Molecular mechanisms of 1,2-dichloroethane-induced neurotoxicity

The production of industrial solvents and adhesives often utilizes 1,2-dichloroethane (1,2-DCE), a highly toxic halogenated hydrocarbon compound. Occupational 1,2-DCE poisoning occurs frequently and is a public health concern. Exposure to 1,2-DCE can damage the brain, liver, and kidneys. The main and most severe damage caused by exposure to 1,2-DCE is to the nervous system, especially the central nervous system. Current research on 1,2-DCE mainly focuses on the mechanism of brain edema. Several possible mechanisms of 1,2-DCE neurotoxicity have been proposed, including oxidative stress, calcium overload, blood-brain barrier damage, and neurotransmitter changes. This article reviews the research progress on 1,2-DCE neurotoxicity and the mechanism behind it to provide a scientific basis for the prevention and treatment of 1,2-DCE poisoning.

Creating an efficient 1,2-dichloroethane-mineralizing bacterium by a combination of pathway engineering and promoter engineering

Currently, 1,2-dichloroethane (DCA) is frequently detected in groundwater and has been listed as a potential human carcinogen by the U.S. EPA. Owing to its toxicity and recalcitrant nature, inefficient DCA mineralization has become a bottleneck of DCA bioremediation. In this study, the first engineered DCA-mineralizing strain KTU-P8DCA was constructed by functional assembly of DCA degradation pathway and enhancing pathway expression with a strong promoter P8 in the biosafety strain Pseudomonas putida KT2440. Strain KTU-P8DCA can metabolize DCA to produce CO₂ and utilize DCA as the sole carbon source for cell growth by quantifying ¹³C stable isotope ratios in collected CO₂ and in lyophilized cells. Strain KTU-P8DCA exhibited superior tolerance to high concentrations of DCA. Excellent genetic stability was also observed in continuous passage culture. Therefore, strain KTU-P8DCA has enormous potential for use in bioremediation of sites heavily contaminated with DCA. In the future, our strategy for pathway construction and optimization is expected to be developed as a standard pipeline for creating a wide variety of new contaminants-mineralizing microorganisms. The present study also highlights the power of synthetic biology in creating novel degraders for environmental remediation.

Cubic CuFe2O4 Spinel with Octahedral Fe Active Sites for Electrochemical Dechlorination of 1,2-Dichloroethane

CuFe₂O₄ spinel has been considered as a promising catalyst for the electrochemical reaction, while the nature of the crystal phase on its intrinsic activity and the kind of active site need to be further explored. Herein, the crystal phase-dependent catalytic behavior and the main active sites of CuFe₂O₄ spinel for electrochemical dechlorination of 1,2-dichloroethane are carefully studied based on the combination of experiments and theoretical calculations. Cubic and tetragonal CuFe₂O₄ are successfully prepared by a facile sol-gel method combined with high temperature calcination. Impressively, CuFe₂O₄ with the cubic phase shows a higher activity and ethylene selectivity compared to CuFe₂O₄ with the tetragonal phase, suggesting a significant facilitation of electrocatalytic performance by the cubic crystal structure. Moreover, the octahedral Fe atom on the surface of cubic CuFe₂O₄(311) is the active site responsible to produce ethylene with the energy barrier of 0.40 eV. This work demonstrates the significance of crystal phase engineering for the optimization of electrocatalytic performance and offers an efficient strategy for the development of advanced electrocatalysts.

ZnO/Graphene Composite from Solvent-Exfoliated Few-Layer Graphene Nanosheets for Photocatalytic Dye Degradation under Sunlight Irradiation

ZnO/graphene nanocomposites were prepared using a facile approach. Graphene nanosheets were prepared by ultrasonication-based liquid phase exfoliation of graphite powder in a low boiling point organic solvent, 1,2-Dichloroethane, for the preparation of ZnO/graphene nanocomposites. Structural properties of the synthesized ZnO/graphene nanocomposites were studied through powder XRD and micro-Raman analysis. The characteristic Raman active modes of ZnO and graphene present in the micro-Raman spectra ensured the formation of ZnO/graphene nanocomposite and it is inferred that the graphene sheets in the composites were few layers in nature. Increasing the concentration of graphene influenced the surface morphology of the ZnO nanoparticles and a flower shape ZnO was formed on the graphene nanosheets of the composite with high graphene concentration. The efficiencies of the samples for the photocatalytic degradation of Methylene Blue dye under sunlight irradiation were investigated and 97% degradation efficiency was observed. The stability of the nanocomposites was evaluated by performing five cycles, and 92% degradation efficiency was maintained. The observed results were compared with that of ZnO/graphene composite derived from other methods.

