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PubMed1993

Influence of pentachlorophenol on light emission from single barnacle muscle fibers preloaded with aequorin.

Experiments show that the resting ouabain-insensitive sodium efflux in giant fibers from the barnacle Balanus nubilus is stimulated by external application of pentachlorophenol (PCP). This work has now been extended to include a study of muscle fibers preloaded with the Ca2+ indicator aequorin to determine whether PCP is able to increase light emission; and whether its potency depends on the number of chlorine atoms and external pH. The results obtained are as follows: 1) PCP causes a dose-dependent, multiphasic rise in light emission; the threshold concentration in fibers not poisoned with ouabain was in the low micromolar range. 2) The efficacy of PCP is considerably greater than that of less-chlorinated phenols and phenol. 3) The response to PCP is a sigmoidal function of external pH both in unpoisoned and ouabain-poisoned fibers. Reducing external pH potentiates its efficacy. 4) The response to PCP depends on the external Ca2+ concentration, and the requirement for Ca2+ is usually absolute.

Aequorin↗
PubMed1998

A morbidity study of former pentachlorophenol-production workers.

Pentachlorophenol (PCP) is a pesticide that was once widely used for wood preservation. Commercial PCP contained impurities including higher chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs). We investigated the effects of occupational exposure to PCP and its CDD and CDF contaminants on the skin, liver, porphyrin metabolism, and central and peripheral nervous systems. In 1986 we conducted a medical survey of 366 workers who had been engaged in the production of PCP at a single plant between 1938 and 1978. The referent group consisted of 303 workers from the same plant who were not exposed to these or related compounds. Exposure was determined from computerized personnel records. The medical survey included an administered questionnaire, medical record review, physical examination by dermatologists, internists, and neurologists, and analysis of 24-hr urine for quantitative porphyrins among other tests. In this paper we present the results of analyses of the general health, chloracne, and porphyrin metabolism end points. The general health status of PCP workers was similar to unexposed workers, but 17.8% of PCP workers had evidence of current or past chloracne. PCP workers with chloracne had significantly higher mean urinary excretion of coproporphyrins (117. 0 vs. 90.6 microg/24 hr) than unexposed workers after controlling for potential confounders. Workers with chloracne who had worked with both PCP and polychlorinated biphenyls had significantly higher mean urinary excretions of hepta-, penta-, and coproporphyrins than unexposed workers. We conclude that occupational exposure to PCP is associated with chloracne and biochemical abnormalities which may persist years after exposure.

Acne Vulgaris↗
PubMedDate not supplied

X-ray and fluorescence studies on phospholipid bilayers. IX. Interactions with pentachlorophenol.

Pentachlorophenol (PCP) is a widely used and highly toxic fungicide. Its toxicity is mainly expressed at the cell membrane level. It is, therefore, of interest to test its ability to alter the lipid bilayer organization. The present study was performed by X-ray diffraction techniques on dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidylcholine (DMPC) bilayers and by fluorescence on DMPC liposomes. These two phospholipids are respectively found at the inner and outer monolayers of human erythrocyte membranes. Each type of phospholipid was made to interact with different concentrations of the sodium form of PCP in absence and in presence of water. It was found that PCP significantly affected the structure of both phospholipids, being the damage much higher in DMPC bilayers.

Chlorophenols↗
PubMedDate not supplied

Degradation of pentachlorophenol by Mycena avenacea TA 8480--identification of initial dechlorinated metabolites.

Cultures of the basidiomycete Mycena avenacea TA 8480 were shown to metabolize pentachlorophenol (PCP), 2,3,5,6-tetrachloro-p-hydroquinone (TeCHQ), and 2,3,5,6-tetrachloro-p-benzoquinone (TeCBQ). The first metabolite of the PCP degradation pathway was identified as TeCBQ which in a second reaction is reduced to the hydroquinone TeCHQ. Subsequently dechlorination of TeCHQ yielded 3,5,6-trichloro-2-hydroxy-p-benzoquinone (TCOHBQ). The specific degradation rate for PCP was 1.4 mg x g dry mycelia -1 x day-1. The initial dechlorination rate of TeCHQ was 5.9 mg x g dry mycelia-1 x hour-1. None of the compounds supported growth of the fungus.

Basidiomycota↗
PubMedDate not supplied

X-ray studies on phospholipid bilayers. XII. Interactions of pentachlorophenol with myelin.

