 μg/L and 600 μg/L for 28 days, and intestinal tissue and microbial samples were collected for analysis to reveal the underlying toxic mechanisms. Transcriptome sequencing results demonstrated a dose-dependent pattern of substantial gene differential expression in the group exposed to BDE-209, and the differentially expressed genes were mainly concentrated in pathways related to protein synthesis and processing, redox reaction, and steroid and lipid metabolism. In addition, BDE-209 exposure caused damage to intestinal structure and barrier function, and promoted intestinal oxidative stress, inflammatory response, apoptosis and steroid and lipid metabolism disorders. Mechanistically, BDE-209 induced intestinal inflammation by increasing the levels of TNF-α and IL-1β and activating the NFκB signaling pathway, and might induce apoptosis through the p53-Bax/Bcl2-Caspase3 pathway. BDE-209 also significantly inhibited the gene expression of rate-limiting enzymes such as Sqle and 3βhsd (p < 0.05) to inhibit cholesterol synthesis. In addition, BDE-209 induced lipid metabolism disorders through the mTOR/PPARγ/RXRα pathway. 16S rRNA sequencing results showed that BDE-209 stress reduced the richness and diversity of intestinal microbiota, and reduced the abundance of probiotics (e.g., Bifidobacterium and Faecalibacterium). Overall, the results of this study help to clarify the intestinal response mechanism of BDE-209 exposure, and provide a basis for evaluating the health risks of BDE-209 in animals., 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 © 2023 Elsevier B.V. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) are organic pollutants widely detected in various environmental media due to their high persistence and bioaccumulation. PBDE-induced visual impairment and neurotoxicity were previously demonstrated using zebrafish (Danio rerio) models, and recent research reported the phenotypic depigmentation effect of PBDEs at high concentrations on zebrafish, but whether those effects are still present at environment-relevant levels is still unclear. Herein, we performed both phenotypic examination and mechanism investigation in zebrafish embryos (48 hpf) and larvae (5 dpf) about their pigmentation status when exposing to PBDE congener BDE-47 (2,2',4,4'-tetrabrominated diphenyl ether) at levels from 0.25 to 25 μg/L. Results showed that low-level BDE-47 can restrain the relative melanin abundance of zebrafish larvae to 70.47% (p < 0.05) and 61.54% (p < 0.01) respectively under 2.5 and 25 μg/L BDE-47 compared with control, and the thickness of retinal pigment epithelium (RPE) remarkably reduced from 571.4 nm to 350.3 nm (p < 0.001) under 25 μg/L BDE-47 exposure. We also observed disrupted expressions of melanin synthesis genes and disorganized mitfa differentiation patterns based on Tg(mifta:EGFP), as well as visual impairment resulting from thinner RPE. Considering both processes of visual development and melanin synthesis are highly sensitive to ambient light conditions, we prolonged the light regime of maintaining zebrafish larvae from 14 hours light versus 10 hours dark (14L:10D) to 18 hours light versus 6 hours dark (18L:6D). Lengthening photoperiod successfully rescued the fluorescent level of mitfa in zebrafish epidermis and most gene expressions associated with melanin synthesis under 25 μg/L BDE-47 exposure to the normal level. In conclusion, our work reported the effects of low-level PBDEs on melanin production using zebrafish embryos and larvae, and identified the potential role of a light-mediated pathway in the neurotoxic mechanism of PBDEs., 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 © 2023 Elsevier B.V. All rights reserved.)

The persistent organic pollutant 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47), a prevalent congener among polybrominated diphenyl ethers (PBDEs), exhibits potent bioaccumulation and toxicity. Despite extensive research into the adverse effects of BDE-47, its neurotoxicity in sea cucumbers remains unexplored. Given the crucial role of the sea cucumber's nervous system in survival and adaptation, evaluating the impacts of BDE-47 is vital for sustainable aquaculture and consumption. In this study, we employed ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF-MS) to analyze metabolomic changes in neuro-related tissues of Apostichopus japonicus exposed to low (0.1 µg/L), medium (1.0 µg/L), and high (10.0 µg/L) BDE-47 concentrations. We identified significantly changed metabolites in each exposure group (87 in low, 79 in medium, and 102 in high), affecting a variety of physiological processes such as steroid hormone balance, nucleotide metabolism, energy metabolism, neurotransmitter levels, and neuroprotection. In addition, we identified concentration-dependent, common, and some other metabolic responses in the neuro-related tissues. Our findings reveal critical insights into the neurotoxic effects of BDE-47 in sea cucumbers and contribute to risk assessment related to BDE-47 exposure in the sea cucumber industry, paving the way for future neurotoxicological research in invertebrates., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Polybrominated diphenyl ether (PBDE) contamination is common in aquatic environments and can severely damage aquatic organisms. However, there is a lack of information on the response and self-adaptation mechanisms of these organisms. Chlorella pyrenoidosa was treated with 2,2',4,4'-tetrabromodiphenyl ether (BDE47), causing significant growth inhibition, pigment reduction, oxidative stress, and chloroplast atrophy. Photosynthetic damage contributed to inhibition, as indicated by Fv/Fm, Chl a fluorescence induction, photosynthetic oxygen evolution activity, and photosystem subunit stoichiometry. Here, Chl a fluorescence induction and quinone electron acceptor (Q A - ) reoxidation kinetics showed that the PSII donor and acceptor sides were insensitive to BDE47. Quantitative analyses of D1 and PsaD proteins illustrated that PSII and PSI complexes were the main primary targets of photosynthesis inhibition by BDE47. Significant modulation of PSII complex might have been caused by the potential binding of BDE47 on D1 protein, and molecular docking was performed to investigate this. Increased activation of antioxidant defense systems and photosystem repair as a function of exposure time indicated a positive resistance to BDE47. After a 5-day exposure, 23 % of BDE47 was metabolized. Our findings suggest that C. pyrenoidosa has potential as a bioremediator for wastewater-borne PBDEs and can improve our understanding of ecological risks to microalgae., 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 © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

