Halomethanes Research Articles

The Generation of ROS by Exposure to Trihalomethanes Promotes the IκBα/NF-κB/p65 Complex Dissociation in Human Lung Fibroblast.

Background: Disinfection by-products used to obtain drinking water, including halomethanes (HMs) such as CH2Cl2, CHCl3, and BrCHCl2, induce cytotoxicity and hyperproliferation in human lung fibroblasts (MRC-5). Enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) modulate these damages through their biotransformation processes, potentially generating toxic metabolites. However, the role of the oxidative stress response in cellular hyperproliferation, modulated by nuclear factor-kappa B (NF-κB), remains unclear. Methods: In this study, MRC-5 cells were treated with these compounds to evaluate reactive oxygen species (ROS) production, lipid peroxidation, phospho-NF-κB/p65 (Ser536) levels, and the activities of SOD, CAT, and GPx. Additionally, the interactions between HMs and ROS with the IκBα/NF-κB/p65 complex were analyzed using molecular docking. Results: Correlation analysis among biomarkers revealed positive relationships between pro-oxidant damage and antioxidant responses, particularly in cells treated with CH2Cl2 and BrCHCl2. Conversely, negative relationships were observed between ROS levels and NF-κB/p65 levels in cells treated with CH2Cl2 and CHCl3. The estimated relative free energy of binding using thermodynamic integration with the p65 subunit of NF-κB was -3.3 kcal/mol for BrCHCl2, -3.5 kcal/mol for both CHCl3 and O2•, and -3.6 kcal/mol for H2O2. Conclusions: Chloride and bromide atoms were found in close contact with IPT domain residues, particularly in the RHD region involved in DNA binding. Ser281 is located within this domain, facilitating the phosphorylation of this protein. Similarly, both ROS interacted with the IPT domain in the RHD region, with H2O2 forming a side-chain oxygen interaction with Leu280 adjacent to the phosphorylation site of p65. However, the negative correlation between ROS and phospho-NF-κB/p65 suggests that steric hindrance by ROS on the C-terminal domain of NF-κB/p65 may play a role in the antioxidant response.

Study on the molecular interactions of binary mixtures of N-methyl benzyl amine with halo methane’s through thermodynamic properties and correlation with the Jouyban–Acree model

ABSTRACT The thermodynamic and transport properties of binary mixtures of N-methyl benzyl amine (NMBA) with halo methane compounds at temperatures from 303.15 K to 313.15 K were investigated. The study analysed the excess molar volume, excess isentropic compressibility, deviation in viscosity, and excess Gibbs free energy for activation of viscous flow using measured densities (ρ), viscosities (η), and speeds of sound (u). The research also examined the impact of the inductive effect on excess properties concerning intermolecular attractive forces between the respective constituents. Furthermore, the Jouyban–Acree model was employed to correlate density, speed of sound, and viscosity with composition and obtained good agreement.

Determination of Tri halo methanes in indoor swimming pools, Kuwait and development of health risk index

Determination of Tri halo methanes in indoor swimming pools, Kuwait and development of health risk index

Investigation of directly suspended droplet micro extraction method for extraction of trihalomethane and halomethane in water samples

Simple and efficient directly suspended droplet micro extraction (DSDME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of Halomethane and Trihalomethane from water samples. In this technique a micro drop of n-hexane is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Factors relevant to the extraction efficiency were studied and optimized. The optimized extraction conditions were extraction solvent: n- hexane; NaCl concentration: 1M; solvent extraction volume: 50μL; stirring rate: 720rpm and the extraction time: 5min. The detection limits of the method were in the range of 0.059–0.137µgL−1, relative standard deviation (n=3) range were 0.019–0.048%. A good linearity (r2≥0.997) and a relatively broad dynamic linear range (10–200µgL−1) were obtained and recoveries of method were in the range of 97.69–99.51%. Finally, the proposed method was successfully utilized for pre concentration and determination of halo methane in different real samples. Successfully DSDME technique combined with capillary GC-ECD for the analysis of THMs and HMs in the water investigated samples.

Increased formation of halomethanes during chlorination of chloramphenicol in drinking water by UV irradiation, persulfate oxidation, and combined UV/persulfate pre-treatments