Pentachlorophenol (PCP) is a widely used pesticide, particularly for the preservation of wood. Given its high toxicity and resistance to degradation it has become a dangerous environmental pollulant. Due to its high lipophilicity, PCP is able to partition into the lipid bilayer of cell membranes disrupting several vital functions. The present research was concerned with the effects that the chronic administration of PCP could produce in vivo to the sciatic nerve of rats. X-ray diffraction patterns obtained from freshly dissected and dried sciatic nerves of PCP treated rats did not show significant differences in their reflections with respect to those present in the patterns from untreated animals. However, morphological studies performed by optical and electron microscopy showed degenerative changes in about 10% of the A and B type of nerve fibers.

Animals↗
PubMed2005

Recovery of microbially mediated processes in soil augmented with a pentachlorophenol-mineralizing bacterium.

Specific physiological groups can be used to evaluate the recovery of soil microbial communities following disturbance. In this study, soil was contaminated with pentachlorophenol (PCP) to assess the resiliency of microorganisms responsible for carbon and nitrogen cycling. Methane fluxes were monitored in soil microcosms to evaluate the effects of contamination and augmentation on microbial populations involved in carbon cycling. The addition of a PCP-mineralizing bacterium, Sphingomonas chlorophenolica strain RA2, enhanced the recovery of methane-oxidizing capacity relative to uninoculated treatments when soil was contaminated with low concentrations of PCP (10 and 50 microg/g soil, ppm). At the highest level of PCP contamination tested (300 ppm), there was no recovery of methane-oxidizing capacity whether or not the PCP-mineralizing bacterium was added to soil. The nitrogen-cycling capacity of contaminated and augmented soil was tested by measuring nitrification potentials. The addition of PCP resulted in a concentration-dependent reduction in nitrification rates. After three months of incubation, all augmented soils had nitrification rates equivalent to the uncontaminated control, and the uninoculated soils contaminated with 100 and 300 ppm PCP still were impaired in their nitrification potentials. These results indicate that biological removal of a contaminant has the potential to restore microbially mediated processes to levels observed prior to contamination.

Ammonia↗
PubMed2006

Oxidation kinetics of pentachlorophenol by manganese dioxide.

This study examined the abiotic transformation kinetics of pentachlorophenol (PCP) by manganese dioxide (MnO2) at different solution chemistry and initial concentrations of PCP and MnO2. The measured PCP transformation rates were found to be on the order of 1.07 with respect to [PCP] and 0.91 and 0.87 with respect to [MnO2] and [H+], respectively. Dissolved Mn2+ and Ca2+ as background electrolytes considerably decreased the reaction rate because of their adsorption and hence blocking of active sites on MnO2 surfaces. The dechlorination number, 0.59 chloride ions per transformed PCP after a 1-h reaction, suggests that a fraction of the transformed PCP was not dechlorinated and may be coupled directly to dimeric products. Gas chromatography/ mass spectrometry and liquid chromatography/mass spectrometry/mass spectrometry techniques were used to identify two isomeric nonachlorohydroxybiphenylethers as major products and 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol as minor products. Product identification suggested that the reaction may include two parallel reactions to form either dimers or 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol via simultaneous dehydrochlorination and hydroxylation.

Calcium↗
PubMed2001

Modeling pentachlorophenol bioavailability and bioaccumulation by the freshwater fingernail clam Sphaerium corneum using artificial particles and humic acids.

The uptake of anthropogenic chemicals by benthic bivalves may occur through the water phase and also by the ingestion of particles from both the suspended matter and bottom sediments. Many chemicals sorb to sediments and, subsequently, are released in the digestive tract of animals. The assessment of sediment-bound chemicals has been difficult because of the complexity of the association between these chemicals and natural particles. To simplify this complexity, we previously devised a test system using artificial particles with known chemical structures. In the present work, we improved this experimental design by adding humic materials as a source of organic matter. Bioassays were conducted by exposing the fingernail clam Sphaerium corneum to sublethal levels of pentachlorophenol (PCP) in the presence or absence of the artificial particles, treated with or without a commercial preparation of humic acids. The results showed that the bioavailability and bioaccumulation could be explained on the basis of the interactions of PCP with the active groups and/or the backbone of the resins, both in systems with or without humic acids. This model may constitute a useful approach to modeling and predicting the uptake and accumulation of chemicals bound to natural sediments.

