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1.
Chemosphere ; 257: 127248, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526471

RESUMO

The toxicity characteristics of HBCD and resistance mechanism of flavonols are investigated based on physiological and metagenomic analysis. Toxicology research of HBCD on Arabidopsis thaliana (Col and fls1-3) not only shows the toxic effect of HBCD on plants, but also indicates that flavonols could improve plant resistance to HBCD, including root length, shoot biomass and chlorophyll content. Analysis of eggNOG and GO enrichment demonstrates that HBCD has toxic effect on both gene expression and protein function, which concentrates on energy production - conversion and amino acid transport - metabolism. Differential expressed genes in flavonols-treated groups indicates that flavonols regulate the metabolism of amino acids, cofactors and vitamins, which is involved in plant defense system against oxidative damage caused by HBCD stress. HBCD is believed to affect the synthesis of proteins via genes expression of ribosome biogenesis process. Flavonols could strengthen the plant resistance and alleviate toxic effect under HBCD stress.


Assuntos
Arabidopsis/fisiologia , Flavonóis/metabolismo , Hidrocarbonetos Bromados/toxicidade , Poluentes do Solo/toxicidade , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Metagenoma , Solo , Poluentes do Solo/metabolismo
2.
Aquat Toxicol ; 225: 105523, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32531534

RESUMO

Hexabromocyclododecane (HBCD) is a ubiquitous environmental contaminant of current concern despite its global ban in 2013 due to its characteristics as a persistent organic pollutant. While the toxicity of HBDC in vertebrates has been extensively studied, the specific molecular mechanisms underlying its toxicity in fish are not fully understood to date. Therefore, the aim of this work was to determine the in vitro cytotoxicity of HBCD in the fathead minnow (Pimephales promelas) using liver explants, and to investigate the molecular mechanisms underlying these effects. Explants were incubated with nine different concentrations of HBCD (0.00032, 0.0016, 0.008, 0.04, 0.2, 1, 5, 25 and 125 mg HBCD/L) for 6 and 24 h, and cytotoxicity was tested by using the Lactate Dehydrogenase (LDH) assay. The expression of genes with a key role in the regulation of apoptosis, oxidative stress, cryoprotective responses to reactive oxygen species (ROS), and xenobiotic metabolism was also measured in liver explants after exposure to 0.00032, 0.0016, 0.008, 0.2, and 25 mg HBCD/L. After 6 h, a concentration-dependent significant increase in cytotoxicity was found between 0.008 and 1 mg/L HBCD, followed by a decrease between 1 and 25 mg/L. Cytotoxicity reached 100 % at a concentration of 125 mg/L HBCD. After 24 h, HBCD showed a biphasic response with a concentration-dependent decrease in cytotoxicity between 0.0016 and 1 mg/L that returned to baseline levels at 5 mg/L. Then, cytotoxicity increased at concentrations greater than 5 mg/L to reach a maximum value at 125 mg/L. Changes in the expression of genes related to apoptosis (apoEn, apoIn, caspase2, caspase9 and bax) were also time- and concentration-dependent. Genes related to antioxidant responses such as gst and catalase were generally decreased after 6 h of incubation and increased after 24 h. The same pattern was observed for cyp1a and cyp3a, both related to xenobiotic metabolism. The expression of genes related to cryoprotective responses anti ROS (akt and pi3k) decreased at almost all HBCD concentrations tested after 6 h but remained unaltered after 24 h. Overall, we demonstrated that the cytotoxic effect of HBCD in fathead minnow liver explant was not proportional to its concentration in the culture media. Cytotoxicity was highly dynamic and did not follow a typical concentration-response pattern, complicating its toxicological characterization.


