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Common carp (Cyprinus carpio) is extensively cultured and widely consumed in Heilongjiang Province, China. Due to the proximity of freshwater ponds to agricultural cultivated areas, these aquatic systems are inevitably influenced by the historical application of organochlorine pesticides (OCPs), due to their prolonged half-life and resistance to degradation. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized to quantify the levels of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in the muscle tissue of cultured common carp. This study examined the enrichment characteristics of HCHs and DDTs in fish muscle, as well as their correlation with sediment and associated risk assessments. The results showed that the residual levels of HCHs and DDTs in fish muscle ranged from 0.387 μg·kg−1 to 3.418 μg·kg−1 and from 0.114 μg·kg−1 to 0.420 μg·kg−1, respectively. They were all below the maximum residue limits specified in GB 2763-2021 (HCHs: 100 μg·kg−1, DDTs: 500 μg·kg−1). The concentrations of HCHs and DDTs in sediment were found to be lower than those in muscle tissue. Notably, the concentrations of HCHs were higher than those of DDTs in both muscle and sediment. Among the HCHs, γ-HCH was the predominant residual substance, contributing a significant proportion of 42.16% to 86.47%. No significant residues of DDT derivatives were detected. A significant correlation was observed between the concentrations of HCHs and DDTs in the muscle tissue and those present in the sediment (p < 0.01). The health risk assessment indicated that both the carcinogenic and non-carcinogenic risks associated with OCPs from common carp muscle and sediment were within acceptable limits. Therefore, it was recommended to regulate fish consumption during the breeding period. [ABSTRACT FROM AUTHOR]

Haloalkane dehalogenase, LinB, is a member of the α/β hydrolase family of enzymes. It has a wide range of halogenated substrates, but, has been mostly studied in context of degradation of hexachlorocyclohexane (HCH) isomers, especially β-HCH (5–12% of total HCH isomers), which is the most recalcitrant and persistent among all the HCH isomers. LinB was identified to directly act on β-HCH in a one or two step transformation which decreases its toxicity manifold. Thereafter, many studies focused on LinB including its structure determination using X-ray crystallographic studies, structure comparison with other haloalkane dehalogenases, substrate specificity and kinetic studies, protein engineering and site-directed mutagenesis studies in search of better catalytic activity of the enzyme. LinB was mainly identified and characterized in bacteria belonging to sphingomonads. Detailed sequence comparison of LinB from different sphingomonads further revealed the residues critical for its activity and ability to catalyze either one or two step transformation of β-HCH. Association of LinB with IS6100 elements is also being discussed in detail in sphingomonads. In this review, we summarized vigorous efforts done by different research groups on LinB for developing better bioremediation strategies against HCH contamination. Also, kinetic studies, protein engineering and site directed mutagenesis studies discussed here forms the basis of further exploration of LinB’s role as an efficient enzyme in bioremediation projects. [ABSTRACT FROM AUTHOR]

The potential usage of activated carbon from plantain peel (Musa paradisiaca) (TPPC) and unactivated carbon from plantain peel (UPPC) for the removal of Hexachlorocyclohexanes (HCHs) from water systems was investigated. The TPPC and UPPC were characterized using Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Adsorption experiments were conducted as a function of adsorbent weight (2 – 10 g), temperature (30 -50 °C), and solution pH (2 - 9) under an adsorbent packed column. The Optimum removal efficiency of 98.23 % was achieved in the column studies under the following conditions: pH = 5, the dosage of adsorbent = 5 g/100 mL, temperature = 30 °C. The batch adsorption process was employed to evaluate the kinetics, equilibrium, and thermodynamics of the adsorption processes. The equilibrium study showed that Langmuir among other isotherm models applied performed better in fitting the data. Additionally, the kinetic data was best described by the pseudo-second-order model (R2 > 0.97), indicating a chemisorption mechanism. Furthermore, the thermodynamic calculations of the adsorption process suggest that HCH adsorption was exothermic (ΔH = -110.87) and spontaneous (-ΔG).

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.

Common carp (Cyprinus carpio) is extensively cultured and widely consumed in Heilongjiang Province, China. Due to the proximity of freshwater ponds to agricultural cultivated areas, these aquatic systems are inevitably influenced by the historical application of organochlorine pesticides (OCPs), due to their prolonged half-life and resistance to degradation. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized to quantify the levels of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in the muscle tissue of cultured common carp. This study examined the enrichment characteristics of HCHs and DDTs in fish muscle, as well as their correlation with sediment and associated risk assessments. The results showed that the residual levels of HCHs and DDTs in fish muscle ranged from 0.387 μg·kg−1 to 3.418 μg·kg−1 and from 0.114 μg·kg−1 to 0.420 μg·kg−1, respectively. They were all below the maximum residue limits specified in GB 2763-2021 (HCHs: 100 μg·kg−1, DDTs: 500 μg·kg−1). The concentrations of HCHs and DDTs in sediment were found to be lower than those in muscle tissue. Notably, the concentrations of HCHs were higher than those of DDTs in both muscle and sediment. Among the HCHs, γ-HCH was the predominant residual substance, contributing a significant proportion of 42.16% to 86.47%. No significant residues of DDT derivatives were detected. A significant correlation was observed between the concentrations of HCHs and DDTs in the muscle tissue and those present in the sediment (p < 0.01). The health risk assessment indicated that both the carcinogenic and non-carcinogenic risks associated with OCPs from common carp muscle and sediment were within acceptable limits. Therefore, it was recommended to regulate fish consumption during the breeding period.

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.

