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PubMed2005

Residue of pentachlorophenol in freshwater sediments and human breast milk collected from the Pearl River Delta, China.

Pentachlorophenol (PCP) was investigated in freshwater sediments and human breast milk collected from the Pearl River Delta, China. The average level of PCP in river sediments was 7.93 ng/g based on dry weight, ranging from 1.44 to 34.4 ng/g. As to the sediments from fishponds, samples from Zhongshan had the highest PCP levels (37.5 ng/g on average), followed by Dongguan (21.1 ng/g on average) and the least in Shenzhen (3.69 ng/g on average) and Shunde (2.20 ng/g on average). Negative relationship was obtained between the PCP level and pH value in sediment (r=0.553, n=13, p<0.05), while positive relationship was found between the PCP levels and the total organic matter (TOM) levels in sediment (r=0.700, n=17, p<0.01). These results indicated that pH and TOM played important roles during the process of PCP settling down to the sediment. PCP was also detected in human breast milk with an average of 2.15 ng/g. The PCP concentration increased with the age increasing of donors. The estimated PCP body burden for mother, daily and yearly PCP intake of infants ranged from 0.16 to 4.17 mg/person, from 0.26 to 10.23 mug/infant.day and from 0.09 to 3.73 mg/infant.year, respectively.

Adult↗

PubMed2004

Estimation of apparent rate coefficients for phenanthrene and pentachlorophenol interacting with sediments.

To gain information on organic pollutants in water-sediment systems, a compartment model was applied to study the sorption course of phenanthrene and pentachlorophenol (PCP) in sediments. The model described the time-dependent interaction of phenanthrene and PCP with operationally defined reversible and irreversible (or slowly reversible) sediment fractions. The interactions between these fractions were described using first order differential equations. By fitting the models to the experimental data, apparent rate constants were obtained using numerical optimization software. The model optimizations showed that the amount of reversible phase increased rapidly in the first 10 d with the sorption time, then decreased after 10 d, while the amount of irreversible phase increased in the total sorption course. That suggested the mass transport between reversible phase and irreversible phase. The extraction efficiency with hot methanol ranged from 36% to 103% for phenanthrene and from 65% to 101% for PCP, with the trend of decreasing with sorption time.

Chemical Phenomena↗

PubMed2005

High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: influence of contaminated fish consumption.

An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P<0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory.

Adolescent↗

PubMed2006

Photoelectrocatalytic degradation of pentachlorophenol in aqueous solution using a TiO2 nanotube film electrode.

Titanium dioxide (TiO2) nanotube film electrodes are fabricated by the anodic oxidation method. Scanning electron microscopy (SEM) showed that these tubes were well aligned and organized into high-density uniform arrays. XRD analysis showed the TiO2 nanotubes to be in the anatase crystal form. The TiO2 nanotube film electrode exhibited increased photoelectrocatalytic (PEC) capability compared to a traditional TiO2 film electrode fabricated using the anodizing method for pentachlorophenol (PCP) degradation in aqueous solution. The bias potential, pH value, and electrolyte concentration were shown to be important factors influencing the degradation of PCP by the PEC method using the TiO2 nanotube film electrode as the working electrode.

Catalysis↗

PubMed2006

Generalized models for prediction of pentachlorophenol dissipation dynamics in soils.

Dissipation of pentachlorophenol (PCP) in soil was investigated and the chemical relationships with soil properties were addressed. The results indicate that the dissipation of extractable PCP residues can be described using first-order kinetics equations, with a half-dissipation time (T(1/2)) ranging from 6.5 to 173.3d. The sharply different patterns of PCP dissipation in different soils were closely related to soil properties. Correlations of stepwise regression equations obtained were significant at 0.01 probability level between soil parameters and extractable PCP residues (R(2)=0.974**) as well as T(1/2) values (R(2)=0.882**). Using pH together with organic carbon content (OC) and soil particle size distribution, the dissipation dynamics of PCP in soil could be accurately predicted.

