Sensitive spectrophotometric method for determining pentachlorophenol in various environmental samples

A new, simple, and sensitive spectrophotometric method is described for determination of pentachlorophenol, a widely used insecticide and herbicide, in various environmental samples. The method is based on the reaction of pentachlorophenol with concentrated nitric acid to form chloranil, which liberates iodine from potassium iodide. The liberated iodine then selectively oxidizes leucocrystal violet to form crystal violet, which has an absorption maximum at 592 nm. Beer's law is obeyed over the concentration range of 0.1-1.6 micrograms pentachlorophenol/25 mL (0.004-0.064 ppm). The method was applied satisfactorily to determination of pentachlorophenol in air, water, plant material, textile effluent, and biological samples.

Effects of drinking pattern on the peak/trough blood concentrations in drinking water studies

The effects of changes in drinking patterns on the expected peak/trough blood concentrations of test compounds were examined during rodent dosed drinking water studies. They were based on the assumption that the kinetics of the test compound is linear and time-invariant. Results indicate that drinking patterns have minor effects on the expected peak/trough concentrations and the time to reach these concentrations. If a 12-hr light/dark cycle starting at 7.00 is used for all the drinking patterns studied, the peak and trough concentrations will occur in the early morning and late afternoon, respectively. A comparison of the predicted versus experimentally determined pentachlorophenol (PCP) plasma concentrations in a 1-wk rat drinking water study revealed that using a circadian rhythm drinking pattern in the model generated the most satisfactory prediction. Predictions based on a square wave drinking pattern with 90% drinking activities in the night phase were also excellent. Triangular or sinusoidal drinking patterns were least accurate in predictions.

Impaired in-vitro lymphocyte responses in patients with elevated pentachlorophenol (PCP) blood levels

Immune parameters were examined in 188 patients who were exposed for more than 6 mo to pentachlorophenol-containing pesticides. Blood levels of pentachlorophenol, lymphocyte subpopulations, in-vitro responses to mitogenic and allogeneic stimulation, plasma neopterin levels, and plasma cytokine and cytokine receptor levels were determined. Impaired in-vitro lymphocyte stimulation responses were impaired in 65% of the patients. The likelihood of impaired lymphocyte stimulation increased significantly with levels of pentachlorophenol that exceeded 10 microliters/l (p < .05). Patients who had high blood levels of pentachlorophenol and abnormal lymphocyte stimulation also had increased proportions of blood monocytes in blood (p < .05), as well as increased IL-8 serum levels (p < .02). Eleven patients who had abnormal mitogen stimulation experienced decreased CD4/CD8 ratios of < 1.0; 5 of these patients had decreased CD4+ lymphocyte counts of < 500/microliters, and 3 patients had increased plasma neopterin of > 15 nmol/l. These results indicate that increased levels of pentachlorophenol in blood can lead to severe T lymphocyte dysfunction.

Hexachlorobenzene-induced hypothyroidism. Involvement of different mechanisms by parent compound and metabolite

Rats received repeated oral treatment with different doses of hexachlorobenzene (HCB) (0-3.5 mmol/kg) for 2 or 4 weeks. Measurements of thyroid hormone status after 2 weeks showed a dose-dependent decrease of total thyroxine (TT4) levels, decreased free thyroxine (FT4) levels and little change of total triiodothyronine (TT3) levels. The effects on thyroid hormone status were more pronounced after 4 weeks and also included increased thyroid stimulating hormone (TSH) levels. These conditions suggest that HCB had induced hypothyroidism in these animals. Indications for occupation of thyroid hormone binding proteins were found in serum of exposed animals. The major metabolite pentachlorophenol (PCP) also caused, by competitive interactions with thyroid hormone binding proteins in serum, a rapid and dose-dependent decrease of TT4 and FT4 levels, but not of TT3 levels in serum. The decrease of serum TT4 levels by repeated dosing with 3.5 mmol HCB/kg for 4 weeks could be attributed to competitive interactions of PCP with hormone serum binding proteins and to increased metabolism induced by HCB to an equal degree. At lower dose levels or with shorter dosing periods, increased metabolism of T4 is the main cause of decreased TT4 serum levels. This is the first indication that a similar effect is caused simultaneously by the parent compound and its metabolite through different and independent mechanisms.