Structural Analyses of the Glycolipids in Lipid Rafts

Lipid rafts are usually isolated from cells or tissues using sucrose gradient ultracentrifugation in the presence of detergents such as Triton X-100 at 4 °C. Although detergents should be removed for further structural characterization following fractionation, these compounds are often difficult to completely remove, especially from the glycolipids. In this chapter, we describe a novel method for the fast and convenient removal of detergents from lipid raft glycolipids following fraction and describe the application of this method.

Rapid removal of detergent in glycolipids using ionic liquids

Detergent removal in glycolipid after sample preparation, such as enzymatic reaction or isolation of detergent-resistant membrane microdomain, is indispensable for further structural characterization. We previously established the rapid and effective method of detergent removal in glycolipid samples from glass test tube using 1,2-dichloroethane (DCE) washing. However, the use of DCE has several drawbacks, such as environmental risks, harmful effects (potentially carcinogenic), and high vaporability and flammability. To solve the issue, we used ionic liquids to remove detergents from glycolipid samples, and found 1-butyl-3-methylimidazolium iodide was a suitable alternative for DCE.

Removal of 1,2-dichloroethane in groundwater using Fenton oxidation

Among the chlorinated aliphatic hydrocarbons, 1,2-dichloroethane (1,2-DCA) is widely used for the synthesis of vinyl chloride monomers. Despite the high demand for 1,2-DCA, it poses a risk to the environment because it is persistent and carcinogenic. Therefore, in this study, several reagents (dithionite, hydrosulfide, sulfite, persulfate, sulfate radicals, and hydroxyl radicals) were evaluated for the degradation of 1,2-DCA. Among these, the hydroxyl radicals generated by the Fenton reaction were the most suitable oxidant, decomposing 92% of 1,2-DCA. Chloride, one of the final oxidized products, was observed, which supported the oxidation reaction. Moreover, with an increasing concentration of hydroxyl radicals, the degradation of 1,2-DCA increased. Furthermore, sufficient amounts of hydrogen peroxide were more important than Fe(II) in the decomposition of 1,2-DCA. The radical reaction can generate larger molecules via the degradation of 1,2-DCA, which are degraded over time. The applicability of Fenton oxidation was evaluated using real 1,2-DCA-contaminated groundwater. Although the degradation of target contaminant was lowered due to the alkaline pH and the presence of chloride and bicarbonate ions in groundwater, the Fenton reaction was still efficient to oxidize 1,2-DCA. These results indicate that Fenton oxidation is an effective technique for the treatment of 1,2-DCA in contaminated groundwater.

Strain IAE Dihaloeliminates 1,1,2-Trichloroethane and 1,2-Dichloroethane

Chlorinated ethanes, including 1,2-dichloroethane (1,2-DCA) and 1,1,2-trichloroethane (1,1,2-TCA), are widespread groundwater contaminants. Enrichment cultures XR_DCA and XR_TCA derived from river sediment dihaloeliminated 1,2-DCA to ethene and 1,1,2-TCA to vinyl chloride (VC), respectively. The XR_TCA culture subsequently converted VC to ethene via hydrogenolysis. Microbial community profiling demonstrated the enrichment of Geobacter 16S rRNA gene sequences in both the XR_DCA and XR_TCA cultures, and Dehalococcoides mccartyi (Dhc) sequences were only detected in the ethene-producing XR_TCA culture. The presence of a novel Geobacter population, designated as Geobacter sp. strain IAE, was identified by the 16S rRNA gene-targeted polymerase chain reaction and Sanger sequencing. Time-resolved population dynamics attributed the dihaloelimination activity to strain IAE, which attained the growth yields of 0.93 ± 0.06 × 10⁷ and 1.18 ± 0.14 × 10⁷ cells per μmol Cl^- released with 1,2-DCA and 1,1,2-TCA as electron acceptors, respectively. In contrast, Dhc growth only occurred during VC-to-ethene hydrogenolysis. Our findings discover a Geobacter sp. strain capable of respiring multiple chlorinated ethanes and demonstrate the involvement of a broader diversity of organohalide-respiring bacteria in the detoxification of 1,2-DCA and 1,1,2-TCA.