Carbon↗

PubMed2006

Detailed sorption isotherms of pentachlorophenol on soils and its correlation with soil properties.

Insight into the sorption mechanism of pentachlorophenol (PCP) was gained by constructing highly detailed isotherms over the widest possible concentration range. Using the dual-mode model, sorption isotherms of PCP were accurately predicted, the sorption capacities were determined, and the mechanisms of adsorption (hole-filling) and partitioning were elucidated. Sorption-desorption hysteresis in the present study was manifested to some significant degree in 10 soils with different properties. Such hysteresis might result from the pore deformation and entrapment of PCP molecules within organic matter. Total nitrogen in soils also has its contribution in these kinds of processes. Correlations of stepwise regression equations obtained confirm that pH, soil organic carbon and organic carbon fractions, and particle size distribution are the main factors responsible for the sorption and desorption hysteresis processes. These factors worked in concert in influencing the fate of PCP sorption-desorption in soil. The empirical models developed in this study accurately predict PCP sorption and desorption hysteresis phenomena for the soils that were investigated.

Adsorption↗

PubMed2006

An observational study of the potential exposures of preschool children to pentachlorophenol, bisphenol-A, and nonylphenol at home and daycare.

The Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study investigated the potential exposures of 257 preschool children, ages 1 1/2-5 yr, and their primary adult caregivers to more than 50 anthropogenic chemicals. Field sampling took place in selected counties in North Carolina (NC) and Ohio (OH) in 2000-2001. Over a 48-h period in each child's daycare center and/or home, food, beverages, indoor air, outdoor air, house dust, soil, participants' hand surfaces and urine were sampled. Additional samples-transferable residues, food preparation surface wipes, and hard floor surface wipes-were collected in the approximately 13% of the homes that had pesticide applications within the 7 days prior to field sampling. Three phenols were among the measured chemicals: pentachlorophenol (PCP), bisphenol-A [2,2-bis(4-hydroxyphenyl)propane], and nonylphenol (4-n-nonylphenol). Nonylphenol (NP) was detected in less than 11% of the samples in any medium. Among samples that were collected at all participants' homes and daycare centers, PCP was detected in >50% of indoor air, outdoor air, house dust, and urine samples; bisphenol-A (BPA) was detected in >50% of indoor air, hand wipe, solid food, and liquid food samples. The concentrations of the phenols in the sampled media were measured, and the children's potential exposures and potential absorbed doses resulting from intake through the inhalation, dietary ingestion, and indirect ingestion routes of exposure were estimated. The children's potential exposures to PCP were predominantly through inhalation: 78% in NC and 90% in OH. In contrast, their potential exposures to BPA were predominantly through dietary ingestion: 99%, for children in both states. The children's estimated exposures to PCP, calculated from the amounts excreted in their urine, exceeded their estimated maximum potential intake, calculated from the multimedia PCP concentrations, by a factor greater than 10. This inconsistency for PCP highlights the need for further research on the environmental pathways and routes of PCP exposure, investigation of possible exposures to other compounds that could be metabolized to PCP, and on the human absorption, metabolism, and excretion of this phenol over time periods longer than 48 h.

Benzhydryl Compounds↗

PubMed2005

Pentachlorophenol reduces B lymphocyte function through proinflammatory cytokines in Carassius auratus.

Cytokines and IgM levels are important parameters in the acquired immunity of fish. In the present study, the effect of pentachlorophenol (PCP) on the expression of proinflammatory cytokines, TNF-alpha (tumor necrosis factor-alpha) and IL-1beta (interleukin 1) mRNA levels of crucian carp, were determined by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method. To put the deduction of PCP's immunotoxicity on B cell function, B cells secretion of IgM under exposure of PCP-administrated fish macrophage was determined by enzyme-linked immunosorbent assay (ELISA), and the ability of B cells to secrete IgM was determined by enzyme-linked immunospot (ELISPOT). The results showed that the mRNA expressions of these two cytokines were suppressed by the administration of PCP. The supernatants from PCP-administrated fish macrophage showed less stimulation on B cell, lower maturation of B cells and secretion of IgM. These results suggested that PCP might have impact on micromilieu immune factors as proinflammatory cytokines.