Assuntos
Cyprinidae , Hidrocarbonetos Bromados/toxicidade , Fígado/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Apoptose/efeitos dos fármacos , L-Lactato Desidrogenase/metabolismo , Fígado/metabolismo , Fígado/patologia , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Técnicas de Cultura de Tecidos
3.
Chemosphere ; 257: 127151, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32470539

RESUMO

Spatial distributions of bromocarbons, including bromoform (CHBr3), dibromochloromethane (CHBr2Cl), and dibromomethane (CH2Br2), and influential oceanographic parameters that determine their concentrations were measured in the marine atmosphere and seawater of the East China Sea (ECS) and western Pacific Ocean during two cruises from 14 to 24 September, 2017 and from 5 October to 3 December, 2018. The atmospheric concentrations of CHBr3, CHBr2Cl, and CH2Br2 were 0.33-3.02, 0.16-1.96, and 0.85-1.75 pptv over the western Pacific Ocean and 2.23-4.92, 0.26-1.52, and 0.24-7.47 pptv over the ECS, respectively. There was significant spatial variability in atmospheric bromocarbon concentrations in the study region, with higher concentration over the ECS. The atmospheric mixing ratios of bromocarbons were significantly correlated to the surface seawater bromocarbon concentrations and wind speed. In the ECS, input from terrestrial sources also significantly influenced the distributions of bromocarbons in air. PCA analysis revealed that seawater bromocarbon concentrations were correlated with both water mass and chlorophyll a. Generally lower CH2Br2/CHBr3 ratios were observed in the ECS, which was indicative of mixing and/or dilution in coastal areas. The estimated average sea-to-air fluxes of CHBr2Cl, CH2Br2, and CHBr3 were 46.86, -3.77, and -6.71 nmol m-2 d-1 in the western Pacific Ocean and 111.49, 0.89, and 321.74 nmol m-2 d-1 in the ECS, respectively. These results of the net sea-to-air fluxes indicated oceanic net uptake of CH2Br2 and CHBr3 for the western Pacific Ocean and oceanic emission of bromocarbons for the ECS.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Hidrocarbonetos Bromados/análise , Atmosfera/análise , China , Clorofila A , Oceanos e Mares , Oceano Pacífico , Água do Mar/análise , Trialometanos/análise
4.
Chemosphere ; 254: 126843, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32339796

RESUMO

In a 3-day duplicate diet study of a nursing mother-infant cohort (n = 20), the levels of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), and 5 novel brominated flame retardants (BFRs) were measured in 60 24-h duplicate diet samples and 20 breast milk samples provided by the mothers. The dietary BFR intake and related health risks of the mothers and their babies due to food consumption or human milk ingestion were subsequently assessed. At median concentrations of 284, 264 and 177 pg/g wet weight (ww) in the diet, decabrominated diphenyl ethers (BDE-209), decabromodiphenyl ethane (DBDPE) and HBCDD were predominant among the total BFRs. In human milk, HBCDD was the most abundant BFR, followed by BDE-209 and DBDPE, which indicates that BDE-209 and HBCDD have remained ubiquitous in the environment because of their continuous production and use in China. Meanwhile, concentrations of DBDPE were comparative to those of PBDEs and HBCDD in both diet and human milk, and DBDPE also had much higher concentrations than any other NBFRs, which indicates that the BFR consumption pattern in China is shifting from legacy BFRs to NBFRs. The median estimated dietary intakes (EDIs) of BDE-209, HBCDD and DBDPE for the mothers were 6.83, 3.73 and 5.44 ng/kg bw/day, respectively, and EDIs for their nursing babies were 24.7, 41.9 and 7.83 ng/kg bw/day, respectively. The nursing infants showed higher BFR body burden than the mothers. However, the EDIs obtained for both mothers and their babies discloses a low health risk to this mother-infant cohort.


Assuntos
Exposição Dietética/estatística & dados numéricos , Poluentes Ambientais/metabolismo , Retardadores de Chama/metabolismo , Exposição Materna/estatística & dados numéricos , Adulto , Pequim , Bromobenzenos , China , Estudos de Coortes , Dieta , Feminino , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Halogenação , Humanos , Hidrocarbonetos Bromados , Lactente , Leite Humano/química , Mães
5.
Environ Sci Process Impacts ; 22(3): 679-707, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32163052