This study investigated the quantitative sources of persistent organic pollutants (POPs), their biomagnification factors, and their effect on POP biomagnification in a typical waterbird (common kingfisher, Alcedo atthis) food web in South China. The median concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in kingfishers were 32,500 ng/g lw and 130 ng/g lw, respectively. The congener profiles of PBDEs and PCBs showed significant temporal changes because of the restriction time points and biomagnification potential of different contaminants. The concentrations of most bioaccumulative POPs, such as CBs 138 and 180 and BDEs 153 and 154, decreased at lower rates than those of other POPs. Pelagic fish (metzia lineata) and benthic fish (common carp) were the primary prey of kingfishers, as indicated by quantitative fatty acid signature analysis (QFASA) results. Pelagic and benthic prey species were the primary sources of low and high hydrophobic contaminants for kingfishers, respectively. Biomagnification factors (BMFs) and trophic magnification factors (TMFs) had parabolic relationships with log K OW , with peak values of approximately 7. Significant negative correlations were found between the whole-body elimination rates of POPs in waterbirds and the log-transformed TMFs and BMFs, indicating that the strong metabolism of waterbirds could potentially affect POP biomagnification., 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 © 2023 Elsevier B.V. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants and recognized developmental toxicants that are detectable in placental tissues. Higher levels of in utero PBDE exposure have been associated with an increased risk of adverse birth outcomes. During pregnancy, cytotrophoblasts (CTBs) from the placenta play critical roles in the formation of the maternal-fetal interface via uterine invasion and vascular remodeling. The differentiation of these cells towards an invasive phenotype is crucial for proper placental development. We previously have shown that BDE-47 can impact CTB viability and hinder the ability of these cells to migrate and invade. To expand on potential toxicological mechanisms, we utilized quantitative proteomic approaches to identify changes in the global proteome of mid-gestation primary human CTBs after exposure to BDE-47. Using sequential window acquisition of all theoretical fragment-ion spectra (SWATH), we identified 3024 proteins in our CTB model of differentiation/invasion. Over 200 proteins were impacted as a function of BDE-47 exposure (1 μM and 5 μM) across the treatment period (15, 24, and 39 h). The differentially expressed molecules displayed time- and concentration-dependent changes in expression and were enriched in pathways associated with aggregatory and adhesive processes. Network analysis identified CYFIP1, a molecule previously unexplored in a placental context, to be dysregulated at BDE-47 concentrations previously seen to impact CTB migration/invasion. Our SWATH-MS dataset thus demonstrates BDE-47 impacts the global proteome of differentiating CTBs and serves as a valuable resource for further understanding of the relationship between environmental chemical exposures and placental development and function. AVAILABILITY OF DATA AND MATERIAL: Raw chromatograms are deposited on the MassIVE proteomic database (https://massive.ucsd.edu) under accession number MSV000087870. Normalized relative abundances are also available as Table S1., 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 © 2023 Elsevier B.V. All rights reserved.)

