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This study aimed to determine the levels of cypermethrin and hexachlorobenzene in milk and dairy products in Isfahan, Iran. In this study, 50 samples including raw milk, pasteurised milk, ultra-high temperature milk, traditional butter, pasteurised butter, traditional cheese, and pasteurised cheese were randomly collected from distribution centres in Isfahan city from June to September 2022. The pesticide levels in the samples were determined using high-performance liquid chromatography. The results indicated that the highest levels of cypermethrin, with 81.02 ± 23.77 µg/kg, were found in traditional butter, pasteurised butter, pasteurised cheese, and traditional cheese, which did not significantly differ. Regarding hexachlorobenzene, traditional butter with 66.68 ± 19.87 µg/kg and pasteurised butter with 47.16 ± 14.45 µg/kg had the highest contamination levels, which were not significantly different. The results indicated contamination of milk and dairy products supplied in Isfahan with pesticide residues. [ABSTRACT FROM AUTHOR]

A study was conducted to assess the concentrations of persistent organochlorine pollutants (POPs) in high-moor peats of the Primorsky and Mezensky districts of the Arkhangelsk oblast. Peat deposits located in the zone of potential influence of pollutants and outside it were analyzed. Based on the results of chromatographic determination, data on the concentrations of some organochlorine compounds in the studied peats, in particular, persistent toxic hexachlorobenzene (HCB), pentachlorophenol (PCP), pentachloroanisole (PCA), and chlorinated phenols and their derivatives, were obtained. Target POPs were detected in all analyzed peat samples with noticeable variability in their concentrations across the study areas HCB (0.4–3.2 ng/g), PCP (0.2–1.8 ng/g), and PCA (up to 0.4 ng/g). The CP content of the studied peats varied over a wider range from 1.2 to 571 ng/g. The identified quantities of POPs (HCB, CP, and PCA) were most likely due to the entry of pollutants by atmospheric transport from various sources in the territories of nearby regions and neighboring states. The influence of local pollution sources associated with thermal processes should also be taken into account. Keywords: : [ABSTRACT FROM AUTHOR]

Hexachlorobenzene （HCHs）, dichlorodiphenyltrichloroethane（DDTs） and poly-chlorinated biphenyls （PCBs） were determined in water, soil and mussel samples using GC-MS/MS, in order to investigate the concentrations, composition and distribution characteristics of legacy persistent organic pollutants （POPs） in different medium in the mussel mariculture area of the Huaniao Island, Yangtze estuary. The results showed that legacy POPs were widely detected in the samples, and the concentrations of HCHs, DDTs and PCBs ranged from 10. 8 to 49. 1, 169 to 900 and 10. 4 to 34. 4 ng/g（lipid weight） in mussel, 0. 22 to 1. 76, 0. 07 to 0. 29 ng/L and 9. 45-51. 8 pg/L in water, and 0. 18 to 10. 4, 2. 62 to 69. 6 and 0. 40 to 0. 69 ng/g（dry weight） in soil, respectively. DDTs were the main pollution compounds in mussel. The composition of target compounds in water and soil samples from the mariculture area reflected their exposure to residual pollutant emissions, with a dominance of highly chlorinated PCBs and DDT degradation products in mussels, which was associated with bioaccumulation characteristics. There were many significant positive correlations among HCHs, DDTs and PCBs in soils, as well as in mussels, reflecting the possible existence of similar sources of contaminants. The relationship between mussel tissues and non-biological medium can be seen in the principal component analysis. Health risk assessment showed that population ingestion of local mussels posed little risk of exposure and carcinogenic potential. This study can provide a basis for understanding the fate of legacy POPs among the different medium in the mussel mariculture area and the risk of mussel consumption by the population. [ABSTRACT FROM AUTHOR]

Exposure to certain chemicals prenatally and in childhood can impact development and may increase risk for attention-deficit/hyperactivity disorder (ADHD). Leveraging a larger set of literature searches conducted to synthesize results from longitudinal studies of potentially modifiable risk factors for childhood ADHD, we present meta-analytic results from 66 studies that examined the associations between early chemical exposures and later ADHD diagnosis or symptoms. Studies were eligible for inclusion if the chemical exposure occurred at least 6 months prior to measurement of ADHD diagnosis or symptomatology. Included papers were published between 1975 and 2019 on exposure to anesthetics (n = 5), cadmium (n = 3), hexachlorobenzene (n = 4), lead (n = 22), mercury (n = 12), organophosphates (n = 7), and polychlorinated biphenyls (n = 13). Analyses are presented for each chemical exposure by type of ADHD outcome reported (categorical vs. continuous), type of ADHD measurement (overall measures of ADHD, ADHD symptoms only, ADHD diagnosis only, inattention only, hyperactivity/impulsivity only), and timing of exposure (prenatal vs. childhood vs. cumulative), whenever at least 3 relevant effect sizes were available. Childhood lead exposure was positively associated with ADHD diagnosis and symptoms in all analyses except for the prenatal analyses (odds ratios (ORs) ranging from 1.60 to 2.62, correlation coefficients (CCs) ranging from 0.14 to 0.16). Other statistically significant associations were limited to organophosphates (CC = 0.11, 95% confidence interval (CI): 0.03–0.19 for continuous measures of ADHD outcomes overall), polychlorinated biphenyls (CC = 0.08, 95% CI: 0.02–0.14 for continuous measures of inattention as the outcome), and both prenatal and childhood mercury exposure (CC = 0.02, 95% CI: 0.00–0.04 for continuous measures of ADHD outcomes overall for either exposure window). Our findings provide further support for negative impacts of prenatal and/or childhood exposure to certain chemicals and raise the possibility that primary prevention and targeted screening could prevent or mitigate ADHD symptomatology. Furthermore, these findings support the need for regular review of regulations as our scientific understanding of the risks posed by these chemicals evolves. [ABSTRACT FROM AUTHOR]

This study aimed to estimate the carcinogenic and non-carcinogenic risk as well as the attributable cases due to exposure to organochlorine pesticides (OCPs): hexachlorobenzene (HCB), dichlorophenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), heptachlor, and chlordane. From serum concentrations of pesticides of interest in a sample of 908 women from Northern Mexico, the risk for both cancer and non-cancer health effects was evaluated. The population attributable fraction (PAF) was also calculated based on summary association estimates between exposure to OCPs and different health events. Findings revealed that due to their OCP exposure slightly less than half of the women in the sample were at increased risk of developing non-cancerous diseases. Moreover, approximately 25% and 75% of participants were at risk of develop some type of cancer associated with their HCB and DDE concentrations, respectively. In addition, it was estimated that 40.5% of type 2 diabetes, 18.7% of endometriosis, and 23.1% of non-Hodgkin's lymphoma cases could have been prevented if women had not been exposed to these OCPs. Results suggest that the use of OCPs may have contributed to the disease burden in the study area and, based on the time required for these substances to be eliminated from the body, there are probably some women who are still at elevated risk of developing diseases associated to OCPs. [ABSTRACT FROM AUTHOR]