Single-Atom Ru on Al2O3 for Highly Active and Selective 1,2-Dichloroethane Catalytic Degradation

1,2-Dichloroethane (1,2-DCE) is a toxic volatile organic compound, which is harmful to the environment and human health. Herein, we develop a single-atom Ru catalyst anchored on the mesoporous schistose γ-Al₂O₃ (Ru SACs/m-γ-Al₂O₃) to enhance the catalytic activity and selectivity toward 1,2-DCE degradation. The Ru SACs/m-γ-Al₂O₃ shows low T₅₀ and T₉₀ (the temperature for 50 and 90% conversion) of 215 and 289 °C, which are lower than those for Ru NPs/m-γ-Al₂O₃ (291 and 374 °C) and pristine m-γ-Al₂O₃ (323 and 386 °C). The degradation products are mainly CO₂ (>94%) and HCl (>90%) by using the Ru SACs/m-γ-Al₂O₃ catalyst, and almost no byproducts are detected. Furthermore, Ru SACs/m-γ-Al₂O₃ also presents excellent anti-chlorine poisoning effect and water resistance during the stability test. This work may shed light on the development of efficient single-atom catalysts for the degradation of industrial pollutants.

Insights into enhanced removal of 1,2-dichloroethane by amorphous boron-enhanced Fenton system: Performances and mechanisms

In this study, amorphous boron was employed as a reductant in traditional Fenton system for the first time to accelerate the regeneration of Fe(II). The degradation of 1,2-dichloroethane (DCA) was only 40.0% in Fenton system, while in the presence of amorphous boron, it could reach to 93.0% in 60 min. HO• was demonstrated to be the major reactive oxygen species (ROSs) and responsible for DCA degradation. Further, the mechanism of amorphous boron-enhanced Fenton system was described as follows. With the addition of amorphous boron, the reduction process occurred on its surface and Fe(III) was regenerated to Fe(II) to further utilize H₂O₂ and produce more HO• for DCA removal. Meanwhile, amorphous boron was oxidized to B₂O₃ and a portion of H₃BO₃ leaching into the solution occurred. Both B₂O₃ and H₃BO₃ had no reactivity for Fe(III) reduction. Moreover, DCA could be entirely dechlorinated and mineralized to CO₂, Cl^- and H₂O. Vinyl chloride (VC) and dichloromethane (DCM) were the mainly intermediates in DCA degradation and two possible pathways were inferred. Eventually, the performance of DCA degradation in complex solution matrixes and for other contaminants removal were tested, demonstrating the broad-spectrum reactivity and superiority of amorphous boron-enhanced Fenton system in the remediation of contaminated groundwater.

Ozone-Activated Cataluminescence Sensor System for Dichloroalkanes Based on Silica Nanospheres

The detection and monitoring of dichloroalkanes, which are typical chlorinated volatile organic compounds (CVOCs) with obvious biological toxicity, is of significance for environmental pollution and public health. Herein, a novel ozone-activated cataluminescence (CTL) sensor system based on silica nanospheres was developed for highly sensitive and fast quantification of dichloroalkanes. A typical CTL system coupled with a plasma-ozone-assist unit was designed for promoting the CTL response of dichloroalkanes. The ozone generated by plasma provides a new pathway of catalytic oxidation process, which accompanied by the CTL signal amplification of dichloroalkanes results in an enhanced CTL sensor system with improved limit of detection (1,2-dichloroethane: 0.04 μg mL^-1, 1,2-dichloropropane: 0.03 μg mL^-1) and benign selective performance under the interference of CO₂, H₂O, NO, NO₂, SO₂, CS₂, and other common CVOCs. Moreover, a segmented CTL mechanism including co-adsorption of ozone and dichloroalkanes, thermal elimination, the ozonation route, and a luminous step was ratiocinated based on multiple characterizations and discussion. The proposed methodology and theory open up an attractive perspective for the analysis of less active volatile organic compounds.

