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National identity and controversy: New Zealand's clean green image and pentachlorophenol.

In the 1990s regulatory bodies in New Zealand worked to develop guide-lines to clean up the contamination of land caused by the use of pentachlorophenol in the treatment of timber. In contrast, there has been little effort to identify and compensate workers contaminated at these sites. This paper explores some of the reasons why action over the contaminated land was relatively quickly taken, whilst there was a lingering controversy over the health of the workers who used pentachlorophenol. The case study suggests that symbols of national identity can play an important role in the resolution of controversy.

Environmental Pollution↗

Evidence that pcpA encodes 2,6-dichlorohydroquinone dioxygenase, the ring cleavage enzyme required for pentachlorophenol degradation in Sphingomonas chlorophenolica strain ATCC 39723.

An enzyme that catalyzes an Fe2+-dependent reaction of 2, 6-dichlorohydroquinone with O2 has been isolated from Sphingomonas chlorophenolica sp. strain ATCC 39723, a soil microorganism capable of complete mineralization of pentachlorophenol. The product of the reaction is too unstable to allow spectroscopic characterization, but is apparently negatively charged and retains the two chlorine atoms of the substrate. The enzyme was partially sequenced using electrospray LC-MS, and one peptide was used to search the NCBInr database. This peptide matched a part of PcpA, a protein of unknown function that is induced in S. chlorophenolica in response to pentachlorophenol. Several other peptides could also be mapped onto the sequence of PcpA, suggesting that the enzyme is encoded by pcpA. PcpA has low but significant sequence similarity to an unusual class of extradiol dioxygenases. On the basis of the sequence analysis, the Fe2+ and O2 dependence of the enzyme, and the characteristics of the product, the enzyme is proposed to be a 2,6-dichlorohydroquinone dioxygenase. The position of ring cleavage has not yet been identified.

Amino Acid Sequence↗

Determination of pentachlorophenol by negative ion chemical ionization with membrane introduction mass spectrometry.

Pentachlorophenol (PCP) was used as a model compound to explore the potential of desorption chemical ionization (DCI) in the determination of polychlorinated pesticides using membrane introduction mass spectrometry (MIMS). A direct insertion membrane probe was modified so that a chemical ionization plasma could be established at the membrane surface. Using selected ion monitoring (SIM) in a tandem triple quadrupole mass spectrometer with isobutane chemical ionization (CI), the PCP detection limit under positive chemical ionization is 20 ppb whereas negative CI gives detection limits in the low ppb range. This performance is achieved without any pre-treatment or derivatization of the sample. Negative ion CI gives a signal that is linear over a concentration range of 2-1000 ppb. Comparison of data obtained with low ppb samples of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol suggests that the sensitivity of this analytical procedure increases with increase in the number of electronegative substituents in the molecule.

Food Contamination↗

Successive rapid reductive dehalogenation and mineralization of pentachlorophenol by the indigenous microflora of farmyard manure compost.

AIMS: To determine whether composting with animal manure can be used to effectively remediate soil from a pentachlorophenol (PCP)-contaminated site, and to establish the fate of the degraded xenobiotic. METHODS AND RESULTS: Contaminated soil from a sawmill site was mixed with farm animal manure and composted in a 0.5 m3 silo under fully aerobic conditions. The disappearance and fate of PCP was monitored by gas chromatography (GC-ECD) and extensive mineralization confirmed in experiments with 14C-radiolabelled PCP. The disappearance of PCP was rapid and virtually complete within 6 days, prior to the onset of thermophilic conditions. Dechlorination of the PCP was found to be both reductive and sequential. CONCLUSIONS: PCP removal from contaminated soil by aerobic composting with animal manure is efficient and proceeds via reductive dechlorination to virtually complete mineralization. This contrasts with other chlorophenol composting regimes in which mineralization is achieved but dechlorination intermediates do not accumulate to detectable levels. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study demonstrate that anaerobic reductive dechlorination can proceed in an aerobic composting environment and contribute to efficient pentachlorophenol removal. Farmyard manure composts may represent a rapid, low-cost, low-technology option for treatment of chlorophenol-contaminated soils.