Purpose: Alkaline-thermal coupling activation of persulfate (PS) is an effective method for hexachlorocyclohexane (HCH) degradation. However, the process of this method requires high concentrations of NaOH and PS. Since HCH can be easily hydrolyzed into trichlorobenzene (TCB), in this study, we adopted the strategy of sequential addition of reagents (adding NaOH first and maintaining for 4 h before adding PS) and explored the effect of temperature and alkalinity on HCH hydrolysis and TCB oxidation, in order to develop a better degradation method for HCH which persists in the environment. Methods: Shake flask experiments were performed, which allowed for the examination of specific factors. The degradation of HCH was evaluated by measuring the concentrations of HCH and TCB during the reaction by gas chromatography. Results and discussion: It was found that high pH favored HCH hydrolysis but inhibited TCB oxidation. Almost no HCH degradation occurred under simultaneous addition (20 mM NaOH and 50 mM PS), while 80% of HCH was hydrolyzed within 4 h under sequential addition in soil. The results demonstrated that the concentration of alkali should be controlled and that sequential addition was more beneficial for the degradation of HCH, especially in the case of low alkali concentration. Moreover, the degradation efficiency was higher in soils with low soil organic matter (SOM) content, as SOM would affect PS and NaOH consumption and compete for radicals. Conclusion: This study provides practical information for future design of activated PS treatment for in situ remediation of HCH-contaminated environments. [ABSTRACT FROM AUTHOR]

Hexachlorocyclohexane (HCH) is one of the most widely used insecticides, which is included in the list of persistent organic pollutants. The genes involved in HCH degradation are known as lin genes. linA codes for the enzyme HCH dehydrochlorinase, which is a type of lyase dehalogenase and catalyzes the first step of dehydrochlorination of α-, γ- and δ-HCH. It is important to understand the phylogeny of lyase dehalogenases, as they are involved in the degradation of various xenobiotics. Lyase dehalogenases are underrepresented in the database. Homology search suggested that HCH dehydrochlorinase shares similarities with bile-acid 7-alpha dehydratase, scytalone dehydratase, ketosteroid isomerase, nuclear transport factor 2, and biphenyl 2,3 dioxygenase. This similarity is supported by secondary structure, homology modeling, and catalytic motif prediction. The catalytic site residues of HCH dehydrochlorinase are similar to bile-acid 7-alpha dehydratase and scytalone dehydratase. Dichloromethane dehalogenase shares homology with glutathione S-transferases and maleylacetoacetate isomerase. This similarity is further supported by the presence of similar glutathione binding sites and similar secondary structures. This study provides evidence that HCH dehydrochlorinase may have evolved from the enzymes having dehydratase activity and dichloromethane dehalogenase from the theta class of glutathione S-transferase. This study also identified key catalytic residues that can be mutated to make more efficient HCH and dichloromethane-degrading enzymes that can be used for enzymatic bioremediation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hexachlorocyclohexane (HCH) is a widely distributed organochlorine pesticide and a well-known endocrine modulator. The population residing near the lindane manufacturing plant and its dumping sites in Lucknow, India are at high risk of HCH exposure. METHODS: A cross-sectional study was designed to investigate the reproductive toxicity of HCH in 57 HCH exposed and 57 unexposed men in relation to oxidative stress (malondialdehyde [MDA], glutathione [GSH]), genetic alteration in SRY and AZF gene, semen quality and infertility. RESULTS: The mean blood HCH level and MDA level were found significantly higher (P<0.01) in the exposed group as compared to the unexposed group. However, antioxidant glutathione (GSH) levels and semen quality were found significantly lower (P<0.01) in the exposed group as compared to the unexposed group. The prevalence of infertility was found to be significant (P<0.05) in the exposed group. Multiple correlation analyses showed the significant impact of HCH isomers on semen quality and oxidative stress parameters (GSH and MDA). The odds ratio for semen volume (OR=9.37, P=0.01), sperm motility (OR=28.75, P<0.01), and sperm count (OR=21.40, P<0.01), GSH (OR=0.97, P=0.01) MDA (OR=1.14, P<0.01) were found to be significant. We found three patients (5.3%) with Yq deletion in AZFa and AZFc regions in exposed men. In addition, the five subjects showed a mutation in the HMG box of the SRY gene. CONCLUSIONS: Our findings provide evidence that higher HCH exposure may cause oxidative damage to DNA in terms of AZF microdeletions and point mutation in the SRY gene, and poor semen quality, resulting in male infertility. [ABSTRACT FROM AUTHOR]

This review elucidates different bioremediation approaches used for degradation of HCH from contaminated sites. It highlights the significance of degradative pathways, microbial diversity and impact of different environmental factors for developing viable bioremediation strategies. The application of innovative biotechnological approaches and a thorough understanding of HCH biodegradation pathways show great promise for the creation of long-term solutions to HCH pollution and the restoration of polluted soil ecosystems. Bioremediation technologies viz. biostimulation, bioaugmentation, phytoremediation have been considered till date for treating HCH-contaminated sites. Different bacterial and fungal strains have been reported for degradation of HCH residues. However, these methods are limited to γ-HCH degradation, at laboratory scale and achieving lower success rate for large scale demonstration trials. This review presents a theoretical background for degradation of different HCH isomers in soil through plants, microbes and through their cooperative interactions. This work briefly overviews the substantial contamination of the environment by HCH residues, along with spontaneous evolution of degradation pathways through various HCH degrading microbes. Bioremediation mechanism and pathways of HCH degradation through plants and microbes have been discussed thoroughly. Through molecular and genetic investigations, the complex metabolic pathways used by these microbes, including reductive dechlorination, hydrolysis, and ring cleavage, has been clarified. This study seeks to give a thorough summary of recent discoveries and developments in bioremediation methods for soil HCH degradation. Numerous microbial consortia, including fungi, plants, and bacteria have been recognised as important participants in the transformation of HCH. [ABSTRACT FROM AUTHOR]

