Use of 1H nuclear magnetic resonance longitudinal relaxation times in structure elucidation of chlorinated polyaromatic compounds.
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Hydrocarbons, Chlorinated↗
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Distal site and surface mutations of cytochrome P450 1A2 markedly enhance dehalogenation of chlorinated hydrocarbons.
Chlorinated compounds such as chlorinated ethylenes and ethanes are serious environmental pollutants. In the present study, we examined whether or not a recombinant strain of Saccharomyces cerevisiae that expresses rat liver cytochrome P450 1A2 (P450 1A2) wild-type and mutant proteins can efficiently catalyze oxidative and reductive dehalogenations of trichloroethylene, pentachloroethane, and hexachloroethane. Mutations at putative heme distal and protein surface sites of P450 1A2 greatly enhanced turnover values toward those substrates under both aerobic and anaerobic conditions. For example, a Thr319Ala mutation at the putative heme distal site enhanced the degradation rate of trichloroethylene and pentachloroethane by 2- and 2.7-fold, respectively, under aerobic conditions. The Thr319Ala mutation also strongly facilitated the reaction with hexachloroethane up to 13- and 4.5-fold under aerobic and anaerobic conditions, respectively. The Thr319Ala mutation increased dechlorinated over protonated product ratios by 3-fold as well when either pentachloroethane or hexachloroethane was used as a substrate. A Lys250Leu mutation on the putative protein surface site enhanced the dehalogenation rate of hexachloroethane up to 4.8-fold under anaerobic conditions. In contrast, a Glu318Ala mutation at the putative distal site markedly decreased the activities with trichloroethylene and pentachloroethane substrates under aerobic conditions. Conserved amino acids Thr319 and Glu318 at the heme distal site have been suggested to be important in the O2 activation during monooxidation reactions of P450s. However, the present study indicates that Thr319 is likely to be an inhibitor of dechlorination of trichloroethylene and penta- and hexachloroethanes. The roles of Thr319, Glu318, and Lys250 in the catalysis with chlorinated hydrocarbons are discussed in association with reaction mechanisms.
Animals↗
Organophosphate triesters in indoor environments.
In this study the occurrence of ten organophosphate triesters in indoor air at 29 different locations was investigated. They were detected at all locations and a total of ten compounds were identified. The predominant compounds were the chlorinated compounds tris(chloroisopropyl) phosphate and tris(2-chloroethyl) phosphate with a concentration around 2 microg m(-3) in some indoor environments. A rough estimation gives at hand a daily inhalation of around 10 microg for each of these two compounds.
Air Pollution, Indoor↗
A comparison of indoor air pollutants in Japan and Sweden: formaldehyde, nitrogen dioxide, and chlorinated volatile organic compounds.
Indoor and outdoor concentrations of formaldehyde (HCHO), nitrogen dioxide (NO2), and selected chlorinated volatile organic compounds (chlorinated VOC) were measured in 37 urban dwellings in Nagoya, Japan, and 27 urban dwellings in Uppsala, Sweden, using the same sampling procedures and analytical methods. Indoor as well as outdoor air concentrations of HCHO, NO2, and chlorinated VOC were significantly higher in Nagoya than in Uppsala (P<0.01), with the exception of tetrachlorocarbon in outdoor air. In Nagoya, HCHO and NO2 concentrations were significantly higher in modern concrete houses than in wooden houses and higher in newer (less than 10 years) than in older dwellings (P<0.01), possibly due to less natural ventilation and more emission sources in modern buildings. Dwellings heated with unvented combustion sources had significantly higher indoor concentrations of NO2 than those with clean heating (P<0.05). Moreover, dwellings with moth repellents containing p-dichlorobenzene had significantly higher indoor concentrations of p-dichlorobenzene (P<0.01). In conclusion, there appear to be differences between Nagoya and Uppsala with respect to both indoor and outdoor pollution levels of the measured pollutants. More indoor pollution sources could be identified in Nagoya than in Uppsala, including construction and interior materials emitting VOC, use of unvented combustion space heaters, and moth repellents containing p-dichlorobenzene.
Air Pollutants↗
Chemical changes of organic compounds in chlorinated water. XVI. Gas chromatographic-mass spectrometric studies of reactions of tricyclic aromatic hydrocarbons with hypochlorite in dilute aqueous solution.
