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Hexachlorobutadiene (HCBD), as an emerging contaminant, brings great risks to the ecological environment and human health due to its high toxicity, non-degradability, bioaccumulation and longdistance migration. The hazards of HCBD are briefly described, the sources and pollution status of HCBD in China are analyzed, and the status of environmental control and the progress of treatment technology of HCBD in China are summarized. In view of the existing problems, suggestions are put forward from environmental management, monitoring and analysis technology and emission reduction management technology to provide references for controlling source emission of HCBD, reducing environmental pollution level and strengthening environmental risk control. Future research should focus on the mechanism and toxicology of HCBD production, monitoring techniques for HCBD, and the development of efficient control of HCBD and remediation technologies. [ABSTRACT FROM AUTHOR]

The possibility of using the polymer sorbent Polysorb-1 for the treatment of nitric acid solutions to remove organophosphorus compounds, including tributyl phosphate (TBP) and hexachlorobutadiene (HCBD), is studied. It is shown that decontamination of nitric acid solutions containing organophosphorus compounds, HCBD, U(VI), and Pu(IV) with Polysorb-1 sorbent under dynamic conditions allows reducing the phosphorus and HCBD content to ~2 mg/dm3 or less and to 0.05 mg/dm3 or less, respectively. In this case, sorption of U(VI) and Pu(IV) does not occur. The procedures of vacuum distillation and overheated steam stripping are described for regeneration of Polysorb-1 sorbent containing TBP and HCBD. The optimal process temperature was chosen to be 170°C. [ABSTRACT FROM AUTHOR]

With the popularization and high-intensity utilization of greenhouse cultivation for crops growth, the pollution of greenhouse soils has been of concern. Therefore, a national-scale survey was conducted to investigate the contamination status, sources, influence factors and the risks of polychlorinated biphenyls (PCBs) and hexachlorobutadiene (HCBD) in greenhouse and nearby open-field soils. Contents of PCBs ranged from 10−6). This study provided a full insight on the contamination status and risks of PCBs and HCBD when guiding greenhouse agriculture activities. [ABSTRACT FROM AUTHOR]

Hexachloro-1,3-butadiene (HCBD) has received increasing attention because of its adverse effects on human health. Although HCBD is regulated under the Stockholm Convention, it is still widely detected in the environment. However, detailed reports on the chemical mechanisms of HCBD reactions in the environment are lacking. This review comprehensively summarizes HCBD's unintentional industrial sources and formation mechanisms, and chemical reactions and transformations in different media (gas, water, and biological phases). Photochemical reactions in the atmosphere can degrade and transform HCBD and potentially form other toxic compounds, such as phosgene. Aerobic pyrolysis of HCBD can generate complex byproducts. Further research is essential to fully understand the environmental behavior of HCBD. [Display omitted] • Understanding the synthesis pathway of HCBD can help to reduce its emissions. • Knowledge of HCBD transformations is crucial to controlling its risks. • HCBD may undergo photolysis, oxidation, and reduction in the environment. • HCBD may produce toxic substances such as phosgene in the atmosphere. [ABSTRACT FROM AUTHOR]

With the popularization and high-intensity utilization of greenhouse cultivation for crops growth, the pollution of greenhouse soils has been of concern. Therefore, a national-scale survey was conducted to investigate the contamination status, sources, influence factors and the risks of polychlorinated biphenyls (PCBs) and hexachlorobutadiene (HCBD) in greenhouse and nearby open-field soils. Contents of PCBs ranged from Pseudomonas as the PCBs-degrader in open-field soils. Although the higher values of mean contents were found in greenhouses, the health risks of ΣPCBs in open-field soils were higher than in greenhouse soils due to the higher percentages of high-toxicity PCBs, especially the carcinogenic risks to children (>10−6). This study provided a full insight on the contamination status and risks of PCBs and HCBD when guiding greenhouse agriculture activities.

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Twenty years since coming into force, the Stockholm Convention has become a "living" global agreement that has allowed for the addition of substances that are likely, as a result of their long-range environmental transport (LRET), to lead to significant adverse effects. The recent listing of the phenolic benzotriazole UV-328 in Annex A and a draft nomination of three cyclic volatile methylsiloxanes (cVMS) for Annex B draw attention to the fact that many chemicals are subject to LRET and that this can lead to questionable nominations. The nomination of UV-328 and the draft nomination of cVMS also raise the spectre of regrettable substitutions. At the same time, atmospheric monitoring across the globe reveals that environmental releases of several unintentionally produced POPs listed in Annex C, such as hexachlorobenzene and hexachlorobutadiene, are continuing unabated, highlighting shortcomings in the enforcement of the minimum measures required under Article 5. There is also no evidence of efforts to substitute a chemical whose use has been known for three decades to unintentionally produce polychlorinated biphenyls. These developments need to be rectified to safeguard the long-term viability and acceptance of a global treaty of undeniable importance.

Hexachlorobutadiene (HCBD) was classed as a persistent organic pollutant under the Stockholm Convention in 2015. HCBD is mainly an unintentionally produced by-product of chlorinated hydrocarbon (e.g., trichloroethylene and tetrachloroethylene) synthesis. Few studies of HCBD formation during chemical production processes have been performed, so HCBD emissions from these potentially important sources are not understood. In this study, HCBD concentrations in raw materials, intermediate products, products, and bottom residues from chemical plants producing chlorobenzene, trichloroethylene, and tetrachloroethylene were determined. The results indicated that HCBD is unintentionally produced at much higher concentrations in trichloroethylene and tetrachloroethylene plants than chlorobenzene plants. The sum of the HCBD concentrations in the samples from all of the trichloroethylene and tetrachloroethylene production stages in plant PC was 247000 µg/mL, about three orders of magnitude higher than the concentrations in the tetrachloroethylene production samples (plant PB) and about six orders of magnitude higher than the concentrations in the chlorobenzene production samples (plant PA). The HCBD concentrations were highest in bottom residues from all of the plants. The concentrations in the bottom residue samples contributed 24%–99% of the total HCBD formed in the chemical production plants. The bottom residue, being hazardous waste, could be disposed of by incineration. The HCBD concentrations were much higher in intermediate products than raw materials, indicating that HCBD formed during production of the intended chemicals. The results indicate the concentrations of HCBD unintentionally produced in typical chemical plants and will be useful in developing protocols for controlling HCBD emissions to meet the Stockholm Convention requirements. [ABSTRACT FROM AUTHOR]

