Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chlorophenols”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2006

[Nonlinear Kalman filter simultaneous determination of mixture of phenol and 2-chlorophenol].

An analysis method of nonlinear absorbance for binary composition mixture was proposed. The nonlinear absorbance was composed of the contributions from both themselves and the change in their contributions due to mixing, as well as the contribution from their interaction. The mixture of phenol and 2-chlorophenol was simultaneously determined using nonlinear Kalman filter UV spectrophotometry. UV absorption spectra were obtained with 32 standard solutions (range 1-15 mg x L(-1)) and 71 wavelengths(250-290 nm). Standard work matrix of extended Kalman filter was performed from partial least-squares method. The vectors function Jacobi matrix was obtained by linearization of Taylor series for nonlinear absorbance formula. The recovery experiment showed that the extended Kalman filter simultaneous determination of mixture of phenol and 2-chlorophenol that is not only exact, but also stable.

English Abstract↗
PubMed2000

Growth kinetics of Pseudomonas putida in cometabolism of phenol and 4-chlorophenol in the presence of a conventional carbon source.

Growth kinetics of Pseudomonas putida (ATCC 49451) in cometabolism of phenol and 4-chlorophenol (4-cp) in the presence of sodium glutamate (SG) were studied. In the ternary substrate mixture, phenol and SG are growth substrates while 4-cp is a nongrowth substrate. Cell growth on phenol was found to follow Andrews kinetics and cells displayed substrate inhibition pattern on sodium glutamate in the range of 0-4 g L(-1) as well. A cell growth model for the ternary substrate system was established based on a simplified cell growth mechanism and subsequently modified by experimental results. Model analysis over a wide range of substrate concentrations shows that the inhibition of SG is much larger than phenol at low phenol concentrations (</=200 mg L(-1)) while phenol exerts dominant inhibition on cell growth at higher phenol concentrations (>/=600 mg L(-1)). The nongrowth substrate, 4-cp, inhibits cell growth mainly through inactivation of cells (cell decay) and competitive inhibition to cell growth on phenol. In the absence of SG, 4-cp retards cell growth severely and cells cannot grow at 250 mg L(-1) 4-cp. Addition of sodium glutamate, however, greatly attenuates the toxicity of 4-cp and supports cell growth at 4-cp concentration higher than 250 mg L(-1). By using the proposed cell growth model, we were able to optimize the amount of SG needed to enhance cell growth rate and validate model predictions against experimental data.

Biotechnology↗
PubMed1993

Occupational exposure to phenoxy herbicides and chlorophenols and cancer mortality in The Netherlands.

As part of the "IARC International Register of Persons Exposed to Phenoxy Herbicides and Contaminants," a cohort of workers who manufacture and prepare chlorophenoxy herbicides was recruited in The Netherlands. The cohort comprised 2,310 workers from two plants, operated by different companies, who were followed during the periods 1955-1985 and 1965-1986, respectively. In 1963, there had been an industrial accident in one factory with concomitant release of dioxin into the environment. Loss to follow-up was 3%. Mortality data on 963 exposed and 1,111 nonexposed men were evaluated by external and internal comparison. Compared with national rates, total mortality (94 deaths, standardized mortality ratio [SMR] = 101; 95% confidence interval [CI], 82-124) and cancer mortality (31 deaths, SMR = 107; 95% CI, 73-152) for exposed workers were not significantly increased. A statistically insignificant increase was observed for non-Hodgkin's lymphoma (2 deaths, SMR = 299; 95% CI, 36-1,078). No cases of soft-tissue sarcoma were encountered. There was no increase in either total mortality (25 deaths, SMR = 111; 95% CI, 72-163) or cancer mortality (10 deaths, SMR = 137; 95% CI, 66-252) among the 139 workers probably exposed to dioxins during the 2,4,5-trichlorophenol production accident or the subsequent clean-up operations. Compared with nonexposed workers, exposed workers did not exhibit a higher total mortality (rate ratio [RR] = 1.28; 95% CI, 0.89-1.82). Mortality due to all cancers (RR = 1.7; 95% CI, 0.9-3.4) and respiratory cancer (RR = 1.7; 95% CI, 0.5-6.3) was insignificantly elevated. These findings suggest that the increases in cancer mortality among workers exposed to phenoxy herbicides and chlorophenols may be attributable to chance. Lack of power prevented evaluation with respect to specific cancers.