The toxicological and pathological influences of polybrominated diphenyl ethers (PBDEs) on the animal central nervous system have attracted worldwide attention. However, their mechanism of action has not been completely elucidated. Given that retinoic acid (RA) and thyroid hormone (TH) signaling pathway are closely related to neurodevelopment, the crosstalk between the two signaling pathways at the levels of metabolite conversion, gene expression and ligand-receptor interaction after exposure to two representative PBDE congeners (BDE-47 and BDE-209) using zebrafish larvae, dual reporter gene assay, and docking simulation was studied. Our results clarified that BDE-47 could disrupt the transport and metabolism of retinoids, induce changes in expression of key genes, bind with the seven nuclear receptors, and activate RA signaling pathway. BDE-47 exhibited more effects on the indicators of the two signaling pathways than BDE-209. Furthermore, BDE-47 may disrupt TH signaling pathway by disrupting RA signaling pathway, indicating that RA signal is priorly influenced than TH signal. This work offered a new perspective to elucidate TH signal disruption mechanism induced by PBDEs from RA signaling pathway, which is of great significance to elucidate the health effects of PBDEs., Competing Interests: Declaration of competing interest All authors read and approved the final version of this manuscript. The authors declare no competing financial interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This study was conducted to assess the mitigating effects of curcumin (Cur) on immunotoxicity in the spleen of broilers induced by the polybrominated diphenyl ether BDE-209. Eighty one-day-old broilers were allocated to the following four groups: control group, BDE-209 (0.4 g/kg) group, BDE-209 (0.4 g/kg) + Cur (0.3 mg/kg) group, and Cur (0.3 mg/kg) group. Growth performance, immunological function, inflammation, and apoptosis were assessed after 42 days of treatment. The findings demonstrate that firstly, Cur restored spleen damage caused by BDE-209 by increasing body weight, decreasing feed-to-gain ratio, correcting the spleen index, and improving the histopathological structure of the spleen. Secondly, Cur relieved BDE-209-induced immunosuppression by increasing the levels of the immunoglobulins IgG, IgM, and IgA in the serum, as well as the levels of white blood cells and lymphocytes. The levels at which GATA binding protein 3, T-box expressed in T cells, interferon-γ, and interleukin (IL)- 4 are expressed were controlled. The ratio of T helper (Th) type 1 (Th1) to Th2 cells in the spleen of broilers was also controlled. Thirdly, Cur reduced the expression of Toll like receptor (TLR) 2, TLR4, nuclear factor (NF)-κB, IL-8, IL-6, and IL-1β, which alleviated BDE-209-induced inflammation in broilers. Cur reduced BDE-209-induced apoptosis by increasing the expression of the bcl-2 protein, decreasing the expression of cleaved caspase-3 and bax proteins, decreasing the bax/bcl-2 protein ratio, and decreasing the mean optical density of TUNEL. These results suggest that Cur protects broiler spleens from BDE-209-induced immunotoxicity via modulating humoral immunity, the equilibrium between Th1 and Th2 cells, the TLRs/NF-κB inflammatory pathway, and the apoptotic pathway., 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 © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is a persistent organic pollutant that spreads widely in the marine environment. Our previous studies found that it had adverse effects on the marine rotifer Brachionus plicatilis and caused a series of stress responses. The present study was performed to verify the occurrence of autophagy and explore its role in B. plicatilis' coping with BDE-47 exposure. Rotifers were exposed to 0.05, 0.2, 0.8, and 3.2 mg/L BDE-47 for 24 h, respectively. Detections of the autophagy marker protein LC3 by western blot and autophagosomes by MDC staining demonstrated the occurrence of autophagy. The levels of autophagy were significantly increased in BDE-47-treated groups with a peak in 0.8 mg/L group. A series of indicators responded to BDE-47 exposure, including reactive oxygen species (ROS), GSH/GSSG ratio, superoxide dismutase (SOD) activity, and malonaldehyde (MDA), collectively indicating the occurrence of oxidative stress. The potential interplay between autophagy and oxidative stress in B. plicatilis was explored in the 0.8 mg/L group through a series of additions. The ROS level was significantly decreased by the addition of the ROS generation inhibitor diphenyleneiodonium chloride, to a level even lower than that in the blank control, and concomitantly, autophagosome was almost undetectable, indicating that a certain level of ROS was essential for the occurrence of autophagy. Autophagy was weakened by the addition of the autophagy inhibitor 3-methyladenine coincident with the great elevation of ROS, indicating that activated autophagy contributed to reducing the ROS level. Additional proof of this relation was obtained from the direct opposite effects of the autophagy inhibitor bafilomycin A1 and the autophagy activator rapamycin: the former increased the MDA content significantly, whereas the latter decreased it significantly. The combined results suggested that autophagy alleviated oxidative stress and might be a newly discovered protective mechanism in B. plicatilis coping with BDE-47 exposure., 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 © 2023. Published by Elsevier B.V.)

BDE47 (2,2,4,4-tetrabromodiphenyl ether) is a member of the most important congeners of polybrominated diphenyl ethers (PBDEs) and has been identified as a developmental, reproductive and nervous system toxicant and endocrine system disruptor due to its frequent detection in human tissue and environmental samples. Our preliminary work suggested that high- and low-level of bromodiphenyl ethers have different effects on neuronal cells with differential targets of actions on neural tissues. In this study, we presented the underlying mechanism of BDE47 neurotoxicity from the perspective of thyroid hormone (TH) metabolism using in vitro model of human SK-N-AS neuronal cells. BDE47 could induce local TH metabolism disorder in neuronal cells by inhibiting the expression of the main enzyme, human type III iodothyronine deiodinase (Dio3). Further elucidation revealed that BDE47 effectively up-regulating miR-24-3p, which binds to the 3'-UTR of Dio3 and inhibits its expression. In addition, BDE47 could also inhibit the deiodinase activity of Dio3. Collectively, our study demonstrates the molecular mechanism of BDE47 regulating Dio3-induced TH metabolism disorder through inducing miR-24-3p, providing new clues for the role of miRNAs in neurodevelopmental toxicity mediated by environmental pollutants., 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 © 2023 Elsevier B.V. All rights reserved.)

Deca brominated diphenyl ether (BDE-209) is a widely used flame retardant with endocrine-disrupting activity which reportedly caused sperm quality decline and damaged blood-testis barrier (BTB). However, whether BDE-209 exposure led to BTB integrity dysfunction through affecting microtubule cytoskeletal organization and junctions was not well-elucidated. This study aimed to investigate the role of estrogen receptor α (ERα) in BDE-209-mediated perturbation of BTB integrity. Male rats and primary culture Sertoli cells were co-treated with BDE-209 and propylpyrazoletriol (PPT). The data demonstrated that BDE-209 impaired BTB integrity by reducing crucial tight junction-related proteins with ZO-1 and Occludin. Furthermore, the data suggested that BDE-209 diminished the apical ectoplasmic specialization markers with Eps8 and Formin1. In addition, BDE-209 damaged BTB ultrastructure including tight junctions and ectoplasmic specialization structures with broken tight junctions and the absence of actin microfilaments. Further experiments revealed that ERα was triggered in BDE-209-treated Sertoli cells. Unexpectedly, we found that PPT rescued BDE-209-mediated disruption of BTB integrity including tight junction and apical ectoplasmic specialization by activating ERα in Sertoli cells. Taken together, these findings indicated that intratesticular BDE-209 exposure perturbed BTB integrity and destroyed BTB structure by blocking ERα pathway. Our findings provide a new therapeutic target for male reproductive dysfunction., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants being widely distributed and harmful to human health and wildlife, and the development of sustainable rehabilitation strategies including microbial degradation is of great concern. Although the increasing number of bacteria, especially the broad-spectrum and potent aerobes have been isolated for the efficient removal of PBDEs, the external influences and the corresponding influential mechanism on biodegradation are not fully understood yet. Given the wide-spectrum biodegradability of aerobic bacterial isolate, B. xenovorans LB400 for PBDEs, the dual impacts of many pivotal factors including pH, temperature, presence of dissolved organic matter (DOM) and cadmium ion etc. were comprehensively revealed on biodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Due to the structural resemblance and stimulation of specific enzyme activity in bacteria, the biphenyl as substrates showed the greater capacity than non-aromatic compounds in improving biodegradation. The individual adaptation to neutrality and cultivation at about 30 °C was beneficial for biodegradation since the bacterial cellular viability and enzyme activity was mostly preserved. Although it was possibly good for the induction of hormesis and favorable to enhance the permeability or bioavailability of pollutant, the exceeding increase of Cd 2+ or DOM may not give the profitable increase of biodegradation yet for the detrimental effect. For biodegradation, the mechanistic relationship that took account of the integrative correlation with the influential factors was artfully developed using partial least square (PLS) regression technique. Relative to the most significant influence of culture time and initial concentration of BDE-47, the larger relevance of other factors primarily marked as pH and DOM was consecutively shown after the quantitative prioritization. This may not only help understand the influential mechanism but provide a prioritizing regulation strategy for biodegradation of BDE-47. The PLS-derived relationship was validated with the certain predictability in biodegradation, and could be used as an alternative to accelerate a priori evaluation of suitability or improve the feasibility of such bacteria in remediation of PBDEs in the environment., 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 © 2023 Elsevier Ltd. All rights reserved.)