Gibbs Transfer Energies of Ions from a Mixed Solvent of 2H,3H-Decafluoropentane and 1,2-Dichloroethane to Water

The transfer of hydrophilic, lipophilic, and fluorophilic ions at the interface between water (W) and a mixed solvent (MIX) of 2H,3H-decafluoropentane (DFP) and 1,2-dichloroethane (DCE) was studied voltammetrically and potentiometrically, and the formal Gibbs transfer energies of the ions from MIX to W, ΔG^0'_tr,MIX→W, were determined. The ΔG^0'_tr,MIX→W values of all the ions tested were higher than those from DFP to W. Namely, the ions would exist more stably in MIX than DFP, even for fluorophilic ions. This is due to the addition of DCE, which has a higher dielectric constant. A comparison of ΔG^0'_tr,MIX→W with that from DCE to W showed a superior affinity of fluorophilic ions to the fluorous solvent in spite of equivolume addition of DCE. Therefore, the mixed solvent would be a practically superior extraction medium for fluorophilic ions. In practice, the MIX | methylene blue⁺ (W) system showed higher extractability of a fluorophilic ion C₈F₁₇SO₃^- than the DFP | W and DCE | W systems.

Toxic effects of combined treatment of 1,2-dichloroethane and ethanol on mouse brain and the related mechanisms

The aim of this study was to explore the mechanisms of brain damage induced by the combined treatment of mice with 1,2-dichloroethane (1,2-DCE) and ethanol. Mice were divided into control group; 1,2-DCE-intoxicated group; ethanol-treated group; and low-, medium-, and high-dose combined treatment groups. Histological observations along with brain organ coefficients and water content were used to measure the brain damage directly and indirectly. The levels of nonprotein sulfhydryls, malondialdehyde (MDA), and superoxide dismutase activity were used as parameters to evaluate oxidative stress in the brain. Protein and messenger RNA (mRNA) levels of cytochrome P450 2E1 (CYP2E1), zonula occludens-1 (occludin and zo-1), aquaporin-4 (AQP4), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase (HO)-1, and the γ-glutamyl cysteine synthetase catalytic and modulatory subunits (γ-GCSc, GR, and γ-GCSm) in the brain were examined by Western blot analysis and quantitative polymerase chain reaction analysis, respectively. Effects of the combined treatment of 1,2-DCE and ethanol were evaluated by analysis of variance with a factorial design. The results suggested that combined exposure to ethanol and 1,2-DCE synergistically increased CYP2E1 protein and mRNA levels, accelerated the metabolism of ethanol and 1,2-DCE in the brain tissue, induced high production of reactive oxygen species (ROS), and increased MDA levels, thereby damaging the blood-brain barrier and causing obvious pathological changes in brain tissue. However, the increased level of ROS activated the Nrf2 signal transduction pathway, promoting the expression of HO-1 and glutathione-related antioxidant enzymes in the brain to protect the cells from oxidative damage.

Aliphatic Halogenated Hydrocarbons: Report and Analysis of Liver Injury in 60 Patients