Abstract Background The effects of organochlorine pesticide (OCP) exposure on the development of human papillary thyroid cancer (PTC) are not well understood. A nested case-control study was conducted with data from the U.S. Department of Defense Serum Repository (DoDSR) cohort between 2000 and 2013 to assess associations of individual OCPs serum concentrations with PTC risk. Methods This study included 742 histologically confirmed PTC cases (341 females, 401 males) and 742 individually-matched controls with pre-diagnostic serum samples selected from the DoDSR. Associations between categories of lipid-corrected serum concentrations of seven OCPs and PTC risk were evaluated for classical PTC and follicular PTC using conditional logistic regression, adjusted for body mass index category and military branch to compute odds ratios (OR) and 95% confidence intervals (CIs). Effect modification by sex, birth cohort, and race was examined. Results There was no evidence of associations between most of the OCPs and PTC, overall or stratified by histological subtype. Overall, there was no evidence of an association between hexachlorobenzene (HCB) and PTC, but stratified by histological subtype HCB was associated with significantly increased risk of classical PTC (third tertile above the limit of detection (LOD) vs.

Background: The effects of organochlorine pesticide (OCP) exposure on the development of human papillary thyroid cancer (PTC) are not well understood. A nested case-control study was conducted with data from the U.S. Department of Defense Serum Repository (DoDSR) cohort between 2000 and 2013 to assess associations of individual OCPs serum concentrations with PTC risk. Methods: This study included 742 histologically confirmed PTC cases (341 females, 401 males) and 742 individually-matched controls with pre-diagnostic serum samples selected from the DoDSR. Associations between categories of lipid-corrected serum concentrations of seven OCPs and PTC risk were evaluated for classical PTC and follicular PTC using conditional logistic regression, adjusted for body mass index category and military branch to compute odds ratios (OR) and 95% confidence intervals (CIs). Effect modification by sex, birth cohort, and race was examined. Results: There was no evidence of associations between most of the OCPs and PTC, overall or stratified by histological subtype. Overall, there was no evidence of an association between hexachlorobenzene (HCB) and PTC, but stratified by histological subtype HCB was associated with significantly increased risk of classical PTC (third tertile above the limit of detection (LOD) vs.

(1) Background: Hexachlorobenzene (HCB) is a persistent organic pollutant that is possibly carcinogenic to humans. It is still found in the environment, humans and animals, and in foods, including milk and dairy products; (2) Methods: The influence of the probiotic cultures Lacticaseibacillus rhamnosus LCR and Lactiplantibacillus plantarum subsp. plantarum LP on the possibility of effecting the biodegradation of HCB in dairy products fermented from mare milk was investigated, taking into account the product storage time (maximum 21 days). HCB content was determined using the GC/MS method; (3) Results: A strong negative Pearson correlation (p < 0.05) was found between HCB concentration and the refrigeration storage time of the fermented beverages. The highest HCB reduction was observed in milk fermented with both Lacticaseibacillus rhamnosus LCR and Lactiplantibacillus plantarum subsp. plantarum LP (78.77%), while the lowest was noted when only Lactiplantibacillus plantarum subsp. plantarum LP was used (73.79%); (4) Conclusions: This pilot study confirmed that probiotics commonly used to give products health-promoting properties can also contribute to reducing the content of undesirable substances, and the bacterial cultures used might provide an alternative method for reducing HCB residues in fermented drinks. [ABSTRACT FROM AUTHOR]

Hexachlorobenzene (HCB) is a pesticide that is constantly produced as a by-product in many industrial processes. Rutin (RUT) is a flavonoid found in many plants with numerous biological and pharmacological properties. However, there is no scientifical information on the impact of RUT on HCB-induced reproductive toxicity in male rats. Thus, we investigated the effect of rutin on HCB-induced reproductive toxicity. Rats were divided into four groups consisting of control administered with corn oil, HCB alone (16 mg/kg), RUT alone (100 mg/kg) and HCB + RUT that were treated orally by gavage for 28 days. Hexachlorobenzene caused a significant reduction in epididymal sperm count, sperm progressive motility, viability, number of hypo-osmotic tail swelled spermatozoa and increased sperm morphological abnormalities (head, midpiece and tail). Furthermore, HCB decreased the activities of gamma glutamyl transferase, lactate dehydrogenase, sorbitol dehydrogenase, superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, levels of glutathione and total protein with increased malondialdehyde level. Additionally, HCB increased the levels of total cholesterol, low density lipoprotein, triglycerides, follicle stimulating hormone, luteinizing hormone but decreased high density lipoproteins, serum testosterone, steroidogenic enzymes (3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase), B-cell lymphoma and increased pro-apoptotic markers (Bcl-2 associated protein (Bax), caspases-3 and-9) alongside histological and histomorphometrical abnormalities. Nevertheless, RUT prevented all the aberrations caused by HCB. Our result showed that HCB induced reproductive toxicity in rats and RUT protected against HCB-induced r reproductive toxicity.

The aim of this study was to determine pesticide residues in milk and dairy product samples from Tehran, Iran. A total of 50 samples (raw milk, ultra-high temperature milk, pasteurised milk, pasteurised and traditional butter, and pasteurised and traditional cheese) were randomly collected from June to August 2022, and their pesticide contents were examined through high-performance liquid chromatography. Out of the 50 samples, 38, 42, and 100% contained cypermethrin, deltamethrin, and hexachlorobenzene over the maximum residue limit set by the EU, respectively. Traditional butter had Cypermethrin and hexachlorobenzene means concentration of 75.64 ± 22.40 and 61.69 ± 17.78 µg/kg, respectively. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed amination of 1,2,4,5-tetrachlorobenzene with morpholine or pyrrolidine in the presence of 2-dicyclohexylphosphino-2'-(dimethylamino)biphenyl (DavePhos, the Buchwald ligand) afforded the corresponding 2,4,5-trichloroaniline derivatives in moderate yields. In the cases of hexachlorobenzene as well as other Buchwald ligands, the amination products were formed in low yields and the process was accompanied by hydrodechlorination. [ABSTRACT FROM AUTHOR]