The constant use of the pesticide oxyfluorfen (OFF) in farmland contaminates the soil, posing threats to crop growth and human health. To avoid the contamination of food crops with OFF, it is critically important to understand its absorption and degradation mechanisms. In this study, we characterized a new functional locus encoding an acetyltransferase (OsACE2) that can facilitate OFF degradation in rice. OsACE2 was drastically induced by OFF at 0.04-0.2 mg L -1 for 6 days and the rice growth was significantly inhibited. To demonstrate the regulatory role of OsACE2 in resistance to OFF toxicity, we generated OsACE2 overexpression (OE) and knockout mutant using genetic transformation and gene-editing technologies (CRISPR/Cas9). The OE plants grown in the hydroponic medium showed improved growth (plant elongation and biomass), increased chlorophyll content, and reduced OFF-induced oxidative stress. The OsACE2-improved growth phenotypes of rice were attributed to the significantly lower OFF accumulation in OE plants. Conversely, knocking out OsACE2 resulted in compromised growth phenotypes compared to the wild-type (WT). Using LC-LTQ-HRMS/MS, five mono-metabolites and eleven conjugates of OFF were characterized through various canonical pathways, such as hydrolysis, oxidation, reduction, glycosylation, acetylation, malonylation, and interaction with amino acids. These metabolites increased in the OE plants, and five acetylated conjugates were reported for the first time. Collectively, OsACE2 plays a primary role in catabolizing OFF residues in rice through multiple degradation pathways and reducing OFF in its growth environment., 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 © 2023 Elsevier B.V. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) are well-known endocrine disrupting chemicals identified as organic persistent pollutants. Their metabolites OH-BDE and MeO-BDE have been reported to be potentially more toxic than the postulated precursor PBDEs. One of the most predominant congeners of PBDEs in the environment is BDE-47, due to its high presence in industrially used mixtures. In the present study, the bioaccumulation and biotransformation of BDE-47 into its major metabolites is evaluated using zebrafish (Danio rerio) eleutheroembryos adapting a previously developed alternative method to bioconcentration official guideline Organisation for Economic Co-ordination and Development 305, which reduces the animal suffering, time, and cost. For the simultaneous determination of BDE-47 and its metabolites in larvae and exposure medium, and considering the polarity difference of the analytes and the small sample size, the development of a validated analytical method is a step to ensure quality results. In the present study, an ultrasound-assisted extraction followed by a solid phase extraction dispersive clean-up step and gas chromatography-mass spectrometry-microelectron capture detector (GC-MS-μECD) with a previous derivatization process was optimized and validated. Bioconcentration factors (BCFs) were calculated using a first-order one-compartment toxicokinetic model. The profiles found show rapid absorption in the first hours of larval development and great bioaccumulative capacity, finding BCFs of 7294 ± 899 and 36 363 ± 5702 at nominal concentrations of 10 and 1 μg L -1 , respectively. Metabolization studies show increasing concentrations of the metabolites BDE-28, 2'-OH-BDE-28, and 5-MeO-BDE-47 throughout the exposure time. The results obtained show the feasibility of the method for bioaccumulation and open up the possibility of metabolic studies with zebrafish eleutheroembryos, which is a very underdeveloped field without official testing or regulation. Environ Toxicol Chem 2023;42:835-845. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., (© 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.)

Glucuronoyl esterase (GE) is a promising agent for the delignification of plant biomass since it has been shown to cleave the linkage between xylan and lignin in vitro. In this study, we demonstrate that NcGE, a GE from Neurospora crassa, stimulates plant biomass degradation. In vitro, NcGE synergistically increased the release of reducing sugars from plant biomass when added together with cellulase or xylanase. In vivo, overexpression of NcGE in N. crassa resulted in an increase in xylanolytic activity. Consistently, elevated transcription of genes encoding the major plant biomass degrading-enzymes (PBDEs) was observed in the NcGE overexpression strain. Increased xylanolytic activity and transcription of PDBE genes were largely abolished when the transcription factors clr-1, clr-2, or xlr-1 were deleted. Interestingly, the expression of some PBDE genes was increased when the hydrolysate of plant biomass by NcGE was added to the culture medium. We propose that NcGE boosts the production of PBDEs through the activation of key transcription factors, which is presumably caused by NcGE-mediated generation of hypothetical inducer(s) from plant biomass.