Abstract Exposure to certain chemicals in the environment may contribute to the risk of developing cancer. Although cancer risk from environmental chemical exposure among general populations is considered low compared to that in occupational settings, many people may nevertheless be chronically exposed to relatively low levels of environmental chemicals which vary by such various factors as residential area, lifestyle, and dietary habits. It is therefore necessary to assess population-specific exposure levels and examine their association with cancer risk. Here, we reviewed epidemiological evidence on cancer risk and exposure to dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), cadmium, arsenic, and acrylamide. Japanese are widely exposed to these chemicals, mainly through the diet, and an association with increased cancer risk is suspected. Epidemiological evidence from Japanese studies to date does not support a positive association between blood concentrations of DDT, HCH, PCBs, and PFASs and risk of breast or prostate cancer. We established assessment methods for dietary intake of cadmium, arsenic, and acrylamide using a food frequency questionnaire. Overall, dietary intakes of cadmium, arsenic, and acrylamide were not significantly associated with increased risk of total cancer and major cancer sites in the Japan Public Health Center-based Prospective Study. However, statistically significant positive associations were observed between dietary cadmium intake and risk of estrogen receptor-positive breast cancer among postmenopausal women, and dietary arsenic intake and risk of lung cancer among male smokers. In addition, studies using biomarkers as exposure assessment revealed statistically significant positive associations between urinary cadmium concentration and risk of breast cancer, and between ratio of hemoglobin adducts of acrylamide and glycidamide and risk of breast cancer. Epidemiological studies of general populations in Japan are limited and further evidence is required. In particular, studies of the association of organochlorine and organofluorine compounds with risk of cancer sites other than breast and prostate cancer are warranted, as are large prospective studies of the association between biomarkers of exposure and risk of cancer.

This paper focuses on the evaluation of the mobility of four hexachlorocyclohexane (HCH) isomers by soil vapor extraction (SVE) coupled with direct electrokinetic (EK) treatment without adding flushing fluids. SVE was found to be very efficient and remove nearly 70 % of the four HCH in the 15‐days of the tests. The application of electrokinetics produced the transport of HCH to the cathode by different electrochemical processes, which were satisfactorily modelled with a 1‐D transport equation. The increase in the electric field led to an increase in the transport of pollutants, although 15 days was found to be a very short time for an efficient transportation of the pollutants to the nearness of the cathode. Loss of water content in the vicinity of the cathode warns about the necessity of using electrokinetic flushing technologies instead of simple direct electrokinetics. Thus, results point out that direct electrokinetic treatment without adding flushing fluids produced low current intensities and ohmic heating that contributes negatively to the performance of the SVE process. No relevant differences were found among the removal of the four isomers, neither in SVE nor in EK processes. [ABSTRACT FROM AUTHOR]

Exposure to certain chemicals in the environment may contribute to the risk of developing cancer. Although cancer risk from environmental chemical exposure among general populations is considered low compared to that in occupational settings, many people may nevertheless be chronically exposed to relatively low levels of environmental chemicals which vary by such various factors as residential area, lifestyle, and dietary habits. It is therefore necessary to assess population-specific exposure levels and examine their association with cancer risk. Here, we reviewed epidemiological evidence on cancer risk and exposure to dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), cadmium, arsenic, and acrylamide. Japanese are widely exposed to these chemicals, mainly through the diet, and an association with increased cancer risk is suspected. Epidemiological evidence from Japanese studies to date does not support a positive association between blood concentrations of DDT, HCH, PCBs, and PFASs and risk of breast or prostate cancer. We established assessment methods for dietary intake of cadmium, arsenic, and acrylamide using a food frequency questionnaire. Overall, dietary intakes of cadmium, arsenic, and acrylamide were not significantly associated with increased risk of total cancer and major cancer sites in the Japan Public Health Center-based Prospective Study. However, statistically significant positive associations were observed between dietary cadmium intake and risk of estrogen receptor-positive breast cancer among postmenopausal women, and dietary arsenic intake and risk of lung cancer among male smokers. In addition, studies using biomarkers as exposure assessment revealed statistically significant positive associations between urinary cadmium concentration and risk of breast cancer, and between ratio of hemoglobin adducts of acrylamide and glycidamide and risk of breast cancer. Epidemiological studies of general populations in Japan are limited and further evidence is required. In particular, studies of the association of organochlorine and organofluorine compounds with risk of cancer sites other than breast and prostate cancer are warranted, as are large prospective studies of the association between biomarkers of exposure and risk of cancer. [ABSTRACT FROM AUTHOR]

Hexachlorocyclohexane (HCH) is an organochlorine synthetic substance composed of different isomers (α-, β-, γ-, δ-, and ε-HCH), but only γ-HCH isomer or lindane has insecticidal properties. From 1984 to 1992, INQUINOSA Company dumped HCH wastes in the Bailín landfill (Sabiñánigo, Spain), and in 2014 these HCH residuals were transferred to a secure landfill, dispersing a small amount of HCH-isomers in the surrounding area. To explore the spatial distribution of this pollution, we evaluated HCH concentration in the soil-vegetation system around the Bailín landfill site. Physicochemical properties showed a greater percentage of organic matter, cation exchange capacity, carbon content, and conductivity in soil samples, while only pH increased in subsoil samples. Our findings also revealed that the concentration of HCH-isomers is very heterogeneous in topsoil samples from <1 μg/kg to 780 μg/kg, whereas in subsoil samples fluctuated from <1 μg/kg to 70 μg/kg. Moreover, the accumulated HCH-isomers among species and plant tissues displayed large variations, with pine needles showing the greatest values. Interestingly, spatial distribution of HCH contamination was mainly concentrated close to the old landfill and secure landfill, suggesting that the removal processes largely influence soil contamination. Correlation of HCH levels in soil and plant material suggests that HCH uptake onto plants was accomplished either by translocation from soil via the root system or by deposition from air into the above-ground parts of the plants. As HCH-isomers are hydrophobic compounds that tend to be adsorbed by soil organic matter, HCH probably do not leach into groundwater, and the main sinks are surface runoff, volatilization, and degradation. However, more studies would be required to assess the potential sinks of HCH wastes in the Bailín landfill site. [Display omitted] • The September 2014 waste relocation operation caused surficial pollution of Bailín area. • HCH concentration was more heterogeneous in topsoil than in subsoil samples. • Pine needles accumulated greater concentrations of HCH-isomers. • The contour maps showed higher contamination levels around both landfills. [ABSTRACT FROM AUTHOR]