Rainbow trout (Oncorhynchus mykiss) was exposed through the diet to a mixture of non-ionic organic chemicals for 28 d, followed by a depuration phase, in accordance with OECD method 305. The mixture included hexachlorobenzene (HCB), 2,2′,5,5′-tetrachlorobiphenyl (PCB-52), 2,2′,5,5′-hexachlorobiphenyl (PCB-153), decachlorobiphenyl (PCB-209), decabromodiphenyl ether (BDE209), decabromodiphenyl ethane (DBDPE), bis-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH), perchloro-p-terphenyl (p-TCP), perchloro-m-terphenyl (m-TCP), and perchloro-p-quaterphenyl (p-QTCP), the latter six of which are considered highly hydrophobic based on n-octanol/water partition coefficients (KOW) greater than 108. All chemicals had first-order uptake and elimination kinetics except p-QTCP, whose kinetics could not be verified due to limitations of analytical detection in the elimination phase. For HCB and PCBs, the growth-corrected elimination rates (k2g), assimilation efficiencies (α), and biomagnification factors (BMFL) corrected for lipid content compared well with literature values. For the highly hydrophobic chemicals, elimination rates were faster than the rates for HCB and PCBs, and α's and BMFLs were much lower than those of HCB and PCBs, i.e., ranging from 0.019 to 2.8%, and from 0.000051 to 0.023 (g-lipid/g-lipid), respectively. As a result, the highly hydrophobic organic chemicals were found be much less bioavailable and bioaccumulative than HCB and PCBs. Based on the current laboratory dietary exposures, none of the highly hydrophobic substances would be expected to biomagnify, but Trophic Magnification Factors (TMFs) > 1 have been reported from field studies for TBPH and DBDPE. Additional research is needed to understand and reconcile the apparent inconsistencies in these two lines of evidence for bioaccumulation assessment. [ABSTRACT FROM AUTHOR]

The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl2-. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl2- formation can only occur in 1,2-C6H4Cl2, where the two closest C-Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C-Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation.

Persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (p,p'-DDT) were reported to influence immunological activity. As endocrine-disrupting chemicals (EDC), these pollutants may disrupt normal thyroid function and act as catalysts for development of autoimmune thyroid disease by directly and indirectly affecting levels of thyroid peroxidase antibodies (TPOAbs). Native American communities are disproportionately exposed to harmful toxicants and are at an increased risk of developing an autoimmune disease. The aim of this study was to determine the association between POPs and TPOAbs in serum obtained from Native American women. This assessment was used to measure whether increased risk of autoimmune thyroid disease occurred as a result of exposure to POPs. Data were collected from 183 Akwesasne Mohawk women, 21–38 years of age, between 2009 and 2013. Multivariate analyses were conducted to determine the association between toxicant exposure and levels of TPOAbs. In multiple logistic regression analyses, exposure to PCB congener 33 was related to elevated risk of individuals possessing above normal levels of TPOAbs. Further, HCB was associated with more than 2-fold higher risk of possessing above normal levels of TPOAbs compared to women with normal levels of TPOAbs. p,p'-DDE was not associated with TPOAb levels within this study. Exposure to PCB congener 33 and HCB was correlated with above normal levels of TPOAbs, a marker of autoimmune thyroid disease. Additional investigations are needed to establish the causes and factors surrounding autoimmune thyroid disease which are multiple and complex. [ABSTRACT FROM AUTHOR]

Results of a 2019 human biomonitoring study indicated that several parameters, including lead, cobalt, manganese, and hexachlorobenzene, were elevated in blood and urine samples in Old Crow, Yukon, in comparison to the general Canadian population. This study aims to identify possible local determinants of levels of these parameters, including consumption of locally harvested traditional foods, lifestyle factors, and demographics, in Old Crow and, for comparison, two other northern populations: communities in the Dehcho and Sahtú regions of the Northwest Territories. We ran generalized linear models to identify possible associations between individual determinants of exposure and key biomarkers, controlling for age and sex. In Old Crow, several variables were associated with elevated exposure levels of these biomarkers, including drinking untreated river water (29% higher blood manganese levels and 120% higher blood lead levels), eating caribou kidneys (22% higher blood manganese levels and 58% higher blood lead levels), and eating whitefish (28% higher blood cobalt levels). Additionally, in order to differentiate results in Old Crow from those in other northern regions and to identify trends across regions, we observed relationships between consumption of moose and caribou organs and lead and hexachlorobenzene levels in the reference populations and pooled population groups. Though levels of particular contaminants may be elevated in some traditional foods, these foods remain an important source of nutrients for members in these communities and provide other benefits, including increased physical activity through harvesting, mental health improvements, and spiritual wellness. [ABSTRACT FROM AUTHOR]

Although organochlorine pesticides (OCPs) in the Stockholm Convention List were banned for a period of time, the residue of OCPs in environment was still detected recently. Therefore, the continuous environmental monitoring was necessary and important for the deep understanding on the temporal trend of environmental fate of OCPs. In this study, the national scale surface soil samples in 26 provinces of China in 2012 were collected, and 28 OCPs were analyzed. The mean concentrations (ng/g dw) of Σhexachlorocyclohexanes (HCHs), Σdichlorodiphenyltrichloroethane (DDTs), hexachlorobenzene (HCB), and hexachlorobutadiene (HCBD) were 2.47 ± 5.4, 4.29 ± 8.28, 3.33 ± 7.68, and 0.041 ± 0.097, respectively. The correlations between OCPs concentrations with temperature, latitude, and longitude were conducted for the deep study of the spatial distribution pattern of OCPs. It was found that HCHs, HCB, and HCBD are positively correlated with latitude and longitude; however, the correlations were not significant. HCHs followed the secondary distribution pattern, and DDTs followed both the primary and/or secondary distribution patterns. Except for HCB, other OCPs showed a gradual downward trend from 2005 to 2012, indicating the effectiveness of the phase-out of OCPs. In summary, the results of the study provided new insight into the related studies, which will help us to better understand the long-term environmental fate of OCPs on large scales. [ABSTRACT FROM AUTHOR]

Detector response of 12 chlorobenzenes was investigated (mono-, di-, tri-, tetra-, penta-, and hexachlorobenzene, CBs) using flame ionization detector in a capillary gas chromatographic system. We determined the signal-reducing effect of the chlorine atom on the aromatic ring relative to the number of the chlorine substituents and expressed with the effective carbon number (ECN). Benzene was applied as a reference substance. Using the signal-modifying pattern of the chlorine atoms on the benzene's response, we developed an alternative calibration measurement method (CBs-ECN method) for the 12 CBs and compared it with classic calibration. The differences in the concentrations calculated by the two quantitative methods were under 4.5% for 11 CBs and 7% for one compound. Taking advantage of the opportunities provided by the CBs-ECN pattern it is not necessary to apply all of the 12 CBs but only one single component, the hexachlorobenzene for the calibration. With this simplification, the preparation of the calibration standards is faster, does not require purchasing all 12 CBs for each subsequent calibration, and the exposure to harm and expenses are reduced. [ABSTRACT FROM AUTHOR]

(1) Background: Hexachlorobenzene (HCB) is a persistent organic pollutant that is possibly carcinogenic to humans. It is still found in the environment, humans and animals, and in foods, including milk and dairy products; (2) Methods: The influence of the probiotic cultures Lacticaseibacillus rhamnosus LCR and Lactiplantibacillus plantarum subsp. plantarum LP on the possibility of effecting the biodegradation of HCB in dairy products fermented from mare milk was investigated, taking into account the product storage time (maximum 21 days). HCB content was determined using the GC/MS method; (3) Results: A strong negative Pearson correlation (p < 0.05) was found between HCB concentration and the refrigeration storage time of the fermented beverages. The highest HCB reduction was observed in milk fermented with both Lacticaseibacillus rhamnosus LCR and Lactiplantibacillus plantarum subsp. plantarum LP (78.77%), while the lowest was noted when only Lactiplantibacillus plantarum subsp. plantarum LP was used (73.79%); (4) Conclusions: This pilot study confirmed that probiotics commonly used to give products health-promoting properties can also contribute to reducing the content of undesirable substances, and the bacterial cultures used might provide an alternative method for reducing HCB residues in fermented drinks.