Animals↗
PubMed2003

Pentachlorophenol poisoning.

Despite being banned in many countries and having its use severely restricted in others, pentachlorophenol (PCP) remains an important pesticide from a toxicological perspective. It is a stable and persistent compound. In humans it is readily absorbed by ingestion and inhalation but is less well absorbed dermally. Its distribution is limited, its metabolism extensive and it is eliminated only slowly. Assessment of the toxicity of PCP is confounded by the presence of contaminants known to cause effects identical to those attributed to PCP. However, severe exposure by any route may result in an acute and occasionally fatal illness that bears all the hallmarks of being mediated by uncoupling of oxidative phosphorylation. Tachycardia, tachypnoea, sweating, altered consciousness, hyperthermia, convulsions and early onset of marked rigor (if death occurs) are the most notable features. Pulmonary oedema, intravascular haemolysis, pancreatitis, jaundice and acute renal failure have been reported. There is no antidote and no adequate data to support the use of repeat-dose oral cholestyramine, forced diuresis or urine alkalinisation as effective methods of enhancing PCP elimination in poisoned humans. Supportive care and vigorous management of hyperthermia should produce a satisfactory outcome. Chronic occupational exposure to PCP may produce a syndrome similar to acute systemic poisoning, together with conjunctivitis and irritation of the upper respiratory and oral mucosae. Long-term exposure has also been reported to result in chronic fatigue or neuropsychiatric features in combination with skin infections (including chloracne), chronic respiratory symptoms, neuralgic pains in the legs, and impaired fertility and hypothyroidism secondary to endocrine disruption. PCP is a weak mutagen but the available data for humans are insufficient to classify it more strongly than as a probable carcinogen.

Animals↗
PubMedDate not supplied

Generalized model of pentachlorophenol distribution in amended soil-water systems.

This paper describes laboratory experiments and subsequent statistical data analysis performed to reevaluate the overall effect of soil characteristics and liquid-phase composition on the extent of pentachlorophenol (PCP) adsorption in complex soil-water systems. The PCP adsorption isotherms were first generated for eight soils of varying physical and chemical properties. Binding tests were then performed in the presence of different additives (surfactant, oil, etc.) and conditions (temperature and pH) based on a fractional factorial design. Statistical analysis of data showed strong interdependencies among several of the soil parameters, but confirmed that organic carbon content (foc) and pH of the soils were the best predictors of the adsorption constant of PCP (Kd) for nonamended soil-water systems. It was determined that the effect on Kd of a 0.2 unit decrease in soil pH was approximately the same as increasing foc by 1%. From studying the effect of the amendments, two interactions (surfactant-pH and surfactant-oil) and two primary effects (surfactant and oil) have been detected. The effectiveness of the surfactant in decreasing Kd varied depending on the pH and oil content of the soil. A generalized nonlinear model expressing Kd as a function of pH, foc, oil content of soil, and surfactant dose was developed for the range of conditions studied. The proposed model and modeling approach can be adapted to other types of contaminants or variables for specific natural and engineered systems.

Adsorption↗
PubMed1989

Metabolism of pentachlorophenol by fish.

1. Interspecies variability in the metabolism of pentachlorophenol (PCP) was investigated by exposing rainbow trout, fathead minnows, sheepshead minnow, firemouth, and goldfish to water-borne 14C-PCP for 64 h. 2. The amounts of metabolites in bile and exposure water were species-dependent; all of the metabolites excreted into the water were sulphate conjugates while bile was enriched in glucuronide conjugates. 3. Biliary excretion accounted for less than 30% of the total PCP metabolites. 4. Biliary metabolites alone were a poor indication of the metabolites produced and of the major routes of elimination.

Animals↗
PubMed1990

Metabolic studies on pentachlorophenol (PCP) in rats.

1. The metabolism of pentachlorophenol in rats was studied. 2. Metabolites isolated from rat urine and identified were: 2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, 2,3,5,6-tetrachlorophenol, tetrachlorocatechol, tetrachlororesorcinol, trichlorohydroquinone, tetrachlorohydroquinone, and traces of trichloro-1,4-benzoquinone, and tetrachloro-1,4-benzoquinone.

Animals↗
PubMed1991

Pentachlorophenol toxicokinetics after intravenous and oral administration to rat.

