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PubMedDate not supplied

[Dependence of transformation of chlorophenols by Rhodococci on position and number of chlorine atoms in the aromatic ring].

Study of the conversion of chlorophenols by Rhodococcus opacus 1G, R. rhodnii 135, R. rhodochrous 89, and R. opacus 1cp disclosed the dependence of the conversion rate and pathway on the number and position of chlorine atoms in the aromatic ring. The most active chlorophenol converter, strain R. opacus 1cp, grew on each of the three isomeric monochlorophenols and on 2,4-dichlorophenol; the rate of growth decreased from 4-chlorophenol to 3-chlorophenol and then to 2-chlorophenol. The parameters of growth on 2,4-dichlorophenol were the same as on 3-chlorophenol. None of the strains studied utilized trichlorophenols. A detailed study of the pathway of chlorophenol transformation showed that 3-chloro-, 4-chloro-, and 2,4-dichlorophenol were utilized by the strains via a modified ortho-pathway. 2-Chlorophenol and 2,3-dichlorophenol were transformed by strains R. opacus 1cp and R. rhodochrous 89 via corresponding 3-chloro- and 3,4-dichloropyrocatechols, which were then hydroxylated with the formation of 4-chloropyrogallol and 4,5-dichloropyrogallol; this route had not previously been described in bacteria. Phenol hydroxylase of R. opacus 1G exhibited a previously undescribed catalytic pattern, catalyzing oxidative dehalogenation of 2,3,5-trichlorophenol with the formation of 3,5-dichloropyrocatechol but not hydroxylation of the nonsubstituted position 6.

Biotransformation↗
PubMed1993

Biodegradation kinetics of a mixture containing a primary substrate (phenol) and an inhibitory co-metabolite (4-chlorophenol).

Batch experiments on the simultaneous utilization of phenol (primary substrate) and 4-chlorophenol (cometabolic secondary substrate) demonstrated two critical substrate interactions. First, the cometabolic degradation of 4-chlorophenol was proportional to the rate of phenol oxidation, which provided the electrons for the initial monooxygenase reaction. Second, 4-chlorophenol inhibited the oxidation of the primary substrate, phenol. Modeling analyses of the degradation of phenol alone and of phenol and 4-chlorophenol together showed that the proportionality between phenol and 4-chlorophenol degradation rates averaged 0.1 mg 4-CP/mg phenol, which corresponds to 0.5% of the electrons generated by phenol oxidation being used as a cosubstrate for the monooxygenase reaction of 4-chlorophenol. In addition, modeling analyses suggest that 4-chlorophenol was a noncompetitive inhibitor of phenol oxidation for high phenol concentrations, but a competitive inhibitor for low phenol concentrations.

Biotechnology↗
PubMed1994

Isolation and characterization of a novel bacterium growing via reductive dehalogenation of 2-chlorophenol.

A bacterium capable of anaerobic growth via reductive dehalogenation of 2-chlorophenol was isolated from a culture enriched from sediment taken from a small stream near Lansing, Mich. The organism, designated strain 2CP-1, is a gram-negative rod ca. 3 by 0.5 micron in size and is a catalase-negative, oxidase-negative, facultative anaerobe that forms small red colonies in anaerobic media. The organism grew in reduced anaerobic mineral medium supplemented with 2-chlorophenol, acetate, and vitamins, producing phenol as a product. It did not grow when either 2-chlorophenol or acetate was omitted. The growth yield was about 3 g of protein per mol of 2-chlorophenol dechlorinated, and the doubling time was 3.7 days. Only the ortho position was dehalogenated, and additional chlorines at other positions decreased or blocked ortho dechlorination. The organism also grew with fumarate as its electron acceptor. Dechlorination activity is inducible, since cultures grown in fumarate containing medium with 2-chlorophenol rapidly dechlorinated additional 2-chlorophenol, while cultures grown in the same medium without 2-chlorophenol did not. Analysis of the organism's 16S rRNA sequence revealed that it is a member of the delta proteobacteria, more closely related to the myxobacteria than to the sulfidogenic bacteria.