Pentachlorophenol carcinogenicity: extrapolation of risk from mice to humans

1. Pentachlorophenol (PCP) has been found to be carcinogenic in mice. The objective of this study was to extrapolate to humans the risk of cancer from data obtained in mice using information on disposition, serum protein binding and metabolism of PCP across species. 2. A review of the literature indicates that neither PCP nor a mutagenic metabolite, tetrachlorohydroquinone (TCHQ), has been specifically identified as responsible for the carcinogenicity. In addition, the occurrence of TCHQ as a metabolite of PCP in humans is still questionable. Therefore, cancer risk assessment is performed on the assumption that PCP itself is responsible for the carcinogenicity. 3. For interspecies extrapolation, a new method in which interspecies differences in clearance and serum protein binding are taken into account is used. The method gives estimates of equivalent human doses of PCP which are up to 4 times smaller than those obtained using body surface area. For both interspecies extrapolation methods, the estimated virtually-safe doses of PCP are smaller than the average daily intakes reported in groups of subjects nonspecifically exposed to PCP. Corresponding extra risks of cancer for lifetime exposure are from 20 to 140 times greater than the acceptable extra risk (10(-6)). The results obtained with this approach indicate that PCP is a possible public health hazard.

Toxicokinetics of pentachloroanisole in F344 rats and B6C3F1 mice

1. Toxicokinetics of pentachloroanisole (PCA) were studied in F344 rat and B6C3F1 mouse of both sexes by gavage at doses of 10, 20 and 40 mg/kg and by i.v. at 10 mg/kg. 2. PCA was rapidly demethylated to pentachlorophenol (PCP) in both rat and mouse and the resulting PCP plasma concentrations were much higher than that of parent PCA due to the much smaller apparent volume of distribution of PCP. 3. Peak plasma concentrations of PCA and PCP increased with dose in both rat and mouse. 4. Bioavailability of PCA was low in both rat and mouse and was sex independent. 5. The high plasma concentrations and relatively long biological half-life of PCP in both species after both i.v. and oral dosing with PCA indicate possible bioaccumulation of PCP upon multiple oral administrations of PCA.

Modeling blood/plasma concentrations in dosed feed and dosed drinking water toxicology studies

A computer model for predicting blood/plasma concentrations of test chemicals in dosed feed and dosed drinking water toxicology studies was developed. The model was constructed based on linear theory. The animal's feeding and drinking habits and the linear disposition kinetics of the test chemical obtained after a bolus gavage dose were built into the model. Blood/plasma concentrations of oxazepam and pentachlorophenol in dosed feed and dosed drinking water studies were predicted and compared with the experimentally determined data. The model proved highly reliable in predicting the blood/plasma concentrations of test chemical in dosed feed and dosed drinking water studies. The results suggest that if the kinetics of test chemicals fit a one-compartment model then bioaccumulation of the test chemical will occur in dosed feed or in dosed drinking water studies when absorption half-lives are less than 1.38 hr and elimination half-lives are longer than 5 hr. The extent of accumulation is mainly dependent on the elimination half-lives. For chemicals with absorption half-lives less than 1.38 hr and elimination half-lives less than 2 hr, the extent of bioaccumulation will be minimal. Blood/plasma concentrations of test chemicals in rats and mice will fluctuate daily and a quasi-steady state will be achieved after ad libitum exposure to dosed feed or dosed drinking water for approximately 4 days. If a daily 12-hr light cycle is used with the light cycle starting at 7:00 AM, the expected peak and trough blood concentrations in dosed feed studies will occur approximately in the early morning (5:00 AM) and in the late afternoon (4:00 PM), respectively. Similar results were obtained for dosed drinking water studies. The model should be applicable to dosed feed and dosed drinking water studies using other species.