RESUMO

The organic bromine compounds bromoform (CHBr3) and dibromomethane (CH2Br2) influence tropospheric chemistry and stratospheric ozone depletion. Their atmospheric abundance is generally related to a common marine source, which is not well characterized. A cruise between the three Macaroenesian Archipelagos of Cape Verde, the Canaries and Madeira revealed that anthropogenic sources increased oceanic CHBr3 emissions significantly close to some islands, especially at the Canaries, while heterotrophic processes in the ocean increased the flux of CH2Br2 from the sea to the atmosphere in the Cape Verde region. As anthropogenic disinfection processes, which release CHBr3 in coastal areas increase, and as more CH2Br2 may be produced from increased heterotrophy in a warming, deoxygenated ocean, both sources could supply higher fractions of stratospheric bromine in the future, with yet unknown consequences for stratospheric ozone.


Assuntos
Atmosfera , Hidrocarbonetos Bromados , Oceanos e Mares , Portugal , Trialometanos
6.
Environ Sci Process Impacts ; 22(3): 751-758, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32067016

RESUMO

The oceans play an important role in the biogeochemical cycle of methyl bromide (CH3Br), as not only the sinks but also the sources. However, many uncertainties exist regarding the way of CH3Br generation in the marine environment. To illustrate the possibility of photochemical formation of CH3Br in saline water, its generation in bromide aqueous solution containing humic acid (HA) and ferric ions (Fe(iii)) was investigated. CH3Br was obviously generated after irradiation, and its amounts increased with increasing HA concentration from 0.82 to 12.2 mgC L-1. Fe(iii) significantly promoted CH3Br production, and the described production process in the presence of Fe(iii) was pH-dependent, decreasing with the increase of pH. Finally, the concentrations of CH3Br in natural coastal seawater and seawater with HA were measured, and the results showed that CH3Br was significantly generated under irradiation. Our results suggest that the photochemical process of dissolved organic matter may be one source of CH3Br in the marine environment.


Assuntos
Hidrocarbonetos Bromados/química , Processos Fotoquímicos , Luz Solar , Compostos Férricos , Substâncias Húmicas , Oceanos e Mares
7.
Chemosphere ; 250: 126155, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32105853

RESUMO

Aggregation of nanoparticles (NPs) can hinder the degradative reactivity of particles towards organic pollutants as it reduces available surface area for reaction. This limitation may be circumvented by applying dispersant to improve colloidal stability of nanoparticle suspension. This study examined the removal of hexabromocyclododecane (HBCD), a recently listed persistent organic pollutant, by carboxymethylcellulose (CMC) stabilized nanoscale zerovalent iron (CMC-NZVI) and bimetallic Ni/Fe nanoparticles (CMC-Ni/Fe) under the influence of suspension chemistry. The mass-normalized removal rate constants of HBCD by CMC-Ni/Fe NPs increased with lower particle aggregation. However, the coating could introduce diffusion resistance as HBCD diffused through the CMC layer to the Fe surface. The activation energy was estimated to be 26.8 kJ mol-1, indicating the overall reaction process was neither surface-limited nor diffusion-controlled. The reactivity of CMC-Ni/Fe NPs toward HBCD was not affected by aqueous initial pH substantially. Common monoanions (Cl-, NO3-, and HCO3-) generally enhanced HBCD adsorption but diminished its debromination. The removal rate did not differ significantly among the studied monoanions over a concentration of 2.5-10 mM except HCO3-. Overall, CMC coating can stabilize Ni/Fe NPs, increase their adsorption of HBCD, provide buffer pH capacity, and overcome common inhibition effects of anions in water. These findings suggested the high potential of using CMC-Ni/Fe NPs for in-situ remediation.