This work describes the complete decontamination of three parcels of a dump site located in Lomas de Zamora county, Buenos Aires province (Argentina) heavily polluted with hexachorocyclohexane (HCH), where phytoremediation, successful in the surrounding areas, was ineffective. HCH contained in contaminated soil (10 g/kg average) was oxidized with sodium persulfate activated with citric acid chelated Fe(II). This chemical remediation process required treatment in situ in each parcel of approximately 10900 tons total of soil that were mechanically removed and initially mixed with 1750 tons of sodium persulfate. The mixture was then transferred to the excavation site, and 105 tons of ferrous sulfate and 35 tons of citric acid were finally added. The process, started in January 2011 and completed in February 2016, was very effective since chemical remediation average efficiency in the three parcels was higher than 99.99%. To the best of our knowledge this work is the first demonstration that persulfate oxidation activated with citric acid chelated Fe(II) can be successfully applied for field remediation of a relatively large area. [ABSTRACT FROM AUTHOR]

In this study, the levels of indicator PCBs congeners and PAHs compounds were reported in cow milk from selected areas in Dhaka, Bangladesh, and the potential human health risks were assessed. A total of 100 milk samples were collected and analyzed using gas chromatography-tandem mass spectrometry (GC-MS/MS). Method validation was performed using recovery performance, linearity, limit of detection (LOD), and limit of quantification (LOQ) assays. PCBs congeners, including PCB No. 52 (2,2´,5,5´-tetrachlorobiphenyl), PCB No. 101 (2,2´,4,5,5´-pentachlorobiphenyl), PCB No. 153 (2,2,4,4,5,5–hexachlorobiphenyl), and PCB No 209 (Decachloro-1,1′-biphenyl perchlorobiphenyl) were detected, whereas PCB No 28 (2,2 ´,4–trichlorobiphenyl), PCB No. 138 (2,2´,3,4,4´,5´–hexachlorobiphenyl), and PCB No 180 (2,2´,3,4,4´,5,5´–heptachlorobiphenyl) were not detected in the analyzed milk samples. Among the 16 PAHs compounds, benzo (a) anthracene and chrysene were detected in milk samples. The Σ hazard risk index (HI) of all detected PCBs congeners was below the limit set by the European Food Safety Authority, which indicates limited health risks to animals and humans in the study area. However, the presence of PCBs and PAHs in milk samples from industrial areas may negatively affect human health, and further detailed studies are required to ensure public health safety.

Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.

Today, more than two and a half thousand compounds are known that are used in the production of food products. This is usually done to increase the preservation and storage period and improve organoleptic parameters. However, some of these toxic compounds may inadvertently enter food through packaging material and technological additives. Residues of toxic chemicals and industrial pollutants in food are a serious problem for a healthy body, which can lead to oncogenetic processes. Among such persistent organic pollutants are organochlorine pesticides, polychlorinated biphenyls, as well as by-products of chemical production and combustion processes, such as dioxins and furans. One of the most toxic pesticides is the organochlorine pesticide γ-isomer of hexachlorocyclohexane (C6H6Cl6). Pure hexachlorocyclohexane is a hydrophobic white powder with a crystalline structure that has strong acid-resistant parameters. To date, it is known for sure that hexachlorocyclohexane is a polytropic toxic chemical that primarily affects the central and autonomic nervous system of mammals. Hexachlorocyclohexane has been widely used in agriculture for pest control. Now the substance is banned everywhere. This article is devoted to the effect of hexachlorocyclohexane on the human body. [ABSTRACT FROM AUTHOR]

Background Organochlorine pesticides (OCPs) exposure may induce an endocrine disruption which may lead to the risk of developing diabetes through alteration and disturbance of glucose metabolism, insulin resistance, and destruction of β-cells. The present study determines the recent trend of OCPs residue in blood samples and their association with the known risk factors responsible for developing the risk of diabetes among the North Indian population. Methods Blood sample of 300 patients (100 each of normal glucose tolerance [NGT], prediabetes and newly detected diabetes mellitus [DM]) between the age group of 30 to 70 years were collected. OCPs residue in whole blood samples was analyzed by using gas chromatography equipped with a 63Ni selective electron capture detector. Results Significantly higher levels of β-hexachlorocyclohexane (HCH), dieldrin, and p,p’-dichloro-diphenyl-dichloroethylene (DDE) were found in the prediabetes and newly detected DM groups as compared to NGT group. Insulin resistance showed to be significantly positive correlation with β-HCH and dieldrin. Also, fasting and postprandial glucose levels were significantly positively correlated with levels of β-HCH, dieldrin, and p,p’-DDE. Further, when OCPs level was adjusted for age and body mass index (BMI), it was found that β-HCH, dieldrin, and p,p’-DDE levels in blood increases the risk of diabetes by 2.70, 2.83, and 2.55 times respectively. Moreover, when we adjust OCPs level based on BMI categories (BMI 25 kg/m2); β-HCH and p,p’-DDE showed a significant risk of developing newly detected DM with BMI >25 and ≥23 and ≤25 kg/m2. Conclusion The OCPs level present in the environment may be responsible for biological, metabolic, and endocrine disruptions within the human body which may increase the risk of developing newly detected DM. Hence, OCPs exposure can play a crucial role in the etiology of diabetes.