It is well known that many chlorinated organic pollutants can be dechlorinated by nanoscale zero-valent iron. However, in the real chlorinated organic compounds contaminated soil, the congeners of high- and low-chlorinated isomer often coexist and their dechlorination behaviors are poorly known, such as hexachlorobenzene (HCB). In this work, the degradation behaviors of three coexisting chlorobenzene congeners pentachlorobenzene (PeCB), 1,2,4,5-tetrachlorobenzene (1,2,4,5-TeCB) and 1,2,4-trichlorobenzene (1,2,4-TCB) and the influence of initial pH and reaction temperature on the dechlorination of HCB in HCB-contaminated soil by nanoscale zero-valent iron were studied. The amount and extent of accumulated coexisting chlorobenzenes was analyzed under different environmental conditions. The results indicate that nanoscale zero-valent iron can improve the degradation efficiency of highly toxic chlorinated benzenes and reduce the accumulative effects of highly toxic chlorinated benzenes on dechlorination of HCB. The accumulative effects of three coexisting chlorobenzene congeners on the dechlorination of HCB were ranked as follows: 1,2,4-TCB > 1,2,4,5-TeCB > PeCB. [ABSTRACT FROM AUTHOR]

To obtain the distribution behavior and dietary risk of pesticide residues in different parts of ginseng (Panax ginseng C. A. Mey), two-, three- and four-year-old ginseng from Jidong city and two-, three-, four-, five- and six-year-old ginseng from Hulin city, Heilongjiang Province, were sampled. Gas chromatography-mass spectrometry (GC-MS) method was established for the determination of pentachloronitrobenzene, hexachlorobenzene and chlorpyrifos residues in root-heads, taproots and fibrous roots of ginseng, and the short-term dietary risks of all samples were evaluated. The detection rate of pentachloronitrobenzene was 74% of total 72 ginseng samples, and the detected residues were0.005-0.062 mg/kg. The detection rate of hexachlorobenzene was 78%, and the residues were 0.057- 0.150 mg/kg. The detection rate of chlorpyrifos was 61%, and the detected residues were 0.018-0.073 mg/kg. According to the Chinese Pharmacopoeia (2020), the maximum residue limit (MRL) of pentachloronitrobenzene and hexachlorobenzene was 0.1 mg/kg. Among the detected samples, the residues of hexachlorobenzene in five- and six-year-old ginseng root-heads and the six-year-old ginseng taproots from Hulin city exceeded the MRL, with the exceeding rates of 2.8%, 5.6% and 2.8%, respectively. The pesticide residues increased with the increase of growth year of ginseng. The accumulated pesticide residues in various parts of ginseng from high to low were root-heads, taproots and fibrous roots. The short-term risk quotient (RQST) was far less than 100%, which indicated that there was no unacceptable short-term dietary exposure risk to human body via ginseng. [ABSTRACT FROM AUTHOR]

Bioremediation measures to restore soil ecosystems are environmentally safe, promising and relevant. Soil ecosystems contaminated with hexachlorobenzene require remediation measures. Studying the effectiveness of applying the microbial remediator Comamonas testosteroni UCM B-400, phytoremediator Zea mays L. cultivar Olena and microbial and phytoremediation complex to remove hexachlorobenzene contamination was carried out. The HCB content was determined by chromatographic method, the microbial groups reactions to application of various remediators in the soil were studied by classical microbiological methods. The results showed that the most effective is the complex using remediators Comamonas testosteroni UCM B-400 and Zea mays L. cultivar Olena, where HCB content was reduced to 82%.

Hexachlorobenzene (HCB), a representative of hydrophobic organic chemicals (HOC), belongs to the group of persistent organic pollutants (POPs) that can have harmful effects on humans and other biota. Sorption processes in soils and sediments largely determine the fate of HCB and the risks arising from the compound in the environment. In this context, especially HOC–organic matter interactions are intensively studied, whereas knowledge of HOC adsorption to mineral phases (e.g., clay minerals) is comparatively limited. In this work, we performed batch adsorption experiments of HCB on a set of twelve phyllosilicate mineral sorbents that comprised several smectites, kaolinite, hectorite, chlorite, vermiculite, and illite. The effect of charge and size of exchangeable cations on HCB adsorption was studied using the source clay montmorillonite STx-1b after treatment with nine types of alkali (M+: Li, K, Na, Rb, Cs) and alkaline earth metal cations (M2+: Mg, Ca, Sr, Ba). Molecular modeling simulations based on density functional theory (DFT) calculations to reveal the effect of different cations on the adsorption energy in a selected HCB-clay mineral system accompanied this study. Results for HCB adsorption to minerals showed a large variation of solid–liquid adsorption constants Kd over four orders of magnitude (log Kd 0.9–3.3). Experiments with cation-modified montmorillonite resulted in increasing HCB adsorption with decreasing hydrated radii of exchangeable cations (log Kd 1.3–3.8 for M+ and 1.3–1.4 for M2+). DFT calculations predicted (gas phase) adsorption energies (− 76 to − 24 kJ mol−1 for M+ and − 96 to − 71 kJ mol−1 for M2+) showing a good correlation with Kd values for M2+-modified montmorillonite, whereas a discrepancy was observed for M+-modified montmorillonite. Supported by further calculations, this indicated that the solvent effect plays a relevant role in the adsorption process. Our results provide insight into the influence of minerals on HOC adsorption using HCB as an example and support the relevance of minerals for the environmental fate of HOCs such as for long-term source/sink phenomena in soils and sediments. [ABSTRACT FROM AUTHOR]

The fate of chemical pollutants in the environment is determined by various factors including the type and strength of their interactions with reactive surfaces in soils and sediments. In the present work the interactions of hexachlorobenzene (HCB) with the surface of a common clay mineral belonging to the smectite group montmorillonite (MNT) is studied by means of the density functional theory method. The MNT net surface charge, induced by isomorphic substitutions, is systematically varied and compensated by Ca 2 + cations. Based on the calculated electron densities, conclusions are drawn revealing the nature of their mutual interactions, the related stability of such surface complexes as well as possible molecular arrangements. It becomes apparent that the dominant contribution to the stability of HCB-MNT complexes arises from the cation- π interactions between the HCB molecule and the nearest compensating Ca 2 + cation and thus besides the MNT net surface charge the type and size of the compensating cations are expected to play a crucial role in understanding the HCB adsorption on MNT. This systematic study aims to contribute to a better mechanistic understanding of the interactions between hydrophobic organic compounds and reactive mineral surfaces. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of aromatic organic pollutants such as hexachlorobenzene, decachlorobiphenyl, benzene, and biphenyl by 2D nanomaterials was investigated using quantum chemical methods. The calculation results include reaction enthalpies, non-covalent intermolecular and intramolecular interactions, optimized structures, hydrogen bonds, and molecular electrostatic potentials. Fukui's FMO electrophile sensitivity is used to predict the most reactive positions on the chemical species for both nucleophilic and electrophilic roles. The results of hard–soft acid-base reactivity descriptors show that the electronic structures of BN-doped graphene and C-doped hexagonal boron nitride depend on the degree of doping and the modification of β-cyclodextrin. C doping helps to significantly improve the conductivity of h-BN, and β-cyclodextrin enhances the binding stability of aromatic organic pollutants. Hydrogen bonding between β-cyclodextrin and chlorine-substituted compounds can enhance non-covalent interactions. In particular, the high adsorption capacity and electron transfer capacity of decachlorobiphenyl laid the foundation for the development of new sensors. [ABSTRACT FROM AUTHOR]