Assuntos
Hidrocarbonetos Bromados/química , Nanopartículas Metálicas/química , Poluentes Químicos da Água/química , Adsorção , Carboximetilcelulose Sódica/química , Ferro , Modelos Químicos , Nanopartículas , Água
8.
Ecotoxicol Environ Saf ; 192: 110246, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32028153

RESUMO

The thermal processes of cement kilns are sources of polybrominated dibenzofurans and dioxins (PBDD/Fs); however, when co-processing decabromodiphenyl ether (BDE-209) soil in cement kilns, very few reports have investigated the mechanism of PBDD/Fs formation from BDE-209. Therefore, the pathways and factors that influence the formation of PBDD/Fs were investigated using Box-Behnken design (BBD) of the response surface methodology (RSM) at lab-scale. The PBDEs, HBr/Br2 and PBDD/Fs emissions in flue gas from the simulated thermal process were analyzed using gas chromatography/mass spectroscopy (GC/MS), high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS), and ion chromatography (IC). Density functional theory (DFT) was also used to further discuss the formation of PBDD/Fs. The major products of BDE-209 thermal decomposition in flue gas were 97.1% HBr/Br2 (a.v. 26.6%/70.6%) > 2.7% PBDEs >0.2% PBDD/Fs. Formation of precursors were the main pathways for PBDD/Fs, and those precursors were dominated by higher-brominated PBDEs (heptã deca-BDEs); debromination of BDE-209 was also a crucial pathway for the formation of PBDD/Fs throughout the thermal process. Interestingly, it was easier to form HpBDD/Fs from OBDD/Fs than from PBDEs. The O2 percentage and interaction factors of O2 percentage, temperature, and CaCO3 percentage have the largest influence on PBDD/Fs emissions and formation.


Assuntos
Dibenzofuranos/metabolismo , Dioxinas/metabolismo , Éteres Difenil Halogenados/metabolismo , Hidrocarbonetos Bromados/metabolismo , Poluentes do Solo/metabolismo , Materiais de Construção , Monitoramento Ambiental
9.
Phytopathology ; 110(5): 956-968, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32075499

RESUMO

Strawberry production has historically been affected by soilborne diseases such as Verticillium wilt. This disease was a major limiting factor in strawberry production in California in the 1950s and was the main reason that preplant soil fumigation with methyl bromide (MB) was developed in the late 1950s. MB fumigation was so successful that over 90% of the commercial strawberry fruit production in California utilized this technique. However, MB was subsequently linked to ozone depletion, and its use was phased out in 2005. The California strawberry industry was awarded exemption to the full phase-out until 2016, when all MB use in strawberry fruit production was prohibited. MB use continues in strawberry nurseries under an exemption to prevent spread of nematodes and diseases on planting stock. This review examines the impact of the MB phase-out on the California strawberry industry and evaluates the outlook for the industry in the absence of one of the most effective tools for managing soilborne diseases. New soilborne diseases have emerged, and historically important soilborne diseases have reemerged. Registration of new fumigants has been difficult and replacement of MB with a new and effective alternative is unlikely in the foreseeable future. Thus, crop losses due to soilborne diseases are likely to increase. Host plant resistance to soilborne diseases has become a top priority for strawberry breeding programs, and cultivars are increasingly selected for their resistance to soilborne diseases. The intelligent integration of a variety of management tactics is necessary to sustain strawberry production in California.


Assuntos
Fragaria , Hidrocarbonetos Bromados , California , Doenças das Plantas
10.
Environ Sci Process Impacts ; 22(3): 567-582, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31993605

RESUMO

Compound-specific isotope analysis (CSIA) is a powerful tool to evaluate transformation processes of halogenated compounds. Many halogenated hydrocarbons allow for multiple stable isotopic systems (C, H, Cl, Br) to be measured for a single compound. This has led to a large body of literature describing abiotic and biotic transformation pathways and reaction mechanisms for contaminants such as chlorinated alkenes and alkanes as well as brominated hydrocarbons. Here, the current literature is reviewed and a new compilation of Λ values for multi-isotopic systems for halogenated hydrocarbons is presented. Case studies of each compound class are discussed and thereby the current strengths of multi-element isotope analysis, continuing challenges, and gaps in our current knowledge are identified for practitioners of multi-element CSIA to address in the near future.