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In this study, we evaluated the residual levels and distribution characteristics of 10 organochlorine pesticides (OCPs) in the soil of agricultural lands (paddy field, vegetable field, and orchard, n = 150) nationwide. As a result of the investigation, 3–10 types of OCPs were detected in combination in 144 locations (96%) of the total 150 locations. Among those OCPs, dichlorodiphenyltrichloroethane (DDT) and endosulfan were detected in high amounts. The geometric mean concentrations of DDT and endosulfan were ∑DDT 0.31 ng g−1 (ND-2187.18 ng g−1) and ∑endosulfan 0.33 ng g−1 (ND-312.68 ng g−1), respectively. OCP concentrations were generally higher in orchards than in other agricultural fields due to a large amount of pesticides used. DDT in two orchards was detected at 2187.18 ng g−1 and 1061.78 ng g−1, exceeding the levels stated in the Canadian DDT Soil Quality Guidance (SQG, 700 ng g–1). The result of applying the isomer ratio to evaluate the recent or past use of DDT, endosulfan, and hexachlorocyclohexane (HCH), which had a high detection rate, showed that it could be attributable to historical usage. DDT and HCH showed statistically similar residual distribution patterns; however, endosulfan did not show a clear correlation with DDT and HCH due to the effect of its recent use. Thus, the results of evaluation of OCP residual levels and distribution characteristics can be used for the soil management policy of OCPs in agricultural lands in Korea. [ABSTRACT FROM AUTHOR]

Pakistan is an agro-economy country where hexachlorocyclohexane (HCH) pesticides are being used to improve crop productivity, as a result the risk of contamination of soil and sediment has been increased. HCH exhibits all the characteristics of persistent organic pollutants (POP), and was therefore added to the list of ‘new POPs’ in 2009. This review report revealed that the major rivers of Pakistan such as the Indus Basin, River Ravi, River Chenab and their tributaries all are contaminated with HCH and the highest residual concentration (4,090 ng/g) was detected in a pesticide burial ground in Hyderabad city. Major sources of HCH contamination were identified as agricultural runoff, discharge of untreated industrial effluents and surface runoff. In order to manage HCH pollution, various ex-situ and in-situ remediation techniques along with their merits and demerits are thoroughly reviewed. Among these, microbial bioremediation is a low cost, environment friendly, effective in-situ remediation technique for remediation of HCH. Overall, the information provided in this manuscript will provide a future reference to the scientific community and bridge the knowledge gap between HCH release in the environment and their mitigation through proper treatment methods. HIGHLIGHTS Hexachlorocyclohexane is most widely pesticide and toxic to environment.; Hexachlorocyclohexane as persistent organic pollutants contaminates fresh water resources and pose a potential risk to ecosystem.; Pakistan's major rivers and tributaries are contaminated hexachlorocyclohexane.; Appropriate treatment of water and mitigation policies are required.;

Post pesticides production landfills are often a source of large uncontrolled contamination of groundwater. Therefore, there is a need to find suitable technologies to reduce the concentration and ecotoxicity of these pesticides. In this paper, both lab- and field-scale technology of permeable reactive barrier (PRB) for the treatment of hexachlorocyclohexanes (HCHs) and chlorobenzenes (CBs) at a site in Jaworzno, Poland are described. The results showed the high efficiency of the treatment process for hexachlorocyclohexane (90%) and chlorobenzenes (99%) in lab-scale which slowly decreased to 86% and 97%, respectively with the time of PRB operation (112 d). The efficiency of treatment of HCHs and CBs by PRB technology in pilot scale in the 8th day operation was ca. 82% and 60%, respectively during the first phase of operation and highly decreased after two months of operation due to the loss of sorption capacity of peat bed and the passivation process of iron chips. Base on the measured data, it could be determined that the treatment train in such barrier relies on subsequent reductive dehalogenation and adsorption. Therefore, the results obtained and presented in this paper could be useful for further design of full-scale permeable reactive barriers on sites with groundwater contaminated by similar organochlorine pesticides. [ABSTRACT FROM AUTHOR]

The level, composition, and distribution of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) residues were determined by GC-ECD technique in soil samples from the Soroca district, Republic of Moldova. The concentrations of DDTs and HCHs were up to 1100 and 640 mg/kg, respectively. The obtained results indicated that in 77% of analyzed soil samples the (DDE+DDD)/DDT ratios showed aged sources of DDT pollution, suggesting that in the studied area, the DDT residues have been transformed significantly into their degradation products. The α-HCH/γ-HCH ratios were generally high (in the range of 1-28) suggesting that technical HCH is the main source of contamination. The high concentration and the degradation rates of the pesticides in soil suggest that the contaminated sites are acting as continuous sources of pollution for the environment. Thus, remediation measures are required to reduce the level of the contaminants in soil.

Introduction: One of the most adverse chemical factors of the outdoor environment is pesticides entering the organism of newborns via mother's breast milk, and also receive a pesticide load through a polluted environment. The heavy demonstration of pesticides impact on the brain is violation of autonomic regulation mechanisms of newborns' cardiac rhythm. The purpose of the study is early detection of violation of autonomic regulation mechanisms of cardiac function of children with perinatal hypoxia in the region of hexachlorocyclohexane use in cotton planting., Material and Methods: The hygienic state of the environment of the cotton planting region has been studied by means of measurement of pollution level of the atmospheric air, water and soil with pesticide hexachlorocyclohexane, the concentration of which was in 7,55-9,38 more than their maximum permissible concentration (MPC). 148 children took part in the study who were treated in neonatal center of Turkestan Regional Children's Clinical Hospital in Shymkent city. 30 infants without any signs of hypoxic-ischemic syndrome were assigned to the comparison group (I group). 118 children with signs of hypoxic-ischemic central nervous system injury were included in the study group and were divided into 1 and 2 subgroups. Among them 85 children with detected hypoxic-ischemic central nervous system injury of I-II degree were included in the 1st subgroup, and 33 children with cerebral hypoxic-haemorrhagic central nervous system damage of III degree in the 2nd subgroup. The study has been carried out by means of Holter monitoring using instrumental-software system "Kardiotechnika-4000" within 15-38 days of infants' lives., Results: Advanced complex of QRS prevails in infants who underwent a heavy perinatal hypoxia. Changes in this electrocardiogram are one of the most unfavorable heart changes and is indicative of bioelectric myocardium instability. Using a program to compare short records of cardiac rhythm, the average daily value of the indicator was calculated. The use of such method enables elimination of such impact of long-term malignant causes in the spectrum. The analysis of heart vegetative reaction conducted among infants of 15-22-day age demonstrated decrease of parasympathetic impact on heart rate of I group infants, and activity of sympathetic segment of vegetative nervous system was unchanged. So, the decrease of parasympathetic impact on heart rate of infants in the study groups was observed in the result of Holter monitoring, but the absence of changes of sympathetic effect in general. It was reflected by the increase of the value of vagosympathetic index (LF/HF), similarly to this disease suggesting low evidence of respiratory sinusal arrhythmia.