Polybrominated diphenyl ethers (PBDEs) are persistent environmental contaminants with developmental neurotoxicity, the mechanism of which remains obscure. The present study aimed to evaluate cognitive deficits and microglia-originated neuroinflammation in the hippocampus of offspring rats exposed to BDE-209 (30 and 100 mg/kg) during perinatal period. Compared to the control, BDE-209-treated rats showed significant longer escape latency and less platform crossings in tests of Morris water maze. Besides obvious hippocampal neuron damage, increased microglial activation and pro-inflammatory markers (CD86, TNFα, and IL-1β), meanwhile, decreased anti-inflammatory molecules (CD206, IL-10, and Arg1) were induced by BDE-209. Furthermore, we investigated the neuroprotection of melatonin against BDE-209 and whether through sirtuin 1 (SIRT1). Consistent with restored SIRT1 activity, enhanced deacetylation of HMGB1 and inhibited cytoplasmic translocation of HMGB1, reduced expression of proteins involved in TLR4-NF-κB pathway and nuclear transfer of phosphorylated-NF-κB p65, and ultimately suppressed microglial activation and improved spatial memory were observed in 10 mg/kg melatonin-pretreated rats, compared with BDE-209-exposed alone. These results demonstrated that melatonin ameliorated BDE-209-caused cognitive impairment partially through shifting microglia polarization towards anti-inflammatory phenotype in a SIRT1-dependent manner, suggesting a potential mechanism for prevention., 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.)

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are formed by metabolism from the flame retardants polybrominated diphenyl ethers (PBDEs). In the aquatic environment, they are also produced naturally. OH-PBDEs are known for their potential to disrupt energy metabolism, the endocrine system, and the nervous system. This is the first study focusing on the effects of OH-PBDEs at the metabolite level in vivo. The aim of the current study was to investigate the metabolic effects of exposure to OH-PBDEs using metabolomics, and to identify potential biomarker(s) for energy disruption of OH-PBDEs. Zebrafish (Danio rerio) embryos were exposed to two different concentrations of 6-OH-BDE47 and 6-OH-BDE85 and a mixture of these two compounds. In total, 342 metabolites were annotated and 79 metabolites were affected in at least one exposure. Several affected metabolites, e.g. succinic acid, glutamic acid, glutamine, tyrosine, tryptophan, adenine, and several fatty acids, could be connected to known toxic mechanisms of OH-PBDEs. Several phospholipids were strongly up-regulated with up to a six-fold increase after exposure to 6-OH-BDE47, a scarcely described effect of OH-PBDEs. Based on the observed metabolic effects, a possible connection between disruption of the energy metabolism, neurotoxicity and potential immunotoxicity of OH-PBDEs was suggested. Single compound exposures to 6-OH-BDE47 and 6-OH-BDE85 showed little overlap in the affected metabolites. This shows that compounds of similar chemical structure can induce different metabolic effects, possibly relating to their different toxic mechanisms. There were inter-concentration differences in the metabolic profiles, indicating that the metabolic effects were concentration dependent. After exposure to the mixture of 6-OH-BDE47 and 6-OH-BDE85, a new metabolic profile distinct from the profiles obtained from the single compounds was observed. Succinic acid was up-regulated at the highest, but still environmentally relevant, concentration of 6-OH-BDE47, 6-OH-BDE85, and the mixture. Therefore, succinic acid is suggested as a potential biomarker for energy disruption of OH-PBDEs., 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 The Authors. Published by Elsevier B.V. All rights reserved.)

Nanoplastics (NPs) are good carriers of persistent organic pollutants (POPs) such as polybrominated diphenyl ethers (PBDEs) and can modify their bioavailability and toxicity to aquatic organisms. This study highlights the single and combined toxic effects of polystyrene nanoplastics (PS-NPs) and 2,2 ',4,4 '-tetrabromodiphenyl ether (BDE-47, one of the major PBDE congeners) on zebrafish embryos after an exposure of up to 120 hpf. Our results showed that PS-NPs and BDE-47 formed larger particle aggregates during co-exposure, which attached to the surface of the yolk membrane and even changed its structure, and these particles also bioaccumulated in the intestine of zebrafish larvae, compared with the PS-NPs single exposure. Further, the co-exposure significantly increased mortality, accelerated voluntary movements, enhanced hatching rate, and decreased heart rate. Hepatoxicity analyses revealed that the mixture exposure induced a darker/browner liver colour, atrophied liver and greater hepatotoxicity in zebrafish larvae. In addition to increased ROS accumulation, the reduced expression of the antioxidant gpx1a gene and increased expression of cyp1a1 were found after co-treatment. Moreover, ache and chrn7α genes associated with neurocentral development, were significantly downregulated, mainly in the co-exposure group. In conclusion, simultaneous exposure to PS-NPs and BDE-47 exacerbated oxidative stress, developmental impacts, hepatotoxicity, and neurodevelopmental toxicity in zebrafish larvae. Therefore, neurotoxic effects of complex chemical interactions between PS-NPs and persistent organic pollutants in freshwater environments should be paid more attention., 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.)