Assuntos
Hidrocarbonetos Halogenados , Isótopos de Carbono , Fracionamento Químico , Hidrocarbonetos Bromados
11.
Chemosphere ; 246: 125749, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927367

RESUMO

Brominated flame retardants (BFRs) are found at quantifiable levels in both humans and wildlife and may potentially cause a health risk. For BFRs and their derivatives, limited information regarding the relationship among the structure, binding affinity to the target protein and toxicity is currently available. In the present work, representative BFRs with different hydroxyl- or bromo-substituents, namely 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47), 3-hydroxy-2, 2', 4, 4'-tetrabromodiphenyl ether (3-OH-BDE-47) and tetrabromobisphenol A (TBBPA), were selected to investigate the interactions with transthyretin (TTR) by electrospray ionization mass spectrometry (ESI-MS) and cytotoxicity on HepG2 cells. It was noted that BDE-47 had a weak binding affinity to TTR, while 3-OH-BDE-47 and TBBPA had a stronger binding affinity than BDE-47 and thyroxine (T4). Hence, 3-OH-BDE-47 and TBBPA could affect the binding of TTR with its native ligand T4 by competitive binding to TTR, even at equal concentrations, which might be associated with BFR toxicity of endocrine disruption. Negative cooperativity was found for 3-OH-BDE-47 and TBBPA binding to TTR, similar to T4 with a well-established negatively cooperative binding mechanism. The tendency of toxic effects on HepG2 cells for these three BFRs was, 3-OH-BDE-47 > TBBPA > BDE-47, and this order was in good agreement with the binding ability explored by ESI-MS experiments and molecular docking simulation. The observations obtained by this study demonstrate that the binding properties of these BFRs to TTR and their cytotoxicity are correlated with structure differentials and functional substituents.


Assuntos
Retardadores de Chama/toxicidade , Pré-Albumina/metabolismo , Testes de Toxicidade , Animais , Animais Selvagens , Ligação Competitiva , Disruptores Endócrinos , Retardadores de Chama/análise , Éteres Difenil Halogenados , Células Hep G2 , Humanos , Hidrocarbonetos Bromados/análise , Simulação de Acoplamento Molecular , Bifenil Polibromatos , Tiroxina/metabolismo
12.
Food Chem ; 313: 126027, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31923865

RESUMO

Tetrabromobisphenol A (TBBPA) and Hexabromocyclododecanes (HBCDs) are commonly used as brominated flame retardants in large volumes, and accumulate in plants and animals in the environment, and people are exposed to them when consuming food. As many countries are monitoring them in food, it is necessary to develop a method to analyze them simultaneously for cost efficiency. A method was developed and optimized under different conditions using accelerated solvent extraction to extract the lipids from the samples, acid silica column to clean the samples and liquid chromatography coupled with tandem mass spectrometry to determine TBBPA and HBCDs. The method was validated in different kinds of food. Uncertainty of measurement was calculated by combining all uncertainties of contributors. Intermediate precision (reproducibility) was the most influential contributor to uncertainty. 5 food categories with 115 samples were analyzed with the method, and mackerels containing high level of fat were highly contaminated by TBBPA and HBCDs.


Assuntos
Análise de Alimentos/métodos , Hidrocarbonetos Bromados/análise , Bifenil Polibromatos/análise , Animais , Cromatografia Líquida de Alta Pressão , Retardadores de Chama/análise , Hidrocarbonetos Bromados/química , Carne/análise , Alimentos Marinhos/análise , Espectrometria de Massas em Tandem
13.
Chemosphere ; 246: 125621, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31896015

RESUMO

The persistent organic pollutant, brominated flame retardant, hexabromocyclododecane (HBCD), identified as an emerging contaminant has been detected in various environmental matrix. The increased level of this toxic organic compound in the environment has been associated with serious human health risks. The results obtained from this study revealed that various Rhodopseudomonas palustris strains isolated from paddy soil in Taiwan possessed good HBCD biodegradation capability when they were cultured aerobically. Among these strains, YSC3 was considered as one of the most potential isolates for HBCD degradation. The optimum HBCD biodegradation occurred at neutral pH and at 35 °C in all our pH and temperature tests at an initial HBCD concentration of 1 ppm. HBCD degradation kinetics generally decreased with the increase of initial HBCD concentration. The study also suggested that the cultivation temperature played a vital role on YSC3 for its initiation of cellular HBCD degradation. The relative-molar ratio of the released bromide ions during the biodegradation of HBCD was observed in the range between 1 and 3.5, suggesting that the debromination reactions occurred. Concomitant with the loss of HBCD, there was a concurrent production of two metabolites, pentabromocyclododecanol and pentabromocyclododecene, which were determined by liquid chromatography and mass spectrometry techniques. On the basis of the obtained results, the possible biodegradation pathways were also proposed in this study.


