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PubMedDate not supplied

Pharmacokinetic study of p-chloronitrobenzene in humans suffering from acute poisoning.

The pharmacokinetics of p-chloronitrobenzene (p-CNB) in human subjects suffering from acute poisoning was studied from the urinary excretion of p-CNB metabolites. The time course for excretion of five metabolites--2-chloro-5-nitrophenol,N-acetyl-S-(4-nitrophenyl)- L-cysteine, 2,4-dichloroaniline, p-chloroaniline, and 2-amino-5-chlorophenol-were determined by reversed-phase HPLC analysis of urine collected from six subjects during their hospitalization after accidental exposure to p-CNB. The cumulative excretion amount at infinite time (X infinity) and mean residence time for each metabolite were estimated by moment analysis of excretion rate vs. the time curve. The rate constants for p-CNB metabolism were calculated by nonlinear least squares fitting of the time course data using a one-compartment model. The results indicated that the average values of the ratio of excreted amount of each metabolite to the total amount of the five metabolites (X infinity metabolite/X infinity Total) and mean residence time in the six subjects were, respectively: 12.2% and 6.7 days for 2-chloro-5-nitrophenol, 48.0% and 7.0 days for N-acetyl-S-(4-nitrophenyl)-L-cysteine, 1.2% and 3.7 days for 2,4-dichloroaniline, 29.9% and 10.0 days for p-chloroaniline, and 8.7% and 6.0 days for 2-amino-5-chlorophenol. The average values of rate constants in the metabolism of p-CNB to 2-chloro-5-nitrophenol, N-acetyl-S-(4-nitrophenyl)-L-cysteine, and p-chloroaniline were 0.021, 0.082, and 0.067 day-1, respectively. Similarly those in further metabolism of p-chloroaniline for C-chlorination, C-hydroxylation, and N-conjugation were 0.205, 1.206, and 3.526 day-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

[Study of combinations of antimicrobial agents. Development of the method].

We developed and validated a micromethod similar to the checkerboard method in antibiotherapy to study the efficiency of antiseptic and disinfectant molecules. The determination of the FBC index (Fractional Bactericidal Concentration) on 4 reference strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus hirae) for 4 associations (2-benzyl-4 chlorophenol--iodophor; cetrimide-iodophor, 2 benzyl-4 chlorophenol--formaldehyde; hexamidine--formaldehyde) revealed 2 synergistic associations and 2 antagonistic associations for one or more strains.

Anti-Bacterial Agents↗
PubMed2000

Visible-light detoxification and charge generation by transition metal chloride modified titania.

Amorphous microporous metal oxides of titanium (AMM-Ti) modified with chlorides of PtIV, IrIV, RhIII, AuIII, PdII, CoII, and NiII have been prepared by the sol-gel method and characterized by various surface analytical methods. These hybrid AMM-Ti powders are catalysts for the photodegradation of 4-chlorophenol (4-CP) in aqueous solution when illuminated with visible (lambda > or = 400 or 455 nm) or UV (lambda > or = 335 nm) light. The initial rate depends on the dopant level and is highest at 3.0% Pt in the case of PtIV/AMM-Ti. When employed in a photoelectrochemical cell, the activity spectrum of the photocurrent extends downward to about 600 nm, as does the photodegradation of 4-CP. It is suggested that the metal salt acts as a redox-active chromophore, transmitting the photogenerated charges to the amorphous matrix.

Catalysis↗
PubMed1990

Phenoxy acid herbicides and contaminants: description of the IARC International Register of Workers. IARC Working Group.

An International Register of Persons Exposed to Phenoxy Herbicides and Contaminants was established in 1984 by the International Agency for Research on Cancer in collaboration with the National Institute of Environmental Health Sciences (U.S.A.). The purpose of this Register is to investigate the long-term hazards associated with exposure to these herbicides and to serve as a system of scientific collaboration at the international level. Presently, 18,972 workers from 19 cohorts in 10 countries are enrolled in this Register. Fifteen cohorts are from companies that manufacture and formulate phenoxy acids or chlorophenols, and four cohorts are sprayers of phenoxy herbicides. Cancer incidence and mortality are the main outcomes of interest, and vital status for members of the Register has periodically been updated. The great advantage of this Register is its large size, facilitating the detection of hazardous effects of exposure.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMedDate not supplied

Fluorescence analysis of photoinduced degradation of ecotoxicants in the presence of humic acids.