This present study was designed to investigate ameliorating potential of thymol (THY) on hexachlorobenzene (HBC)-induced epididymal and testicular toxicities in adult male rats. Forty adult male rats were orally treated by gavage daily for 28 consecutive days and divided into four groups; control group administered with corn oil, HBC-treated group (16 mg/kg b. wt), thymol-treated group (30 mg/kg b. wt), and HBC + THY-treated group. The results revealed that HBC exposure caused a significant decrease in the body weight change, organ weights, sperm functional parameters, serum testosterone level with widespread histological abnormalities. Furthermore, HBC-treated rats showed increased in the serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH), epididymal and testicular myeloperoxidase activity, tumor necrosis-α, interleukin-1β level and caspase-3 activity, induced oxidative damage as evidenced by elevated malondialdehyde (MDA), reactive oxygen species (RONS) levels and significant reduction in antioxidant enzyme activities and reduced glutathione (GSH). However, co-treatment of THY with HBC alleviated the HBC-induced epididymal and testicular toxicities. Our findings revealed that HBC acts as a reproductive toxicant in rats and thymol could be a potential remedial agent for HBC-induced reproductive toxicity. [ABSTRACT FROM AUTHOR]

This study investigated the degradation of two chlorothalonil formulations [Chlorcal 70% Wettable Powder (WP) and Open 72% Suspension Concentrate 72% (SC)]. The tested fungicides were stored at 54 ± 2°C for 14 days. During the different storage periods, samples were taken after 1, 3, 7, and 14 days to determine physical properties, evaluate the chemical stability of the active ingredient: Hexachlorobenzene as impurities by HPLC and fingerprint (GC/MS and IR), as well as the evaluation of their efficacy, by testing them against the mycelial growth of Fusarium solani and Botrytis cinerea under in vitro condition. The results indicated that Open 72% SC was the most effective fungicide against F. solani and B. cinerea it recorded the lowest EC50 value of 28.4 and 46.8 ppm respectively, followed by Chlorcal 70%WP with EC50 values of 42.9 and 59.4 ppm respectively. On the other hand, the effectiveness of tested fungicides deteriorated as the result of storage at 54 ± 2 °C for 14 days with EC50 values increased from 28.4 to 130.9 and 46.8 to 278.1 in the case of Open 72% SC against F. solani and B. cinerea respectively, while the degradation efficiency of Chlorcal 70%WP was decreased at storage with EC50 values from 42.9 to 89.4 and 59.4 to 145.3 against these two fungi respectively. Chlorcal 70%WP was more stable at during storage and less effective against fungal pathogens and determination of chemical content (total soluble sugar; total protein; free amino acids) and some enzymes (amylase and catalase) activities of mycelium fungi. Potato dextrose (PD) media treated with chlorothalonil formulations induced a significant decrease in all components in each fungus except the catalase enzyme in the case of B. cinerea. The obtained results showed that active ingredients were 69.82%, 71.9% and reached 69.3%, and 70.75% after 14 days of storage at 54 ± 2 °C for Chlorcal 70% WP, Open 72% SC, respectively. Also calculated half-life (T0.5) values for Chlorcal 70% WP, Open 72% SC were 1382.07 days and 614.035 days, respectively. This result refers that Chlorcal 70% WP is more stable than Open 72% SC after storage at 54 ± 2 oC for 14 days, whereas the amount of hexachlorobenzene was within the FAO limits for all sources before and after storage. Then the other tested GC / MS was used for the degradation of chlorothalonil fungicide, the two major degradation products in chlorothalonil were 2,5,6-trichloro-4-hydroxyisophthalonitrile and 2,4,6-trichloroisophthalonitrile. [ABSTRACT FROM AUTHOR]

Several reports have shown that nanomaterials have been found to be effective for gas sensing application and the adsorption of hazardous organochloride. Herein, dispersion corrected density functionals; D3-B3LYP-D3, ωB97XD, M06-2X and PBE0 all at the 6-311G (d) basis set was used to study the interactions of metal-doped fullerenes (silicon (C59Si) and germanium (C59Ge)) with Hexachlorobenzene (C6Cl6) gas molecule. The adsorption properties of the adsorbents viz; the pure fullerene nanocage (C60) and the doped system; Silicon (C59Si) and Germanium (C59Ge) were all investigated in terms of reactivity, stability, bond order, intermolecular interaction, van der waals, and weak interaction as well as adsorption energy. The reactivity levels of the examined surfaces were observed within the same range at the B3LYP-D3/6-311G (d) level of theory to be 5.996 eV, 5.309 eV, and 5.188 eV for C60, C59Si and C59Ge adsorbents respectively. From our calculation for adsorption energies; the high negative value -1.010 eV of for the C59Ge nanocage suggests that the doped surface adsorbs hexachlorobenzene better in comparison to the other surfaces and adsorption is thermodynamically favored. The results for natural bond orbitals (NBO), quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) were consistent across all systems and favored physical adsorption.

Studies have shown the negative effects of organochlorine pesticide (OCP) exposure on humans, but few studies focus on the transmission of OCPs to the foetus during pregnancy and the effects of prenatal exposure on the newborn. In this study, maternal and cord blood samples were collected at deliveries and the prenatal exposures of OCPs were investigated. OCPs, analysed in the samples, were hexachlorobenzene (HCB), p,p'dichlorodiphenyldichloroethylene (p,p'DDE), o,p′dichlorodiphenyltrichloroethane (o,p'DDT) and p,p′dichlorodiphenyltrichloroethane (p,p′DDT). A statistically significant difference of OCPs concentration between the cord and maternal blood was not observed (respectively; p = 0.372; 0.441; 0.379; 0.611). In other words, it was found that OCPs in mothers were transferred to the newborns through cord blood. Besides, the effects of OCPs exposure on newborns were investigated and the method of delivery was marginally associated with o,p'-DDT concentration. Maternal OCPs residue levels measured in this study were positively correlated with concentrations measured in the umbilical cord blood suggesting that these OCPs were transferred to the foetus. [ABSTRACT FROM AUTHOR]