Background and Aims: Intoxications by aliphatic halogenated hydrocarbons (AHH), used as effective solvents, are rare and may cause life-threatening liver injury. Patients with acute intoxications by AHH received an innovative treatment. Methods: Analyzed were data of 60 patients intoxicated by AHH, such as dichloromethane (n = 3), chloroform (n = 2), carbon tetrachloride (n = 12), 1,2-dichloroethane (n = 18), 1,1,2-trichloroethane (n = 2), trichloroethylene (n = 2), tetrachloroethylene (n = 13) or mixed AHH chemicals (n = 8), who received a new treatment consisting of CO₂-induced hyperventilation to accelerate toxin removal via the lungs. Results: Added to the inspiration air at a flow rate of 2-3 Liter min^-1, CO₂ increased the respiratory volume up to 25-30 Liter min^-1, ensuring forced AHH exhalation. This CO₂-induced hyperventilation therapy was commonly well tolerated by the 60 patients and lasted for 106.0±10.5 hours. In most cases, initially increased liver test results of aminotransferases normalized quickly under the therapy, and liver histology obtained at completion of the therapy revealed, in the majority of patients, normal findings or fatty changes, and rarely severe single cell necrosis but no confluent liver cell necrosis. Despite therapy, clinical outcome was unfavorable for 4/60 patients (6.7%) of the study cohort, due to single or combined risk factors. These included late initiation of the CO₂-induced hyperventilation therapy, intentional intoxication, uptake of high amounts of AHH, concomitant ingestion of overdosed drugs, consumption of high amounts of alcohol, and history of alcohol abuse. Conclusions: For intoxications by AHH, effective therapy approaches including forced hyperventilation to increase toxin removal via the lungs are available and require prompt initiation.

European Restrictions on 1,2-Dichloroethane: C-H Activation Research and Development Should Be Liberated and not Limited

Plan B: 1,2-Dichloroethane was recently subject to regulatory controls in the European Union that will severely limit its commercial use. The practitioners of innovative synthetic methods, particularly C-H bond activation, need to investigate alternative solvents if their chemistry is to stay relevant.

1,2-Dichloroethane Induces Reproductive Toxicity Mediated by the CREM/CREB Signaling Pathway in Male NIH Swiss Mice

1,2-Dichloroethane (1,2-DCE) is a widely used chlorinated organic toxicant but little is known about the reproductive disorders induced by its excessive exposure. To reveal 1,2-DCE-induced male reproductive toxicity and to elucidate the underlying mechanisms, we exposed male National Institutes of Health Swiss mice to 1,2-DCE by inhalation at 0, 100, 350, and 700 mg/m3 for 6 h/day, for 1 and 4 weeks. Our findings showed a significant decrease in body weight with increased testis/body weight ratio, reduced sperm concentration and induced malformation of spermatozoa, and vacuolar degeneration of germ cells in the seminiferous tubules of testes in mice exposed to 1,2-DCE. Cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB) and cAMP-response element modulator (CREM) were significantly inhibited by 1,2-DCE. This is consistent with the declines in the transducer of regulated CREB activity 1 and activator of CREM in testis, which results in the decrease in lactate dehydrogenase C and testis-specific kinase 1 in the testes. Moreover, the activation of p53 and Bax with the inhibition of Bcl-2 might be the reason for the upregulation of caspase-3 in the apoptosis, as detected by TdT-mediated dUTP nick-end labeling assay in the testes induced by 1,2-DCE. Finally, elevated testosterone levels were found along with increased levels of gonadotropin-releasing hormone, cAMP, luteinizing hormone (LH), and LH receptors in the testes. These findings suggest that 1,2-DCE inhibits CREM/CREB signaling cascade and subsequently induces apoptosis associated with p53 activation and mitochondrial dysfunction. This also results in induced malformation of spermatozoa, reduced sperm concentration, and pathological impairment of the testes.

Template-Mediated Ni(II) Dispersion in Mesoporous SiO2 for Preparation of Highly Dispersed Ni Catalysts: Influence of Template Type