Ultraviolet/persulfate (UV/PS) has been widely used to generate sulfate radicals for degradation of water organic pollutants in previous studies. However, its impacts on disinfection byproduct formation during post-chlorination of degraded compounds is unclear. The objective of this study was to evaluate the impacts of UV irradiation, PS oxidation, and the combined UV/PS advanced oxidation process (AOP) pre-treatments on halomethane formation during the following chlorination of chloramphenicol (CAP), a model antibiotic commonly found in wastewater-impacted water. Results showed that CAP could be transformed to more trichloromethane (TCM) than monochloromethane (MCM) and dichloromethane (DCM) in the presence of excess chlorine. UV photolysis, PS oxidation and UV/PS AOP all directly decomposed CAP to produce halomethanes (HMs) before post-chlorination. Moreover, UV and UV/PS pre-treatments both enhanced the formation of all the HMs in the subsequent chlorination. PS pre-oxidation decreased the TCM formation during post-chlorination, but increased the yields of MCM, DCM and total HMs. UV pre-irradiation significantly increased the bromide utilization of HMs, whereas UV/PS pre-oxidation decreased the bromine incorporation and utilization of HMs from the chlorination of CAP in a low-bromide water. UV irradiation, PS oxidation, and UV/PS AOP can inactivate pathogens and degrade organic pollutants, but this benefit should be weighed against a potential risk of the increased halomethane formation from degraded organic pollutants with and without post-chlorination.

Study of Chlorination Application in Tapioca Wastewater Cyanide Removal

Tapioca wastewater contains a high concentration of organic matter and cyanide. Chlorination has known as one of alternative cyanide removal methods. The fact that must be an attention is carcinogenic compound such as Tri Halo Methane could be produced as byproduct chlorination of organic waste. This research aimed to determine condition of chlorination application in tapioca wastewater cyanide removal especially calcium hypochlorite dosage and pH thus meeting the criteria of the quality standard of waste and Tri Halo Methane identification. Efluent of chlorination using calcium hypochlorite dosage based on stoichiometry reaction between chlor and cyanide (mole ratio chlor:cyanide = 1:1) which carried out at pH operation 8 for 60 minutes has observed for cyanide content and Tri Halo Methane identification. Other variation of calcium hypochlorite dosage applied until meet the standart quality or lower cyanide content of effluent with no Tri Halo Methane detected. pH optimum determined from comparation of quality effluent of chlorination using calcium hypochlorite optimum dosage with variation pH operation 6, 7, 8. The results showed that the optimum condition for chlorination application in tapioca wastewater removal was 5,986 mg/L for calcium hypochlorite dosage (1,75 stoichiometry reaction) and 8 for pH operation. This chlorination condition able to reduce cyanide of 192 mg/L to 0,272 mg/L wuth no Tri Halo Methane detected in the effluent.

Generation of oxyradicals ( and H2O2), mitochondrial activity and induction of apoptosis of PBMC of Cyprinus carpio carpio treated in vivo with halomethanes and with recombinant HSP60 kDa and with LPS of Klebsiella pneumoniae

Halomethanes (HM) can be immunotoxic in mammals; however, in the fish immune system HM effects are unknown. In the current study, we evaluated the mitochondrial activity (MA) by MTT, induction of apoptosis by SubG0 technique and quantified serum ROS concentration ( and H2O2) and ROS production in PBMC of Cyprinus carpio carpio treated i.p. with CH2Cl2, CHCl3 and BrCHCl2 (0.004–40.0 mg/kg) for 96 h. Positive controls were recombinant heat shock protein of 60 kDa (rHSP60 kDa) of Klebsiella pneumoniae and its LPS. In addition, for in vitro PBMC cultures, two culture media and two sources of sera were tested. Both positive controls increased the MA more than 4-fold as well as the production of (26-fold) and H2O2 (5-fold) compared to their controls. HM induced different effects on MA, ROS production and an induction of apoptosis, depending on the chlorination patterns and the dose; however, a systemic damage prevails. To fish treated with CH2Cl2, the apoptosis was related with serum ROS concentration and with MA. In contrast, in fish dosed with CHCl3 relationships were not found, deducing a systemic damage. However, in fish treated with BrCHCl2, serum concentration and in vitro ROS generation performed by PBMC were involved in the induction of apoptosis of these cells but not with MA suggesting also immunotoxic effects. The current study demonstrated that HMs are immunomodulators increasing an acute inflammatory response and that rHSP60kDA of K. pneumoniae and its LPS are appropriate antigens to assess the immune response of C. c. carpio.

Haloactamides versus halomethanes formation and toxicity in chloraminated drinking water

In this study we quantified the concentrations of nine haloacetamides (HAcAms) and nine halomethanes (HMs) in the final waters of five drinking water treatment plants (DWTPs) that use either chlorination or chloramination for disinfection and evaluated the toxicity of dichloroacetamide (DCAcAm) and dichloromethane (DCM) in normal rat kidney (NRK) cells using four in vitro toxicity assays. All the DWTPs final waters contained primarily di-HAcAms, followed by tri- and mono-HAcAms, and DCAcAm was the most abundant species of the 9 HAcAms, regardless of chlorination or chloramination being applied. In the final waters of DWTPs using chlorination, tri-HMs (trihalomethanes, THMs) accounted for the majority of HMs, whereas chloramination resulted in more di-HMs (especially DCM) than THMs. All four in vitro toxicity assays indicated that the NRK cell chronic cytotoxicity and acute genotoxicity of DCAcAm were substantially higher than that of DCM. In view of observed occurrence concentrations and quantified toxicity levels, the findings of this study suggest that DCAcAm represents a higher toxicity risk than DCM in chloraminated drinking waters.