Base Sequence↗
PubMedDate not supplied

Rapid determination of nineteen chlorophenols in wood, paper, cardboard, fruits, and fruit juices by gas chromatography/mass spectrometry.

Although the use of pentachlorophenol (PCP) is prohibited in most countries, it is still widely found in the wood of pallets, containers, crates and in cardboard, paper, etc. Such material may contain not only PCP but other chlorophenols as well. Wooden crates and cardboard boxes are often used to store and transport fresh fruits. Consequently, chlorophenols present in the wood may contaminate the stored fruits by migration. To ascertain that packaging, storage material, and fruit raw materials are free from chlorophenol residues, we developed a rapid and sensitive method for the detection of 19 chlorophenols by gas chromatography/mass spectrometry (GC/MS). The test portions are directly extracted and acetylated in a solution of sodium carbonate in the presence of acetic anhydride and hexane. The hexane layer is analyzed, without further purification, by GC/MS in the selective-ion monitoring mode. The method allows the analysis of >40 samples/day with detection limits of <20 microg/kg for chlorophenols in wood, cardboard, and paper, and <2 microg/kg for chlorophenols in fruits. Typical recoveries of all chlorophenols were 94% from paper, 115% from cardboard, 51% from wood (depending on the size of the chips or shavings), and 93% from fruit puree.

Beverages↗
PubMed2000

Occupational exposure to chlorophenol and the risk of nasal and nasopharyngeal cancers among U.S. men aged 30 to 60.

BACKGROUND: Elevated rates of nasal and nasopharyngeal cancers have been associated with wood-related occupational exposures, including chlorophenols, formaldehyde, and wood dust. METHODS: Occupational information was obtained from 43 nasal carcinoma cases, 92 nasopharyngeal carcinoma cases, and 1909 controls, by interview. Exact conditional logistic regression was used to evaluate the association of these cancers with chlorophenol exposure, estimated from a review of verbatim responses. RESULTS: Both nasal and nasopharyngeal cancers were significantly associated with estimated duration of chlorophenol exposure. For nasopharyngeal cancer, elevated risk was observed among those who held jobs assigned medium or high intensity chlorophenol exposure (n(exposed)=18, OR=1.94, 95% CI=1.03-3.50) and among those with 10+ years in jobs assigned high intensity with high certainty (n(exposed)=3, OR=9.07, 95% CI=1.41-42. 9). Controlling for estimated formaldehyde and wood dust exposure did not alter these findings, as much of the estimated chlorophenol exposure was among machinists. CONCLUSIONS: These findings support the hypothesis that occupational exposure to chlorophenol is a risk factor for nasal and nasopharyngeal cancer, although the role of machining-related exposures warrants further assessment.

Adult↗
PubMed1987

Urinary chlorophenols in sawmill workers.

The concentration of urinary chlorophenol was assayed for 230 sawmill workers. Information on the work tasks was obtained through questionnaires from occupational health centres. The workers were divided into three groups on the basis of the type of exposure: (1) those with skin absorption as the main route, (2) those with skin and respiratory route of equal importance and (3) those with respiratory tract as the main route. The concentrations of urinary chlorophenol were higher in workers with skin absorption as the main route (median concentration: 7.8 mumol l-1; range 0.1 to 210.9 mumol l-1) than in those with both routes of equal importance (1.4 mumol l-1; range 0.1 to 47.8 mumol l-1, P less than 0.001) or in those with mainly respiratory route (0.9 mumol l-1; range 0.1 to 13.3 mumol l-1, P less than 0.001). The urinary chlorophenol concentration was below 15 mumol l-1 in all workers with the lungs as the main absorption route. In nine out of 112 workers whose main absorption route was the skin, the urinary chlorophenol values were above 50 mumol l-1. Six were loaders when the through-dipping method was used. In two of them urinary chlorophenol concentrations were as high as 170.8 and 210.9 mumol l-1. These results emphasize the need to develop and use simple methods of protection against skin contact with chlorophenols.

Administration, Inhalation↗
PubMed1994

Environmental monitoring of bleached kraft pulp mill chlorophenolic compounds in a northern Canadian river system.