Assuntos
Biodegradação Ambiental , Hidrocarbonetos Bromados/química , Rodopseudomonas/patogenicidade , Cromatografia Líquida , Poluentes Ambientais/química , Retardadores de Chama/análise , Halogenação , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Fixação de Nitrogênio , Rodopseudomonas/isolamento & purificação , Taiwan
14.
Arch Environ Contam Toxicol ; 78(3): 337-349, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31938850

RESUMO

Occurrence of traditional (PBDEs) and novel (HBB, PBEB, DBDPE) brominated flame retardants, as well as the natural compounds of MeO-PBDEs, were studied in a shellfish species (Hexaplex trunculus) sampled from Bizerte Lagoon. PBDE and MeO-PBDE mean concentrations in murex soft tissues were 187 and 264 ng g-1 lw respectively. The alternative flame retardants were not identified. The sum of PBDE and MeO-PBDE levels recorded in murex from the investigated aquatic ecosystem were comparable or a relatively lower than those reported for other organisms from other regions across the world. The amount of PBDE and MeO-PBDE concentrations from the Bizerte Lagoon recorded in murex were comparable or a relatively lower than those recorded from other areas across the world for other species. There is not a danger to the population health with regard to PBDE intakes associated with the consumption of murex in Bizerte city. We believe that this is the first study of the analysis of these pollutants in marine gastropod mollusks from Tunisian aquatic areas.


Assuntos
Monitoramento Ambiental/métodos , Retardadores de Chama/análise , Gastrópodes/química , Éteres Difenil Halogenados/análise , Hidrocarbonetos Bromados/análise , Poluentes Químicos da Água/análise , Animais , Ecossistema , Humanos , Medição de Risco , Frutos do Mar/análise , Tunísia
15.
Chemosphere ; 244: 125524, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31812044

RESUMO

Two currently used brominated flame retardants (BFRs), α, ß, γ-hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA), were measured in 111 breast milk samples from 37 Beijing mothers. Each mother provided one milk sample per month for 3 months. HBCDD was detected in almost all samples, and the median level reached 5.67 ng g-1 lipid weight (lw). α- HBCDD was the most abundant isomer (median: 4.23 ng g-1 lw), followed by γ- and ß-HBCDD. For TBBPA, a relatively lower detecting frequency (64%) and contamination level (median: 1.57 ng g-1 lw) were obtained. A comparison to our previous study revealed that the occurrence of TBBPA and HBCDD in Beijing human milk significantly rose from 2011 to 2014, whereas another commonly used class of BFRs, polybrominated diphenyl ethers (PBDEs), showed significantly decreased during this period. However, a comparison among currently used BFRs showed that levels of some BFRs, such as HBCDD, surpassed those of PBDEs, which indicated that PBDEs were no longer the primarily used BFR in China. However, no significant temporal trends for BFR levels were observed over the 3 months of lactation. Daily intakes of TBBPA and HBCDD were calculated for nursing infants and the median TBBPA and HBCDD intakes via breastfeeding were 6.62 and 26.4 ng kg-1 bw day-1, respectively. These values were several times higher than those for adults via food consumption. However, risk assessment using the margin of exposure approach indicated that intakes of TBBPA and HBCDD via breastfeeding can scarcely cause significant health risks to infants.