The photolysis of humic acids and phenols in water containing humic acids was investigated. Humic acids extracted from peat (Vasuygan Bog, Tomsk Region, Russian Federation) induce the phototransformation of 4-chlorophenol at 365 and 222 nm. Humic acids were characterized by UV-, fluorescence-, IR- and EPR-spectroscopy and laser-induced fluorescence. The influence of humic acids on the phototransformation of phenols in different irradiation conditions was investigated. Comparison of the data on mercury lamp irradiation showed that the most effective phenols degradation was observed under exposure to KrCl* exilamp light (lambda = 222 nm) in the presence of humic acids.

Chlorophenols↗
PubMed2006

Impact of long-term partial aeration on the removal of 2,4,6-trichlorophenol in an initially methanogenic fluidized bed bioreactor.

A fluidized bed bioreactor (FBBR) was operated for more than 1000 days under two regimes, Methanogenic (M) and Methanogenic-Aerobic (M-A), to remove 2,4,6-trichlorophenol (TCP) and phenol (Phe) from a synthetic wastewater, containing different amounts of TCP and Phe, using different aeration flow-rates (0, 2.13, and 1.06 NL O(2)/L.day). M conditions (80:20 mg/L of TCP:Phe, 0 NL O(2)/L.day) showed similar TCP and Phe removal (>95%). Nevertheless accumulation of 4-chlorophenol (4CP) up to 16 mg/L and Phe up to 4 mg/L was observed, while in M-A conditions (80:20 mg/L of TCP:Phe, 2.13 NL O(2)/L.day) TCP and Phe removal achieved 99.9(+)% and after 70 days no accumulation of intermediates were detected. The increase of TCP and Phe in the influent under M-A conditions from 80:20 to 120:30 mg/L of TCP:Phe did not negatively affect the removal of TCP, intermediates and Phe; in fact, they were similar to those in previous M-A conditions. The decrease in the oxygen flow rate from 2.13 to 1.06 NL O(2)/L.day had no negative effect on pollutant removals, which were as high as in previous two M-A conditions. The specific methanogenic activity of bioparticles of the fluidized bed decreased with long-term partial aeration, starting from 1.097 mmol CH(4)/h.g(TKN) in the M regime (day 60) to <0.02 mmolCH(4)/h.g(TKN) at day 1050, suggesting aerobic regime in the bioreactor rather than an M-A regime. In conclusion, complete removal of TCP and less chlorinated intermediates could be achieved in an initially methanogenic FBBR under conditions of partial aeration, although long-term operation seemed to negatively affect the methanogenic activity of biomass. It is also likely that after extended aeration the microbial community was finally enriched with strains with the ability to attack 2,4,6-TCP under aerobic conditions. This report represents the first evidence of a long exposure to oxygen of an anaerobic microbial consortium that efficiently remove TCP.

Air↗
PubMed1992

The Ca(2+)-transport-ATPase of human erythrocytes as an in vitro toxicity test system--acute effects of some chlorinated compounds.

Investigations to determine the inhibitory activity on the Ca(2+)-transport-ATPase of human erythrocyte membranes were performed with various compounds of toxicological significance, mostly chlorinated and mainly used as biocides, such as phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, 2,3,4-trichlorophenol, 2,3,4,5-tetrachlorophenol, pentachlorophenol (PCP), captan, folpet, captafol, (+)-camphene, toxaphene, dichlorodiphenyltrichloroethane (DDT), lindane, endrin, dieldrin, alpha-endosulfan, beta-endosulfan, paraquat, diallate, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Some of the compounds investigated display an inhibitory effect on the Ca(2+)-transport-ATPase at very low concentrations. The in vitro results obtained in this enzyme assay can be correlated directly with the results of other in vitro assays and with the results of in vivo investigations in different species in which an inhibitory effect on various biological functions is observed. Therefore, an inhibitory effect on the Ca(2+)-transport-ATPase indicates a toxic effect of these compounds to cell functions. Since the inhibitory effect of these compounds can be measured rapidly and the enzyme is easy to handle, it might be a useful tool to screen the toxic effects of various compounds on cell function. The aim of the authors was to investigate the usefulness of this screening test system for the characterization of the cellular toxicity of various compounds.