Pharmacokinetic concepts in assessing intake of pentachlorophenol by rats after exposure through drinking water

The objective of this study was to predict concentrations of a toxicant in plasma after exposure to the toxicant through drinking water using basic pharmacokinetic principles. As an example, we studied pentachlorophenol (PCP), a widely used wood preservative of public health concern as an environmental pollutant. We added PCP to the drinking water (30 micrograms/mL) of five rats for 3 days. Blood was sampled, and water consumption was monitored every 12 h on the days 1 and 2 and every 3 h on day 3. After a 4-day washout, a PCP dose of 2.5 mg/kg was given intravenously, and blood was withdrawn at selected times for 2 days. PCP concentrations in plasma were measured by capillary gas chromatography. A one-compartment model with zero-order input and kinetic parameters (clearance, volume of distribution, and bioavailability) estimated after intravenous administration adequately predicted PCP concentrations in plasma during exposure to PCP. The average steady-state concentration (Css), which reflects the overall exposure, was predicted using the clearance (CL) concept [i.e., Css = (bioavailability.rate of intake)/CL] and compared with the observed value. The data for PCP demonstrate the potential utility of CL and other kinetic concepts in assessing exposure to a toxicant in drinking water, food, or air.

[Is it appropriate to consider wood preservative poisoning in the differential diagnosis of chronic recurrent respiratory tract infections?]

Wood preservatives as pentachlorophenol and lindane containing the highly toxic compound dioxin were common to be used to protect woods inside the house. In a case report a couple of symptoms are shown as upper airway irritation with dry mucosa, headaches, sleeplessness, lack of concentration and psychosomatic problems caused by those wood preservatives. The typical sequence of the symptoms is given. The results of blood and urine analysis on pentachlorophenol and lindane lead to investigations on indoor materials, air and dust. Taking out the contaminated materials is the best and only treatment.

Simultaneous assay of pentachlorophenol and its metabolite, tetrachlorohydroquinone, by gas chromatography without derivatization

A sensitive capillary gas chromatographic method was developed for the simultaneous determination of pentachlorophenol and its major metabolite, tetrachlorohydroquinone, in plasma, urine and feces. The method involved a simple one-step liquid-liquid extraction with diethyl ether and electron-capture detection gas chromatography on a fused-silica capillary column coated with 50% methylsilicone-50% trifluoropropylsilicone. The detection limit of both compounds was 50 ng/ml in plasma (from an initial volume of 0.1 ml), 100 ng/ml in urine and 100 ng/g in feces. Optimal conditions for both chemical and enzymatic hydrolysis were defined to measure conjugates of both pentachlorophenol and tetrachlorohydroquinone in urine. Tetrachlorohydroquinone was found to be unstable in plasma and urine; means to prevent its degradation during sample collection and storage by addition of ascorbic acid and ethylenediaminetetracetic acid are presented. This chromatographic method was shown to be precise, accurate and specific. It was successfully applied to toxicokinetic studies in rat.

Liquid chromatographic determination of pentachlorophenol in serum, using pre-column phase-transfer catalysed dansylation and post-column photolysis with fluorescence detection

Dansylation of pentachlorophenol was carried out after solid-phase extraction of acidified human serum and desorption with dichloromethane, in a dichloromethane-water two-phase system using tetrabutyl-ammonium bromide as the phase-transfer catalyst. Derivatisation was complete within 2 min at room temperature. After evaporation of an aliquot of the organic phase, the residue was dissolved in methanol and injected into a reversed-phase chromatographic system, equipped with a post-column photochemical reactor. In the reactor, dansylated pentachlorophenol is converted into highly fluorescent products. The recovery of the analyte from serum was 85 +/- 4%. Calibration graphs for horse and human serum were linear over two decades, with correlation coefficients ranging from 0.996 to 0.999. The detection limit of pentachlorophenol in horse and human serum was 400 pg ml-1. The reproducibility of the total procedure for a human serum sample containing 4 ng ml-1 was 4.5%.

Plasma binding of 1-butanol, phenol, nitrobenzene and pentachlorophenol in the rainbow trout and rat: a comparative study

1. The in vitro binding of 1-butanol, phenol, nitrobenzene, and pentachlorophenol in trout plasma and rat plasma was determined. 2. Binding to rainbow trout plasma proteins agreed within 9% of that observed in rat plasma. 3. Percentage bound to rainbow trout (2-99%) or rat (10-99%) plasma proteins increased as the log octanol/water partition coefficient of the chemicals increased within the Log P 1-3 range, and was suggestive of hydrophobic interactions in binding.