The present study investigated the individual and collective effect of organochlorinated fungicide hexachlorobenzene (HCB) and manganese (Mn), a metal, on the hepatorenal function in adult rats. Rats were divided into four groups of rats comprising of control, HCB alone (15 mg/kg), Mn alone (10 mg/kg) and co-exposure group that were orally treated for 25 consecutive days. After sacrifice, hepatorenal damage and antioxidant status markers, myeloperoxidase (MPO) activity, levels of nitric oxide, total antioxidant capacity (TAC), total oxidative stress (TOS) and lipid peroxidation (LPO) were analyzed spectrophotometrically. Levels of tumor necrosis factor alpha (TNF-α), interleukin-1 β (IL-1β) and caspase-3 activity were assessed using ELISA. Results revealed that the HCB administration significantly (p < 0.05) increased the biomarkers of hepatorenal toxicity, decreased the antioxidant status and TAC, raised the levels of TOS and LPO as well as increased the levels of TNF-α, IL-1β and caspase-3 activity. Rats co-exposed to HCB and Mn showed decreased biomarkers of hepatorenal damage, increased antioxidant status and TAC with simultaneous reduction in the levels of TOS and LPO significantly (p < 0.05). Furthermore, the increased levels of TNF-α, IL-1β and caspase-3 activity were significantly (p < 0.05) reduced in the liver and kidney of rats' co-expose to HCB and Mn. Histological examination showed that damages induced by HCB were assuaged in rats co-treated with HCB and Mn. In conclusion, the results demonstrated that co-treatment of HCB and Mn in rats' alleviated HCB-induced oxidative stress, inflammation and caspase-3 activation in the liver and kidney of the rats. [ABSTRACT FROM AUTHOR]

Background: The bacterial destructing activity toward pesticides has been the focus of research in the last few decades. Hexachlorobenzene is included in the organochlorine pesticides group that are prohibited for use. However, large hexachlorobenzene amounts are still concentrated in the soil, stressing the relevance of research on hexachlorobenzene-destroying bacteria. Methods: The ability to destroy hexachlorobenzene by Comamonas testosteroni UCM B-400, B-401, B-213 strains was investigated and established. Bacteria were cultivated (7 days at 28 °C) in mineral Luria-Bertrani (LB) medium with three hexachlorobenzene doses: 10, 20, 50 mg/L. The hexachlorobenzene concentrations were recorded by a gas chromatography method. Results: The results showed that C. testosteroni UCM B-400, B-401 have high destructive activity toward hexachlorobenzene. The highest (50 mg/L) initial concentration decreased to 41.5 and 43.8%, respectively, for C. testosteroni UCM B-400, B-401. The unadapted C. testosteroni UCM B-213 was tolerant to hexachlorobenzene (cell titers after cultivating with 10.0, 20.0, 50.0 mg/mL were higher compared to initial titer), but had a low-destructing activity level (two times less than B-400 and B-401). Conclusions: Bacterial strains C. testosteroni UCM B-400, B-401 can be seen as a potential soil bioremediation from hexachlorobenzene pollution. [ABSTRACT FROM AUTHOR]

Environmental pollutants and climate change are the major cause of abiotic stresses. Hexachlorobenzene (HCB) is an airborne and aero-disseminated persistent organic pollutants (POP) molecule causing severe health issues in humans, and temperature extremes and HCB in combination severely affect the growth and yield of crop plants around the globe. The higher HCB uptake and accumulation by edible plants ultimately damage human health through the contaminated food chain. Hence, confining the passive absorbance of POPs is a big challenge for researchers to keep the plant products safer for human consumption. BioClay functional layered double hydroxide is an effective tool for the stable delivery of acidic molecules on plant surfaces. The current study utilized gibberellic acid (GA3) impregnated BioClay (BioClayGA) to alleviate abiotic stress in Brassica alboglabra plants. Application of BioClayGA mitigated the deleterious effects of HCB besides extreme temperature stress in B. alboglabra plants. BioClayGA significantly restricted HCB uptake and accumulation in applied plants through increasing the avoidance efficacy (AE) up to 377.61%. Moreover, the exogenously applied GA3 and BioClayGA successfully improved the antioxidative system, physiochemical parameters and growth of stressed B. alboglabra plants. Consequently, the combined application of BioClay and GA3 can efficiently alleviate low-temperature stress, heat stress, and HCB toxicity. [ABSTRACT FROM AUTHOR]

The species of Comamonas testosteroni is the most common human pathogen of the genus, which can be associated with acute appendicitis, infections of the bloodstream, the peritoneal cavity, cerebrospinal fluid, inflammatory bowel disease, and in general, bacteremia. According to the literature, Comamonas testosteroni has destructive activity to a wide range of toxic chemical compounds, including chlorobenzenes. The specified strains were isolated from the soil of the organochlorine waste landfill, where hexachlorobenzene (HCB) was predominant. These strains were expected to be capable of degrading HCB. Microbiological (bacterial enrichment and cultivating, bacterial biomass obtaining), molecular biology, biochemical (enzymatic activities, malondialdehyde measuring, peroxidation lipid products measuring), and statistical methods were carried out in this research. The reaction of both strains (UCM B-400 and UCM B-401) to the hexachlorobenzene presence differed in the content of diene and triene conjugates and malondialdehyde, as well as different catalase and peroxidase activity levels. In terms of primary peroxidation products, diene conjugates were lower, except conditions with 20 mg/L HCB, where these were higher up to two times, than the pure control. Malondialdehyde in strain B-400 cells decreased up to five times, in B-401, but increased up to two times, compared to the pure control. Schiff bases in strain B-400 cells were 2–3 times lower than the pure control. However, in B-401 cells Schiff bases under higher HCB dose were in the same level with the pure control. Catalase activity was 1.5 times higher in all experimental variants, compared to the pure control (in the strain B-401 cells), but in the B-400 strain, cells were 2 times lower, compared to the pure control. The response of the two strains to hexachlorobenzene was similar only in peroxidase activity terms, which was slightly higher compared to the pure control. The physiological response of Comamonas testosteroni strains to hexachlorobenzene has a typical strain reaction. The physiological response level of these strains to hexachlorobenzene confirms its tolerance, and indirectly, the ability to destroy the specified toxic compound. [ABSTRACT FROM AUTHOR]

Bioremediation measures to restore soil ecosystems are environmentally safe, promising and relevant. Soil ecosystems contaminated with hexachlorobenzene require remediation measures. Studying the effectiveness of applying the microbial remediator Comamonas testosteroni UCM B-400, phytoremediator Zea mays L. cultivar Olena and microbial and phytoremediation complex to remove hexachlorobenzene contamination was carried out. The HCB content was determined by chromatographic method, the microbial groups reactions to application of various remediators in the soil were studied by classical microbiological methods. The results showed that the most effective is the complex using remediators Comamonas testosteroni UCM B-400 and Zea mays L. cultivar Olena, where HCB content was reduced to 82%. [ABSTRACT FROM AUTHOR]