Animals↗

PubMed2006

Effect of bisphenol A, tetrachlorobisphenol A and pentachlorophenol on the transcriptional activities of androgen receptor-mediated reporter gene.

Previously, we developed an androgen receptor (AR)-mediated reporter gene assay system, and verified the antiandrogenic activity of bisphenol A (BPA) based on this assay. There were some similar phenol-ring structure chemicals which were widely used while little had been done to evaluate their effect to androgen. In the present study, we applied this assay to evaluate the androgenic and antiandrogenic activities of some phenolic chemicals including BPA, tetrachlorobisphenol A (TCBPA), and pentachlorophenol (PCP). The results showed that BPA exhibited potent antiandrogenic activity with IC50 value of 2.14 microM. TCBPA showed relative weaker activity with IC50 value of 10.45 microM and PCP did not show AR antagonistic activity. On the other hand, we failed to find AR agonistic effects of the three chemicals. To study the reason why BPA and TCBPA reduced the reporter gene expression, we increased the DHT concentration to 100 nM and 10 microM in the reporter assay. Then, we found that the antagonist activity of BPA and TCBPA decreased with the increase of concentration of DHT. This result indicated that these two test chemicals could compete with DHT for the binding of AR. When comparing the structure difference between BPA, TCBPA and PCP, we got a preliminary founding that 3,5-substituents of phenol ring of BPA decrease its antiandrogenic activity. These results provide some useful information for the assessment of the antiandrogenic activity of BPA like chemicals and the potential mechanism.

Androgen Antagonists↗

PubMed2006

Revised reference value for pentachlorophenol in morning urine.

Reference values are continuously derived by the Human Biomonitoring Commission of the German Federal Environment Agency to give help in assessing the exposure of individuals or population groups in comparison to the background exposure. As environmental conditions may change reference values should be checked periodically and they have to be updated, if new data become available. The results of the German Environmental Survey 1998 (GerES III) showed the decreasing pentachlorophenol (PCP) exposure of the German adult population. Therefore, the reference value for PCP in morning urine was lowered: from 8 to 5 microg/l for adults (aged 18-69 years) living in homes where wood preservatives had not been used.

Adolescent↗

PubMed2004

Cyclodextrin-enhanced solubilization of pentachlorophenol in water.

The solubilization of pentachlorophenol (PCP) by beta-cyclodextrin (beta-CD) and three of its most used derivatives, methyl-beta-cyclodextrin (MCD), hydroxypropyl-beta-cyclodextrin (HPCD) and carboxymethyl-beta-cyclodextrin (CMCD), has been investigated. The formation of soluble inclusion complexes between PCP and cyclodextrin (CDs) increases the aqueous solubility of PCP. Due to the ionizable nature of PCP, the effects of pH and ionic strength on the equilibrium complexation were evaluated. All CDs were found to form 1:1 inclusion complexes. Equilibrium constants calculated from solubility enhancement experiments revealed that the stability of the complexes was dependent on the polarity of the compound, on the ionic strength and on the cyclodextrin type. In general, weaker equilibrium constants were observed for PCP with beta-CD than with MCD or CMCD. For all CDs, the complexation or the solubilization efficiency of PCP (weak acid) depended on pH and ionic strength. Moreover, we observed that the solubility of the beta-CD/PCP complex was lower than that of the beta-CD molecule and dependent on the ionic strength of the solution. Although the equilibrium constant of PCP/CD complex was found to be higher at pH 3 than at pH 7 in water, extraction of PCP from porous media by a CD solution at neutral pH would be achievable due to the higher PCP aqueous solubility in neutral/basic media.