Calcium-Transporting ATPases↗
PubMedDate not supplied

Involvement of oxidative sress in the toxicity of 4-monochlorophenol in Hep G2 cells in culture.

Chlorophenols, mainly used as biocides, are compounds with a wide spectrum of toxic effects, including teratogenic and carcinogenic actions. The aim of this study was to examine possible 4-monochlorophenol (4-MCP) toxicity related to metabolic pathways, which may implicate semiquinones and reactive oxygen species (ROS), in human Hep G2 cells. The effects of 4-MCP were performed through cytotoxicity assays (viability, ATP level), metabolic activities (4-MCP intracellular concentration, NADPH cytochrome P-450 reductase (Cyt P-450 red.) and glutathione-S-transferase activities, CYP 3A7 mRNA expression) and oxidative stress (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities, glutathione status, malondialdehyde concentration, CYP 2E1 mRNA expression). According to the literature, in this work Hep G2 cells were incubated in the continuous presence of 4-MCP at 350 microM over 24 or 48 h. Results showed statistically significant decreases in ATP levels (24 or 48 h, P < 0.05) versus controls. The 4-MCP intracellular concentrations increased as early as 8-24 h and then decreased (P < 0.01). Decreases in Cyt. P-450 red. (24 h, P < 0.05), catalase (24 h, P < 0.05; 48 h, P < 0.01), glutathione peroxidase activities (48 h, P < 0.05) and reduced glutathione concentrations (48 h, P < 0.05) were observed. In addition, exposure to 4-MCP increased mRNA expressions of CYP 3A7 (24 h, P < 0.05; 48 h, P < 0.01) and CYP 2E1 (24 h, P < 0.01) versus controls. Taken together, these results suggest that 4-MCP metabolites could induce oxidative stress conditions in Hep G2 cells.

Actins↗
PubMed1990

Mechanisms of bacterial degradation and transformation of chlorinated monoaromatic compounds.

Chloroaromatics are xenobiotic compounds of environmental concern. They can be removed from the environment by (bio)degradation or by (bio)transformation. Recognition of the mechanisms and requirements of their biodegradation is of cardinal importance for understanding the fate of these chemicals in the environment, and for developing methods for biological treatment of wastes containing compounds of this type. Cleavage of the carbon-halogen bond is the critical step in degradation of chloroaromatics. As exemplified with chlorophenols, chlorobenzoates and chlorobenzenes in this review, two distinct strategies are employed by bacteria for degradation of chlorinated aromatic compounds: the particular chlorine substituents are removed either directly from the aromatic ring (as an initial step in degradation) or after oxygenative ring cleavage (from chlorinated aliphatic intermediates). Direct elimination of chlorine substituents from the aromatic ring occurs by displacement with either hydroxyl groups (hydrolytically or oxygenolytically) or hydrogen atoms (reductive dechlorination). Dechlorinations of the latter type require reducing power and are significant in anaerobic environments, but have also been observed with strictly aerobic bacteria. Various biotransformation reactions, with only minor alteration of the parent compound, are an alternative to biogradation. Two environmentally significant transformation reactions discussed here are O-methylation and O-demethylation. The capability to O-methylate chlorinated hydroxybenzenes seems to be widespread in bacteria. O-Methylation is an environmentally important transformation reaction, since methylation increases the lipophilicity of the compound and thus the potential for bioaccumulation. Bacterial O-demethylation of chlorinated methoxylated compounds has been observed under both aerobic and anaerobic conditions.

Bacteria↗
PubMed2004

Evaluation of a new solid-phase cartridge for the preconcentration of phenolic compounds in water.