Assuntos
Exposição Dietética/estatística & dados numéricos , Poluentes Ambientais/metabolismo , Hidrocarbonetos Bromados/metabolismo , Exposição Materna/estatística & dados numéricos , Leite Humano/metabolismo , Bifenil Polibromatos/metabolismo , Adulto , Pequim , Peso Corporal , China , Feminino , Retardadores de Chama/análise , Retardadores de Chama/metabolismo , Éteres Difenil Halogenados/análise , Humanos , Lactente , Isomerismo , Leite Humano/química , Mães , Medição de Risco
16.
Chemosphere ; 244: 125536, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31816547

RESUMO

Hexabromocyclododecane (HBCD) has been listed in Annex A of the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2013, but till now there is a lack of efficient methods for its degradation. In this study, nanoscale zero-valent aluminum (nZVAl), an excellent reductant with a very low redox potential of E0(Al3+/Al0) = -1.662 V and strong electron transfer ability, was used to reductively degrade HBCD. Nearly 100% HBCD was degraded within 8 h reaction at 25 °C in ethanol/water (v/v, 50/50) solution without pH adjustment. And about 67% cyclododecatriene (CDT) was obtained, which is the complete debromination product. What's more, the yield of Br- could achieve nearly 100% after optimizing conditions. The reaction was strongly promoted by increasing the dosages of nZVAl or decreasing the initial concentration of HBCD. The temperature had the most significant influence and the degradation was completed in 40 min with elevating the reaction temperature to 45 °C. The reaction mechanism was further revealed through the characterization of nZVAl particles before and after the reaction by SEM-EDS, TEM, HRTEM, XRD, and XPS. It was found that, after corrosion of the oxide film on the surface of nZVAl, metallic aluminum inside was exposed. The reactive sites were provided and electrons released were transferred from nZVAl to HBCD, causing HBCD degraded to dibromocyclododecadiene (DBCD) and then CDT by reductive debromination. These findings imply that nZVAl can degrade HBCD efficiently with no extra energy input and this offers a new idea for better treatment of HBCD.


Assuntos
Alumínio/química , Hidrocarbonetos Bromados/química , Nanopartículas Metálicas/química , Modelos Químicos , Ferro/química , Óxidos
17.
Ecotoxicol Environ Saf ; 189: 109936, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31767460

RESUMO

Due to its widespread use, large amounts of expanded polystyrene (EPS) have been released into the marine environment, where it is broken down into small pieces with large surface areas. As such, chemical additives may be released into the environment, which can affect marine organisms; however, studies of the effects of such additives are lacking. We assessed the effects of leachate from EPS on the photosynthetic activities of four microalgal species (Dunaliella salina, Scenedesmus rubescens, Chlorella saccharophila, and Stichococcus bacillaris). They were exposed to EPS leachate for seven days and their photosynthetic activities were analyzed based on seven parameters. Overall, leachate exposure increased photosynthetic activity in all four species, albeit to different degrees and showing slightly different trends among the seven parameters. Based on chemical analysis, hexabromocyclododecane concentrations were higher in small-fragment leachate, whereas UV326 concentrations were higher in low-concentration-large-sphere leachate; bisphenol-A and total organic carbon showed no major differences among leachates. Thus, we speculate that exposure to trace chemicals influenced microalgal photosynthesis and overall growth. These results support further investigation of the impacts of plastic debris and chemical additives on marine ecosystems and organisms.


Assuntos
Microalgas/fisiologia , Fotossíntese/efeitos dos fármacos , Poliestirenos/toxicidade , Poluentes Químicos da Água/toxicidade , Organismos Aquáticos , Chlorella , Ecossistema , Hidrocarbonetos Bromados , Plásticos , Resíduos/análise , Poluentes Químicos da Água/análise
18.
Environ Pollut ; 258: 113661, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31796314

RESUMO

While a large body of studies have examined polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (ABFRs) in wildlife, information on the bioaccumulation of these contaminants in reptiles in general, and snakes in particular, are scarce. We investigated the bioaccumulation characteristics of PBDEs and several ABFRs including decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB) and pentabromotoluene (PBT) in a frog-eating snake, the striped keelback snake (Amphiesma stolata), from an e-waste recycling site in South China. The concentrations of ∑PBDEs and ∑ABFRs in the snakes ranged 53-5200 and 3.1-87 ng/g lipid weight, respectively; with higher levels in males than females. Additionally, the concentrations of BDE-28, -47, and -66 were positively correlated with snake size (snout-vent length and body mass), while negative correlations were found for most of the higher brominated PBDE congeners and HBB, PBT and BTBPE. The biomagnification factors (BMFs) estimated in the snake/frog relationship indicated a mild to moderate biomagnification of BDE-28, -47, -66, -100, -153 and -154 (with mean BMFs of 1.1-5.3), while a lack of magnification for the other PBDE congeners and all the ABFRs. This is the first report on the sex- and size-related accumulation and biomagnification potentials of PBDEs and ABFRs in snakes.


