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PubMed2003

A flow injection biosensor system for highly sensitive detection of 2,4,6-trichlorophenol based on preoxidation by ceric sulfate.

A flow injection biosensor system was proposed for the highly sensitive detection of 2,4,6-trichlorophenol (2,4,6-TCP). The system is based on the preoxidation by ceric sulfate to the corresponding benzoquinone (2,6-dichloro-1,4-benzoquinone: 2,6-DC-1,4-BQ), which was characterized using cyclic voltammetry, hydrodynamic voltammetry, and UV-vis spectrophotometry. The laccase-based biosensor used in this analytical system responded sensitively to 2,4,6-TCP after the preoxidation by ceric sulfate. The response could be based on the bioelectrocatalytic recycling of oxidation product (2,6-DC-1,4-BQ) between laccase membrane and the electrode, because the oxidation product (2,6-DC-1,4-BQ) of 2,4,6-TCP was an electrochemically reversible redox species. The signal current was linearly related to the 2,4,6-TCP concentrations in a dynamic range of 2 nM - 2 microM; the slope and the y-intercept of the straight line were 1150 nA microM(-1) and 0.88 nA, respectively. The detection limit was 1.2 nM (S/N = 3) for a 20 microl injection. Among a variety of chlorophenols and some phenolic compounds, the only interferent was 2,4-dichlorophenol.

Biosensing Techniques↗
PubMed2006

An integrated anaerobic/aerobic bioprocess for the remediation of chlorinated phenol-contaminated soil and groundwater.

An investigation of biodegradation of chlorinated phenol in an anaerobic/aerobic bioprocess environment was made. The reactor configuration used consisted of linked anaerobic and aerobic reactors, which served as a model for a proposed bioremediation strategy. The proposed strategy was studied in two reactors before linkage. In the anaerobic compartment, the transformation of the model contaminant, 2,4,6-trichlorophenol (2,4,6-TCP), to lesser-chlorinated metabolites was shown to occur during reductive dechlorination under sulfate-reducing conditions. The consortium was also shown to desorb and mobilize 2,4,6-TCP in soils. This was followed, in the aerobic compartment, by biodegradation of the pollutant and metabolites, 2,4-dichlorophenol, 4-chlorophenol, and phenol, by immobilized white-rot fungi. The integrated process achieved elimination of the compound by more than 99% through fungal degradation of metabolites produced in the dechlorination stage. pH correction to the anaerobic reactor was found to be necessary because acidic effluent from the fungal reactor inhibited sulfate reduction and dechlorination.

Bacteria, Aerobic↗
PubMed1987

The metabolism of phenol and substituted phenols in zebra fish.

1. The metabolism of five phenols in zebra fish was studied after uptake from the medium. The results showed no qualitative differences to other Cyprinid fish species, only the oxidation rate seemed to be lower. 2. Phenyl glucuronide, phenyl sulphate, and quinol sulphate were identified as metabolites of phenol. 3. Identified metabolites of 2-cresol were 2-cresyl glucuronide, 2-cresyl sulphate, and 2-hydroxybenzoic acid in trace amounts. 4. Only the glucuronide and sulphate conjugates were detected as metabolites of 4-nitrophenol, 4-chlorophenol, and pentachlorophenol.

Animals↗
PubMed1994

Identification of beta-galactosidase activity in purified bovine retinal rod outer segments.

We have identified beta-galactosidase activity in purified bovine rod outer segments (ROS), using rho-nitrophenyl-beta-D-galactopyranoside (PNPG) and chlorophenol red-beta-D-galactopyranoside (CPRG) as substrates. This glycosylhydrolase activity did not appear to represent contamination from other retinal subcellular fractions, based upon the relative specific activities of beta-galactosidase vs. other hydrolases (N-acetyl-beta-glucosaminidase, alpha- and beta-mannosidase, alpha-fucosidase, and acid phosphatase) in bovine retina and ROS homogenates. Using PNPG as a substrate, two pH optima were observed (at 3.5 and 5.5), while the hydrolysis of CPRG exhibited a single, broad pH optimum centered at 5.5. In contrast, hydrolysis of PNPG and CPRG by retinal homogenates exhibited single pH optima, at 3.5 and 5.5., respectively. ROS beta-galactosidase activity increased linearly with time, temperature, and protein concentration, and obeyed Michaelis-Menten kinetics with both substrates. For PNPG, Vmax approximately 88 nmol/h/mg protein and the apparent Km approximately 147 microM. For CPRG, Vmax approximately 33 nmol/h/mg protein and the apparent Km approximately 50 microM. ROS beta-galactosidase activity was affected by carbohydrates and their derivatives: glucose, fucose, sucrose, maltose and N-acetyl-galactosamine were found to stimulate the activity, while D-galactono-gamma-lactone and, to a lesser extent, D-galactose were inhibitory. The enzyme activity also was slightly stimulated by [Cl-] and markedly by dithiothreitol (DTT), while rho-chloro-mercuribenzoic acid (PCMB) and rho-hydroxymercuribenzoic acid (PHMB) inactivated the enzyme. In addition, the enzymatic activity was also found to be differentially sensitive to various anionic and nonionic detergents. However, n-octyl-beta-D-glucoside was slightly stimulatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Reproductive effects of paternal exposure to chlorophenate wood preservatives in the sawmill industry.