Pro-oxidant and antioxidant responses in the liver and kidney of wild Goodea gracilis and their relation with halomethanes bioactivation

In mammals, it has been shown that halomethanes (HM) are bioactivated by enzymes such as CYP 2E1 and the theta isoform of GST to produce reactive metabolites. However, in fish, little information is available, although HM can form autochthonously in aquatic environments. This study assessed the effect of HM in dusky splitfin (Goodea gracilis) from three lakes of the Valley of Mexico by analysing specific HM biomarkers as well as a broad range of biomarkers. The concentration of HM was a function of its half-life (higher in deep waters), while its precursors and solar radiation are secondary factors that determine its concentration. The kidney showed higher basal metabolism than the liver, probably because of its function as a haematopoietic and filtration organ. Using integrated biological response version 2 (IBRv2), it was found that the hepatic and renal O₂· content is a pro-oxidant force capable of inducing oxidative stress (ROOH, TBARS and RC=O). Early damage was found to be dependent on low concentrations of HM in Major Lake, whereas late damage was observed in fish exposed to higher concentrations of HM in Zumpango Lake and Ancient Lake. The activities of enzymes involved in antioxidant defence seemed to be inefficient. The quantitative assessment of biomarkers (ANOVA) and the estimate of parameter A obtained from IBRv2 provided different information. However, the data support the greater predictive power of IBRv2, but it requires a series of interrelated biomarkers to infer these possibilities. G. gracilis presents marked patterns of adaptation, which are dependant on the HM concentrations in environmental mixtures, although the response is complex and many toxicants could induce similar responses.

Pro-oxidant and antioxidant response elicited by CH2Cl2, CHCl3 and BrCHCl2 in Goodea gracilis using non-invasive methods

The development of non-invasive methods aimed to evaluate the effects of many toxicants is required. Although there are some studies conducted in successful ways, a lack of information prevails especially for those substances that could be formed autochthonously in the water bodies, such as halomethanes (HMs). In this study, induction of pro-oxidant forces (CH2O, O2, H2O2), oxidative stress (TBARS, RCO) and antioxidant defenses (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in the skin mucus layer regarding to the liver of Goodea gracilis exposed to CH2Cl2, CHCl3 and BrCHCl2 were evaluated, in addition to the hepatic cytochrome P450 (CYP 2E1) and glutathione S-transferase theta (GSTT) activities. Regardless of the implicit toxicity involved in the bioactivation of the HMs, carried out by the CYP 2E1 and GST, it was noticeable that this process induces oxidative stress. The usefulness of the mucus layer for the evaluation of the oxidative stress response was demonstrated, despite some peculiar characteristics concerning induction of oxidative stress in liver and skin mucous layer. However, for the understanding of the induction of reactive oxygen species in both targets it is essential to evaluate the activity of antioxidant defenses; otherwise the interpretation of toxic effects elicited by HMs would be erroneous. In the skin mucus layer, lower activities of the enzymes involved in antioxidant defense than in liver were observed. The evaluation of the biomarkers in the skin mucus layer involved in the oxidative stress is useful due the consistent response regarding to concentration of the HMs.

Halomethane-induced cytotoxicity and cell proliferation in human lung MRC-5 fibroblasts and NL20-TA epithelial cells

Halomethanes (HMs) can be formed during the chlorination process to obtain drinking water. In liver cells, HMs had been shown to be mutagenic and carcinogenic; however, their bioactivation by CYP 2E1 and GSTT1 is required. Although inhalation is the most common pathway of exposure, reports on the toxic effects induced by HMs in human lung are contradictory. The aim of this study was therefore to evaluate in vitro cytotoxicity and cell proliferation induced by CH2Cl2, CHCl3 and BrCHCl2 in human lung NL20-TA epithelial cells and MRC-5 fibroblasts, and their relationship with CYP 2E1 and GSTT1 activity. High concentrations of these HMs induced cytotoxicity, particularly in cells treated with BrCHCl2. Low concentrations of BrCHCl2 stimulated hyperproliferation of fibroblasts, the most probable consequence of which is regenerative proliferation related to collagen induction. Fibroblasts exposed to BrCHCl2 exhibited low levels of CYP 2E1 activity suggesting that released bromine is able to alter this activity by affecting the active site or auto regulating the activity itself. GSTT1 was up to ten times more active than CYP 2E1 in both cell lines, indicating that potential lung damage is due to formation of pro-carcinogens such as formaldehyde.