The kinetic reactions of hexachlorobenzene (HCB) and coexisting chlorobenzene congeners in real HCB-contaminated soil and effects of environmental factors on degradation rate, such as solid-liquid ratio, pH and incubation temperatures, were investigated. The Monod model was adopted for the kinetic study and the related kinetic parameters were evaluated. The Monod model showed good fitness for HCB degradation, not for coexisting chlorobenzene congeners. For pentachlorobenzene (PeCB), 1,2,4,5-tetrachlorobenzene(1,2,4,5-TeCB) and 1,2,4-trichlorobenzene(1,2,4-TCB), the calculated value of average degradation rate may not be “positive” or “negative” invariably, depending on production and degradation of these halogenated organic compounds. For HCB, a maximum degradation rate constant of 0.0359 d−1 and half-life time of 19.3 d were achieved, respectively. The hydrogen ion played the most important role in degradation of four chlorobenzenes. However, this role could be weakened if the solubility of compound was considered. Also, the results showed that the initial weak acid to neutral pH (5 – 7) environment with the incubation temperature of 45 °C was favorable for the rapid kinetic degradation of chlorobenzenes and the removal of chlorobenzenes was evaluated to reach 46%. This study offers direct kinetic behaviors and environmental factors analysis of the biodegradation process of HCB and coexisting chlorobenzene congeners, and is beneficial to explored the potential of optimized anaerobic microbial degradation for remediation engineering of chlorobenzenes contained soil.

The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl2−. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl2− formation can only occur in 1,2-C6H4Cl2, where the two closest C–Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C–Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation. [ABSTRACT FROM AUTHOR]

In the last century, many Mediterranean coastal areas have been subjected to anthropogenic disturbances from industrial activities, uncontrolled landfills, shipyards, and high maritime traffic. The Augusta Bay (eastern Sicily, Italy) represents an example of a strongly impacted coastal environment with an elevated level of sediments contamination due to the presence of one of the largest European petrochemical plants, combined with an extensive commercial and military harbor. The most significant contaminants were represented by mercury (Hg) and hexachlorobenzene (HCB), derived from a former chlor-alkali plant, and other organic compounds like polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs). Since the 1970s, Augusta Bay has become internationally recognized as a contaminated marine environment, although very little information is available regarding the temporal trend of contaminants bioavailability and biological impacts on aquatic organisms. In this study, the Hg and HCB concentrations were investigated over 10 years (from 2003 to 2013) in sediments and invertebrate and vertebrate organisms; these two contaminants' ecotoxicity was further evaluated at a biochemical and cellular level by analyzing the induction of organic biotransformation processes and DNA damages. The results showed high concentrations of Hg and HCB in sediments and their strong bioaccumulation in different species with significantly higher values than those measured in reference sites. This trend was paralleled by increased micronuclei frequency (DNA damage biomarker) and activity of the biotransformation system. While levels of chemicals in sediments remained elevated during the time course, their bioavailability and biological effects showed a gradual decrease after 2003, when the chlor-alkali plant was closed. Environmental persistence of Hg and HCB availability facilitates their bioaccumulation and affects the health status of marine organisms, with possible implications for environmental risk, pollutants transfer, and human health.

Based on the analysing phenotypic and genotypic properties, the taxonomic position of isolates # 46 and # 47 was established and assigned to the species Comamonas testosteroni UCM B-400 and UCM B-401. Isolates were selected from the soil with organochlorine wastes landfill of chemical enterprises in Kalush, Ivano-Frankivsk region, Ukraine. The strains are resistant to high hexachlorobenzene concentrations. According to morphological, cultural and biochemical properties, the studied strains are related to typical members of the Comamonadaceae family, they are motile gram-negative rods, aerobic, chemoorganotrophic. Saturated and unsaturated fatty acids with a carbon chain length from C10 to C18 were found in composition of cellular lipids. The qualitative and quantitative composition of marker hydroxy acids, namely: 2 hydroxyhexadecane (C16: 0 2OH) and 3 hydroxydecane (C10: 0 3OH) in the lipids of the strains ranged from 2-5%, which corresponded to their content in the representatives of the Comamonas genus. Phylogenetic analysing the nucleotide sequences of the 16S rRNA gene revealed the affinity of isolates # 46 (97.77%) and # 47 (98.05%) with a similar nucleotide sequence of a typical strain of Comamonas testosteroni LMG 1800. The 16S rRNA nucleotide sequences of Comamonas testosteroni UCM B-400 and UCM B-401 were placed in GenBank under the numbers SUB9376895 Comamonas_testosteroni_46 MW861636 and SUB9376895 Comamonas_testosteroni_47 MW861637. [ABSTRACT FROM AUTHOR]

Environmental hexachlorobenzene (HCB) increases blood pressure (BP) in female rats, causing alterations in arterial structure and function. Here we study the role of Angiotensin II receptor type 1 (AT1) in HCB-induced hypertension through the use of AT1 antagonist losartan.HCB-treated male rats showed a 22.7% increase in BP which was prevented by losartan. Losartan blocked HCB-induced changes in arterial morphology (decreased aorta cell number and increased wall thickness). Losartan also prevented HCB-induced alterations in artery relaxation by acetylcholine and nitroprusside but not the reduction in the maximum contraction by phenylephrine. Losartan rescued arterial molecular alterations caused by HCB (i.e. an increase in TGF-β1 and AT1 expression and a decrease in eNOS expression and nitrite levels) and reduced hydrogen sulfide plasma concentration.In conclusion: in this work we demonstrate that AT1 activity is involved in HCB effects on the vascular system leading to hypertension.

Marine protected areas (MPAs) are zones geographically delimited under pre-defined management goals, seeking to reduce anthropogenic threats to biodiversity. Despite this, in recent years reports of MPAs affected by chemical contamination has grown. Therefore, this study addresses this critical issue assessing legacy and current chemical contamination in filter-feeder bivalves obtained in very restrictive no-take MPAs from Brazil. The detected pollutants encompass polycyclic aromatic hydrocarbons (PAHs), linear alkylbenzenes (LABs), and persistent organic pollutants (POPs) like dichlorodiphenyltrichloroethane (DDTs) and polychlorinated biphenyls (PCBs). Despite protective measures, bivalves from nine MPAs exhibited high LABs (13.2–1139.0 ng g−1) and DDTs levels (0.1–62.3 ng g−1). PAHs were present in low concentrations (3.1–29.03 ng g−1), as PCBs (0.7–6.4 ng g−1), hexachlorobenzene (0.1–0.2 ng g−1), and Mirex (0.1–0.3 ng g−1). Regardless of the sentinel species, MPAs and management categories, similar accumulation patterns were observed for LABs, DDTs, PAHs, and PCBs. Based on the limits proposed by Oslo Paris Commission, the measured levels of PAHs, PCBs and were below the environmental assessment criteria. Such findings indicate the no biological effects are expected to occur. However, they are higher considering background conditions typically measured in remote or pristine areas and potential simultaneous exposure. Such findings indicate an influence of anthropogenic sources, emphasizing the urgency for monitoring programs guiding strategic management efforts to safeguard these areas. [Display omitted] • Contaminants were assessed in bivalves from no-take Marine Protected Areas - MPAs. • Levels were below than ones able to induce deleterious effects, but above to background. • Similar levels were seen for different species, MPAs and management categories. • No-take MPAs of Brazil are under threat of legacy and current chemical contamination. • Monitoring programs assessing MPAs should be implemented, to guide decision-making. [ABSTRACT FROM AUTHOR]