As a kind of phenolic chemical with endocrine disrupting potency, hydroxylated polybrominated diphenyl ethers (OH-PBDEs) cause a latent threat to human health from their residue in the environment. Their binding efficiency with lysozyme (LYSO) was studied by molecular simulation combined with fluorescence, UV-vis absorption and circular dichroism (CD), so as to assess their toxicity at the molecular level. Molecular docking data indicate that van der Waals force is the principal interaction force between OH-PBDEs and LYSO. The binding site for 5'-OH-BDE-25 in LYSO is ascertained as the active site, which interaction with the TRP63 and TRP108 residues of LYSO to take shape a strong face-to-face stacked rank (F-shaped). Both 4'-OH-BDE-99 and 3'-OH-BDE-154 display a certain degree of deviation from the active site. Nevertheless, their F-shaped interaction with TRP63 conduce to bind LYSO and stabilize the docking conformation. Combined with dynamics simulation and spectral analysis, the secondary structure of LYSO can be induced by the three kinds of OH-PBDEs. CD spectrum shows that the combination of LYSO and OH-PBDEs will make α- Helix content increased. The combination of OH-PBDEs and LYSO touch upon a static quenching mechanism as a result of steady state fluorescence. The energy decomposition analysis exhibited that LYSO-OH-PBDEs binding site was stable by van der Waals and hydrophobic interaction. As enzyme activity experiments demonstrate that OH-PBDEs can inhibit the activity of LYSO, which is helpful to clarify the molecular toxicity mechanism of OH-PBDEs., 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.)

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been identified as the strong endocrine disrupting chemicals to humans, which show structural similarity with endogenous thyroid hormones (THs) and thus disrupt the functioning of THs through competitive binding with TH receptors (TRs). Although previous studies have reported the hormone activities of some OH-PBDEs on TH receptor β (TRβ), the interaction mechanism remains unclear. Furthermore, hydroxyl dissociation of OH-PBDEs may alter their TR disrupting activities, which has not yet been investigated in depth. In this work, we selected 18 OH-PBDEs with neutral and anionic forms and performed molecular dynamics (MD) simulations to estimate their binding interactions with the ligand binding domain (LBD) of TRβ. The results demonstrate that most of OH-PBDEs have stronger binding affinities to TRβ-LBD than their anionic counterparts, and the hydroxyl dissociation of ligands differentiate the major driving force for their binding. More Br atoms in OH-PBDEs can result in stronger binding potential with TRβ-LBD. Moreover, 5 hydrophobic residues, including Met313, Leu330, Ile276, Leu346, and Phe272, are identified to have important contributions to bind OH-PBDEs. These results clarify the binding mechanism of OH(O - )-PBDEs to TRβ-LBD at the molecular level, which can provide a solid theoretical basis for accurate assessment of TH disrupting effects of these chemicals., 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.)

Decabromodiphenyl ether (BDE-209), as a brominated flame retardant (BFR), is widely applied to various consumer products due to its superior performance and affordable pricing to improve the flame resistance of materials. To better comprehend the pyrolysis behavior of BDE-209 and the evolution process of main pyrolysis products, the thermal degradation mechanism of BDE-209 was studied using density functional theory (DFT) method at the theoretical level of M06/cc-pVDZ, and thermodynamic parameters were calculated in this paper. Unimolecular degradation was dominated by cleavage of the ether linkage, which results in a high yield of hexabromobenzene, and fission of the ortho-position C-Br bond is the main competitive reaction channel. In the system of BDE-209 + H, the pyrolysis reaction is majorly characterized by debromination, leading to the formation of considerable HBr and low-brominated diphenyl ethers. Additionally, the hydrogen-derived splitting of the ether bond acts as a mainly competitive channel, which is the source of polybromophenols and polybromobenzenes. The formation of polybrominated dibenzofuran (PBDF) derives from the cyclization reaction of ortho-phenyl-type radicals, which are readily generated through the ortho-position Br atom abstraction by H radical. The formation of polybrominated dibenzo-p-dioxin (PBDD) involves the ortho-C-O coupling reaction of polybromophenoxy radicals, debromination reaction, and cyclization reaction. And the total yield of PBDD/Fs was significantly increased when H was involved. Results presented in this work will provide the helpful information for the treatment and reuse of BDE-209-containing waste plastics through using pyrolysis technology., 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.)

Microalgae act as the entrance of polybrominated diphenyl ethers (PBDEs) from abiotic to biotic environments, which controlled the environmental fate of PBDEs in aquatic environments. Combing with typical coastal environmental characteristics including extracellular polymer substances (EPS) enrichment, light limitation and nitrogen starvation, the changes of adsorption and absorption kinetics of BDE-47 by Chlorella sp. and the role of EPS therein were investigated. The results quantified the adsorption and absorption kinetics of BDE-47 by Chlorella sp. cells and fitted it by the Lagergren pseudo first order model. Furthermore, we found the adsorption and absorption kinetics could be changed by the above mentioned environmental factors. To be specific, the total BDE-47 adsorption amounts per microalgal cell were increased as the increase of ambient EPS (proteins or carbohydrates), attributing to the increase of soluble (SL)-EPS contents; increased total BDE-47 adsorption amounts but decreased absorption rates were found under light limitation and nitrogen starvation, which were attributed to increased bound (B)-EPS contents and protein/carbohydrates (P/C) ratios therein, respectively. Therefore, our study elucidated the adsorption and absorption kinetics of PBDEs by microalgae could be influenced by ambient environmental changes, clarified the roles of SL-EPS, B-EPS contents and P/C ratios, providing a solid basis for evaluating the environmental fate of PBDEs in the marine environments., 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 Inc. All rights reserved.)