The environmental transport of pulp mill effluent compounds and the exposure of two fish species has been monitored by parallel analyses of effluent, water column and suspended sediment samples, and fish bile and muscle. Compounds analyzed included over 20 chlorophenolic compounds and 12 fatty and resin acids. The concentration of chlorophenols varied with seasonal river flows and mill process changes such as the substitution of chlorine dioxide (ClO2) for chlorine gas (Cl2) in the bleach plant. At 100% (ClO2) substitution, the effluent and the water column concentrations of most chlorophenolics approached the analytical detection limits of 0.1-1 parts per billion. Chlorophenolic and fatty/resin acid compounds were detected in the bile of both mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus), but were rarely detected in fillets. Fish bile concentrations were observed in an apparent spatial gradient as far as 230 km downstream of the mill. A depuration experiment with fish held in uncontaminated water for eight days indicated a rapid decrease in chlorophenol levels. These observations corroborate previous investigations that chlorophenolic compounds are rapidly excreted and can be used as sensitive markers for recent exposure to mill effluents.

Alberta↗
PubMed2001

Use of green fluorescent protein and luciferase biomarkers to monitor survival and activity of Arthrobacter chlorophenolicus A6 cells during degradation of 4-chlorophenol in soil.

The recently isolated novel species Arthrobacter chlorophenolicus A6 is capable of growth on and degradation of high concentrations of 4-chlorophenol (up to 350 microg ml(-1)) as the sole carbon and energy source. This strain shows promise for bioremediation of environmental sites contaminated with high levels of chlorophenols. In this study, green fluorescent protein (gfp) or luciferase (luc) genes were used as biomarkers for monitoring cell number and activity, respectively, during degradation of 4-chlorophenol by A. chlorophenolicus cells. The individual marked strains, Arthrobacter chlorophenolicus A6L (luc-tagged) and Arthrobacter chlorophenolicus A6G (gfp-tagged), were monitored during degradation of 250 microg ml(-1) 4-chlorophenol in pure culture and 175 microg g(-1) 4-chlorophenol in soil microcosms. Both gene-tagged strains were capable of cleaning up the contaminated soil during 9 d incubation. During the bioremediation experiments, the luc-tagged cells were monitored using luminometry and the gfp-tagged cells using flow cytometry, in addition to selective plate counting for both strains. The cells remained at high population levels in the soil (evidenced by GFP-fluorescent cell counts) and the A. chlorophenolicus A6L population was metabolically active (evidenced by luciferase activity measurements). These results demonstrate that the Arthrobacter chlorophenolicus A6 inoculum is effective for cleaning-up soil containing high concentrations of 4-chlorophenol.

Arthrobacter↗
PubMedDate not supplied

[Inhibition of bacterial bioluminescence by chlorophenols].

Photobacteria were used as a test object for rapid monitoring of ecotoxicants. Specific inhibitory effects of phenol and its chlorinated derivatives (2-chlorophenol, 2,3-dichlorophenol, pentachlorophenol, 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid) on bioluminescence and respiration of intact cells, as well as on the emission activity of the bioluminescence system and luciferase itself, were studied. The toxic effect on the photobacterial cells was found to increase as the number of chlorine atoms in the chlorophenol molecule increases. However, this trend was not observed in cell-free systems (purified luciferase or the protein fraction of a cell-free extract treated with (NH)4SO4 at 40-75% saturation). Bacterial cells have a higher threshold sensitivity to chlorophenols in comparison to the sensitivity of the bioluminescence enzyme system or luciferase. Neutral phenols inhibit luciferase by competing with decanal, whereas a mixed mechanism of inhibition with this substrate is typical of phenoxyacetic acids. With respect to FMNH2, all chlorophenols tested in this work were uncompetitive inhibitors. Oxygen uptake by photobacteria was shown to be insensitive to chlorophenols, at least within the concentration range that was effective in bioluminescence inhibition. The results of this study suggest that bacterial bioluminescence system is not the primary target of the chlorophenol-induced effect on photobacteria.