Cyclodextrins↗

PubMed2006

Effects of pH and cyclodextrins on pentachlorophenol degradation (mineralization) by white-rot fungi.

White-rot fungi (WRF) such as Trametes hirsuta completely degrade (mineralize) pentachlorophenol (PCP) and many other organopollutants. This has led to them being used to decontaminate various substrates (e.g. soil) through biorememediation. However, because PCP is a biocide, it can inhibit fungal growth and thereby its own degradation. It was hypothesized that substrate pH might affect PCP degradation, because when the pH is lower than 4.7 (the pKa for PCP) the phenol predominates, while at higher pH the phenate does. These two PCP species differ markedly in physical and biological properties. The effect of cyclodextrins was also investigated since it is known that the inclusion complexes these form with PCP differ in bioavailability and toxicity from non-complexed PCP. Tests were first made in liquid and agar media (where conditions are relatively easy to control), and then in a sawdust, because it is a common target matrix for WRF bioremediation. Results with the liquid and agar media showed that growth in the presence of inhibitory PCP concentrations decreased as the pH decreased, consistent with the phenol being more toxic. Growth in sawdust was less affected by PCP regardless of the pH, presumably because the PCP sorbed to the wood which decreased its bioavailability. Some cyclodextrins markedly decreased the PCP's toxicity in liquid, agar and sawdust media. Rates of PCP mineralization (measured from production of (14)CO(2) from (14)C PCP) in liquid cultures containing 0.5 mgkg(-1) PCP (a sub-inhibitory concentration) were similar from pH 2.5-7.5, indicating that the phenol and the phenate were equally degradable. Degradation of a growth inhibiting concentration on sawdust (1,000 mgkg(-1)) could be increased slightly by lowering the pH below the pKa, this increasing sorption to the wood. Degradation increased more when the pH was raised well above the pKa, presumably due to the phenate being less toxic and more soluble, making it more available to the degradative system. Although some cyclodextrins decreased growth inhibition, they also interfered with degradation. If this interference could be overcome, cyclodextrins could be used to increase the maximal PCP concentration that could be treated by WRF bioremediation.

Agar↗

PubMed2006

Oxidation and detoxification of pentachlorophenol in aqueous phase by ozonation.

The degradation and detoxification performance of ozonation in treating pentachlorophenol (PCP) contaminated wastewater was determined. All experiments were conducted in a bench scale glass column equipped with ceramic diffuser and a lab-scale ozone generator under ambient temperature and pH 7. The decomposition rate of PCP in this study was primarily controlled by the ozone mass transfer rate from gas to liquid phases. Principal intermediates found were 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TeCP) and phenol. PCP seems to be more vulnerable to ozone than its intermediates. A bioluminescence technique was used to evaluate the toxicity of PCP with Vibrio fisheri NRRL B-11177 as the test bacterium, and the EC(50) of PCP was found to be 1.0 mg l(-1). Detoxification occurred as the PCP and TeCP reacted with ozone and decomposed to less chlorinated congeners and phenol.

Hydrogen-Ion Concentration↗

PubMed2005

Effect of easily degradable substrate on anaerobic degradation of pentachlorophenol in an upflow anaerobic sludge blanket (UASB) reactor.

The effect of microbial easily degradable substrate (MEDS) on the anaerobic degradation of pentachlorophenol (PCP) in two upflow anaerobic sludge blanket (UASB) reactors was investigated. The results indicated that glucose-utilizing activity decreased with the increase of PCP concentration in the mixed culture, and MEDS promoted PCP-dechlorination and degrading activities. The concentration of MEDS increased from 917 to 4580 mg L(-1) with the increase of PCP concentration from 100 to 181 mg L(-1)in influent, which was necessary for maintenance of steady operation of the experimental reactors, the removal rate of PCP and COD ranged up to 99.5 and 90.0% and the concentration of PCP in the effluent was less than 0.5 mg L(-1). The concentration of PCP in effluent was linearly or logarithmically related to sucrose concentration in the influent while PCP was less than the maximum permissible PCP concentration. The activity of anaerobic sludge in the reactor decreased as the concentration of PCP increased, but it could be recovered step by step as time progressed. In the lowest layer of the reactor, the activity of sludge was the highest. So it is feasible to accelerate the degradation of the organic toxic compounds like PCP, by adding suitable quantities of microbial easily degradable substrate to the system.