OBJECTIVES: The purpose of the study was to determine whether paternal occupational exposure to dioxincontaminated chlorophenols is associated with an increased risk of congenital anomalies or other adverse reproductive outcomes in offspring. METHODS: As a result of a multistep linkage, 19675 births between 1952 and 1988 were identified as children of a cohort of 9512 fathers who had worked at least one year in British Columbia sawmills where chlorophenate wood preservatives had been used. A nested case-referent analysis was applied, using conditional logistic regression, with five referents matched per case according to year of birth and gender. Chlorophenate exposure was based on expert raters' estimations of hours of exposure applied to specific time windows prior to birth. RESULTS: The offspring of male sawmill workers were at increased risk for developing congenital anomalies of the eye, particularly congenital cataracts; elevated risks for developing anencephaly or spina bifida and congenital anomalies of genital organs were shown according to specific windows of exposure. No associations were found for low birthweight, prematurity, stillbirths, or neonatal deaths. CONCLUSIONS: The study adds further support to the hypothesis of male-mediated developmental toxicity. Paternal exposure to chlorophenates was associated with the development of certain congenital anomalies in offspring.

Abnormalities, Drug-Induced↗
PubMed1989

Cancer incidence of workers in a Finnish sawmill.

The cancer incidence of 1,223 sawmill workers with continuous employment of at least one year between 1 January 1945 and 31 December 1961 was followed until 31 December 1980. Separate analyses were made for the 801 workers hired after 1 January 1945, and smoking habits were surveyed. Among the men, 90 cases of primary cancer were detected versus 83.5 expected and among the women 55 cancer cases versus 44.5 expected. Skin cancer was in excess among the men, especially among those employed after 1 January 1945. Lip, mouth, and pharynx cancer and lymphomas were also slightly in excess among the men, as was leukemia among both sexes. Workplace exposure, especially to chlorophenols, may be associated with the excess skin cancer and the slight excess of lymphomas, but this finding should be further evaluated with special emphasis on well-defined exposure data.

Adolescent↗
PubMed1999

[Genotoxicity of stack gas condensates of Bavarian waste incineration plants. I. Stack gas condensate--sample collection techniques].

Investigations into the toxicity and the chemical analytics of stack gas condensates from 21 waste incineration plants (locations in Bavaria) were undertaken in the years 1990 to 1995. A decisive prerequisite was the development of a simple, standardizable technique for sample collection. It was done by condensating stack gases at 0 to 5 degrees C in an intensive glass condensator. Certain types of compounds showed a different behaviour of separation at the temperatures which were used. Whereas bivalent ionic mercury and chlorophenols were comparatively well separated with amounts of 60 to 95% and the polychlorinated dioxins, furans and biphenyls (PCBs) were sufficiently separated with 20 to 60%, less than 10% of the chlorobenzenes and polycyclic aromatics (PAHs) were found in the condensates. Sufficiently sensitive biological test procedures must be chosen for a biomonitoring of the condensates on geno- and immunotoxic effects to keep the required quantity of the condensates within practicable limits. The concentration of organic wastes was done through a solid phase extraction for the genotoxicity testing in the period from 1990 to 1991, and uniformly through a dichloromethane extraction for the biological and the simultaneous chemical analytical investigations from 1992 to 1995.

Air Pollutants↗
PubMed2002

Integral toxicity test of sea waters by an algal biosensor.