The products of aqueous chlorination reactions of tricyclic aromatic hydrocarbons (fluorene, carbazole, dibenzofuran, anthracene, phenanthrene and some methyl derivatives) with hypochlorite have been determined by gas chromatography-mass spectrometry. They included chloro-substituted, oxygenated (quinones) and hydroxylated (phenols) compounds, and products of addition which were readily formed at ambient temperature. The extent of the reactions was shown to depend on the chlorine dose, the solution pH, the initial concentrations of both compounds and the structures. Monochlorinated compounds and quinones were shown to be present in chlorinated water under the conditions utilized for water treatment.
Chlorine↗
The acute and chronic toxicity of ten chlorinated organic compounds to the American flagfish (Jordanella floridae).
The acute toxicity (96-hr median lethal concentrations (LC50s) of ten chlorinated isomers of benzene, phenol, ethane, and ethylene to the American flagfish (Jordanella floridae) were determined in both static and flow-through systems. Chronic toxicity to embryo-larval fish was also estimated from hatching success and post-hatch survival as well as fry growth rates and survival. Maximum acceptable toxicant concentrations (MATC) were estimated where possible. In general, for both acute and chronic toxicity tests, the order of increasing relative toxicity based on the water-borne exposure concentrations was: chloroethanes, chloroethylenes, chlorobenzenes, and chlorophenols. Within groups, more highly chlorinated isomers were usually more toxic. The presence of suspended or colloidal 1,2,4,5-tetrachlorobenzene was observed in acute toxicity testing and affected toxicity estimates.
Animals↗
Effect of phenolic and chlorine disinfectants on hepatitis C virus binding and infectivity.
BACKGROUND: The purpose of this study was to evaluate the inhibitory activity of 2 polyphenolic disinfectants and a chlorine compound (NaDCC) on hepatitis C virus (HCV) binding and infectivity. METHODS: VERO cells (a continuous cell line derived from cynomolgus kidney cells) suitable for analyzing HCV binding and replication, and the competitive reverse transcription (cRT-PCR) technique for HCV RNA molecules quantitative evaluation have been chosen as a methodologic approach for the antiviral activity testing. RESULTS: At their recommended use dilutions, polyphenolic disinfectants inhibited HCV binding and replication. The chlorine compound was ineffective, probably a result of its low concentration in the presence of protein substances in VERO cell cultures. CONCLUSIONS: Inhibition of HCV binding and replication by the tested polyphenolic associations confirm their value in instrument decontamination and environmental disinfection against this clinically important lipid virus.
Animals↗
Vertical profile of PCDD/Fs, dioxin-like PCBs, other PCBs, PAHs, chlorobenzenes, DDX, HCHs, organotin compounds and chlorinated ethers in dated sediment/soil cores from flood-plains of the river Elbe, Germany.
Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other organic micropollutants were determined in dated sediment/soil cores collected from the flood-plain of the river Elbe near Pevestorf (PT), approximately 125 km upstream of Hamburg, and Heuckenlock (HL) in southeast of Hamburg. Concentrations of PCDD/Fs peaked sharply at PT in the 1950s and at HL at the end of the 1940s. Cluster analyses provide evidence that the region of Bitterfeld-Wolfen (about 350-400 km upstream of Hamburg) could be the source of the PCDD/F contamination existing in the cores PT and HL since the 1940s. Obviously it is caused by sediments of the river Elbe of a similar composition. Whereas the PCDD/Fs, HCHs (hexacyclohexane isomers), DDX (DDT, DDD, DDE), and tetrachlorinated ethers in PT and HL presumably originated predominantly from the Bitterfeld-Wolfen region, organotin compounds in HL and dichlorinated haloethers in HL during the 1940s and 1950s can probably largely be attributed to emissions from the Hamburg region. Although they are separated by a large distance, in both sediment cores PT and HL concentrations and composition patterns of most organic micropollutants analyzed widely match. Inductively it can be concluded that similar contaminations will be found in many of the river bank soils between the Bitterfeld-Wolfen region and Hamburg. Excavation of top soils may uncover highly contaminated materials. Since the dated sediment cores show the variation in contaminants in the Elbe sediments over a defined time period, it is possible to make an approximate assessment of the actual degree of contamination to be expected in areas where in previous decades contaminated dredged sediments from the Elbe and from the Port of Hamburg have been deposited on land and used for building plots or for agricultural purposes.