The road dust and roadside soil can act as both sinks and sources of hexachlorobutadiene (HCBD) and chlorobenzenes (CBzs), but comparative research on these two adjacent media is extremely limited. In this study, HCBD and CBzs were simultaneously analyzed in road dust and roadside soil samples from an area containing both industrial factories and residential communities in Eastern China. The road dust there was found to have 2–6 times higher contents of HCBD (mean 1.14 ng/g, maximum 6.44 ng/g) and ∑ Cl3-Cl6 CBzs (22.8 ng/g, 90.6 ng/g) than those in the roadside soil. The spatial distributions of HCBD and CBzs in road dusts were affected by various types of sources, showing no significant discrepancy among the sites. On the contrast, HCBD and CBzs contamination in roadside soils occurring near several factories were strongly correlated to their industrial point sources. Risk assessments showed, at current contamination levels in the road dust and roadside soil, HCBD and CBzs are not likely to induce carcinogenic or non-carcinogenic risks to residents in the studied area. Nevertheless, road dust ingestion, as the major exposure pathway of HCBD and CBzs, should be avoided to reduce the exposure risk. These findings based on the contamination differences between two media provide a new perspective and evidence for screening important sources and exposure pathway of HCBD and CBzs, which would be helpful to their source identification and risk control. HCBD and CBzs in road dust and roadside soil in an industrial and residential mixed area. [Display omitted] • Pioneering study on HCBD and CBzs in road dust/soil from multifunctional area in China. • HCBD and CBz occurrences were significantly different between two media. • Roadside soil could reveal sources of HCBD and CBzs, but road dust couldn't. • Road dust was more contaminated by HCBD and CBzs than roadside soil. • HCBD and CBzs exposure via ingesting road dust posed highest risks among pathways. [ABSTRACT FROM AUTHOR]

Research on hexachlorobutadiene (HCBD) has increased since its listing in the Stockholm Convention on Persistent Organic Pollutants in 2011. However, thorough reports on recent data regarding this topic are lacking. Moreover, potential associations between HCBD and some chlorinated organics have usually been ignored in previous research. In this review, possible formation pathways and sources, current environmental occurrences and human exposure risks of HCBD are discussed, as well as the association with several organochlorine compounds. The results reveal that unintentional production and emission from industrial activities and waste treatments are the main sources of HCBD. Similar precursors are found for HCBD and chlorobenzenes, indicating the presence of common sources. Although recent data indicates that levels of HCBD in the environment are generally low, risks from human exposure to HCBD, together with other pollutants, may be high. More attention in the future needs to be paid to the mixed contamination of HCBD and other pollutants from common sources. Image 1 • Sources, environmental occurrences and human exposure risks of HCBD are reviewed. • Similar formation pathways for HCBD and several organochlorines are summarized. • Common sources of HCBD and other pollutants need high attention. • Current levels of HCBD contamination in the environment are generally low. • Comprehensive risk assessments of HCBD along with coexisting pollutants are proposed. This review summarizes current situation of the new POPs HCBD and its association with other pollutants, providing guidance on future research direction in this field. [ABSTRACT FROM AUTHOR]

In recent years, the Stockholm Convention has listed an additional set of persistent organic pollutants (POPs) for elimination or restricted use/release. Data on the occurrence of these contaminants in food is scarce. Validated analytical methodology was developed to investigate the occurrence of hexachlorobutadiene (HCBD), pentachlorobenzene (PCBz), hexachlorobenzene (HCB) pentachlorophenol (PCP) and polychlorinated naphthalenes (PCNs) in 120 retail foods and 19 total diet study samples. The foods covered the range of commonly consumed dietary items including dairy products, eggs (hen and other species), poultry, meat, fish, vegetables, etc. HCBD showed a low frequency of detection, whereas PCBz, HCB and PCNs occurred in most samples (ranges: <0.01 to 0.19 μg/kg; <0.01 to 3.16 μg/kg and 0.1 to 166 ng ΣPCNs/kg respectively). PCP (<0.01 to 1.9 μg/kg) was detected more frequently in meat products, offal and eggs. Fish, shellfish, eggs from all species, animal fats, meat, offal and meat products showed higher contamination levels, which is normal when investigating lipophilic POPs. These levels of occurrence are similar to more recently reported literature levels but perhaps lower, relative to historic data. This is not unexpected, given the restrictions/limitations on these chemicals within the UK and Western Europe. The estimated human exposure to population groups through dietary intake is correspondingly low and based on current toxicological knowledge, the levels in the examined samples do not suggest a cause for health concern. The data also provide a current baseline for HCBD, PCBz and PCP, and update existing data for PCN and HCB occurrence in foods. Unlabelled Image • First structured study investigating HCBD, PCBz, HCB, PCP and PCN collectively in food. • PCBz, HCB & PCNs occurred in most samples; HCBD & PCP occurred less frequently • Based on current toxicology, dietary intake from UK food unlikely to cause health concern [ABSTRACT FROM AUTHOR]

Hexachloro-1,3-butadiene (HCBD) is an industrial by-product that is produced during the manufacturing of various chlorinated hydrocarbons like vinyl chloride, trichloroethene or tetrachloroethene. HCBD is toxic and considered harmful for the environment and especially for aquatic ecosystems. Various processes have been investigated for the abatement of chlorinated hydrocarbons in aqueous solutions. In this study, the physical and chemical remediation of HCBD contaminated groundwater was investigated. On the basis of the results, the costs for the treatment of a contaminated water flow of 200 m³/h were compared. The results show that in the investigated application, a dechlorination reactor would be less expensive than an adsorber. [ABSTRACT FROM AUTHOR]