An integral toxicity test, based on an algal biosensor and suitable to be used in sea water, is presented. The biosensor was designed and built by coupling a Clark oxygen electrode as transducer and the marine alga Spirulina subsalsa as biological mediator; it constitutes the "core" in a lab-scale prototype of a flow apparatus suitable to continuously monitor, in sea water, the photosynthetic activity of the alga and, from its variation, the marine pollution from the toxicological point of view. Inorganic pollutants (heavy metals) were tested in previous researches while organic ones (chlorophenols, pesticides and surfactants) are the object of the present paper.

Bacterial Proteins↗
PubMed2002

Toxicity assessment of 255 chemicals to pure cultured nitrifying bacteria using biosensor.

The bioassay has been attracting attention as a method of toxicity assessments of micropollutants in the environment. In this study, we report the characteristics (selectivity and sensitivity) of the nitrifying bacteria biosensor for 255 kinds of chemicals as a model of chemical contaminant in the environment and the results of evaluation of mixed samples of several substances. In the nitrifying bacteria respiration inhibition test using the biosensor, 56 chemicals were detected. It was found that this biosensor is especially sensitive to seven chemicals that have a thiocarbonyl functional group (>C=S), such as a thioamide group of thiocarbamate group. These chemicals are considered to specifically inhibit AMO by chelation of copper. The samples consisted of a mixture of seven types of anilines that inhibit respiration in the bacteria, a mixture of five types of chlorophenols, and a mixture of eight types of substances that contain thiocarbonyl groups were examined. All of the mixed samples inhibited the respiration of the nitrifying bacteria more than 10% by the inhibition rate, and observed a synergistic effects of the substances in the samples.

Aniline Compounds↗
PubMed2003

Heterogeneous ultrasonic destruction of aqueous organic contaminants.

Sonolysis is emerging as an effective advanced technology for destruction of organic pollutants in wastewater. The focus of this study is to investigate the potential of enhancing the sonochemical destruction of aqueous organics. Increasing the contaminant destruction rate will reduce the reaction time, and possibly reduce the cost of treatment. For this purpose, the effect of H2O2 and/or silica in the presence of ultrasound is examined for destruction of 2-chlorophenol (2-CP). The effect of silica dosage (1, 5, 10, and 20 g/L), peroxide dosage (60, 75, and 100 mg/L), and pH (3, 7, and 11) is examined. Low solution pH provided higher destruction of 2-CP. The presence of peroxide or silica enhanced the destruction of 2-CP. The optimum silica dosage was 5 g/L. 100 mg/L of peroxide and 5 g/L of silica present together enhanced 2-CP sonolytic destruction by a factor of approximately 2 as compared to 2-CP destruction with ultrasound only.

Chlorophenols↗
PubMed2003

Influence of the initial substrate to microorganisms concentration ratio on the methanogenic inhibition test.

The influence of the initial substrate to microorganisms ratio (So/Xo) on the inhibition of the methane production caused by 4-chlorophenol, 4CP, was studied. The effect of the 4CP on glucose degradation was evaluated measuring the quantity of methane produced during the test. One part of the inoculum was used as it came from its origin and another was fed with ethanol in order to maintain its activity. The inhibition tests were carried out using the same initial concentration of glucose, three initial suspended solids concentrations and eight initial concentrations of 4CP. The use of ethanol-acclimatized sludge presented a great influence on the inhibition results, since the inhibition was greater in the raw sludge than the acclimated one. Significant differences in the inhibition tests were found depending on the initial So/Xo ratio with respect to the glucose as substrate. It was observed that the inhibition decreases as the So/Xo decreases, in other words as the initial biomass concentration increases. When the results were analyzed in respect to the 4CP it was observed that the inhibition increases as the So/Xo increases. Also, it was observed that for the same value of So/Xo there is an increase of the inhibition when the quantity of Xo decreases.

Bacteria, Anaerobic↗
PubMed2004

Mechanistic implications of the effect of TiO2 accessibility in TiO2-SiO2 coatings upon chlorinated organics photocatalytic removal in water.

The photocatalytic removal rates r of dichloroacetic acid (DCAA), 4-chlorobenzoic acid (4-CBA) and 4-chlorophenol (4-CP) in water were compared for TiO2 samples used either as a powder or as a coating on a fiber glass tissue, SiO2 being the binder. From SEM-EDX measurements it was deduced that SiO2 prevails over TiO2 in the coating top layers and 18O2-Ti16O2 isotopic exchange showed that the accessibility of O2 to TiO2 was markedly reduced when TiO2 was thus coated. The unfavorable effect of the restricted TiO2 accessibility on r was drastic for DCAA, much less pronounced for 4-CBA, and still smaller for 4-CP. It is inferred that DCAA can be attacked only when it directly interacts with TiO2, whereas 4-CP can also react within the near-TiO2 surface water layers. The 4-CBA intermediate behavior is in line with the structural similarities of 4-CBA with DCAA and 4-CP.