Pentachlorophenol and hexachlorobenzene in serum and urine of the population of Barcelona

1 Urinary chlorophenols of the general population of Barcelona, Spain were determined. Pentachlorophenol (PCP: 25.0 +/- 3.9 ng/ml; mean +/- s.e.m., n = 50) and tetrachlorophenol (TCP: 6.2 +/- 1.6 ng/ml; mean +/- s.e.m., n = 25) were found in all samples. 2 Pentachlorophenol and hexachlorobenzene were also determined in serum. Both were present in all samples (PCP: 21.9 +/- 1.9 ng/ml; HCB: 11.1 +/- 1.1 ng/ml; mean +/- s.e.m., n = 100). Their concentrations do not show any correlation, suggesting no metabolic relation between them.

Sister chromatid exchange and chromosomal breakage in pentachlorophenol (PCP) exposed workers

A cytogenetic study was performed on 20 healthy workers exposed to pentachlorophenol (PCP) in concentrations ranging from 1.2 to 180 micrograms/m3 (Maximum Concentration at the workplace is 500 micrograms/m3) for 3 to 34 years. PCP was determined in the blood plasma of all probands, yielding concentrations between 23 and 775 micrograms/l (Biological Tolerance Value is 1000 micrograms/l). In vitro PCP up to 90 mg/l was added to phytohaemagglutinin stimulated lymphocytes of normal healthy donors without any effect on sister chromatid exchange (SCE) or chromosomal aberrations (CA), whereas a slowdown of cell proliferation could be detected in the presence of 60 mg PCP/l. In vivo we neither observed a relation between PCP concentrations and the number of SCE nor an increase of CA.

Thermotropic properties of human erythrocyte membrane proteins as affected by hydroxychloroaromatic compounds

The thermal stability of the anion transport protein (band 3) and other proteins of the human erythrocyte membrane, as influenced by hydroxychloroaromatic (HO-Cl2-Ar) compounds, was studied by differential scanning calorimetry. Various hydroxychlorodiphenyl ethers (HO-Clx-DPEs) and hexachlorophene, but not pentachlorophenol, caused a marked decrease in the thermal stability of band 3. Most of the other calorimetric transitions of the erythrocyte membrane were only slightly affected. The activity of HO-Clx-DPEs toward lowering the transition temperature of band 3 generally increased with the degree of chlorination, and was somewhat dependent on the position of hydroxyl substitution. At higher concentrations of HO-Clx-DPEs, there was a decrease in the enthalpy change and a broadening of the endothermic transition of band 3. The order of effectiveness of these compounds, as determined from band 3 denaturation temperatures, was similar to the order of potency previously observed for hemolysis of human erythrocytes.

[Pentachlorophenol concentrations in the organs and blood of 11 dead infants]

For 11 children, died on age between 2.5 and 57 month due to different causes, the concentrations of pentachlorophenol in liver, kidney, brain and blood were located in the lower part of the spread of test values found for adults which had died in the same region and during the same time phase. The concentrations of pentachlorophenol in the blood of the 11 children were compared further with the findings from 20 living children with an age up to 10 years and were all located below the median of the test values (45,4 micrograms PCP/1) from the group last mentioned. There are no hints for connections between the body-burden of pentachlorophenol and the death-cases concerning the 11 children.

Absorption study of pentachlorophenol in persons working with wood preservatives

Plasma and urinary pentachlorophenol (PCP) was measured in 209 workers who had occupational exposure to wood preservatives containing this compound and 101 workers not exposed occupationally to PCP. Workers were examined for chloracne and blood concentrations of bilirubin, gamma-glutamyltransferase (GGT), cholesterol and high-density lipoproteins (HDL) were determined. All the occupationally exposed groups showed evidence of PCP absorption; highest mean concentrations were found in remedial timber-treatment operatives (6.0 mmol/l for plasma and 274 nmol/mmol of creatinine for urine). Timber-yard workers also showed substantial evidence of absorption (mean plasma concentration 4.8 mmol/l). Persons formulating PCP-containing wood preservatives had the lowest concentrations of any exposed group sampled (mean plasma concentration 1.3 mmol/l, mean urinary concentration 39.6 nmol/mmol of creatinine). The occupational groups studied were not standardized for factors known to affect bilirubin, GGT, cholesterol and HDL. The inference that can be drawn from the results of these measurements is therefore limited. There was, however, no evidence of any disadvantageous effect of PCP on health as measured by these parameters. No overt case of chloracne was found.