Abstract A special initiative in the Global Atmospheric Passive Sampling (GAPS) Network was implemented to provide information on new and emerging persistent organic pollutants (POPs) in the Group of Latin America and Caribbean (GRULAC) region. Regional-scale atmospheric concentrations of the new and emerging POPs hexachlorobutadiene (HCBD), pentachloroanisole (PCA) and dicofol indicators (breakdown products) are reported for the first time. HCBD was detected in similar concentrations at all location types (<20–120 pg/m3). PCA had elevated concentrations at the urban site Concepción (Chile) of 49–222 pg/m3, with concentrations ranging <1–8.5 pg/m3 at the other sites in this study. Dicofol indicators were detected at the agricultural site of Sonora (Mexico) at concentrations ranging 30–117 pg/m3. Legacy POPs, including a range of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs), were also monitored to compare regional atmospheric concentrations over a decade of monitoring under the GAPS Network. γ-hexachlorocyclohexane (HCH) and the endosulfans significantly decreased (p < 0.05) from 2005 to 2015, suggesting regional levels are decreasing. However, there were no significant changes for the other legacy POPs monitored, likely a reflection of the persistency and slow decline of environmental levels of these POPs. For the more volatile OCs, atmospheric concentrations derived from polyurethane foam (PUF) (acting as an equilibrium sampler) and sorbent impregnated PUF (SIP) (acting as a linear phase sampler), were compared. The complimentary methods show a good agreement of within a factor of 2–3, and areas for future studies to improve this agreement are further discussed. Graphical abstract Image 1 Highlights • First reporting of hexachlorobutadiene and dicofol from the GRULAC region. • First regional scale data of pentachloroanisole from the GRULAC region. • PUF and SIP disk derived atmospheric concentrations agree within factor of 3. • γ-hexachlorohexane and the endosulfans significantly decreased from 2005 to 2015. • Other legacy POPs did not see decreasing concentrations from 2005 to 2015. Regional scale atmospheric concentrations of hexachlorobutadiene, pentachloroanisole and dicofol are reported for the first time in the GRULAC region, along with concentrations of legacy POPs with only γ-hexachlorocyclohexane and endosulfans significantly reducing (p < 0.05) in the region from 2005 to 2015. A comparison study of SIP-PAS vs PUF-PAS demonstrated the applicability of both media for monitoring more volatile POPs. [ABSTRACT FROM AUTHOR]

Remediation of dense non-aqueous phase liquids (DNAPLs) represents a challenging issue because of their persistent behaviour in the environment. This pilot-scale study investigates, by means of in situ experiments and numerical modelling, the feasibility of the pulsed pumping process of a large amount of a DNAPL in an alluvial aquifer. The main compound of the DNAPL is hexachlorobutadiene (HCBD), added in 2015 to the persistent organic pollutants list (POP). A low-permeability keyed enclosure was built at the location of the DNAPL source zone in order to isolate a finite volume of soil and a 3-month pulsed pumping process was applied inside the enclosure to exclusively extract the DNAPL. The water/DNAPL interface elevation at both the pumping well and an observation well was recorded. The cumulated pumped volume of DNAPL was also monitored. A total volume of about 20 m 3 of pure DNAPL was recovered since no water was extracted during the process. The three-dimensional and multiphase flow simulator TMVOC was used and a conceptual model was elaborated and generated with the pre/post-processing tool mView. Numerical simulations reproduce the pulsed pumping process and show an excellent match between simulated and field data of DNAPL cumulated pumped volume and a reasonable agreement between modelled and observed data for the evolution of the water/DNAPL interface elevations at the two wells. This study offers a new perspective in remediation since DNAPL pumping system optimisation may be performed where a large amount of DNAPL is encountered. [ABSTRACT FROM AUTHOR]

Although hexachlorobutadiene (HCBD) has been listed as a persistent organic pollutant (POP) under Annexes A and C of the Stockholm Convention, information about its unintentional production and emission is still very limited. We estimated the historical unintentional production and emission of HCBD during 1992–2016 in China based on aggregated activity data and emission functions. The unintentional production of HCBD increased from 60.8 (95% confidence interval, 38.2–88.5) MT/yr to 2871.5 (2234.2–3530.0) MT/yr during 1992–2016, representing an average annual growth rate of 17.4%. The main unintentional source of HCBD changed from carbon tetrachloride to trichloroethylene production during this period. We estimated that China's cumulative emissions of HCBD were 8211.3 (6131.5–10,579.5) MT during the same period. HCBD consumption and the chlorinated hydrocarbon production sector were the major contributors to total HCBD emissions. Owing to the long-range transport capability of HCBD (8784 km), such high emissions in China may cause adverse effects in other regions. [ABSTRACT FROM AUTHOR]

Hexachlorobutadiene (HCBD) was listed as a new controlling persistent organic pollutant in the Stockholm Convention because of its wide industrial applications and potential genotoxicity and carcinogenicity. However, only limited information exists on the release of HCBD from unintentional sources, such as waste incineration. Identification and quantification of HCBD in fly ash, one of the major outputs of waste incineration, is imperative. This work presents a simple method for determining HCBD in waste incineration fly ash based on ultrasonic extraction coupled with a silica gel–Florisil column cleanup followed by gas chromatography–mass spectrometry detection. Two typical persistent organic pollutants, pentachlorobenzene (PeCB) and hexachlorobenzene (HCB), were measured simultaneously. The parameters that influence the extraction efficiency and the quality of instrument detection were studied. Under the optimum experimental conditions, high sensitivity (detection limit 0.25–0.53 ng g-1), acceptable recoveries (64.0–71.4%) at spiking levels of 5–500 ng g-1, and good repeatability [relative standard deviation (n = 3) of 14% or less] were achieved for all target analytes. The validation of this method was performed by analysis of six real fly ash samples from different waste incinerators in eastern China. The concentrations of HCBD detected in these samples (1.39–97.6 ng g-1) were comparable to those of PeCB (1.22–150 ng g-1) and HCB (0.82–120 ng g-1), indicating that the residual HCBD as well as PeCB and HCB in waste incineration fly ash should not be ignored. The results confirm for the first time that waste incineration is an unintentional source of HCBD in China.An analytical method for hexachlorobutadiene, pentachlorobenzene, and hexachlorobenzene in fly ash from waste incineration. GC-MS gas chromatography–mass spectrometry, Ph-d10 phenanthrene-d10 [ABSTRACT FROM AUTHOR]