Supported Ni catalysts on three mesoporous SiO₂ supports (i.e., SBA-15, MCM-41, and HMS) were prepared using a solid-state reaction between Ni(NO₃)₂ and organic template-occluded mesoporous SiO₂. For comparison, supported Ni catalysts on mesoporous SiO₂ synthesized by the conventional impregnation method were also included. The catalysts were characterized by scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, N₂ adsorption, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction, transmission electron microscopy, and transmission electron microscopy-energy-dispersive X-ray. The catalytic properties of the catalysts were evaluated using gas-phase catalytic hydrodechlorination of 1,2-dichloroethane. The results showed that upon grinding Ni(NO₃)₂ with template-occluded mesoporous SiO₂, strong coordination between Ni²⁺ and dodecylamine was identified in the Ni(NO₃)₂-HMS system. Additionally, the results of H₂ temperature-programmed reduction revealed that NiO in calcined NiO/HMS was reduced at higher temperature than those in calcined NiO/SBA-15 and NiO/MCM-41, reflecting the presence of a strong interaction between NiO and mesoporous SiO₂ in NiO/HMS. Consistently, the average particle sizes of metallic Ni were found to be 2.7, 3.4, and 9.6 nm in H₂-reduced Ni/HMS, Ni/SBA-15, and Ni/MCM-41, respectively, indicative of a much higher Ni dispersion in Ni/HMS. For the catalytic hydrodechlorination of 1,2-dichloroethane, Ni/MCM-41 synthesized by the solid-state reaction method exhibited a catalytic activity similar to that prepared by the impregnation method, while higher catalytic activities were observed on Ni/HMS and Ni/SBA-15 than on their counterparts prepared by the impregnation method. Furthermore, a higher conversion was identified on Ni/HMS than on Ni/SBA-15 and Ni/MCM-41, highlighting the importance of template type for the preparation of highly dispersed metal catalysts on mesoporous SiO₂.

2-Chloroethanol Induced Upregulation of Matrix Metalloproteinase-2 in Primary Cultured Rat Astrocytes Via MAPK Signal Pathways

This study was to explore the mechanisms underlying 1,2-dichloroethane (1,2-DCE) induced brain edema by focusing on alteration of matrix metalloproteinase-2 (MMP-2) in rat astrocytes induced by 2-chloroethanol (2-CE), an intermediate metabolite of 1,2-DCE in vivo. Protein and mRNA levels of MMP-2, and the phosphorylated protein levels of p38 MAPK (p-p38), extracellular signal regulated protein kinase (p-ERK1/2) and c-Jun N-terminal kinase (p-JNK1/2) in astrocytes were examined by immunostaining, western blot or real-time RT-PCR analysis. Findings from this study disclosed that protein levels of MMP-2 were upregulated by 2-CE in astrocytes. Meanwhile, protein levels of p-p38, p-ERK1/2 and p-JNK1/2 were also increased apparently in the cells treated with 2-CE. Moreover, pretreatment of astrocytes with SB202190 (inhibitor of p38 MAPK), U0126 (inhibitor of ERK1/2) or SP600125 (inhibitor of JNK1/2) could suppress the upregulated expression of p-p38, p-ERK1/2, and p-JNK1/2. In response to suppressed protein levels of p-p38 and p-JNK1/2, the protein levels of MMP-2 also decreased significantly, indicating that activation of MAPK signal pathways were involved in the mechanisms underlying 2-CE-induced upregulation of MMP-2 expression.

Route-to-route extrapolation of 1,2-dichloroethane studies from the oral route to inhalation using physiologically based pharmacokinetic models

To help develop a comprehensive, quantitative understanding of the hazards of 1,2-dichloroethane (ethylene dichloride, EDC, CAS No. 107-06-2) exposure by the inhalation route, the results of existing subchronic studies and an extended one-generation reproductive toxicity (EOGRT) study recently conducted by the oral route in rats were extrapolated using a physiologically based pharmacokinetic (PBPK) model. The no observed adverse effects levels (NOAELs) for the endpoints of neurotoxicity and reproductive/developmental toxicity were the highest tested doses of 169 and 155 mg/kg-day, respectively. These NOAELs were equivalent to continuous exposure of rats to minimums of 76 ppm and 62 ppm EDC, respectively, using total metabolism of EDC as the dose metric that is equivalent in the oral and inhalation scenarios. In contrast, the subchronic study NOAEL of 37.5 mg/kg-day corresponded to continuous inhalation of 4.4 ppm EDC, based on equivalent extrahepatic metabolism. The selection of the internal metric which serves to establish route-to-route equivalency was found to profoundly influence the NOAEL-equivalent inhalation exposure concentration and thus will be a key determinant of inhalation toxicity reference criteria developed on the basis of EDC studies conducted by the oral route.