Evidence of Bioactivation of Halomethanes and its Relation to Oxidative Stress Response in Chirostoma riojai, an Endangered Fish from a Polluted Lake in Mexico

Halomethanes (HMs) are produced autochthonously in water bodies through the action of ultraviolet light in the presence of HM precursors, such as dissolved organic carbon and halogens. In mammals, toxic effects induced by HMs are diverse and include oxidative stress, which is also induced by divalent and polyvalent metals; however, in fish little information is available on HM metabolism and its possible consequences at the population level. In the present study, high CYP 2E1 and GST theta-like activities were found in viscera of the Toluca silverside Chirostoma riojai from Lake Zumpango (LZ; central Mexico). Formaldehyde, one of the HM metabolites, was correlated with CYP 2E1 activity and also induced lipid peroxidation in viscera. Hepatic CYP 2E1 activity was correlated with GST theta-like activity, suggesting the coupling of both pathways of HM bioactivation and its consequent oxidative damage. Sediment metals, among others, were also responsible for oxidative stress, particularly iron, lead, arsenic and manganese. However, under normal environmental conditions, the antioxidant enzymes of this species sustain catalysis adapted to oxidative stress. Findings suggest that this fish species apparently has mechanisms of adaptation and recovery that enable it to confront toxic agents of natural origin, such as metals and other substances formed through natural processes, e.g., HMs. This has allowed C. riojai to colonize LZ despite the high sensitivity of this species to xenobiotics of anthropogenic origin.

Comparative mutagenicity of halomethanes and halonitromethanes in Salmonella TA100: structure–activity analysis and mutation spectra

Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DPBs) in drinking water that are mutagenic in Salmonella and potent inducers of DNA strand breaks in mammalian cells. Here we compared the mutagenic potencies of the HNMs to those of their halomethane (HM) homologues by testing all nine HNMs and seven of the nine HMs (minus bromomethane and chloromethane) under the same conditions (the pre-incubation assay) in Salmonella TA100 ± S9. We also determined the mutation spectra for several DBPs. In the presence of S9, all nine HNMs, but only three HMs, dibromomethane (DBM), dichloromethane (DCM), and bromochloromethane (BCM), were mutagenic. Only two DBPs of each class were mutagenic in the absence of S9. The HNMs were generally more potent mutagens than their HM homologues, and the brominated forms of both classes of DBPs were more mutagenic and cytotoxic than their chlorinated homologues. The HNMs were at least 10 times more cytotoxic than the HMs, and the cytotoxicity rankings in the presence of S9 were similar for the HNMs and the HMs. The addition of a nitro-group to BCM did not change the mutation spectra significantly, with both homologues inducing primarily (55–58%) GC → AT transitions. The greater cytotoxic and mutagenic activities of the HNMs relative to the HMs are likely due to the greater intrinsic reactivity conferred by the nitro-group. Energy calculations predicted increased reactivity with increasing bromination and greater reactivity of the HNMs versus the HMs ( E lumo values were ∼20 kcal/mol lower for the HNMs compared to their HM homologues). Given that the HNMs also are potent genotoxins in mammalian cells [Environ. Sci. Technol. 38 (2004) 62] and are more mutagenic and 10× more cytotoxic in Salmonella than the HMs, whose levels are regulated in drinking water, further study of their occurrence and potential health effects is warranted.

Counting halomethanes

Counting halomethanes

Dihydro azoles and free radicals : Part I. 1-aryl-4-methylene-5-morpholino-v-triazolines and halomethyl radicals: fragmentation of triazolinic radical sigma complexes.

1-Aryl-4-methylene-5-morpholino-v-triazolines 1 were reacted with halomethyl radicals generated by reaction of halo methanes 2 with benzoyl peroxide or copper(I)chloride. In the former case the corresponding l-aryl-4-trihaloethyl-v-triazoles 3 and 1-aryl-4-halomethyl-v-triazoles 4 were formed. In the second case the corresponding l-aryl-4-trihaloethyl-5-morpholino v-triazoles 5 accompanied by triazoles 4 were obtained. Reaction mechanisms are discussed.

Nucleophilic trifluoromethylation with the reagent combination (Et 2N) 3P/CF 3Br

By interaction of the reagent combination aminophosphane 1 and bromotrifluoromethane 2 on halides of the 4th–6th maingroup we found a new synthetic route to trifluoromethylated element- organics. ▪ All CF 3-products can be isolated in respectable yields by this simple procedure. In the meantime our method was extended to higher perfluoro- organyl halides inclusive C 6F 5Br and mixed halo(F, Cl, Br)methanes. In this connexion especially the synthesis of a palette of α-fluorinated silanes like ▪ emphasizes the scope and validity of our three component system.

The diffusion of some halo-methanes in polystyrene

The diffusion of some halo-methanes in polystyrene