Hexachlorobutadiene (HCBD) is one of the persistent organic pollutants (POPs) listed by the Stockholm Convention and poses potential risks to human health and ecosystems. To reveal the regional-scale pollution status of HCBD in agricultural soils from fast-developing areas, an extensive investigation was conducted in the core Yangtze River Delta (YRD), China. The detectable concentrations of HCBD in 241 soil samples ranged from 0.07 to 8.47 ng g−1 dry weight, with an average value of 0.32 ng g−1 and a detection rate of 59.3%. Industrial emissions and intensive agricultural activities were the potential source of HCBD. The concentrations of HCBD were highly associated with the soil physicochemical properties such as organic matter contents. Higher concentrations of HCBD were found in paddy fields than other land-use types. The concentrations of HCBD were much lower than those of organochlorine pesticides and polychlorinated biphenyls. Significant positive correlations were found between HCBD and most organochlorine pesticides. HCBD was not found in ten vegetable samples due to its low concentration and detection rate. A positive relationship was observed between the level of HCBD and the biomass of fungi, indicating that the fungi in soils might be influenced by the existence of HCBD. The potential risks of HCBD to ecosystems and health of inhabitants were estimated to be negligible. The finding from this study provides an important basis for soil quality assessment and risk management of HCBD in China. [ABSTRACT FROM AUTHOR]

Sediment downstream of industrial sources in the Upper St. Clair River was historically contaminated with mercury, hexachlorobutadiene, hexachlorobenzene and octachlorostyrene. Concentrations of contaminants of concern in suspended sediment collected from traps in 1994/1995 and 2001 suggested bottom sediment was mobile and a source of contamination to downstream areas. Sediment was dredged in 1996 and in 2002-2004 from two contaminated areas (Cole Drain and Dow waterfront, respectively). Post remediation concentrations of contaminants of concern in bottom sediment and suspended sediment throughout downstream areas were high, relative to concentrations measured at the upstream reference sites; however, data from sediment traps deployed in 2006-2011 indicated that concentrations of contaminants of concern were trending downward since the remediation efforts. There was a significant (p ≤ 0.05) decrease in concentrations of mercury, hexachlorobutadiene and octachlorosytrene for suspended sediment in 2006 (post-remediation of the Dow waterfront) compared to 2001 (pre-remediation) and contaminants of concern suspended sediment concentrations have remained consistent between 2006 and 2011. Contaminant down-flux rates for the upper St. Clair River have also decreased since remediation; however, data for hexachlorobenzene were variable with no apparent trend through time. Bottom sediment data for hexachlorobenzene, octachlorostyrene and hexachlorobutadiene collected in 2006 and 2008 downstream of the remediation areas have also shown a downward trend when compared to concentration reported for 1990-2001; however, declines in mercury were not apparent. [ABSTRACT FROM AUTHOR]

This study evaluates the current situation regarding PBDE and HBCD levels in different river fish species. We collected published data in the last five years in different countries around the world. These levels of pollution were compared with Environmental Quality Standards (EQS) for biota established by the European Directive in the field of water policy. Although HBCD situation is not critical, with only some values exceeding the limit about 5 times, the PBDE levels clearly exceeded the established EQS, with 25% of fish samples exceeding up to ten thousand times. Although it is expected that levels of pollution by PBDEs will decrease over the next years due to the ban in their use, it is not expected that this decrease will reach the EQS values by the end of 2021, as demanded by the European Directive. Hence, it is necessary to implement new strategies in order to minimize the impact of PBDEs on the environment. [ABSTRACT FROM AUTHOR]

Reductive dechlorination of hexachlorobutadiene (HCBD) was performed by a suspension of scattered spots of palladium nanoparticles deposited on iron microparticles (nPd/μZVI) in a mixture of dissolved lactic acid polymers and oligomers (referred to as PLA). The effects of nPd/μZVI loading, temperature, HCBD initial concentration, and PLA content were investigated as to define the best conditions for the dechlorination. HCBD dechlorination by nPd/μZVI occurred in a two-step process: first, HCBD adsorbed onto the nPd surface, which resulted in a rapid initial disappearance of pollutant in solution, and, second, it degraded chemically by atomic hydrogen H*, which resulted from the dissociative adsorption of H2 on nPd. HCBD remained adsorbed on the surface until its complete degradation in nonchlorinated product, in agreement with the formation of an ordered activated complex on the nPd/μZVI surface as suggested by the negative entropy of activation calculated from the Eyring equation. Hence, a minimum amount of nPd/μZVI was required to enable simultaneously HCBD adsorption and H2 production. In these cases, pseudo-first order rate equations were suitable to model HCBD disappearance kinetics. The increase in PLA content resulted in enhancing initial pH decrease such as to maintain acidic conditions and thus high reactivity over a longer period of time. It also resulted in enhancing the contact between HCBD and nPd/μZVI, which was characterized by a more important initial adsorption. As a consequence, deviations from pseudo-first order kinetics were observed and a more representative model with a two-phase decay was proposed. [ABSTRACT FROM AUTHOR]

The solubilization of hexachlorobutadiene (HCBD) and hexachloroethane (HCA) in water as a function of temperature and in the presence of surfactants was investigated in order to predict their fate in groundwater and to increase their recovery. HCBD and HCA solubility data were experimentally determined at five temperatures in the range from (285.15 to 318.15) K. Thermodynamic parameters for dissolution (ΔsolG°, ΔsolH°, and ΔsolS°) have been calculated in order to propose a physical explanation of the minimum solubility observed between 293.15 and 298.15 K for both compounds. The solubilization process appeared to be influenced by the network of water molecules rather than by physical and chemical properties of HCBD or HCA, due to an opposite effect of temperature onto Brownian motion, which increases with temperature, and hydrogen-bond network, which collapses with temperature. Concerning the influence of surfactants, determination of the micelle–water partition coefficients (Kmw) and the molar solubilization ratio (MSR) has shown that the solubilization per micelle was more important for nonionic surfactants Triton X-100 and Tween 80 than for anionic SDBS. Also, the increase of solubility was 1 order of magnitude higher for liquid HCBD than for crystalline HCA irrespective of surfactant. [ABSTRACT FROM AUTHOR]