Several halogenated flame retardants (HFRs) have been identified as thyroid disruptors in birds including the polybrominated diphenyl ether (PBDE) mixtures, which have been replaced with other HFRs such as Dechlorane-604 (Dec-604). Dec-604 Component B (Dec-604 CB), a putative debrominated product of Dec-604, has been frequently reported in urban-adapted ring-billed gulls (Larus delawarensis) breeding in the Montreal area (QC, Canada). The metabolic pathways of Dec-604 are yet to be characterized, although the occurrence of Dec-604 CB in gulls may suggest that enzyme-mediated dehalogenation may occur, potentially involving the thyroid deiodinases. The objective of this study was to investigate the effect of Dec-604 on type 1 deiodinase (DIO1) in the presence of thyroxine (T 4 ) in an in vitro DIO1 assay using liver microsomes of ring-billed gulls that are highly exposed to HFRs in the Montreal area, and to determine whether DIO1 is involved in the in vitro debromination of Dec-604. We tested the in vitro activity of DIO1 in gull liver microsomes in the presence of five concentrations of Dec-604 ranging from 0.86 to 86.21 nM. HFR concentrations (Σ 40 HFR) were also determined in liver samples of gulls. Results showed that total DIO1 activity in gull liver microsomes was increased by three of the five concentrations of Dec-604. No relationship between liver Σ 40 HFR concentrations and DIO1 activity was observed, except for T 2 formation rates that significantly decreased with increasing liver HFR concentrations. Moreover, greater Dec-604 CB to Dec-604 concentration ratios in activated gull microsomes (with the DIO1 cofactor dithiothreitol) were found at the intermediate Dec-604 concentration compared to controls. These results suggested that liver microsome DIO1 activity may be perturbed in ring-billed gulls exposed to Dec-604, and be involved at least in part, in the debromination of Dec-604 leading to the formation of Dec-604 CB., 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 Inc. All rights reserved.)

Persistent organic pollutants (POPs) are highly lipophilic compounds that accumulate at increased concentrations in high tropic level organisms like marine mammals. Marine mammals' reliance on blubber makes them susceptible to accumulating POPs at potentially toxic concentrations. In this study, we analyzed POP concentrations, (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and methoxylated-BDE (MeOBDE), in the blubber of 16 subsistence harvested sub-adult, male northern fur seals as well as assessed changes in mRNA gene expression of nine relevant biomarkers including the aryl hydrocarbon receptor, thyroid receptor-α, and adiponectin. PBDE and MeOBDE concentrations were significantly lower than PCB and OCP concentrations. A negative relationship was observed between percent lipid in the blubber and contaminant concentrations, both individual and sum. Expression changes in eight biomarkers were correlated with individual and sum contaminant concentrations. This study shows that contaminant concentrations measured are correlated to changes in expression of genes from different physiological systems, metabolism and endocrine, that are important for the regulation of blubber metabolism. Northern fur seals are reliant on blubber as an energy source during times of low food intake. Potential contaminant induced changes in blubber metabolism pathways could have significant impacts on the health of individuals during critical periods., 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.)

The 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is the predominant congener of polybrominated diphenyl ethers, and it is also a persistent organic pollutant that with a higher detection rate in samples from environment and animals. To date, there have been few studies of the effects of BDE-47 on locomotion in sea cucumbers. In this study, we investigated the influence of different concentrations of BDE-47 (low: 0.1 μg/L; moderate: 1.0 μg/L; high: 10.0 μg/L) on locomotion of Apostichopus japonicus and evaluated changes in their muscle physiology using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The behavioural studies showed that the average and maximum velocity of movement decreased significantly in both the moderate and high BDE-47 groups after 1 day of exposure. In addition, levels of 55 metabolites were identified and characterized in the longitudinal muscle of A. japonicus exposed to BDE-47. The alteration of taurine and norepinephrine levels indicated that BDE-47 had drastic physiological effects on the longitudinal muscle of A. japonicus., 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. Published by Elsevier Ltd.)

2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) is one of the most widely distributed PBDEs. BDE-47 is also the most abundant in organisms and the most toxic to humans and animals. Herein, we have studied the pathway of BDE-47 degradation and gene involvement in Acinetobacter pittii GB-2. This degradation is dominated by hydroxylation, resulting in hydroxylated products 6-OH-BDE-47, 5-OH-BDE-47 and 2'-OH-BDE-28, and bromophenol products 2,4-DBP and 4-BP. Transcriptome sequencing results showed 359 differentially expressed genes (DEGs) induced by BDE-47, of which 159 were up-regulated and 200 were down-regulated. The up-regulated ones were mainly related to substance transport, degradation and cell stress. From these results, we suggest that 1,2-dioxygenase, phenol hydroxylase and monooxygenase are involved in BDE-47 degradation. The function of AntA gene was identified by constructing a prokaryotic expression vector. Our study contributes to understanding how the metabolism of strain GB-2 changes under BDE-47 stress conditions, and sheds light on the mechanism of BDE-47 degradation., 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 The Authors. Published by Elsevier B.V. All rights reserved.)

The influence of biochar on the biodegradation of persistent organic pollutants (POPs) has been extensively studied. However, the underlying mechanisms behind the response of functional microbial consortia to biochar remain poorly understood. Herein, we systematically explored the effect of biochar on 2,2',4,4'-tetrabrominated ether (BDE-47) biodegradation, and investigated the interaction and assembly mechanism of the functional bacterial consortium QY2. The results revealed that the biodegradation efficiency of QY2 for BDE-47 increased from 53.85% to 94.11% after the addition of biochar. Fluorescence excitation-emission matrix and electrochemical analysis showed that biochar-attached biofilms were rich in redox-active extracellular polymeric substances (EPS, 3.03-fold higher than free cell), whose strong interaction with biochar facilitated the electron transfer of the biofilm, thus enhancing the debromination degradation of BDE-47. Meanwhile, the assembly model and molecular ecological networks analysis indicated that bacterial community assembly in biofilms was more driven by deterministic processes (environmental selection >75.00%) upon biochar stimulation and exhibited closer interspecific cooperative interactions, leading to higher biodiversity and broader habitat niche breadth for QY2 in response to BDE-47 disturbance. Potential degraders (Methylobacterium, Sphingomonas, Microbacterium) and electrochemical bacteria (Ochrobactrum) were selectively enriched, whose role as keystone bacteria may be participated in biofilm formation and redox-active EPS secretion (r > 0.5, P < 0.05). These findings deepen the understanding of the mechanisms by which biochar promotes microbial degradation of PBDEs and provided a theoretical basis for better regulation of functional bacterial communities during environmental remediation., 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.)