Adult↗
PubMed1993

Chemical exposure in manufacture of phenoxy herbicides and chlorophenols and in spraying of phenoxy herbicides.

Exposure patterns are reported for manufacturing and sprayer cohorts incorporated in the "IARC International Register of Workers exposed to Phenoxy Herbicides and Contaminants." Information was based on company questionnaires, company reports, plant visits, and serum 2, 3, 7, 8-TCDD measurements. In addition to phenoxy herbicides and chlorophenols, workers in manufacturing plants may have been exposed to raw materials, process chemicals, other agents synthesized or formulated, and impurities of all these agents. Sprayers also had a complex exposure pattern, including phenoxy herbicides and some other pesticides, their carriers and additives, and residues of chemicals formed during manufacture. Occurrence of agents, including dioxins, varied between countries. Biological monitoring and industrial hygiene data were rarely available, most since the late 1970s. Exposure of workers depended mainly on the jobs they performed, but several factors influenced level of exposure. A quantitative exposure classification is not feasible in this study. Semiquantitative exposure estimates may be derived through a critical interpretation of biological monitoring and industrial hygiene data together with individual work histories.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed2005

Use of microelectrodes to investigate the effects of 2-chlorophenol on microbial activities in biofilms.

In order to assess the applicability of using microelectrodes as a tool for inhibition tests, temporal and spatial inhibitory effects of 2-chlorophenol (2-CP) on O(2) respiration and nitrification activities in municipal wastewater biofilms were investigated using microelectrodes for O(2) and NH(4)(+). The time-course microelectrode measurements demonstrated that 2-CP inhibited O(2) respiration and nitrification activities within 6-18 min. The microbial activities were inhibited only in the upper 400 microm of the biofilms by 2-CP, and the bacteria present in the deeper parts of the biofilms were still active, probably due to limited penetration of 2-CP. These results could reasonably explain the difference in inhibitory ratios of the O(2) respiration and nitrification activities in the biofilms. O(2) respiration activity was incompletely inhibited, which was attributed to the presence of O(2) respiration activities in the deeper parts of the biofilm. In contrast, nitrification activity was significantly inhibited because ammonia-oxidizing bacteria were present in the upper parts of the biofilm. These results indicate that the microelectrodes with a very quick response time and a high spatial resolution are useful tools to study temporal and spatial inhibitory effects of inhibitors on in situ microbial activities in biofilms.

Bacterial Physiological Phenomena↗
PubMed2003

Large-volume stacking with polarity switching and sweeping for chlorophenols and chlorophenoxy acids in capillary electrophoresis.

This paper describes approaches for stacking large volumes of sample solutions containing a mixture of chlorophenols and chlorophenoxyacetic acids as their anions in capillary zone electrophoresis, and compares results to standard capillary electrophoresis (CE) and normal stacking modes. In order to increase the amount of sample injected beyond the optimal conditions and maintain high resolution, the sample introduction buffer must be removed after the stacking process is completed. This is achieved by pumping the sample buffer out of the column using polarity switching. Large sample volumes are loaded by hydrodynamic injection, then stacked at the injection buffer/run electrolyte interface, followed by the removal of the large plug of low-conductivity sample matrix from the capillary column using polarity switching and finally the separation of the stacked anions in a basic buffer (pH 8.65). Around 10- and 40-fold improvement of sensitivity was achieved by normal stacking and large-volume stacking with polarity switching, respectively, when compared to the standard CE analysis. Sweeping-micellar electrokinetic capillary chromatography (MEKC) was also investigated for the purpose of comparison to the stacking technique. The method should be suitable for the analysis of these chemical compound classes in industrial chlorophenoxyacetic acid manufacture.

Buffers↗
PubMed1991

[Residues of organochlorine pesticides, PCB's and chlorophenols in fish from commercial ponds and fish hatcheries from the waters in the area of Frankfurt (Oder)].