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In this study analysis of soil, water and plant residue samples is presented to evaluate the contamination levels and possible health risks. Hexachlorocyclohexane (HCH) is a persistent organic pollutant used as a pesticide in agricultural sector for pest control in order to obtain higher productivity. For analysis soil, water and crop residue samples were collected from different agricultural areas of the northern Punjab region of Pakistan. The investigation of the samples shows significant levels of HCH residues in all types of samples. Gas chromatography–mass spectrometry analysis was used to assess the higher residue levels of HCH in the samples. The concentration of HCH residues detected in samples ranged from 2.43 to 8.88 µg/g in soil, nd –5.87 µg/l in water and nd – 4.87 µg/g in plants. The presence of HCH residues in soil, water and plant samples was beyond the recommended quality guidelines. Human health risk was evaluated for cancer and non-cancer risks through dietary and non-dietary exposure routes. The hazard index was HI > 1 in children and HI < 1 in adults, while the non-dietary incremental lifetime cancer risks (ILCR) were beyond the internationally acceptable limit of 1 × 10–5. Hence, results of the present investigation concluded the presence of high levels of HCH residues in samples and pose high health risk to the inhabitants. These findings are alarming and apprise the concerned departments for the remediation of contamination and proper implementation of environmental laws in the area. [ABSTRACT FROM AUTHOR]

Khat (Catha edulis) chewing is widespread in the region of East Africa. Even low levels of organochlorine pesticides (OCPs) in khat could induce public health concern. In a market-based study, from five popular khat varieties, a total of 35 composite khat samples were analyzed for dichlorodiphenyltrichloroethane (DDT) and its main transformation products, and four hexachlorocyclohexane (HCH) isomers. Extraction was carried out by quick, easy, cheap, effective, rugged and safe method (QuEChERS). OCP concentrations were determined by head space solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME–GC–MS). Every sample contained β-HCH above the maximum residue limit set by the European Commission. For total DDT, this was the case for 25.7% of the samples. The ratios of (p,p′-DDD + p,p′-DDE) to p,p′-DDT were less than one for 85% of khat samples, demonstrating recent use of DDT in khat farmlands. Conversely, the ratio of β-HCH to total HCH varied from 0.56 to 0.96, implying historical input of technical HCH. Assuming a daily chewable portion of 100 g, dietary intakes of p,p′-DDT, total DDT and total HCH by adults ranged from 3.12 to 57.9, 6.49 to 80.2 and 39.2 to 51.9 ng (kg body weight)−1 day−1, respectively. These levels are below acceptable levels suggested by international organizations. Chewing khat showed lower non-cancer health risk, but showed relatively higher cancer risk in terms of OCPs. Because khat is chewed without being subjected to any treatment, uncertainties associated with estimated intakes and health risks should be low. Therefore, this practice is of great concern. [ABSTRACT FROM AUTHOR]

BackgroundSphingobium spp. are efficient degraders of a wide range of chlorinated and aromatic hydrocarbons. In particular, strains which harbour the lin pathway genes mediating the degradation of hexachlorocyclohexane (HCH) isomers are of interest due to the widespread persistence of this contaminant. Here, we examined the evolution and diversification of the lin pathway under the selective pressure of HCH, by comparing the draft genomes of six newly-sequenced Sphingobium spp. (strains LL03, DS20, IP26, HDIPO4, P25 and RL3) isolated from HCH dumpsites, with three existing genomes (S. indicum B90A, S. japonicum UT26S and Sphingobium sp. SYK6).ResultsEfficient HCH degraders phylogenetically clustered in a closely related group comprising of UT26S, B90A, HDIPO4 and IP26, where HDIPO4 and IP26 were classified as subspecies with ANI value >98%. Less than 10% of the total gene content was shared among all nine strains, but among the eight HCH-associated strains, that is all except SYK6, the shared gene content jumped to nearly 25%. Genes associated with nitrogen stress response and two-component systems were found to be enriched. The strains also housed many xenobiotic degradation pathways other than HCH, despite the absence of these xenobiotics from isolation sources. Additionally, these strains, although non-motile, but posses flagellar assembly genes. While strains HDIPO4 and IP26 contained the complete set of lin genes, DS20 was entirely devoid of lin genes (except linKLMN) whereas, LL03, P25 and RL3 were identified as lin deficient strains, as they housed incomplete lin pathways. Further, in HDIPO4, linA was found as a hybrid of two natural variants i.e., linA1 and linA2 known for their different enantioselectivity.ConclusionThe bacteria isolated from HCH dumpsites provide a natural testing ground to study variations in the lin system and their effects on degradation efficacy. Further, the diversity in the lin gene sequences and copy number, their arrangement with respect to IS6100 and evidence for potential plasmid content elucidate possible evolutionary acquisition mechanisms for this pathway. This study further opens the horizon for selection of bacterial strains for inclusion in an HCH bioremediation consortium and suggests that HDIPO4, IP26 and B90A would be appropriate candidates for inclusion.