The aim of this study is to evaluate the efficiency of a new solid-phase extraction cartridge, Spe-ed Advanta, in the extraction and preconcentration of four phenolic compounds (phenol, 2-chlorophenol, 2-nitrophenol, and 2,4-dichlorophenol) from water. The solid phase is a polystyrene-divinylbenzene resin modified with carboxylic groups, these polar groups improve the contact between the matrix and the aqueous solutions in the extraction of polar analytes. We studied several elution solvents in order to find the most efficient one. Sample concentration, sample volume, and sample pH are also investigated as well as the best method for drying the cartridge. Recoveries achieved with the new phase are compared with those obtained with Isolute ENV+, a non-modified polystyrene-divinylbenzene stationary bed. The best experimental conditions were then used for determination of the phenols in spiked environmental waters.

Chlorophenols↗
PubMed1999

A two-component tetrachlorohydroquinone reductive dehalogenase system from the lignin-degrading basidiomycete Phanerochaete chrysosporium.

Tetrachloro-1,4-hydroquinone (TClHQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Two enzymes required for the reductive dehalogenation of TClHQ to trichlorohydroquinone (TrClHQ) were identified in cell-free extracts of P. chrysosporium. In the presence of GSH, a membrane-bound enzyme converted TClHQ to the glutathionyl conjugate of TrClHQ (GS-TrClHQ). This membrane-bound glutathione transferase was specific for GSH as a cosubstrate. In the second step of the reductive dehalogenation reaction, a soluble enzyme fraction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or dithiothreitol. Thus, this second enzyme appears to be a GS-conjugate reductase. These two enzyme fractions, working in tandem, also reductively dehalogenated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism.

Cell Fractionation↗
PubMed2000

Toxicity of three oil spill remediation techniques to the Australian bass Macquaria novemaculeata.

Australian bass, Macquaria novemaculeata, were exposed to the water accommodated fraction (WAF) of Bass Strait crude oil, dispersed crude oil, burnt crude oil, and 4-chlorophenol. The WAF of dispersed crude oil was the most toxic treatment with 96-h LC(50) values of 7. 15% (7.94% upper and 6.42% lower 95% CI) and 7.45% (8.26% upper and 6.71% lower 95% CI). The WAF of crude oil was less toxic, with 96-h LC(50) values of 43.72% (49.21% upper and 38.87% lower 95% CI) and 45.87% (51.51% upper and 40.97% lower 95% CI). The WAF of burnt crude oil was the least toxic treatment with 96-h LC(50) values of 49.81% (63.33% upper and 39.44% lower 95% CI) and 47.28% (59.72% upper and 37.62% lower 95% CI). Sublethal toxicity of the crude oil WAF and burnt crude oil WAF was observed at dilutions seven to eight times less than in the dispersed crude oil WAF.

Animals↗
PubMed1991

Increase of phenol tolerance of Escherichia coli by alterations of the fatty acid composition of the membrane lipids.

In the presence of sublethal concentrations of phenol, 4-chlorophenol, and p-cresol in the growth medium, cells of Escherichia coli modified the fatty acid composition of their lipids. The results of these changes was an increase in the degree of saturation of lipids probably in order to compensate an increase of fluidity of the membrane induced by the phenols. Supplementation of the growth medium with saturated fatty acids could also enhance the degree of lipid saturation due to the incorporation of the acyl chains in the phospholipids. At the same time the growth of cells was less inhibited than in unsupplemented cells. The increase of tolerance of cells by manipulating the lipid composition indicates that the membrane structure plays a crucial role in the mode of action of phenols.

Cell Membrane↗
PubMed1986

Kinetics of 2,4,6-trichlorophenol in different organs of the rat.

The concentration of 2,4,6-trichlorophenol was measured in the blood and various other tissues of the rat after IP administration of the compound at 25 mg per kg body weight. The highest concentration, 329 +/- 117 nmol X g-1, was found in the kidney. Half-times were between 1.4 and 1.8 h in the blood, brain, fat, kidney, liver and muscle. The extent of conjugation of 2,4,6-trichlorophenol was also investigated by measuring total and free chlorophenol in the blood.