1. The toxicokinetics of pentachlorophenol (PCP) were studied in rats. Doses of 2.5 mg/kg were given i.v. (bolus, five rats) and orally (gastric intubation, five rats). Concentrations in plasma, urine and faeces were measured by capillary g.l.c. with electron-capture detection. 2. After i.v. administration, the clearance and volume of distribution at steady state were 0.026 +/- 0.003 l/h per kg and 0.25 +/- 0.02 l/kg, respectively. These two parameters exhibit low inter-rat variability (coefficients of variation less than 15%). The half-life of the initial decline of PCP plasma concn. was less than 1.3 h, while the second phase half-life was 7.11 +/- 0.87 h. 3. After oral administration the peak plasma concn. (7.3 +/- 2.8 micrograms/ml) occurred between 1.5 and 2 h and absorption was complete (bioavailability = 0.91-0.97). No distinct distribution phase was observed and the elimination half-life was 7.54 +/- 0.44 h. 4. PCP clearance is essentially metabolic since only 5.3 +/- 0.2% dose is eliminated unchanged by the kidney. About 60% dose was recovered in urine, mainly as conjugated PCP and conjugated tetrachlorohydroquinone (TCHQ). 5. For both routes of administration, about 10% dose was recovered in faeces as PCP and/or metabolites, which indicates that biliary excretion contributes to total elimination.

Absorption↗
PubMed1992

Disposition and biotransformation of pentachlorophenol in the red abalone (Haliotis rufescens).

1. The disposition and biotransformation of pentachlorophenol (PCP) in the red abalone (Haliotis rufescens) have been determined. 2. In a flow-through system, three abalones were exposed to 1.2 mg/l of [U-14C]PCP for 5 h to determine bioconcentration and tissue distribution. Retained residues were quantified from radioactivity, while excreted residues were identified and quantified by h.p.l.c. and determination of radioactivity. 3. The 5-h total concentration factor ranged from 16.0 to 21.5; individual tissue concentrations ranged from 133.4 nmol/g in gill to 17.5 nmol/g in gonad. Due to its large size, the foot muscle received the largest amount of total retained residue (47.4%). 4. During a 13-h recovery period the abalones depurated 72.2% of retained residues; however, residue concentration in gonad increased over 100%. PCP was primarily excreted unchanged (89.3%), but small amounts of pentachloro-beta-D-glucoside (7.9%), pentachloroanisole (1.3%), pentachlorophenylsulphate (0.9%), and tetrachloro-p-hydroquinone (0.6%) were also formed.

Animals↗
PubMed1994

Toxicokinetics of pentachlorophenol in the F344 rat. Gavage and dosed feed studies.

1. The toxicokinetics of pentachlorophenol (PCP) were studied in the Fischer 344 rat using i.v. and oral (gavage, dosed feed) routes of exposure. 2. Only minor sex differences were observed in the elimination kinetics of PCP after i.v. administration at 5 mg/kg. 3. Absorption of PCP from the gastrointestinal tract after gavage doses of 9.5 and 38 mg/kg in aqueous methylcellulose vehicles was first order with an absorption half-life of about 1.3 h. 4. The absorption rate constant of PCP from doses feed was comparable with that obtained from aqueous methylcellulose gavage formulations. 5. Bioavailability of PCP administered in dosed feed was significantly lower than the bioavailability of PCP administered by gavage. 6. Dose proportionality was established to a dosage of at least 38 mg/kg. 7. Daily fluctuation of PCP plasma concentrations was observed during the dosed feed study with peak and trough concentrations occurring in early morning and late afternoon, respectively. 8. The time course of PCP plasma concentrations during the dosed feed study were simulated using a computer model based on linear theory. The simulations were comparable with the experimentally determined concentrations.

Animals↗
PubMed1994

Toxicokinetics and biotransformation of pentachlorophenol in the sea urchin (Strongylocentrotus purpuratus).