It is known, that highly toxic pesticide hexachlorocyclohexane (HCH) is resistant to decomposition and has a long-term accumulating capacity. Nevertheless, it undergoes complete degradation in reactions with hydroxyl radicals in Fenton-like systems. The goal of this work was to study the influence of HCH on the processes of radical self-purification of water bodies and to explain the mechanisms of chemical transformation of substances occurring in natural waters, as well as to reveal the kinetic characteristics of the processes of radical self-purification of water bodies. It was found, that HCH plays a dual role for aquatic ecosystems – it is not only a scavenger of free radicals, but also an additional initiator. Under the influence of light in the surface layer of water, HCH generates radicals, thus contributing to the self-purification processes.

In this study, bioaugmentation and biostimulation were used to explore the efficiency of bioremediation of hexachlorocyclohexane (HCH)-contaminated soil in the laboratory. A complex microbial community (germ A, abbreviated as A) was used for bioaugmentation. The KNO3 and K2HPO4 (NP), wheat straw (JG), and glucose (PU) were used as exogenous amendments for biostimulation. Five treatments were set up: the control (CK), NP, A + NP, A + NP + JG, and A + NP + PU. After 28 days of remediation, the removal rate of total HCH (HCHs) in NP, A + NP, A + NP + JG, and A + NP + PU was 27.0%, 32.2%, 43.4%, and 45.3%, respectively. The results indicated that the removal of HCHs in A + NP, A + NP + JG, and A + NP + PU was higher than NP, indicating that bioaugmentation combined with biostimulation was more effective than biostimulation. Furthermore, compared with A + NP, A + NP + JG and A + NP + PU were more conducive to the degradation of HCHs. Because applying inorganic and organic nutrient substances simultaneously can effectively improve the living environment of microorganisms and increase microbial quantities in HCH-contaminated soil, therefore, the enzymatic reaction of microorganisms is accelerated, resulting in the efficiency of HCHs degradation improvement. The results indicated that bioaugmentation with germ A combine with biostimulation by organic and inorganic nutrients simultaneously constitutes a promising method for restoring soils contaminated with HCHs. This study would provide the basis for improving the bioremediation efficiency of HCH-contaminated soil. [ABSTRACT FROM AUTHOR]

Background: Organochlorine pesticides (OCPs) exposure may induce an endocrine disruption which may lead to the risk of developing diabetes through alteration and disturbance of glucose metabolism, insulin resistance, and destruction of β-cells. The present study determines the recent trend of OCPs residue in blood samples and their association with the known risk factors responsible for developing the risk of diabetes among the North Indian population. Methods: Blood sample of 300 patients (100 each of normal glucose tolerance [NGT], prediabetes and newly detected diabetes mellitus [DM]) between the age group of 30 to 70 years were collected. OCPs residue in whole blood samples was analyzed by using gas chromatography equipped with a 63Ni selective electron capture detector. Results: Significantly higher levels of β-hexachlorocyclohexane (HCH), dieldrin, and p,p'-dichloro-diphenyl-dichloroethylene (DDE) were found in the prediabetes and newly detected DM groups as compared to NGT group. Insulin resistance showed to be significantly positive correlation with β-HCH and dieldrin. Also, fasting and postprandial glucose levels were significantly positively correlated with levels of β-HCH, dieldrin, and p,p'-DDE. Further, when OCPs level was adjusted for age and body mass index (BMI), it was found that β-HCH, dieldrin, and p,p'-DDE levels in blood increases the risk of diabetes by 2.70, 2.83, and 2.55 times respectively. Moreover, when we adjust OCPs level based on BMI categories (BMI <23, ≥23, and ≤25, and >25 kg/m²); β-HCH and p,p'-DDE showed a significant risk of developing newly detected DM with BMI >25 and ≥23 and ≤25 kg/m². Conclusion: The OCPs level present in the environment may be responsible for biological, metabolic, and endocrine disruptions within the human body which may increase the risk of developing newly detected DM. Hence, OCPs exposure can play a crucial role in the etiology of diabetes. [ABSTRACT FROM AUTHOR]

Over the last 60 years, the use of hexachlorocyclohexane (HCH) as a pesticide has resulted in the production of >4 million tons of HCH waste, which has been dumped in open sinks across the globe. Here, the combination of the genomes of two genetic subspecies (Sphingobium japonicum UT26 and Sphingobium indicum B90A; isolated from two discrete geographical locations, Japan and India, respectively) capable of degrading HCH, with metagenomic data from an HCH dumpsite (∼450 mg HCH per g soil), enabled the reconstruction and validation of the last-common ancestor (LCA) genotype. Mapping the LCA genotype (3128 genes) to the subspecies genomes demonstrated that >20% of the genes in each subspecies were absent in the LCA. This includes two enzymes from the 'upper' HCH degradation pathway, suggesting that the ancestor was unable to degrade HCH isomers, but descendants acquired lin genes by transposon-mediated lateral gene transfer. In addition, anthranilate and homogentisate degradation traits were found to be strain (selectively retained only by UT26) and environment (absent in the LCA and subspecies, but prevalent in the metagenome) specific, respectively. One draft secondary chromosome, two near complete plasmids and eight complete lin transposons were assembled from the metagenomic DNA. Collectively, these results reinforce the elastic nature of the genus Sphingobium, and describe the evolutionary acquisition mechanism of a xenobiotic degradation phenotype in response to environmental pollution. This also demonstrates for the first time the use of metagenomic data in ancestral genotype reconstruction, highlighting its potential to provide significant insight into the development of such phenotypes.