Bacteria↗
PubMed1989

Effects of commercial chlorophenolate, 2,3,7,8-TCDD, and pure phenoxyacetic acids on hepatic peroxisome proliferation, xenobiotic metabolism and sister chromatid exchange in the rat.

The induction of hepatic peroxisome proliferation and drug metabolizing enzymes and of sister chromatid exchange (SCE) in lymphocytes was studied in male Han/Wistar rats after exposing them for 2 weeks to a commercial chlorophenolate formulation (Ky-5) (100 mg/kg/day), to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD; 0.05-5 micrograms/kg/wk) and to the pure phenoxyacetic acids, 2,4-dichlorophenoxyacetic acid (2,4-D; 100 mg/kg/day) and 2-chloro-4-methylphenoxyacetic acid (MCPA; 100 mg/kg/day). The chlorophenolate formulation and pure 2,4-D and MCPA caused significant increases in the number of peroxisomes in liver cells, although the average size of peroxisomes was not affected, whereas the effect of even the highest dose of 2,3,7,8-TCDD remained small. This finding indicates that dioxin impurities do not account for the peroxisome proliferation induced by chlorophenolate. The relative weight of the liver increased significantly in rats treated with the chlorophenolate formulation and with 2,3,7,8-TCDD (5.0 and 0.5 micrograms/kg). The pattern of induction of xenobiotic metabolizing enzymes showed some differences between chlorophenolate treatment and 2,3,7,8-TCDD treatment. Furthermore, the effects of pure phenoxyacetic acids were different from that seen with chlorophenolate and 2,3,7,8-TCDD. The highest dose of 2,3,7,8-TCDD increased the frequency of SCE in circulating lymphocytes slightly, but significantly.

Animals↗
PubMed1998

Investigating the potential impacts of chlorophenols on the lake baikal (Siberia, russia) food web by employing daphnia grazing bioassays and a chlorella growth bioassay

A grazing bioassay was employed to assess the impacts of chlorophenols on Daphnia magna and Daphnia pulex. The effects of two chlorophenols, pentachlorophenol (PCP) and 4-chlorophenol, were investigated at concentrations of 0.001, 0.01, and 0.1 mg . L-1 over a 96-h period. All tests were conducted in water from the southern basin of Lake Baikal (Siberia). For D. magna, grazing rates were significantly depressed after exposure to 0.001 mg . L-1 of PCP for 48 h or to 0.01 mg . L-1 of 4-chlorophenol for 96 h. However, neither chemical continued to depress filtering rates as either dose or time increased, thus effective concentrations (EC50s) could not be determined. This prevents the use of this bioassay as a tool for assessing exposure to chlorophenols, but it is still useful in that it provides insight into potential ecological effects. In the case of D. pulex, depressed rates were also found at 0.001 mg . L-1 of PCP after 48 h; due to problems with the control, no conclusions were drawn for the effect of 4-chlorophenol on this species. The growth rates of Daphnia's prey, Chlorella vulgaris, were also investigated in the presence of these chemicals; no observable effects were found at any concentration during the 96-h period, implying that ecosystem effects may be limited to higher trophic levels.

Journal Article↗
PubMed1999

Determination of chlorophenols in human urine based on the integration of on-line automated clean-up and preconcentration unit with micellar electrokinetic chromatography.

A new method was developed and validated for the determination of chlorophenols in human urine by using micellar electrokinetic chromatography (MEKC) coupled via a mechanic arm to an on-line automatic clean-up and preconcentration unit for urine samples. Separation is accomplished by using a selective buffer consisting of 15 mM borate, 25 mM phosphate and 100 mM sodium dodecyl sulfate (SDS) at pH 9.1 in addition to a positive power supply of 25 kV at 18 degrees C. The proposed capillary electrophoresis (CE) method allows the separation of 11 chlorophenols within 7 min with a reproducibility as relative standard deviation (RSD) between 2.6% and 7.2%, and limits of detection (LODs) between 0.08 and 0.46 microg/mL for all chlorophenols. Urine samples were previously hydrolyzed with 37% HCl at 80 degrees C for 60 min and then cleaned on a C-18 mini-column. Recoveries ranged from 58% to 103%. The preconcentration treatment affords limits of determination between 4 and 12 ng/mL for all chlorophenols except pentachlorophenol and 4-chlorophenol, which could not be determined. The overall analysis time, including on-line clean-up, preconcentration and electrophoretic separation is 20 min per sample.