Catalysis↗
PubMed2004

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis.

The effect of combining the photocatalytic processes using TiO2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 is used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H2O2 and TiO2 in the degradation of DCA.

Chlorophenols↗
PubMed2004

Toxicity increases in ice containing monochlorophenols upon photolysis: environmental consequences.

The toxic effects of photoproducts formed upon the photolysis of 2- and 4-chlorophenol (CP) frozen solutions in polycrystalline ice phase were determined with a bacterial luminescence test (Vibrio fisheri), and in vitro biomarker assay for dioxin-like effects (inductions of AhR-dependent luciferase in H4IIE-luc cells) and compared to the toxic effects of products of the same photoreaction in aquatic phase. Coupling photoproducts formed in ice samples (3'-chlorobiphenyl-2,4'-diol and 3-chlorobiphenyl-2,2'-diol from 2-CP photolysis and 5-chlorobiphenyl-2,4'-diol from 4-CP photolysis) were found to be more toxic to V. fisheri than parent CPs and elicited significant inductions of dioxin-like effects (the effective concentrations EC50 approximately 3 x 10(-5) mol L(-1) corresponded to known weaker ligands of AhR, such as nonplanar polychlorinated biphenyls or polycyclic aromatic hydrocarbons). To complete the picture, a photoproduct formed from 4-CP (5-chlorobiphenyl-2,4'-diol) was synthesized, and a detailed toxicity assessment with purified compound confirmed the results obtained with irradiated samples. Our findings support a recently proposed model according to which solar radiation can trigger the formation of new types of organic pollutants in polar ice or tropospheric ice cloud particles, presenting possibly greater risk to the environment than the parent compounds.

Animals↗
PubMed1987

Cohort mortality study of chemical workers with potential exposure to the higher chlorinated dioxins.

This cohort study evaluated mortality patterns, 1940 through 1982, of 2,192 chemical workers who, having engaged in the manufacture of higher chlorinated phenols and derivative products, had potential occupational exposures to chlorinated dioxins. Relative to United States white male mortality experience, there were no statistically significant deviations from expected for the following categories: all causes, total malignant neoplasms, or specific malignancies of particular interest: stomach cancer, liver cancer, connective and other soft-tissue cancer, the lymphomas, or nasal and nasopharyngeal cancer. For the cirrhosis of the liver category, internal comparisons demonstrated increasing trends associated with duration of employment in the Chlorophenol Production and Finishing areas; but available evidence suggests this finding was related to alcohol abuse. The study does not support a causal association between chronic human disease as measured by mortality and exposures to the higher chlorinated phenols, derivative products, or their unwanted contaminants, the chlorinated dioxins.

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

[Problems in the root canal treatment of premature teeth with open apex].

The root canal treatment of pulpless teeth with open apex was always a problem in the field of endodontics. On occasions, various techniques have been used for the hermetic sealing of these teeth, and finally, the method of root canal filling with calcium hydroxide and CMCP (camphorous para mono chlorophenol) was adopted. This method was considered to be the most biological, and as it was proved the influence of calcium hydroxide, closing of the apex was achieved by various types of tissues. In this study we describe the problems that arise in such cases, as well as the various treatments. Finally cases of children who came for therapy in the clinic of Endodontics will be presented.

Calcium Hydroxide↗
PubMedDate not supplied

[In vivo study of the analgesic action of different methods and drugs in endodontics].

In order to treat the acute pulpal pain of the emergency patient, there are different methods and medicaments in the clinical practice. The aim of this study was to investigate the efficacy of variant treatment methods and medicaments used clinically to manage acute pulpal pain. The material of this method consisted of 100 patients who came in the clinic of endodontics of Athens university, with symptoms of acute pulpitis. The patients were divided in three groups. In the first group the carious dentin was excavated without exposuring the pulp and a cotton pellet with eugenol or comphorted p-chlorophenol was placed in the cavity. In the second group the carious dentin was also removed, a small pulp lesion was made and the same medicaments were placed in the cavity. In the third group pulpotomy was performed and the same drugs were placed in the cavity. The results indicated that the method of pulpotomy was the most effective one for pain alleviation. Furthermore eugenol was proved to be more effective as a sedative drug than comphorted p-monochlorophenol.

Chlorophenols↗