In this paper, a novel strategy for the preparation of 1,2-dichlorotetrafluorocyclobutene (DTB) was proposed via a catalytic gas-phase process of fluorination using hexachlorobutadiene (HCBD) and anhydrous HF. In order to search for suitable catalysts and reveal the reaction pathway for this synthetic route, a series of studies were carried out. First, CrOx/ZnO catalysts with different promoters (Ni, Cu, In, Al) were prepared by a precipitate method and the optimum reaction conditions were investigated. The highest activity was achieved on the Cr-Ni-Zn catalyst, whose yield of DTB reached 90% by a multiple cycle reaction. Second, the effects of different promoters on the properties of catalysts were studied by Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature-programmed desorption in ammonia (NH3-TPD), and X-ray photoelectron spectroscopy (XPS). It was found that the Cr-Ni-Zn catalyst showed the excellent catalytic performances with more CrOxFy species, higher oxygen concentration, and widely distributed acid strength on its surface. Third, combining experimental results with theoretical calculations, a reaction pathway has been proposed. This study offers an economic synthetic route for DTB from HCBD, which is a valuable and promising method for industrial production. [ABSTRACT FROM AUTHOR]

The paper is focused on the possibility of using ozonation process combined with iron nanoparticles (nZVI - nano zero-valent iron) to remove selected specific synthetic substances, such as hexachlorobutadiene, pentachlorobenzene, hexachlorobenzene, lindane and heptachlor. Experimental measurements were performed in order to evaluate the effectiveness of the removal of substances and their removal rates. Removal of pesticides was also monitored through calculated DOC (dissolved organic carbon) as cumulative wastewater quality indicator. We investigated the effectiveness of 5 mL L-1 nZVI suspension (equal to 1 g Fe0) for the optimization of micropollutants removal from model water. Applications of 5 mL L-1 nZVI suspension and combined O3/nZVI processes have been shown as the most effective. Increasing concentrations of nZVI had almost no impact on the efficiency of the degradation process. Higher degradation efficiencies of γ-HCH were measured in O3/nZVI compared to the ozonation process. Degradation of pesticides HCLB, HCLBD and PCLB in all tested processes achieved efficiencies above 88 %. [ABSTRACT FROM AUTHOR]

Two laboratory performance studies with 21 and 11 participants were carried out for passive sampling of nonpolar chemicals in water, using silicone samplers that were deployed for 7 wk and 13 wk at 2 river sites in the Netherlands. Target analytes were polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), hexachlorobutadiene, hexachlorobenzene, and a number of performance reference compounds (PRCs). Calculation of aqueous concentrations based on prescribed input values and a prescribed uptake model was also included. Between-laboratory coefficients of variation ( CVs) in the analysis of target compounds were approximately 20% at concentrations of 100 ng g−1 and approximately 100% at concentrations of 0.01 ng g−1, which was similar to previous results for the analysis of biota samples. The analysis of PRCs yielded water sampling rates with a between-laboratory CV of 18% to 30%. The sampling rate model showed a nearly perfect match with the consensus values of retained PRCs. The implications of the present study for future interlaboratory exercises are discussed. Environ Toxicol Chem 2017;36:1156-1161. © 2016 SETAC [ABSTRACT FROM AUTHOR]

In the context of supporting the EU Member States in the implementation of the EU Water Framework Directive (WFD), a project for the production of a fish reference material (ERM-CE100) certified for its content of the two priority substances hexachlorobenzene (HCB) and hexachlorobutadiene (HCBD) was carried out at the Joint Research Centre (JRC) of the European Commission. The starting material was naturally contaminated Wels catfish (Silurus glanis), caught in the Ebro River (Spain). A novel approach for the processing of the fish was tested that resulted in a homogeneous and stable reference material in the form of a wet paste. The fresh-like texture of the matrix enhances the comparability of this material toward routinely analyzed environmental biota samples and facilitates its use as a quality assurance tool given that the WFD environmental quality standards (EQS) for biota are expressed as wet weight. Certified values for the mass fractions of HCB and HCBD were assigned with 120 ± 8 and 36 ± 4 μg/kg, respectively. The related interlaboratory comparison involved 13 expert laboratories applying a range of analytical methodologies. It is the first biota CRM ever available for HCBD. ERM-CE100 can be used to assess the performance of analytical methods employed in the mandatory monitoring of water bodies under the WFD, thus, providing a benchmark for establishing comparability among measurement results. [ABSTRACT FROM AUTHOR]

A novel synthetic route of Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzz)was developed. It contains three-step reactions as follows: (1) The vapor-phase catalytic fluorination from hexachlorobutadiene to (E/Z)-2,3-dichlorohexafluoro-2-butenepromoted by Cr-based catalyst; (2) The liquid-phase dechlorination reaction from (E/Z)-2,3-dichlorohexafluoro-2-butene to 1,1,1,4,4,4-hexafluoro-2-butyne with Zn in DMF; (3) The gas-phase hydrogenation reaction from 1,1,1,4,4,4-hexafluoro-2-butyne to Z-HFO-1336mzz promoted by Pd + Bi/PAF (porous aluminium fluoride) catalyst. It provided a potential method for industrial production of Z-HFO-1336mzz. [ABSTRACT FROM AUTHOR]