Fishes from fish-hatcheries, lakes and the river Oder in the area of the former district Frankfurt (Oder) were analysed for organochlorine pesticides (HCB, aldrin, HCH-isomeres, DDD, DDE, DDT, endrin, toxaphen and dieldrin), polychlorinated biphenyles and penta- and tetrachlorophenole. A clean up-procedure using acidic digestion mixture has been compared with a column-extraction-procedure followed by column chromatography on aluminia. Furthermore the simultaneous determination of the organochlorine pesticides, PCB's and chlorophenoles by acidic silicagel-extraction is described. The identification and quantification was realized by packed-column and capillary-gaschromatography including electron-capture-detection. The investigations show, that the permissible levels were only reached up to 2 to 10% with exception of toxaphen and pentachlorophenole. Average 50% of the toxaphen- and pentachlorophenole-values were found near the tolerance levels settled for these substances. The application of both substances in the area of the former German Democratic Republic until today can be regarded as a reason for this. The results of our investigations are comparable to last publications on fish contamination in the area of the previous Federal Republic of Germany.

Animals↗
PubMed1992

Effect of cosubstrates on the dechlorination of selected chlorophenolic compounds by Rhodococcus erythropolis 1CP.

Effects of aromatic and nonaromatic cosubstrates on the rate of 2,4-dichlorophenol degradation by R. erythropolis 1CP were studied under growth and nongrowth conditions. Glucose and maltose were found to accelerate 2,4-dichlorophenol (initial conc. 50 mg/l) dechlorination from 11 days to 24 and 20 h, respectively. The stimulating effect was observed within the range of glucose concentration of 0.5-2.0 g/l in the medium. Ascorbic acid at a concentration of 10-70 mg/l as a nongrowth substrate also increased the decomposition of 2,4-dichlorophenol, though at a lower degree than glucose. Experiments with washed cells showed the limiting stage of chlorophenol degradation by R. erythropolis 1CP to be, possibly, aromatic ring dechlorination after its hydroxylation. As an additional source of electrons, glucose introduced into suspensions of washed cells grown on 3-hydroxybenzoate made it possible to eliminate the bottleneck in 2,4-dichlorophenol metabolism by significantly accelerating dechlorination of 3,5-dichlorocatechol. Based on the experimental and literature data, the enzyme systems involved in 2,4-dichlorophenol degradation by the culture R. erythropolis 1CP are assumed to be nonspecific.

Biodegradation, Environmental↗
PubMed2003

Solid-phase microextraction liquid chromatography/tandem mass spectrometry for the analysis of chlorophenols in environmental samples.

Liquid chromatography with atmospheric pressure chemical ionisation mass spectrometry (LC/APCI-MS), using negative ion detection in a triple quadrupole instrument, was used for the determination of chlorophenols (CPs) in environmental samples. In-source collision-induced dissociation (CID) was compared with MS/MS fragmentation. In general, less fragmentation was observed in MS/MS as compared with in-source CID, with the latter providing more intense fragment ions due to chemical ionisation. Under MS/MS conditions [M - H - HCl](-) was the main fragment ion observed for all compounds except for pentachlorophenol, which showed no fragmentation. For multiple reaction monitoring (MRM) acquisition mode, the transition from [M - H](-) to [M - H - HCl](-) was selected, leading to detection limits down to 0.3 ng injected. Direct and headspace-solid-phase microextraction (HS-SPME) were used as preconcentration procedures for the analysis of CPs in wood and in industrially contaminated soils. CPs were quantified by standard addition, which led to good reproducibility (RSD between 4 and 11%) in both SIM and MRM modes, and detection limits down to ng/g. The combination of MS/MS and in-source CID allowed confirmation of the presence of CPs in environmental samples.