1. The toxicokinetics and biotransformation of pentachlorophenol (PCP) were determined in the purple sea urchin (Strongylocentrotus purpuratus). 2. In a static chamber, urchins (n = 9) were individually exposed to 50 micrograms/l of [U-14C]PCP for 24 h to determine bioconcentration and the absorption rate constant (Ka), elimination rate constant (Ke), and elimination half-life (t1/2). Determination was by direct quantitation of radioactivity in the exposure water. 3. After exposure, urchins were placed in a flow-through chamber for 24 h to allow depuration of retained residues, which were identified by hplc and quantified by lsc. The Ka and Ke, calculated using a simplified model, were 0.12 +/- 0.06 h and 0.43 +/- 0.22 h, respectively, whilst the 24-h total concentration factor was 316.3 +/- 209.7, and the t1/2 was 1.6 +/- 0.8 h. 4. Whereas urchins depurated 40.6% of retained residues, only a small amount of PCP was excreted unchanged (17.0%), as the more polar conjugates pentachlorophenyl-beta-D-glucoside (72.4%) and pentachlorophenylsulphate (10.6%) were also formed.

Animals↗
PubMed1984

Induction of ornithine decarboxylase and augmentation of tyrosine aminotransferase activity by N-hydroxy-2-acetylaminofluorene and 2-acetylaminofluorene in rat liver. Influence of sex, retinylacetate, indomethacin, and pentachlorophenol.

IP injection in rats of 2-acetylaminofluorene (AAF) or N-hydroxy-2-acetylaminofluorene (N-OH-AAF) resulted in a transient increase of hepatic ornithine decarboxylase (ODC) and tyrosine aminotransferase (TAT) activity. Maximal activity of ODC was observed 4 hr and of TAT 3 hr after administration of either AAF or N-OH-AAF. A lag-time of 2 hr preceded the increase of ODC and TAT activity. N-OH-AAF dependent ODC induction displayed an almost linear dose-response in the dose range up to 94.1 mumol/kg bw (body weight) when the ODC activity was measured at its maximum 4 hr after administration. Elevation of the dose N-OH-AAF to 126 mol/kg bw resulted in a lower ODC induction. Administration of doses AAF to 31.4 mumol did not change ODC activity. At doses up to 126 mumol/kg bw ODC induction increased linear. TAT induction increased linear in the dose range 15.7-94.1 mumol N-OH-AAF and 31.4-94.1 mumol AAF/kg. Lowering the dose of AAF did not result in a lower ODC or TAT activity. Judged by the effects of actinomycin D or cycloheximide administered 1 hr prior to AAF or N-OH-AAF, the in vivo induction of rat liver ODC activity by AAF and N-OH-AAF appeared to be under transcriptional control, whereas augmentation of TAT activity under influence of AAF or N-OH-AAF appeared the result of (post) translational events. Induction of ODC by AAF or N-OH-AAF was not significantly changed by indomethacin, was slightly increased by pentachlorophenol (PCP) and was synergistically enhanced by retinylacetate (RA). The increase of TAT activity was stimulated by PCP and RA. The effect of PCP indicates that N-sulfonoxy-2-acetylaminofluorene is most probably not involved in the induction of ODC. AAF appeared more effective hepatic ODC inducer in females than males and moreover more effective than N-OH-AAF in females. N-OH-AAF had stronger ODC inducing capacity in males than females. Similar observations were made with respect to TAT activity. When induction of ODC is indicative for a tumor promoting property then the data presented here suggest that tumor promotion of the complete carcinogens AAF and N-OH-AAF is not mediated by N-O-sulfation; this might be due to other metabolic conversions.

2-Acetylaminofluorene↗
PubMed1983

Persistence of tetrachlorophenol and pentachlorophenol in exposed woodworkers.

The decline in urinary concentrations of pentachlorophenol (PCP) and 2,3,4,6-tetrachlorophenol (TCP) were observed for a group of woodworkers chronically exposed to Permatox 100 (3% PCP, 21% TCP) during a 16 day vacation and plant shutdown. The group was monitored annually for two years, with sampling occurring on the last working day prior to shutdown and on the first day after the shutdown. Among those workers with the highest pre-shutdown levels, uniform TCP reductions of 90 +/- 6% were observed, indicating elimination rates similar to those reported for PCP in a single dose human exposure study. Four workers were sampled on alternate days during the shutdown in the second year. Of these, two workers had significant pre-shutdown levels, and showed declines in urine TCP levels over this period consistent with simple one-compartment first order decay. The possible effect of environmental PCP exposure on observed biological decay rates when occupational PCP exposures are low was indicated by the wide variation in urinary PCP reduction and slight decreases or actual increases observed over the shutdown period.

Chlorophenols↗