Benzofurans↗
Genome sequence of the chlorinated compound-respiring bacterium Dehalococcoides species strain CBDB1.
Dehalococcoides species are strictly anaerobic bacteria, which catabolize many of the most toxic and persistent chlorinated aromatics and aliphatics by reductive dechlorination and are used for in situ bioremediation of contaminated sites. Our sequencing of the complete 1,395,502 base pair genome of Dehalococcoides strain CBDB1 has revealed the presence of 32 reductive-dehalogenase-homologous (rdh) genes, possibly conferring on the bacteria an immense dehalogenating potential. Most rdh genes were associated with genes encoding transcription regulators such as two-component regulatory systems or transcription regulators of the MarR-type. Four new paralog groups of rdh-associated genes without known function were detected. Comparison with the recently sequenced genome of Dehalococcoides ethenogenes strain 195 reveals a high degree of gene context conservation (synteny) but exceptionally high plasticity in all regions containing rdh genes, suggesting that these regions are under intense evolutionary pressure.
Base Sequence↗
Simple, quick, and sensitive method for determination of total chlorinated organic compounds in wastes and related materials.
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Aniline Compounds↗
Secular changes of PCB concentration accumulated in organs and tissues of Japanese from 1974 to 1989.
The concentration and component types of PCB in adult human liver and fat tissue (64 samples) from forensic autopsy cases of Osaka Prefecture in 1989 were measured for comparison with the data for the same organ and tissue during the period from 1974 to 1984. The mean values of PCB levels in 1989 were 0.06 microgram/g (whole base) in the liver and 2.20 micrograms/g (fat base) in the fat tissue. These concentrations both were the same as those observed for the 15-year period. The percentages of the 5,6-chlorinated compound of PCB in the liver and fat tissue were lower but those of the 7-chlorinated compound were 15-20% higher.
Adipose Tissue↗
Genetic adaptation of bacteria to chlorinated aromatic compounds.
Genetic mechanisms in bacteria provide a continuous source of alterations in DNA sequences that may lead to favourable adaptations. Bacteria that use chlorinated aromatics as sole carbon and energy sources show evidence of these different genetic alterations. The distinct effects of single base-pair mutations on adaptation of bacterial strains (e.g. by changing the substrate specificity of a key metabolic enzyme or regulator protein) have been demonstrated in various studies. In addition to these small sequence modifications, intermolecular or intercellular gene exchange mechanisms can result in new strains with altered metabolic capabilities. The details of these evolutionary processes with respect to the metabolism of chlorobenzenes and chlorocatechols are reviewed in this manuscript.
Adaptation, Physiological↗
Using the metabolism of PAHs in a human cell line to characterize environmental samples.
P450 reporter gene system (RGS) is an in vitro assay to detect compounds that activate the Ah receptor and induce cytochrome P450 (CYP1A1). This system utilizes a human cell (101L) stably transfected with a luciferase reporter downstream of human CYP1A1 promoter sequences. When CYP1A1-inducing compounds are present, luciferase is produced as well as endogenous CYP1A1 enzymes. Polycyclic aromatic hydrocarbons (PAHs) are more readily degraded than chlorinated compounds including dioxins, furans, and coplanar polychlorinated biphenyls (PCBs). PAH-induced luciferase production begins to decrease between 6 and 16 h, while chlorinated compounds produce a more sustained response. Individual and mixtures of CYP1A1-inducing compounds were tested at both 6 and 16 h. Extracts of soils containing both PAHs and dioxins were also tested, before and after cleanup to remove PAHs. Results indicate that RGS testing at 6 and 16 h is a promising tool to differentiate between PAHs and chlorinated hydrocarbons often co-occurring in environmental samples.
Journal Article↗
Chemical changes of organic compounds in chlorinated water. XIV. Characterization and determination of halogenated organics formed during chlorination of water from the Tama River.