Chlorophenols↗
PubMed2003

Cavitation-induced pyrolysis of toxic chlorophenol by high-frequency ultrasonic irradiation.

p-Chlorophenol (4-CP) is a recalcitrant organic pollutant that is biologically toxic in industrial wastewater. A high-frequency ultrasonic device operated at 1.7 MHz was designed and used successfully to degrade 4-CP. Iodine liberation in the KI aqueous solution confirmed that effective cavitation occurred under the high-frequency ultrasonic irradiation. No products or intermediate products were detected following the sonochemical degradation by 1H-nuclear magnetic resonance spectrum and mass spectrum after ultrasonic irradiation. It was concluded that the dominant degradation mechanism was high-temperature pyrolysis to inorganic products in ultrasonic cavities rather than free-radical oxidation.

Chlorophenols↗
PubMed1999

Applicability of CATALYST in ecotoxicology, a new promising tool for 3D-QSAR: study of chlorophenols.

With the aim of applying recent quantitative structure-activity relationship (QSAR) descriptors coming from the pharmaceutical sciences to the modelization of ecotoxicity data, this work deals with the establishment of 3D-QSAR on chlorophenols by using for the first time in this field the recent CATALYST software. The training set has been intentionally chosen simply because of its homogeneous character and the abundance of reliable experimental values. Among 69 data sets collected in the literature on these chemicals, 9 were selected to have fulfilled CATALYST simulation conditions. The principle of CATALYST is briefly described. The different investigations have led to nine 3D-QSAR called "hypotheses," meeting the criteria of high statistical significance attested by costs and correlation coefficient values. The ecotoxicity values calculated from the 9 models established in this study. Analysis of the graphical representations of hypotheses led to hypotheses about the toxicity mechanisms. A comparison is finally made between the CATALYST models and those previously derived by other modeling methods.

Animals↗
PubMed1993

Cancer incidence and mortality in women occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins.

The association between exposure to chlorophenoxy herbicides contaminated with dioxins and occurrence of cancer has been studied mainly in male populations. In animal experiments, gender differences have been recorded in the cancer response to administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mortality and cancer incidence in an international cohort of 701 women from an International Register of Workers occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins is examined. Cause-specific, national death rates and cancer incidence rates were used as referents. Cancer risk was not increased overall, with a standardized incidence ratio (SIR) of 96 and 95 percent confidence interval (CI) of 64-137, based on 29 cases. Among workers exposed to those chlorophenoxy herbicides contaminated with TCDD, excess cancer incidence (for all sites) was observed (SIR = 222, CI = 102-422, 9 cases); this was highest in the first 10 years after exposure. No excess was observed for breast cancer, the most common cancer in this cohort. Results on cancer mortality were consistent with those on incidence.

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

Biodegradation of the mixtures of 4-chlorophenol and phenol by Comamonas testosteroni CPW301.

A 4-chlorophenol (4-CP)-degrading bacterium, strain CPW301, was isolated from soil and identified as Comamonas testosteroni. This strain dechlorinated and degraded 4-CP via a meta-cleavage pathway. CPW301 could also utilize phenol as a carbon and energy source without the accumulation of any metabolites via the same meta-cleavage pathway. When phenol was added as an additional substrate, CPW301 could degrade 4-CP and phenol simultaneously. The addition of phenol greatly accelerated the degradation of 4-CP due to the increased cell mass. The simultaneous degradation of the 4-CP and phenol is useful not only for enhanced cell growth but also for the bioremediation of both compounds, which are normally present in hazardous waste sites as a mixture.

Biodegradation, Environmental↗
PubMed1989

Short-term effects of chlorophenols on the function and viability of primary cultured rat hepatocytes.

Primary cultured rat hepatocytes were used as an experimental model to detect adverse effects of five chlorophenols (CP) in vitro (penta-CP, 2,3,4,5-tetra-CP, 2,4,5,-tri-CP, 2,4-di-CP, and 4-mono-CP). Monolayer cultures were exposed to the test compounds for 1 h, and concentration-response curves were established with respect to the effects on phase I and phase II metabolism of 7-ethoxycoumarin (7-EC) and on cellular ATP content. All CP tested inhibited the O-dealkylation of 7-EC, with half-maximum effective concentrations (EC50) ranging from about 36 microM for the three highest chlorinated phenols to 215 microM for 4-mono-CP, which proved to be least effective. The subsequent conjugation of the primary metabolite 7-hydroxycoumarin was even more sensitive towards CP exposure than the O-deethylation process. The concentrations which reduced the percentage of conjugated metabolite to 50% of the respective control cultures ranged from 7 microM for penta-CP to 48 microM for 4-mono-CP. Treatment of cultured hepatocytes with CP additionally resulted in a depletion of cellular ATP at EC50 concentrations ranging from 6 microM for penta-CP to 1330 microM for 4-mono-CP. Cellular viability, as measured by the leakage of lactate dehydrogenase from the cells, was not affected by any of the CP within the 1-h exposure period.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1981