Pharmacokinetics of pentachlorophenol in man

Pentachlorophenol (PCP) was given orally to three volunteers at single doses of 3.9, 4.5, 9, and 18.8 mg. Daily urinary excretion of PCP and PCP conjugated to glucuronic acid was monitored using gas chromatography with electron capture detection (GC/ECD). Based on first-order elimination kinetics an elimination half-life of 20 days was derived. To eliminate interference by the uncontrolled absorption of PCP from the environment 0.98 mg 13C-PCP was taken by one of the volunteers. PCP levels in urine and plasma were determined using mass spectrometry (GC/MS) with negative chemical ionization. An elimination half-life of 17 days was found in both urine and blood. The collected data were used to calculate the clearance of PCP: a value of 0.07 ml/min was found. The long elimination half-life of PCP is explained by the low urinary clearance due to the high plasma protein binding (greater than 96%) and the tubular reabsorption. The pH-dependency of the elimination of PCP was investigated, and a distinct increase in the daily excretion was observed following alkalinization by oral administration of sodium bicarbonate. In order to elucidate the role of the enterohepatic circulation as a possible pool for PCP in humans, the bile of cholelithiasis patients with postoperative T-drainage was investigated for PCP and compared with the corresponding urine and plasma levels, but no accumulation of PCP in the enterohepatic circulation could be observed. The daily elimination and plasma levels of PCP in a group of individuals without a specific exposition were found to range from 10 to 48 micrograms/day and 19 to 36 micrograms/1, respectively.

Plasma pentachlorophenol concentrations in calves exposed to treated wood in the environment

Six calves were fed grain and hay from a pentachlorophenol (PCP)-treated feeder twice daily. Samples of blood were collected twice a week. Plasma PCP concentrations increased rapidly to a maximum of 1,086 microgram/L within 10 days. After the 3rd week, calves were denied access to the treated feeder; PCP values returned rapidly to near base line (before calves were fed from the treated feeder). After base-line plasma PCP values were reached, 4 of the 6 calves were housed in a total confinement building and exposed (by inhalation) to lumber that was commercially treated with PCP. The building itself was free of structural PCP-treated lumber. The ratio of building volume to treated wood surface was approximately 49 to 1. During the 3 weeks the calves were confined, PCP values did not increase and were markedly lower than those associated with oral exposure to treated wood. Oral dosing of calves with PCP in capsules--0.05 and 0.5 mg/kg--resulted in maximal plasma PCP values of 1,449 and 9,555 micrograms/L, respectively. Oral exposures (feeding from contaminated feeder; capsule) appeared to be more important than inhalation in causing increased plasma PCP concentrations in cattle. Exposure from these sources may be estimated by comparison with experimental values from dose-response studies. Feeding from treated feeders resulted in lower plasma PCP values than did dosing with 0.05 mg/kg daily.

Use of pentachlorophenol as long-term inhibitor of sulfation of phenols and hydroxamic acids in the rat in vivo

Inhibition of sulfation of the phenolic compound harmol (7-hydroxy-1-methyl-9H-pyrido[3,4-b]indole) by pentachlorophenol (PCP) was studied in the Wistar rat: PCP was administered in various ways to find a convenient method for long-term inhibition of sulfation. High doses of PCP or sodium pentachlorophenolate (NaPCP) in the diet (350 ppm) or NaPCP in the drinking water (1.4 mM) of Wistar rats for one week inhibited the sulfation of harmol by 30-45%. The plasma concentration of PCP in rats with NaPCP (1.4 mM) in their drinking water was highest (270 microM) in the period that the animals were kept in the dark and consumed food and water. This is explained by a rapid elimination: the elimination of PCP from plasma, after intravenous administration, showed a biphasic disappearance curve with half-lives of 2.17 and 7.24 hrs, respectively. This is much faster than in Sprague-Dawley rats. A log-linear correlation was found between the plasma concentration of pentachlorophenol and the inhibition of harmol sulfation. Although administration of NaPCP to rats in their drinking water inhibited the sulfation of harmol only by 45%, it inhibited the sulfation of the carcinogenic arylhydroxamic acid N-hydroxy-2-acetylaminofluorene by 70-75%.