Bacteria, Anaerobic↗

PubMed2006

Degradation of pentachlorophenol in aqueous solution by audible-frequency sonolytic ozonation.

The degradation of pentachlorophenol (PCP) in aqueous solution by audible-frequency sonolytic ozonation was studied. The sonolysis of H(2)O and PCP/H(2)O solutions and the dissolution and decomposition of ozone under audible-frequency sonication were evaluated as well. The results showed that the ozone dissolution rate and PCP degradation rate were significantly enhanced by sonication in comparison to using mechanical stirring and O(3) bubbling alone. This enhancement is most likely attributed to the strong turbulence induced by sonication. The first-order rate constant of PCP degradation by ozonation with sonication is more than 15 times faster than that with bubbling ozone alone, while the rate constant with mechanical stirring is only four times faster. The influence of the ozone feed rate on PCP degradation and the degradation byproducts were examined as well. In addition, results showed that no H(2)O(2) was generated by sonolysis of water with audible-frequency sonication and no PCP was degraded by sonolysis alone.

Adsorption↗

PubMed2006

Effect of pentachlorophenol and chemical oxygen demand mass concentrations in influent on operational behaviors of upflow anaerobic sludge blanket (UASB) reactor.

Upflow anaerobic sludge blanket (UASB) reactor that was seeded with anaerobic sludge acclimated to chlorophenols was used to investigate the feasibility of anaerobic biotreatment of synthetic wastewater containing pentachlorophenol (PCP) with additional sucrose as carbon source. Two sets of UASB reactors were operated at one time. But the seeded sludge for the two reactors was different and Reactor I was seeded with the sludge that was acclimated to PCP completely for half a year, and Reactor II was seeded with the mixed sludge that was acclimated for half a year to PCP, 4-CP, 3-CP or 2-CP, respectively. The degradation of PCP and the operation fee treating the wastewater are affected by the concentration of MEDS (microorganism easily degradable substrate). So the confirmation of the suitable ratio of [COD] and [PCP] was the key factor of treating the wastewater containing PCP economically and efficiently. During the experiment, the synthetic wastewater with 180.0 mg L(-1) PCP and 1250-10000 mg L(-1) COD could be treated steadily in the experimental Reactor I. The removal efficiency of PCP was more than 99.5% and the removal efficiency of COD was up to 90%. [PCP] (concentration of PCP) in effluent was less than 0.5 mg L(-1). [PCP] in influent could affect proper [COD] (concentration of COD) range in influent that was required for maintenance of steady running of the experimental reactor with a hydraulic retention time (HRT) from 20 to 22 h. [PCP] in influent would directly affect the necessary [COD] in influent when the UASB reactor ran normally and treated the wastewater containing PCP. When [PCP] was 100.4, 151.6 and 180.8 mg L(-1) in influent, respectively, [COD] in influent had to be controlled about 1250-7500, 2500-5000 and 5000 mg L(-1) to maintain the UASB reactor steady running normally and contemporarily ensure that [COD] and [PCP] in effluent were less than 300 and 0.5 mg L(-1), respectively. With the increase of [PCP] in influent, the range of variation of [COD] in influent endured by the UASB reactor was decreasing. The ratios of [COD] and [PCP] in influent could affect removal efficiency of PCP and COD, the concentration of total volatile fatty acids (VFA) in effluent, biogas quantity and methane content in biogas. [PCP] in influent was linearly or semi-logarithmically correlated to [COD] in effluent when [COD] in influent was 5750+/-250 mg L(-1), and so was the relationship between [COD] in influent and [PCP] in effluent when [PCP] in influent was 100.4 or 151.6 mg L(-1), less than the maximum permissible [PCP]. The sources of seeded sludge, the way of sludge acclimation and the characteristics of anaerobic sludge could all affect the UASB reactor capacity treating PCP. When [PCP] were less than 180.8 mg L(-1) for Reactor I and 151.6 mg L(-1) for Reactor II, the variation of [PCP] in influent had little effect on the UASB reactor volume gas production rate and substrate gas production rate. And [VFA] and pH value in effluent were affected a little. Volume biogas production rate and substrate biogas production rate of the UASB reactor were only affected by [COD] and loading rate in influent. But when [PCP] was more than 151.6 mg L(-1) for Reactor II, the biogas production fell quickly and was over 3 days later. [VFA] in effluent from Reactor II increased up to 2198.1 mg L(-1) quickly and the pH value fell to less than 7. Reactor II could not run normally. The component of VFA accumulated quickly was mainly acetate (above 50%). With [PCP] increased from 7.9 to 180.8 mg L(-1) gradually in influent, the methane content in biogas from Reactor II decreased from 70% to 60%, but the reactor could still run normally. Then as for Reactor II, the content of methane have fallen from 75% to 45% or so quickly. And Reactor II could not run steadily. So the conclusion could be drown that too high [PCP] in influent for UASB reactor mainly inhibited the activity of methane-producing bacteria cultures utilizing the acetate.