Chlorophenols↗
PubMed1982

Epidemiological study of nasal and nasopharyngeal cancer and their relation to phenoxy acid or chlorophenol exposure.

Soft tissue sarcoma and malignant lymphoma have been related to exposure to chlorinated phenoxy acids or chlorophenols as well as exposure to organic solvents and malignant lymphoma. However, colon cancer studied by the same case-referent design did not show any such associations, which helps to rule out alleged systematical bias of the study approach. Further considerations about exposure routes for phenoxy acids and chlorophenols suggested that nasal and nasopharyngeal cancers should be studied. Forty-four cases with nasal cancer and 27 cases with nasopharyngeal cancer were eligible for study during 1970-1979 together with 541 referents, as utilized also in the aforementioned studies. Exposure to phenoxy acids gave formally a doubled but insignificant risk for the studied cancer types. Exposure to chlorophenols, as present particularly in woodwork, was related to an about sevenfold and significant increase in the risk for both cancer types. In woodworkers without exposure to chlorophenols there was an approximate normal risk, but cabinet makers, even without exposure to chlorophenols, had nearly doubled (but insignificant) risk of nasal cancer.

Adenocarcinoma↗
PubMed1988

Toxicity and bioaccumulation of chlorophenols in earthworms, in relation to bioavailability in soil.

The acute toxicity of five chlorophenols for two earthworm species was determined in two sandy soils differing in organic matter content and the results were compared with adsorption data. Adsorption increased with increasing organic matter content of the soils, but for tetra- and pentachlorophenol was also influenced by soil pH. Earthworm toxicity was significantly higher in the soil with a low level of organic matter. This difference disappeared when LC50 values were recalculated to concentrations in soil solution using adsorption data. Eisenia fetida andrei showed LC50 values lower than those of Lumbricus rubellus although bioaccumulation was generally higher in the latter species. Toxicity and bioaccumulation based on soil solution concentrations increased with increasing lipophilicity of the chlorophenols. The present results indicate that the toxicity and bioaccumulation and therefore the bioavailability of chlorophenols in soil to earthworms are dependent on the concentration in soil solution and can be predicted on the basis of adsorption data. Both the toxicity of and bioaccumulation data on chlorophenols in earthworms demonstrated surprisingly good agreement with those on chlorophenols in fish.

Adsorption↗
PubMed1989

The excretion of chlorophenylmercapturic acid, chlorophenols and a guanine adduct in the urine of chlorobenzene-treated rats after phenobarbital pretreatment.

Chlorobenzene (CB) was administered to male Wistar rats. Twenty-four-hour urine samples were collected over a period of 7 days. p-Chlorophenylmercapturic acid, chlorophenols and a guanine adduct were determined by chromatographic methods. The excretion pattern of p-chlorophenyl-mercapturic acid did not seem to be significantly affected by phenobarbital. To analyze for the chlorophenols and guanine adducts, diluted urine was subjected to cation exchange chromatography using UV-detection. Fractions were found containing chlorophenols and a compound showing chromatographic properties similar to those of the synthetic N7-phenylguanine. The results of the HPLC analyses suggested the presence of a guanine adduct excreted on days 1 and 2 and between days 4 and 6 post-administration. There were no compounds detected which were identical with p-, m- or o-isomers of N7-chlorophenylguanine. The excretion of p- and m-chlorophenols by phenobarbital-pretreated animals was twice as high as that in untreated rats. A 4-fold increase was detected for o-chlorophenol. It is assumed that it is mainly direct hydroxylation that can be induced by phenobarbital. Dehalogenated phenolic metabolites may be capable of covalent binding to DNA.

Acetylcysteine↗
PubMed2000

Oxidation of chlorophenols with hydrogen peroxide in the presence of goethite.