Animals↗
PubMed1983

Occupational exposure to hexachlorocyclohexane. VI. Metabolism of gamma-hexachlorocyclohexane in man.

Metabolism of gamma-Hexachlorocyclohexane (HCH) was studied examining 21 workers producing this insecticide. Using gas chromatography in combination with ECD and mass spectrometry 14 mono-, di-, tri- and tetrachlorophenols were identified in the urine samples of the workers. Seven dihydroxychlorobenzenes of still unknown configuration were detected by mass spectrometry. Ten of the more abundant metabolites, di-, tri- and tetrachlorophenols were determined quantitatively in all urine samples. 2,4,6-; 2,3,5- and 2,4,5-trichlorophenol turned out to be the main metabolites of gamma-HCH. They were excreted in nearly equal quantities. On account of their potential liver toxicity, the determination of chlorophenols in urine should be part of a biological monitoring program of HCH-exposed persons.

Adult↗
PubMed1995

Degradation of 4-chloro-2-methylphenol by an activated sludge isolate and its taxonomic description.

The Gram-negative strain S1, isolated from activated sludge, metabolized 4-chloro-2-methylphenol by an inducible pathway via a modified ortho-cleavage route as indicated by a transiently secreted intermediate, identified as 2-methyl-4-carboxymethylenebut-2-en-4-olide by gas chromatography/mass spectrometry. Beside 4-chloro-2-methylphenol only 2,4-dichlorophenol and 4-chlorophenol were totally degraded, without an accumulation of intermediates. The chlorinated phenols tested induced activities of 2,4-dichlorophenol hydroxylase and catechol 1,2-dioxygenase type II. Phenol itself appeared to be degraded more efficiently via a separate, inducible ortho-cleavage pathway. The strain was characterized with respect to its physiological and chemotaxonomic properties. The fatty acid profile, the presence of spermidine as main polyamine, and of ubiquinone Q-10 allowed the allocation of the strain into the alpha-2 subclass of the Proteobacteria. Ochrobactrum anthropi was indicated by fatty acid analysis as the most similar organism, however, differences in a number of physiological features (e.g. absence of nitrate reduction) and pattern of soluble proteins distinguished strain S1 from this species.

Biodegradation, Environmental↗
PubMed1993

Effects of media composition on substrate removal by pure and mixed bacterial cultures.

Continuous culture experiments with identical experimental designs were run with a mixed microbial community of activated sludge origin and an axenic bacterial culture derived from it. Each culture received 2-chlorophenol (2-CP) at a concentration of 160 mg/L as COD and L-lysine at a concentration of 65 mg/L as COD. A factorial experimental design was employed with dilution rate and media composition as the two controlled variables. Three dilution rates were studied: 0.015, 0.0325, and 0.05 h-1. Media composition was changed by adding four biogenic compounds (butyric acid, thymine, glutamic acid and lactose) in equal COD proportions at total concentrations of 0, 34, 225, and 1462 mg/L as COD. The measured variables were the effluent concentrations of 2-CP as measured by the 4-aminoantipyrene test and lysine as measured by the o-diacetylbenzene procedure. The results suggest that community structure and substrate composition play important roles in the response of a microbial community to mixed substrates. The addition of more biogenic substrates to the axenic culture had a deleterious effect on the removal of both lysine and 2-CP, although the effect was much larger on lysine removal. In contrast, additional substrates had a positive effect on the removal of 2-CP by the mixed community and much less of a negative effect on the removal of lysine. The dilution rate at which the cultures were growing had relatively little impact on the responses to the additional substrates.

Bacteria↗
PubMed1996

Chlorinated phenols in human milk.

The paper deals with the contamination of human milk with chlorinated phenols. The average and median concentrations of the chlorophenols investigated ranged from 0.75 to 9.74 micrograms.kg-1 and from being not detectable to 5.62 micrograms.kg-1, respectively, for the different compounds. The highest average and median levels were found for pentachlorophenol and 2,4,5-trichlorophenol. The concentrations determined were below the permissible levels.

Agriculture↗