Deep-sea ecosystems play a key role in the cycling and vertical transfer of matter and energy in oceans. Although the contamination of deep-sea demersal and benthic organisms by persistent organic pollutants has been proven, deep pelagic species have been far less studied. To fill these gaps, we studied the occurrence of a large variety of hydrophobic organic contaminants including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy and alternative brominated flame retardants (BFRs) and per- and polyfluoroalkyl substances (PFASs) in crustaceans and fish species collected in the Bay of Biscay, northeast Atlantic. The results highlighted the global predominance of PCBs in fish, followed by OCPs, PFASs and PBDEs, with highly variable concentrations among species. Most of the chlorinated or brominated contaminants showed increasing concentrations with increasing δ 15 N values, while most PFASs showed inverse trends. The contaminant profiles and diagnostic ratios revealed species-specific metabolic capacities and peculiar contribution of highly-brominated BFRs., 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.)

Companion animals are in close contact with the human surroundings, and there is growing concern about the effects of harmful substances on the health of pet cats. In this study, we investigated the potential health effects of organohalogen compounds (OHCs) on thyroid hormone (TH) homeostasis and metabolomics in Japanese pet cats. There was a significant negative correlation between concentrations of several contaminants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hydroxylated PCBs (OH-PCBs), hydroxylated PBDEs (OH-PBDEs), and THs in cat serum samples. These results suggested that exposure to OHCs causes a decrease in serum TH levels in pet cats. In this metabolomics study, each exposure level of parent compounds (PCBs and PBDEs) and their hydroxylated compounds (OH-PCBs and OH-PBDEs) were associated with their own unique primary metabolic pathways, suggesting that parent and phenolic compounds exhibit different mechanisms of action and biological effects. PCBs were associated with many metabolic pathways, including glutathione and purine metabolism, and the effects were replicated in in-vivo cat PCB administration studies. These results demonstrated that OHC exposure causes chronic oxidative stress in pet cats. PBDEs were positively associated with alanine, aspartate, and glutamate metabolism. Due to the chronic exposure of cats to mixtures of these contaminants, the combination of their respective metabolic pathways may have a synergistic effect., 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.)

Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants (POPs) that pose serious challenges to aquatic animals and environments. Compared with BDE-47 which was one of the most toxic congeners known to date, BDE-209 is less toxic with higher abundance in biotic and abiotic samples. In this study, we have explored the effects of BDE-47 and BDE-209 at different concentrations on the radical oxygen species (ROS) levels and the antioxidant defense system of Brachionus plicatilis. Antioxidant indexes were measured, including total protein content (TSP), the activities of antioxidant enzymes, lipid peroxidation and DNA damage. The results indicated that while low concentrations of PBDEs could activate the antioxidant defense mechanisms, prolonged exposure to higher concentrations of PBDEs could impair the antioxidative capacity of B.plicatilis (P < 0.05). The overwhelming of the B.plicatilis antioxidant defense mechanism led to an accumulation of free radicals, resulting in the overactivation of lipid peroxidation and the increased frequency of DNA damage (P < 0.05). By studying the toxicity of PBDEs and the detoxification mechanism of B.plicatilis, our research has revealed useful indexes for detecting and monitoring the level of BDE-47 and BDE-209 in the future. Altogether, this study holds immense value in the field of ecotoxicology and environmental safety and will aid in the proper management of PBDEs pollution., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Effects of polybrominated diphenyl ethers (PBDEs) on neonatal birth outcomes vary across previous studies, and the related mechanism investigation remains poorly understood, especially at the metabolic level., Objectives: To evaluate the associations between prenatal PBDEs exposure and neonatal birth outcomes including gestational age, neonatal weight, birth length, head circumference (HC), Apgar score at 1 min (Apgar1) and 5 min, and further reveal the underlying metabolic disorders in a population-based birth cohort study., Methods: Gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) based targeted method and GC-MS based untargeted method were respectively conducted to obtain PBDE levels and metabolic profiles of 200 placental tissue samples from a typical e-waste recycling area (Guiyu) and reference area (Haojiang) in China. Spearman correlation and regression analyses were applied to assess the associations between the placental PBDE levels and birth outcomes. Metabolome-wide association studies and the meet-in-the-middle approach were employed to explore disruptions linking PBDE exposures and the corresponding adverse birth outcomes., Results: Eight out of 27 PBDE congeners were detected in placenta with more than 50% frequency in at least one district and significantly higher in Guiyu than those in Haojiang. The lower HC and Apgar1 had significant associations with PBDE exposures after adjustment for potential confounders. A total of 66, 16 and 14 metabolites were significantly correlated with PBDE exposures, HC and Apgar1, respectively. 4 and 12 PBDE-related metabolites were significantly associated with the risks of decreasing neonatal HC and Apgar1. The disrupted metabolites were mainly involved in the pentose phosphate pathway, ascorbate metabolism, threonine metabolism, butanoate metabolism, lipid metabolism, and arginine biosynthesis., Conclusions: In this birth cohort, higher placental PBDE levels were significantly associated with the lower HC and Apgar1. The associations might be modified by multiple metabolic disturbances through increasing oxidative stress, mediating neurotoxicity, maternal gut microbiota dysbiosis and vasodilatation regulation., 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.)