The use of goethite (alpha-FeOOH) and hydrogen peroxide was recently found that they could effectively oxidize organic compounds. The study was to investigate the effect of goethite particle size, goethite concentration, Fe2+ and Fe3+ on the 2-chlorophenol oxidation. Results indicated that 2-chlorophenol can be decomposed with hydrogen peroxide catalyzed by goethite and the oxidation rate increased with decreasing goethite particle size. 2-Chlorophenol degradation was almost retarded with 0.8 g/l of goethite because ferrous ions could not be produced at this condition. Addition of Fe2+ and Fe3+ can enhance the catalytic oxidation rate of 2-chlorophenol very efficiently. In conclusion, the main mechanism of goethite catalyzing hydrogen peroxide to oxidize 2-chlorophenol may be due to the catalysis of ferrous ions and goethite surface.

Chlorophenols↗
PubMed1999

Degradation of mono-chlorophenols by a mixed microbial community via a meta- cleavage pathway.

A mixed microbial community, specially designed to degrade a wide range of substituted aromatic compounds, was examined for its ability to degrade mono-chlorophenols as sole carbon source in aerobic batch cultures. The mixed culture degraded 2-, 3-, and 4-chlorophenol (1.56 mM) via a meta- cleavage pathway. During the degradation of 2- and 3-chlorophenol by the mixed culture, 3-chlorocatechol production was observed. Further metabolism was toxic to cells as it led to inactivation of the catechol 2,3-dioxygenase enzyme upon meta- cleavage of 3-chlorocatechol resulting in incomplete degradation. Inactivation of the meta- cleavage enzyme led to an accumulation of brown coloured polymers, which interfered with the measurement of cell growth using optical density. Degradation of 4-chlorophenol by the mixed culture led to an accumulation of 5-chloro-2-hydroxymuconic semialdehyde, the meta- cleavage product of 4-chlorocatechol. The accumulation of this compound did not interfere with the measurement of cell growth using optical density. 5-chloro-2-hydroxymuconic semialdehyde was further metabolized by the mixed culture with a stoichiometric release of chloride, indicating complete degradation of 4-chlorophenol by the mixed culture via a meta- cleavage pathway.

Actinomycetales↗
PubMed1996

Isolation and characterization of Desulfitobacterium frappieri sp. nov., an anaerobic bacterium which reductively dechlorinates pentachlorophenol to 3-chlorophenol.

An anaerobic bacterium, strain PCP-1T (T = type strain), which dechlorinates pentachlorophenol (PCP) to 3-chlorophenol, was isolated from a methanogenic consortium. This organism is a spore-forming rod-shaped bacterium that is nonmotile, asaccharolytic, and Gram stain negative but Gram type positive as determined by electron microscopic observations. Inorganic electron acceptors, such as sulfite, thiosulfate, and nitrate (but not sulfate), stimulate growth in the presence of pyruvate and yeast extract. The optimum pH and optimum temperature for growth are 7.5 and 38 degrees C, respectively. The dechlorination pathway is: PCP-->2,3,4,5-tetrachlorophenol -->3,4,5-trichlorophenol-->3,5-dichlorophenol-->3-chlorophenol. This bacterium dechlorinates several different chlorophenols at ortho, meta, and para positions; exceptions to this are 2,3-dichlorophenol, 2,5-dichlorophenol, 3,4-dichlorophenol, and the monochlorophenols. The time course of PCP dechlorination suggests that two enzyme systems are involved in dehalogenation in strain PCP-1T. One system is inducible for ortho dechlorination, and the second system is inducible for meta and para dechlorinations. A 16S rRNA analysis revealed that strain PCP-1T exhibits 95% homology with Desulfitobacterium dehalogenans JW/IU-DC1, an anaerobic bacterium which can dehalogenate chlorophenols only in ortho positions. These results suggest that strain PCP-1T is a member of a new species and belongs to the recently proposed genus Desulfitobacterium. Strain PCP-1T differs from D. dehalogenans JW/IU-DC1 by its broader range of chlorophenol dechlorination. Strain PCP-1 is the type strain of the new species, Desulfitobacterium frappieri.

Bacteria, Anaerobic↗