The fate of chemical pollutants in the environment is determined by various factors including the type and strength of their interactions with reactive surfaces in soils and sediments. In the present work the interactions of hexachlorobenzene (HCB) with the surface of a common clay mineral belonging to the smectite group montmorillonite (MNT) is studied by means of the density functional theory method. The MNT net surface charge, induced by isomorphic substitutions, is systematically varied and compensated by Ca2+ cations. Based on the calculated electron densities, conclusions are drawn revealing the nature of their mutual interactions, the related stability of such surface complexes as well as possible molecular arrangements. It becomes apparent that the dominant contribution to the stability of HCB-MNT complexes arises from the cation-π interactions between the HCB molecule and the nearest compensating Ca2+ cation and thus besides the MNT net surface charge the type and size of the compensating cations are expected to play a crucial role in understanding the HCB adsorption on MNT. This systematic study aims to contribute to a better mechanistic understanding of the interactions between hydrophobic organic compounds and reactive mineral surfaces.

A new photocatalytic reactor with a thin-film TiO2 catalyst attached on the inner wall of quartz glass pipes under UV light radiation was assembled and applied for the removal of hexachlorobenzene (HCB) in water. The results indicated that the degradation effect of HCB was higher in the UV/photocatalytic system at lower flow velocities owing to the longer residence time. As the UV light intensity increased, the degradation efficiency of HCB was enhanced correspondingly. Moreover, an enhancement on the removal effect of HCB was observed with the addition of humic acid. It should be noted that the improvement extent of HCB removal rate was much higher at low humic acid concentration compared to that at higher humic acid concentration. The phenomenon can be ascribed to the photosensitization in the presence of suitable amount of humic acid in the photoreaction system. To further describe these effects, a mathematical model was developed and then verified with experimental data, which validated the predictive capability and demonstrated the removal ratio in terms of initial HCB concentration and UV light intensity. [ABSTRACT FROM AUTHOR]

• A combined additive was proposed to improve mechanochemical treatment (MCT) of HCB. • The combined additive of SiC + Fe resolved the problem of consuming SiC in MCT of HCB. • The generation of toxic products was completely avoided by using the combined additive. • Fe can overwhelmingly compete against SiC to react with Cl radicals shed from HCB. • The combined additive could further accelerate MCT reaction than single SiC additive. Mechanochemical treatment (MTC) with SiC as an additive possessed a good performance on the degradation of hexachlorobenzene (HCB). However, this method consumed the additive of SiC and generated a toxic product of CCl 4. This work attempted to add another additive, iron powder, to the MCT and explored the performance of the combined additive of SiC + Fe to solve this problem. Result indicated that CCl 4 was not produced and SiC was not consumed when Fe was added in proper proportion. Compared with the single additive of SiC, the addition of Fe can further accelerate the degradation of HCB. The reaction pathway was proposed as: HCB can be mostly dechlorinated after a duration of MCT, and only trace-level low chlorobenzenes were generated under the effect of the combined additive. The left benzene skeletons can be broken to produce graphite and amorphous carbon. The shedding Cl radicals preferentially reacted with Fe to form FeCl 3 , and the reaction between Cl radicals and SiC and its toxic products can be avoided. Free electrons generated from the additive of SiC, fast reaction between Cl and Fe, and sparks in the MCT were considered the potential factors to accelerate the HCB degradation in MCT. [ABSTRACT FROM AUTHOR]

The study of cross-coupling between hexachlorobenzene and phenylboronic acid comprised five Buchwald ligands, from which 2-dicyclohexylphosphino-2′-(dimethylamino)biphenyl (DavePHOS) provided the best conversion. When excess of phenylboronic acid was used, a mixture of isomeric tri-, tetra- and pentaphenyl-substituted derivatives in the ∼10:70:20 ratio was obtained, along with minor amounts of hydrodechlorination products. [ABSTRACT FROM AUTHOR]

Organochlorines (OCs) are groups of highly toxic pesticides with known immunotoxicity. The present work aimed to study the potential association between serum residues of OCs and the risk of developing systemic lupus erythematosus (SLE) as well as correlating to the clinical-laboratory manifestations in a sample of Egyptian SLE patients. A cross-sectional study was conducted on 132 patients environmentally exposed to OCs. Patients were diagnosed as SLE based on the American College of Rheumatology (ACR) revised criteria. Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) score was calculated to stratify the disease severity. Blood and urine samples were collected to measure the levels of OCs, serological markers, and urinary protein. The most frequently detected OCs were p,p'- DDE; lindane; and hexachlorobenzene (HCB). The risk of developing SLE was significantly associated with detected p,p'- DDE and HCB (B value 7.704 and 14.33, respectively). Hexachlorobenzene, in addition, was significantly associated with increased SLEDAI-2K score and polycythemia. Lindane was significantly associated with hypocomplementemia, cardiac manifestations of SLE, anemia, and leucopenia. In conclusion, the detected OCs p,p'- DDE and HCB are associated with increased risk of SLE in Egyptian patients and correlates to the manifestations of disease severity. [ABSTRACT FROM AUTHOR]

Hexachlorobenzene is a widespread endocrine disruptor. However, the effect of hexachlorobenzene on the reproductive toxicity of male animals is not described in detail. To investigate the toxic effects of hexachlorobenzene in mouse testes, hexachlorobenzene (100, 400 and 1,600 mg/kg) is fed to mice. The morphology of the testes was analysed by haematoxylin and eosin staining. We also investigated the expression of biomarkers for oxidative stress. Database screening identified proteins that interact with hexachlorobenzene and the aryl hydrocarbon receptor, a weak ligand of hexachlorobenzene. Gene enrichment analysis and protein–protein interaction analyses were also performed. Real‐time PCR detected the expression levels of the aryl hydrocarbon receptor in four different stages of testicular cells. We identified significantly increased activity levels of superoxide dismutase (p < 0.05) and catalase (p < 0.05) in mouse testes that had been subjected to oxidative damage. The cell thickness and the number of cell layers in the seminiferous tubules had decreased by varying degrees after the hexachlorobenzene treatment. Particularly, cytokines and proteins involved in transcriptional regulation showed enrichment. The highest levels of aryl hydrocarbon receptor expression were detected in the spermatocytic cell line. Hexachlorobenzene exposure caused testicular damage in mice. The toxicity characteristics of hexachlorobenzene were not dose‐dependent. [ABSTRACT FROM AUTHOR]