The contamination of organochlorine pesticides (OCPs) and hexachlorobutadiene (HCBD) in soils, plants, and terrestrial fauna from a former pesticide-producing area in Southwest China was investigated. High levels of OCP residues (ΣHCHs and ΣDDTs of 3.89-13,386 and 23.3-11,186 ng g dw, respectively) were found in the soils within the producing factory, indicating that the former pesticide factory brownfield site poses a high environment risk and that effective soil remediation is needed. The OCP concentrations in soils surrounding the pesticide factory were 1-2 orders of magnitude higher than in the other agricultural areas from China. Grass, vegetables, and tree leaves from the surrounding areas of the point source showed moderate OCP pollution, which was likely to be causing potential negative impacts on terrestrial ecosystem. OCP levels in terrestrial species from the studied area including insects, free-range chickens and birds were moderate, and were generally within accepted safe levels. β-HCH was the most prevalent isomer, implying that hexachlorocyclohexane (HCH) residues were mainly derived from the degradation of technical HCH. The dichlorodiphenyltrichloroethane (DDT) profiles reflected obvious degradation of technical DDT. In the study area, the concentrations of HCBD were <0.02-5.59, 0.03-24.6 ng g dw and 1.65-3.80 ng g lw in soils, plants, and animals, respectively, which were relatively low and not sufficient to cause observable adverse biological effects. [ABSTRACT FROM AUTHOR]

Hexachlorobutadiene (HCBD) was listed as a new persistent organic pollutant for global regulation under Stockholm Convention in 2015, and there has been scarce information on its atmospheric concentrations, distributions, and emission sources. HCBD air samples were collected and analyzed to characterize concentrations and distributions at high elevation and urban sites as well as emission source locations in Northern China. We found ambient concentrations of HCBD in Northern China averaged at 34 ± 16 and 36 ± 28 pptv at urban sites in Jinan and Tai'an, respectively, and 31 ± 21 pptv at a high-elevation site Mount Tai. HCBD concentrations at the high elevation and urban sites were found to be affected by long-range transport under the influence of the East Asian monsoon climate. Over potential sources areas, we found concentrations of 76 ± 33 pptv in a mixed factory park, 59 ± 21 pptv in a rubber plant and 74 ± 8 pptv in a municipal solid waste (MSW) landfill area, which were all several times higher than in urban sites. The large concentration gradient across the various environments revealed strong emission sources of HCBD, especially over MSW landfill and Cl-compound production and application areas. An emission rate of 9.2 × 104 kg/yr and an oxidation rate of 32.9 kg/yr for HCBD were estimated for the mixed factory park. OH and Cl are much more active in reaction with HCBD than other oxidants in the atmosphere. Dry deposition and oxidation removed about 5.3% and 0.04%, respectively, of the emitted, suggesting that ∼95% of the emitted HCBD remaining in the atmosphere and could be transported for redistribution. Our findings revealed significant emission sources of HCBD in northern China, which was in turn affected by major sources in East-central China. The regional influence of HCBD pollution warrants serious concerns and points to the need to develop mitigation strategies. • Atmospheric HCBD study was conducted at Mount Tai and nearby urban sites. • Emission and oxidative rates of HCBD in the atmosphere were estimated. • HCBD concentrations at high elevation were affected by East Asian Monsoon. • Mid-eastern China was identified as the potential emission regions of HCBD. [ABSTRACT FROM AUTHOR]

Hexachlorobutadiene reacts with thioalcohols (2-mercaptoethanol, 4-mercapto-1-butanol and 6-mercapto-1-hexanol) in aqueous ethanol in the presence of sodium hydroxide to give the new thioethers 1,2,3,4,4-pentachloro-1-(2-hydroxyethylthio)-1,3-butadiene, 1,2,3,4,4-pentachloro-1-(4-hydroxybutylthio)-1,3-butadiene and 1,2,3,4,4-pentachloro-1-(6-hydroxyhexylthio)-1,3-butadiene. The hydroxy groups of these products are converted to chlorides with SOCl2in pyridine. New long chain sulfides were synthesized by reaction of the S-substituted polychloro-1,3-butadienes with thiols (ethyl-, 2-hydroxyethyl-, propyl- and butyl-) in the presence of sodium ethoxide in ethanol. Furthermore, hexachlorobutadiene gave new S- and -S,S-substituted polychloro-1,3-butadiene derivatives with 2,3,5,6-tetrafluorobenzenethiol and 2,4-difluorobenzenethiol in aqueous ethanol in the presence of sodium hydroxide or in DMF in the presence of triethylamine. The structures of the new compounds were characterized by microanalyses and spectroscopic data. [ABSTRACT FROM PUBLISHER]

Hexachlorobutadiene reacts with MeONa in refluxing methanol to give ( Z)-4,4-dimethoxy2-oxobut-3-enoic acid and 2,4,4-trichloro-1,1,1,3-tetramethoxybut-2-ene, which were converted to methyl ( Z)-4,4-dimethoxy-2-oxobut-3-enoate and methyl ( Z)-2,4,4-trichloro-3methoxybut-2-enoate upon treatment with CHN and acid hydrolysis, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT The influence of γ-irradiation dose and the concentration of hexachlorobutadiene (HCB) on the thermal and mechanical properties of low-density polyethylene (LDPE) and LDPE/isotactic polypropylene (iPP) blends have been investigated. Gel fraction, mechanical properties, and morphological evolution of gamma-irradiated LDPE/HCB and LDPE/iPP/HCB composites were studied. The gel content of LDPE/HCB samples increased with increasing irradiation dose from 150 to 350 kGy and then it slightly decreased at higher irradiation dose (600 kGy). On the other hand, the gel content of LDPE/iPP/HCB (100/0/3, 80/20/3, and 50/50/3 wt%) composites increased gradually with increasing irradiation dose. For LDPE/HCB composites, the tensile strength increases gradually with increasing either the irradiation dose or HCB content. The tensile strength of LDPE/iPP/HCB blend formulations increased with increasing either the irradiation dose or iPP content. The addition of iPP to the LDPE matrix increased the thermal temperature parameters of composites as well as the incorporation of the HCB agent. The thermal stability of LDPE/iPP/HCB composites is higher than that of LDPE/HCB. [ABSTRACT FROM AUTHOR]