Occupational exposure to hexachlorocyclohexane. V. Gas chromatographic determination of monohydroxychlorobenzenes (chlorophenols) in urine.

A sensitive and specific gas chromatographic method is described for the simultaneous determination of ten chlorinated phenols that appear in the urine of persons exposed to hexachlorocyclohexane (HCH). The phenolic compounds in the urinary samples are hydrolysed in an acidic medium and derivatised with acetic anhydride. This sample treatment permits routine application. The stationary phase (8% DC 200 on Chromosorb G AW-DMCS) possesses a high separating capability for the acetic esters of the chlorophenols. The detection limits lie between 4.9 and 18.6 micrograms/l and allow determinations even in the environmentally interesting concentration range. The recoveries determined using aqueous standards range between 87 and 119% and the relative standard deviations are between 4.4 and 10.1%.

Chlorophenols↗
PubMed1991

Quantitation of urinary chlorobenzene metabolites by HPLC: concentrations of 4-chlorocatechol and chlorophenols in urine and of chlorobenzene in biological specimens of subjects exposed to chlorobenzene.

A simple method for the determination of 4-chlorocatechol (ClCh, 4-chloro-1,2-benzenediol) and chlorophenols (ClPh), metabolites of monochlorobenzene (ClBz), in urine by high performance liquid chromatography (HPLC) is described. Enzymatic hydrolysates of urine were applied to a stainless-steel column packed with octadecyl-silanized silica gel, and a mixed solution of 20 mM potassium phosphate monobasic: acetonitryl (75:25, v/v) was used as a mobile phase. The procedures for ether extraction and evaporation of extract could be omitted. The accuracy and precision of the present HPLC method were satisfactory. The excretion kinetics of ClCh and p-ClPh were investigated over 35 h after cessation of ClBz inhalation. Proportional relationships between concentrations of ClBz in air and of its metabolites in urine were observed. The slopes of regression lines predicting the levels of ClCh, p-ClPh and total ClPh in urine taken during the last 2 h of exposure to ClBz in air were 6.56, 1.13 and 2.83 mg/g creatinine for 1 ppm ClBz, respectively. ClBz in the blood and the end exhaled air of subjects at the end of exposure were identified by gas chromatography (GC) and mass spectrometry. A proportional relationship was observed between the concentration of ClBz in air and that in blood. The validity of the threshold limit value (TLV) for ClBz as evaluated from the subjective and objective symptoms is discussed.

Adult↗
PubMed1990

A meta-analysis of exposure to phenoxy acid herbicides and chlorophenols in relation to risk of soft tissue sarcoma.

This analysis combines the results of the epidemiologic studies which appeared in the literature from 1979-1987 concerning the associations between phenoxy acid herbicides (PH) and chlorophenols (CP) and the occurrence of soft tissue sarcoma. Cohort studies and case-control studies are considered separately. After specifying criteria for inclusion, the total number of deaths due to cancer occurring in selected cohorts of people exposed to PH or CP was determined. The proportion of soft tissue sarcoma cases observed versus expected in the cohort studies, calculated using United States SEER registry data, resulted in a proportional mortality ratio of 3.5 (95% confidence interval of 0.7-10.3). Excluding the initial reports, the selected case-control studies had homogeneous risk estimates with a summary odds ratio of 1.1 (95% confidence interval of 0.9-1.4). Other attempts to assess the combined data did not yield results indicating an association. These meta-analyses do not provide strong support for an association between the specified herbicides and soft tissue sarcoma.

Case-Control Studies↗