This study assessed for the first time the bioremediation potential of an organic horse amendment in soils contaminated with solid wastes of the obsolete pesticide lindane (α-hexachlorocyclohexane (α-HCH) = 80 mg kg -1 , β-HCH = 40 mg kg -1 , γ,δ,ε-HCH≈10 mg kg -1 ) searching for a self-sufficient bio-based economy. Four treatments were implemented: polluted (PS, ΣHCHs = 130 mg kg -1 ) and control (CS, ΣHCHs = 1.24 mg kg -1 ) soils and the respective amended soils (APS and ACS). A commercial amendment, coming from organic wastes, was used for soil biostimulation (5% dry weight), and the temporal evolution of the enzymatic activity (dehydrogenase, β-glucosidase activity, phenoloxidase, arylamidase, phosphatase, and urease) and HCHs concentration of the soils was evaluated over 55 days under controlled humidity and temperature conditions. The horse amendment positively influenced the physicochemical properties of the soil by reducing pH (from 8.3 to 8) and increasing the organic matter (TOC from 0.5 to 3.3%) and nutrient content (P and NH 4 + from 24.1 to 13.7 to 142.1 and 41.2 mg kg -1 , respectively). Consequently, there was a notable enhancement in the soil biological activity, specifically in the enzymatic activity of dehydrogenase, phenol-oxidase, phosphatase, and urease and, therefore, in HCH degradation, which increased from <1 to 75% after the incubation period. According to the chlorine position on the cyclohexane ring, the following ranking has been found for HCHs degradation: β-HCH (46%) < ε-HCH (57%) < α-HCH (91%) ≈ δ-HCH (91%) < γ-HCH (100%). Pentachlorocyclohexene (PCCH) and 1,2,4-trichlorobenzene (1,2,4-TCB) were identified as HCHs degradation metabolites and disappeared at the end of the incubation time. Although further research is required, these preliminary findings suggest that organic amendments represent a sustainable, harmless, and cost-effective biostimulation approach for remediating soils contaminated with recalcitrant HCHs, boosting the circular economy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: Hexachlorocyclohexane (HCH) is a pesticide that is persistent in aerobic but not in anaerobic conditions. The aim of this investigation was to elucidate the impacts of different electron donors on the degradation of hexachlorocyclohexane and their relationships with the microbial community in submerged soils. Materials and methods: Soil samples were collected from a pesticides-polluted site which was previously used for long-term storage of pesticides since the 1960s. Residual amounts of HCHs in submerged soils were assessed to evaluate the efficiency of the added electron donors after incubation. Changes in microbial community were monitored during incubation. Results and discussion: The efficiencies of removal of HCHs by Fe0, Fe0 + straw and glucose treatments were 63.8%, 40.3%, and 22.0%, compared with 5.4% by the control. Soil redox potential decreased rapidly following addition of Fe0 and became anaerobic, but there was no significant decrease in redox potential following the addition of glucose. Principal coordinates analysis (PCoA) confirms that the electron donors greatly affected the soil bacterial community. Furthermore, community composition analysis shows that Firmicutes was the dominant phylum after addition of carbon sources (straw and glucose) but Proteobacteria were dominant in the control and the Fe0 treatment. Prauserella, Actinobacteria, and Streptomyces showed highly significant increases in the Fe0 treatment and were positively correlated with total HCH residues. Conclusions: These findings indicate that the addition of organic materials (straw and glucose) had a gradual effect on the degradation of HCH while Fe0 acted rapidly. Elucidation of the relationships between electron donors and soil microbial communities will help in the bioremediation of HCH-contaminated sites. [ABSTRACT FROM AUTHOR]

In order to track the transformation of persistent organic pollutants (POPs) in food webs, field experiments were conducted at two sites using stable isotope and enantiomer fractionation concepts. The enantiomers of α-hexachlorocyclohexane (α-HCH) were selected as representative compounds for POPs. Isotope and enantiomer fractionation allowed the characterization of α-HCH enantiomer biotransformation processes along trophic levels of the food web - from soil and plants to animal livers, fat tissues and milk. The enrichment of heavy isotopes in soils, plants and sediments as well as the changes of enantiomer fractionation indicate that the biotransformation of α-HCH occurred in these compartments. Moreover, the increase of carbon and chlorine isotopic compositions as well as the changes of enantiomer fractionation of liver, fat tissues and milk demonstrated that the overall HCH exposure was much higher than estimates based on concentration levels, while the isotope and enantiomer fractionation revealed the enantiomer specific enantiomer uptake across the blood-brain barriers. Dual element isotope analysis suggested that complex transformation processes have occurred along the potential food web from the HCH sources over different environmental compartments to animal livers, fat tissues and milk. The results imply that the analyses of stable isotope compositions and concentrations has potential to reconstruct the exposure of higher organisms to POPs. [Display omitted] • Isotope and enantiomer fractionation are applied to characterize the fate of POPs. • Transformation of α-HCH was identified in plants, trees and livers of wild animals. • Enantiomer specific uptake of α-HCH was showed in brain and liver. • Different transformation mechanism was revealed in different levels of food webs. • The initial expose of HCH in wild animals are higher than the measured concentration. [ABSTRACT FROM AUTHOR]

• Surfactant-enhanced soil washing is a promising approach for soil decontamination. • Structure and concentration of surfactants affected the solubilisation of HCHs. • α- and γ-HCH isomers were more easily solubilised than β- and δ-HCH. • Blends of surfactants influenced the critical micelle concentration. Surfactant-enhanced remediation of soil can increase the solubility of hydrophobic organic contaminants in water and improve their removal. In this study, the effect of 24 traditional surfactants and surface-active ionic liquids (SAILs) on the solubility of hexachlorocyclohexane isomers (α-, β-, γ-, δ-HCH) was evaluated in batch-type experiments. The combination of two different proportions of a cationic SAIL and an anionic surfactant was also assessed. The solubilisation capacity of the surfactant varied depending on its concentration and structure, but also the HCH isomer considered. In general, the anionic surfactants yielded the best results, increasing solubilisation of HCH up to 2.4 times compared to the control (pure water). α-HCH and γ-HCH isomers were more easily solubilised than β-HCH and δ-HCH regardless of the surfactant's type. The main advantage of ionic liquids being their tunability, some clues are given for formulating surfactants to enhance the solubilisation of HCH. The combination of a traditional surfactant and a SAIL influenced the critical micelle concentration, but not the solubilisation of the contaminant. Further studies on the use of blends for this application are required. The increase of solubility achieved with the studied surfactants encourages their application in washing HCH-contaminated soils through solubility enhancement. [ABSTRACT FROM AUTHOR]