Hexachlorobutadiene (HCBD) is a potential persistent organic pollutant that has been found in abiotic environments and organisms. However, information on HCBD in soils and its accumulation in terrestrial food chains is scarce. This study investigated the accumulation of HCBD in soils, plants, and terrestrial fauna in a typical agricultural area in Eastern China, and drew comparisons with organochlorine pesticides (OCPs). The HCBD concentrations in soils were <0.02–3.1 ng/g dry weight, which were similar to α-endosulfan concentrations but much lower than the concentrations of some other OCPs. The HCBD soil–plant accumulation factors, 8.5–38.1, were similar to those of o,p′ -DDT and higher than those of HCHs and p,p′ -DDT, indicating that HCBD is strongly bioaccumulated by rice and vegetables. HCBD concentrations of 1.3–8.2 ng/g lipid weight were found in herbivorous insects, earthworms, and Chinese toads. The biomagnification factor, the ratio between the lipid-normalized concentrations in the predator and the prey, was found to be 0.16–0.64 for different food chains of Chinese toads, so HCBD was found not to biomagnify, which is in contrast with OCPs. Further research into whether HCBD is biomagnified in high trophic level organisms or through the entire terrestrial food web is required. [ABSTRACT FROM AUTHOR]

Twenty-nine Wels catfish were caught from the Ebro River (Spain) and analyzed for the mass fractions of hexachlorobenzene (HCB) and hexachlorobutadiene (HCBD), two priority substances for which environmental quality standards (EQSs) have been established in biota since 2008. These fish are the starting material for a candidate certified reference material. The results obtained show high variability in the mass-fraction level. Considering the same specimen, tails always have higher contamination levels than heads, the highest results being of about 1000 ng g-1 for both analytes. EQSs were exceeded 17 times for HCB and once for HCBD in tail samples. We discuss the results with regard to representativeness and data evaluation with regard to EQS compliance. We present observations and open questions for the on-going discussion about implementing biota monitoring, in the view of the requirements imposed to Member States by the recently adopted Directive 2013/39/EU. [ABSTRACT FROM AUTHOR]

Although hexachlorobutadiene (HCBD) was recently proposed as a candidate persistent organic pollutant (POP) under the Stockholm Convention, information about its environmental levels and distributions is still very limited. In this work, HCBD was determined in the sewage sludge from 37 wastewater treatment plants (WWTPs) in 23 cities and 17 soils near a chemical plant in China. Three chlorobenzenes (CBs) (1,2,4-trichlorobenzene, 1,2,4,S-tetrachlorobenzene, and hexachlorobenzene) were simultaneously studied to help better understand the environmental behavior of HCBD. Concentrations of HCBD in sludge samples ranged from <0.03 to 74.3 ng/g dry weight (dw) with a median value of 0.30 ng/g dw, which was lower than those of the three CBs. Levels of HCBD were not correlated with capacity of the WWTPs and total organic carbon. For soils, high level of HCBD was found in the sample within the plant, with a rapid decreasing concentration trend with the increase of distance from the plant. It was suspected that releasing as a byproduct during manufacturing of chlorinated chemicals was the primary source of HCBD in the studied location. Further risk assessment indicated that the environmental risk of HCBD to soil organisms and the health risk to employees were very low through soil exposure within the plant. [ABSTRACT FROM AUTHOR]

Abstract: This paper summarizes the validation strategy and the results obtained for the simultaneous determination of hexachlorobenzene (HCB) and hexachlorobutadiene (HCBD) in fish tissue with a maximum of about 10% m/m fat content using a GC–IDMS technique. The method is applicable for the determination of HCB and HCBD at trace levels in different kinds of fish tissue samples in accordance with the requirements of the EU Directive 2008/105/EC establishing Environmental Quality Standard (EQS) levels for biota in aquatic ecosystems (10ng/g for HCB and 55ng/g for HCBD). The method validation aimed to assess performance parameters such as linearity, limit of detection/limit of quantification (LOD/LOQ), trueness, selectivity, intermediate precision, repeatability, stability of the extracts and robustness. The validation experiments have been performed by using uncontaminated fish tissue. Trueness was evaluated by using a certified reference material (NIST SRM 1947) (where applicable) and by the standard addition method. Very good linear signal-concentration curves were obtained for both analytes over the whole range of calibration. The repeatability and the intermediate precision of the method, expressed as relative standard deviation (RSD) and calculated at the EQS level, were estimated to be below 3% both for HCB and HCBD. The limits of quantification were 3.7ng/g for HCB and 15.7ng/g for HCBD in the fish. An uncertainty budget for the measurement of both HCB and HCBD in fish at about the EQS levels, applying the described method, has been established in the order of 10%. The analytical method and its performance characteristics take into account the requirements of EU Directive 2009/90/EC regarding the establishment of minimum performance criteria for the methods of analysis to be used in the water monitoring activity of the Water Framework Directive. Finally, the validated method was successfully tested on contaminated Silurus glanis from Ebro River (Spain). The method will be used in the homogeneity, stability and interlaboratory comparison studies for the characterization of a new candidate certified reference material. [Copyright &y& Elsevier]

Hexachlorobutadiene (HCBD) is a potent nephrotoxin which nowadays contaminates human foods and water. On the other hands, it has been reported that rutin is a chemopreventive flavonoid which exerts some protective effects on the kidney. Therefore, in this work, the possible effect of rutin on HCBD-induced nephrotoxicity was investigated in female rats. The animals were divided into five groups. Groups 1 and 2 were treated with vehicle and HCBD (100 mg/kg, i.p.), respectively. Groups 3-5 were pretreated with rutin (100, 500 and 1000 mg/kg, i.p.) 1 h before HCBD injection. The level of serum urea and creatinine as well as urinary glucose and protein were measured. Total thiol content and lipid peroxidation level were also determined in the kidney homogenate. When compared to control group, a significant increase in the level of serum creatinine and urea ( p < 0.001) as well as urine glucose and protein ( p < 0.001) were observed after 24 h of HCBD administration. HCBD also caused a significant decrease in total thiol content ( p < 0.001) and a significant increase in lipid peroxidation level ( p < 0.001). Pretreatment with rutin could decrease serum creatinine ( p < 0.001) and urea ( p < 0.001) as well as urine protein ( p < 0.001) concentrations when compared with HCBD treated rats. No significant modification on urine glucose was seen ( p > 0.05). Rutin also reversed the HCBD-induced depletion in thiol content ( p < 0.001) and elevation in lipid peroxidation ( p < 0.001) in the kidney. The results of present study showed that rutin clearly attenuated HCBD-induced nephrotoxicity and has the potential to be considered as a nephroprotective agent. [ABSTRACT FROM AUTHOR]