Water samples collected from the Tama River were treated with chlorine under the conditions utilized for water renovation, in order to characterize and determine the halogenated organics formed in this reaction. It was found that the concentrations and compositions of organic halogens in chlorinated river water are strongly dependent on the sampling points. Chlorinated river-water showed total trihalomethane (THM) levels ranging from 26 to 96 micrograms/l. Higher concentrations of THMs and a high ratio of brominated THMs to total THMs were found on chlorination of water samples taken from the midstream of the Tama River, as compared with those observed from the upstream. The range of non-purgeable (NPOX) and n-hexane-extractable organic halogen (EOX) levels in the chlorinated river-water was from 146 to 417 microgram/l and from 15 to 105 micrograms/l, respectively. Gas chromatographic analyses of n-hexane extracts demonstrated that chlorine treatment of river-water not only produces, in addition to THMs, new lower-molecular-weight and chromatographiable organic halogen compounds (COX), but also decomposes the original halogenated organics present. The amounts of THMs, COX, EOX and NPOX in chlorine-treated river-water were found to be dependent on the pH of the solutions.
Chlorine↗
Organochlorine pesticides and chlorinated hydrocarbon solvents in the blood of chemically sensitive patients [corrected]. A statistical comparison with therapeutic medication and natural hormones.
The blood levels of organochlorine pesticides and chlorinated hydrocarbon solvents were measured in 200 and 114 chemically sensitive patients respectively, and compared with blood concentrations of standard medication (non- chlorinated substances. Clonidine, Haloperidol) of comparable toxicity after therapeutically effective dosage, and with reference levels of highly potent chemicals in the blood such as hormones. It was shown that the average blood levels of the most toxic environmental pollutants are comparable with the therapeutic steady state average blood levels of medications which have similar toxicities in the animal model. In addition the toxicity levels of xenoestrogens are at least an order of magnitude higher than normal plasma estrogen or progesterone levels. These findings suggest the possibility of additive or synergistic effects of these chlorinated compounds and the aforementioned medications. Also, these findings suggest the possibility of hormone deregulation from exposure to the aforementioned toxic chlorinated compounds.
Adolescent↗
Toxicity of chlorinated aromatic compounds in animals and humans: in vitro approaches to toxic mechanisms and risk assessment.
Human exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and chlorinated analogs commonly results in pathological changes in the skin and its appendages characterized by thickening of the epidermis (acanthosis), hyperkeratosis and squamous metaplasia of the epithelial lining of the sebaceous glands. Acneform lesions (chloracne) develop as hair follicles dilate and fill with keratin and sebaceous glands become cystic. In animal models it has been found that the chloracneogenic potential of the halogenated aromatic compounds examined corresponds with the relative affinity of these same compounds for the cytosolic TCDD receptor. This receptor controls the coordinate expression of a number of inducible enzyme activities and in certain cell targets can alter normal programs of proliferation and differentiation. In this report we describe some of our ongoing studies on the mechanisms of action of TCDD in normal human epidermal cells and squamous cell carcinoma (SCC) lines. These systems permit detailed investigation of the molecular and biochemical events underlying pathologic changes in the skin and offer the potential of establishing a risk assessment model for halogenated aromatic compounds by using human target cells.
Animals↗
Toxicities of "excessively" chlorinated organic compounds.
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Animals↗
[SARS: diagnosis, therapy, and especially prevention].
The main purpose of this review is to analyze some aspects of the severe acute respiratory syndrome, SARS, in order to obtain useful data to suggest preventive actions to reduce the spreading of the disease. Many elements have been examined to reach some conclusions and to allow an updated discussion. Surgical masks protect more the patient than the caregiver. Simple or double surgical masks may be useful, as double gloving protects the hands of the surgical personnel against percutaneous transmission of HIV eventually present in contaminated blood. The frequent substitution of the external masks with a new one will improve the filtering activity against droplets produced by cough or sneezes of the patient. The use of respiratory masks may be suggested in hospitals or in restricted ventilated areas where, even if coronavirus variant is considered an environmental contaminant more than a respiratory risk, droplets nuclei may persist in the air and add consistent dangers to the heath-care givers. Considering that large and medium droplets may infect floors and surfaces, in addition to gloves, gowns, masks and eyes protection, the available list of viral and bacterial factors implicated in SARS ethiology suggests a better hand antisepsis using frequently the alcohol based gels (containing an high percentage of emollients substances), if available. A liquid soap with triclosan can also be used, if the health-care workers compliance to hand washing increases, as expected in this explosive situation. On the basis of the results of some experimental data, the environmental disinfection may be effected with ethyl alcohol 70% in water. Disinfection of floors or larger surfaces may be obtained with chlorine compounds solutions, after an accurate pre-cleaning. When corrosion, bleaching or gas production have to be avoided, chlorine compounds may be substituted by phenolic detergent disinfectants.
Humans↗