Assuntos
Monitoramento Ambiental , Retardadores de Chama/metabolismo , Éteres Difenil Halogenados/metabolismo , Serpentes/metabolismo , Animais , Bioacumulação , China , Hidrocarbonetos Bromados
19.
Sci Total Environ ; 708: 135199, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31780180

RESUMO

The effects of hexabromocyclododecane (HBCD) on the relationship between physiological responses and metabolic networks remains unclear. To this end, cellular growth, apoptosis, reactive oxygen species, exometabolites and the proteome of Escherichia coli were investigated following exposure to 0.1 and 1 µM HBCD. The results showed that although there were no significant changes in the pH value, apoptosis and reactive oxygen species under HBCD stress, cell growth was inhibited. The metabolic network formed by glycolysis, oxidative phosphorylation, amino acids biosynthesis, membrane proteins biosynthesis, ABC transporters, glycogen storage, cell recognition, compound transport and nucleotide excision repair was disrupted. Cell chemotaxis and DNA damage repair were the effective approaches to alleviate HBCD stress. This work improves our understanding of HBCD toxicity and provides insight into the toxicological mechanism of HBCD at the molecular and network levels.


Assuntos
Escherichia coli , Apoptose , Retardadores de Chama , Hidrocarbonetos Bromados , Espécies Reativas de Oxigênio
20.
Chemosphere ; 238: 124629, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524607

RESUMO

Despite wastewater treatment, sewage sludge is often contaminated with multiple pollutants. Their impact on the phylogenetic composition and diversity of prokaryotic communities in sludge samples remains largely unknown. In this study, we analyzed the phylogenetic structure of bacterial communities and diversity in sludge from six waste water treatment plants (WWTPs) and linked this information with the pollutants identified in these samples: eight potentially toxic metals (PTMs) and four groups of organic pollutants [polychlorinated biphenyls (PCBs), polyromantic hydrocarbons (PAHs), brominated flame retardants (BFRs) and organochlorine pesticides (OCPs)]. Alpha diversity measures and the distribution of dominant phyla varied among the samples, with the community from the thermophilic anaerobic digestion (TAD)-stabilized sample from Prague being the least rich and the least diverse and containing on average 36% of 16S rRNA gene sequence reads of the thermotolerant genus Coprothermobacter of the class Clostridia (phylum Firmicutes). Using weighted UniFrac distance-based redundancy analysis (dbRDA), we found that a collection of 5 PTMs: Cr, Cu, Ni, Pb, Zn, and a pair of BFRs: hexabromocyclododecane (HBCD) and tribromodiphenyl ethers (triBDEs) were significantly associated with the bacterial community structure in mesophilic anaerobic digestion (MAD)-stabilized samples, whereas PCBs were observed to be marginally significant. Altogether, 85% of the variance in bacterial community structure could be ascribed to these pollutants. The data presented here contribute to a greater understanding of the ecological effects of combined pollution on the composition and diversity of bacterial communities, hence have the potential to aid in predicting ecosystem functions and/or disruptions associated with pollution.


Assuntos
Bactérias/metabolismo , Retardadores de Chama/análise , Praguicidas/análise , Esgotos/química , Esgotos/microbiologia , Poluentes Químicos da Água/análise , Bactérias/classificação , Bactérias/genética , Ecossistema , Hidrocarbonetos Bromados/análise , Filogenia , Bifenil Polibromatos/análise , Bifenilos Policlorados/análise , RNA Ribossômico 16S/genética
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