Abstract: Since 2007 about 200 to 300 fish per year – generally roach (Rutilus rutilus) also a few bleak (Alburnus alburnus) and eels (Anguilla anguilla) – have been collected from a number of English river sites and stored at −80°C to build up a Fish Tissue Archive as a resource for the monitoring of pollutants. Some of the fish from the Fish Tissue Archive from the years 2007–2011 were analyzed for substances in current and proposed European legislation regarding environmental quality standards (EQS) in biota. It was found that mercury exceeded the EU EQS of 20μg/kg in 79% of samples with an average and median of 31 and 29μg/kg. The legacy fungicide hexachlorobenzene (HCB) was below the EQS of 10μg/kg in all fish analyzed, with a maximum of 6μg/kg in some eels. The legacy solvent hexachlorobutadiene (HCBD) was below the EQS of 55μg/kg, being <0.2μg/kg in all samples where it was measured. The sums of six polybrominated diphenyl ethers (PBDEs) were several orders of magnitude higher than the new proposed 0.0085μg/kg biota EQS. This study showed that the regular collection and analysis of whole body homogenate samples of relatively small native pelagic fish is suitable for the monitoring of contaminants capable of bioaccumulation. With regard to current or proposed EQS for EU countries, mercury and potentially PBDE in fish are of some concern in these English rivers. [Copyright &y& Elsevier]

Hexachloro-1:3-butadiene (HCBD) causes segment-specific injury to the proximal renal tubule. A time course study of traditional and more recently proposed urinary biomarkers was performed in male Hanover Wistar rats receiving a single intraperitoneal (ip) injection of 45 mg/kg HCBD. Animals were killed on days 1, 2, 3, 4, 5, 6, 7, 10, 14, and 28 postdosing and the temporal response of renal biomarkers was characterized using kidney histopathology, urinary and serum biochemistry, and gene expression. Histopathologic evidence of tubular degeneration was seen from day 1 until day 3 postdosing and correlated with increased urinary levels of α-glutathione S-transferase (α-GST), albumin, glucose, and kidney injury molecule-1 (KIM-1), and increased gene expression of KIM-1, NAD(P)H dehydrogenase, quinone 1, and heme oxygenase (decycling) 1. Histopathologic evidence of tubular regeneration was seen from day 2 postdosing and correlated with raised levels of urinary KIM-1 and osteopontin and increased gene expression of KIM-1 and annexin A7. Traditional renal biomarkers generally demonstrated low sensitivity. It is concluded that in rat proximal tubular injury, measurement of a range of renal biomarkers, in conjunction with gene expression analysis, provides an understanding of the extent of degenerative changes induced in the kidney and the process of regeneration. [ABSTRACT FROM PUBLISHER]

ABSTRACT The present research investigates the occurrence of hyaline droplet (HD) accumulation related to age, dose and time after treatment in male Wistar rats given a single i.p. injection of hexachloro-1:3-butadiene (HCBD). In the study on age, rats from 1 to 12 months of age were treated with 100 mg kg−1 body weight (b.w.) HCBD dose. Rats treated at 2 months of age showed a greater accumulation of HD than the other age groups; HD accumulation was not observed in 1-month-old rats. In the dose-response study, the treatment with 25, 50 and 100 mg kg−1 b.w. at 2 months of age caused HD accumulation in the proximal convoluted tubule at all doses, with the 100 mg kg−1 b.w. group slightly more affected. Finally, in the time-course study, rats treated with a 100 mg kg−1 b.w. dose at 2 months of age and sacrificed at 6, 12, 24, 48, 72 and 96 h post-dosing showed a time-related HD accumulation in terms of incidence and severity, after 6 h, with a peak at 24 and 48 h and decreasing at 72 and 96 h. The present results show that HD accumulation is an early finding, and is unrelated to dose level and particularly evident in rats of 2 month of age. These findings in male rats treated with HCBD emphasize the importance of considering the age of rats at the start of a study. The more sensitive model was used in the detection of nephrotoxic effects of chemicals. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background. Tattooing has recently become increasingly popular. Using tiny needles, tattooists place the tattoo ink in the dermis along with numerous unknown ingredients. Most tattoos consist of black inks, which are predominantly composed of soot products (carbon black with polycyclic aromatic hydrocarbons). Objectives. Black tattoos cause skin problems, including allergic reactions, but the responsible substance frequently remains unknown. Material/methods. We applied gas chromatograph-mass spectrometry analysis to search for hazardous compounds in 14 different commercially available black tattoo ink samples. Results. The analysis revealed that all inks contained the softener substance dibutyl phthalate (0.12-691.2 µg/g). Some of the inks contained hexachloro-1,3-butadiene (0.08-4.52 µg/g), metheneamine (0.08-21.64 µg/g), dibenzofuran (0.02-1.62 µg/g), benzophenone (0.26-556.66 µg/g), and 9-fluorenone (0.04-3.04 µg/g). Conclusion. The sensitizing agent dibutyl phthalate acts directly on keratinocytes and can drive Th2 responses following skin exposure via induction of thymic stromal lymphopoietin gene expression. Hexachloro-1,3-butadiene is genotoxic in vitro and 9-fluorenone is cytotoxic, generating reactive oxygen species under light exposure. The substances found in the inks might be partially responsible for adverse skin reactions to tattoos. [ABSTRACT FROM AUTHOR]