Algorithms↗

PubMed2006

Pentachlorophenol removal from aqueous matrices by sorption with almond shell residues.

Sorption with activated carbon has been the technique preferred for pentachlorophenol (PCP) removal from contaminated waters, but regeneration needs and high operation costs are supporting a renewed interest in the search for alternative sorbents. Among them, almond shell, an agricultural by-product, provides interesting economical advantages, once shells account for 50% (in mass) of the whole almond. In this work, the capacity of almond shells to remove PCP from waters without previous activation was studied in batch conditions. While PCP analysis was performed solid-phase microextraction (SPME) followed by gas chromatography with electron capture detection (GC-ECD), mercury porosimetry and Fourier transform infrared spectroscopy (FTIR) provided a preliminary physical and chemical characterization of the sorbent. Almond shells were essentially a macroporous material, with an average surface area of 12.9+/-2.8 m2/g. The efficiency of PCP removal was 93+/-14%, in 24 h, with an initial concentration of 100 microg/l PCP and 5 microg PCP/g shell. Isotherm data adjusted better to Freundlich equation, where K(F) and 1/n were 0.075+/-0.081 mg(1-1/n) l(1/n) and 1.882+/-0.289, respectively. Average desorption efficiency was 7%, indicating strong adsorption capacity. Results proved that almond shells may be an excellent low-cost alternative for PCP removal from contaminated waters.

Adsorption↗

PubMed2006

Mechanism of the enhanced degradation of pentachlorophenol by ultrasound in the presence of elemental iron.

Ultrasound combined with elemental iron (US/Fe(0)) is effective in oxidizing organic contaminants in water. The sonolysis degradation of pentachlorophenol (PCP) was significantly enhanced by a factor of 4.2 with the addition of elemental iron, mainly via reaction with hydroxyl radicals (OH radicals), and the synergistic mechanism of the enhancement in the combined system was investigated. Experiments were performed with (1) sole ultrasonic treatment; (2) ultrasound in presence of iron; (3) ultrasound combined with copper powder as the same particle size as iron powder; (4) ultrasound in presence of Fe(II). It was observed that PCP degradation and OH radicals production were both enhanced in these combined methods, and the pitting on the sonicated iron surface was apparent. These results indicated that the rate enhancements in US/Fe(0) system were attributed to (1) the iron solid effect and the catalysis of Fe(II) produced from corroded-iron with promoting the production of OH radicals; (2) the increased surface area of iron particles by acoustic cavitation with promoting the adsorption process.

Catalysis↗