One-Pot Three-Component Synthesis of 2-Imino-1,3-Thiazolines on Soluble Ionic Liquid Support

An efficient one-pot, three-component synthesis of 2-imino-1,3-thiazolidines and 2-imino-1,3-thiazolines using ionic liquid-tethered 2-aminobenzimidazoles was reported. The protocol includes reaction of ionic liquid attached 2-aminobenzimidazoles with isothiocyanates to afford isothioureas, followed by its base induced inter and intramolecular nucleophilic displacement reactions with 1,2-dichloroethane (EDC) which results in thiazolidine ring formation. In the next to the last step, the ionic liquid support was removed by methanolysis to deliver 2-imino-1,3-thiazolidines, which were sequentially oxidized with manganese(III) triacetate to yield 2-imino-1,3-thiazolines. The salient feature of this method is the use of 1,2-dichloroethane as a synthetic equivalent for α-haloketone to avoid the use of toxic halogenating reagents.

Genome sequence of the organohalide-respiring Dehalogenimonas alkenigignens type strain (IP3-3(T))

Dehalogenimonas alkenigignens IP3-3^T is a strictly anaerobic, mesophilic, Gram negative staining bacterium that grows by organohalide respiration, coupling the oxidation of H₂ to the reductive dehalogenation of polychlorinated alkanes. Growth has not been observed with any non-polyhalogenated alkane electron acceptors. Here we describe the features of strain IP3-3^T together with genome sequence information and its annotation. The 1,849,792 bp high-quality-draft genome contains 1936 predicted protein coding genes, 47 tRNA genes, a single large subunit rRNA (23S-5S) locus, and a single, orphan, small unit rRNA (16S) locus. The genome contains 29 predicted reductive dehalogenase genes, a large majority of which lack cognate genes encoding membrane anchoring proteins.

Development of an inhalation unit risk factor for ethylene dichloride

The Texas Commission on Environmental Quality (TCEQ) conducts up-to-date carcinogenic assessments for chemicals emitted in Texas. An inhalation unit risk factor (URF) was developed for ethylene dichloride (EDC, CAS 107-06-2) based on tumorigenicity results observed in a 2-year animal inhalation study conducted by Nagano et al. More specifically, the incidence of combined mammary gland tumors (adenomas, fibroadenomas, adenocarcinomas) in female rats demonstrated a statistically significant dose-response relationship, was amenable to benchmark concentration (BMC) modeling, was ultimately determined to be the most sensitive tumorigenic effect in the most sensitive species and sex, and was utilized as the carcinogenic endpoint for the development of the URF. The 95% lower confidence limit of the BMC at the 10% excess risk level (BMCL10 of 40.1 ppm) was determined for calculation of the URF. The resulting URF based on increased incidence of combined mammary gland tumors in female rats is 1.4E-02 per ppm (3.4E-03 per mg/m(3)). The lifetime air concentration corresponding to a no significant excess risk level of 1 in 100 000 is 0.71 ppb (2.9 μg/m(3)), which is considered sufficiently health-protective for use in protecting the general public against the potential carcinogenic effects of chronic exposure to EDC in ambient air.

Effect of benzoic acid on the removal of 1,2-dichloroethane by a siderite-catalyzed hydrogen peroxide and persulfate system

Benzoic acid can affect the iron-oxide mineral dissolution and react with hydroxyl radical. This study investigated its effect on 1,2-dichloroethane removal process by siderite-catalyzed hydrogen peroxide and persulfate. The variation of benzoic acid concentrations can affect pH value and soluble iron concentrations; when benzoic acid varied from 0 to 0.5 mmol/L, pH increased while Fe(2+) and Fe(3+) concentrations decreased, resulting in 1,2-dichloroethane removal efficiency which decreased from 91.2 to 5.0%. However, when benzoic acid varied from 0.5 to 10 mmol/L, pH decreased while Fe(2+) and Fe(3+) concentrations increased, resulting in 1,2-dichloroethane removal efficiency which increased from 5.0 to 83.4%.