Agriculture↗

Chlorinated compounds in tissues of chickens raised on pentachlorophenol-contaminated litter.

Broiler chickens were raised on commercial wood shavings containing 134 p.p.m. pentachlorophenol and on control litter consisting of corn-cob chips. Initial analysis of the wood-shaving litter showed the presence of hepta-, octa- and nonachlorinated diphenyl ethers, octa- and nonachlorinated 2-phenoxyphenols, and hepta- and octachlorinated dibenzodioxins. Analysis of liver, fat, and muscle tissue after nine weeks indicated the assimilation of these compounds with pentachlorophenol being present in the highest concentration. Chlorinated diphenyl ethers were detectable only in fat, while octa- and nonachlorinated 2-phenoxyphenols were found in all three tissues examined. While liver and fat contained hepta- and octachlorinated dibenzodioxins, no hexachlorinated congener was detected nor were significant amounts of dioxin found in muscle tissue. Although gross pathological examination of the birds did not indicate abnormalities, a mixed type of hepatic enzyme induction was observed in those birds raised on wood shavings.

Adipose Tissue↗

The determination of pentachlorophenol and tetrachlorophenols in wadden sediment and clams (Mya arenaria) using triethylsulfonium hydroxide for extraction and pyrolytic ethylation.

A method to determine the concentration of pentachlorophenol and tetrachlorophenols in wadden sediments and clams is described. This method involves the extraction of lyophilized specimens with toluene under acidic conditions and the back extraction of the chlorophenols into a methanol/water solution of triethylsulfonium hydroxide. Upon injection of the methanol/water phase into the gaschromatograph a pyrolytic ethylation is performed and the ethylethers of pentachlorophenol and tetrachlorophenols formed thereby are separated in quartz capillary columns and detected by an electron capture detector. Using tribromophenol as internal standard the recovery rates for the chlorophenols were within the range of 76.7 and 98.8%. The method described does not require any evaporation or chromatographic clean-up steps. The detection limit was found to be 2 nmol/kg (approximately 500 ng/kg) for sediment and 0.1 mumol/kg (approximately 25 micrograms/kg) for clams. Its accuracy was verified by gaschromatography-mass spectrometry experiments.

Animals↗

Bioavailability of pentachlorophenol to earthworms (Eisenia fetida) in artificially contaminated soils.

The bioaccumulation of pentachlorophenol in earthworms (Eisenia fetida) was studied for two artificially contaminated soils (S1 and S2). The uptake kinetics of pentachlorophenol (PCP) in earthworms increased quickly within the initial 10 days. This was followed by a nearly steady state for the next 20 days that fit with the equilibrium partitioning model. The correlation coefficients were 0.812 and 0.715 for S1 and S2, respectively. The average biota-to-soil accumulation factor of PCP in S1 was 0.51 +/- 0.09, whereas that of S2 was 0.79 +/- 0.12. There was a significant correlation between log Csoil and log Cworm, demonstrating the validity of the equilibrium partitioning model. The bioavailability of PCP was assessed by chemical extraction methods. The results demonstrated a close correlation between extractable amounts of PCP freshly added in soils and those in earthworms. With increasing residence time of PCP in soil, there was a progressively smaller amount of PCP assimilated by the earthworms. In contrast, the amount extracted by Soxhlet extraction did not show a similar decline. However, the extractable amount of PCP by methanol and methanol-water (1:1) significantly decreased over 440 days. Compared with the methanol-water (1:1) extraction method, the methanol extraction method was preferred to the prediction of the bioavailability of PCP in aged soils.

Animals↗

The determination of polychlorodibenzo-p-dioxins in pentachlorophenol and wood treatment solutions.

Analytical methods have been implemented to measure levels of polychlorodibenzo-p-dioxins, and polychlorodibenzofurans in pentachlorophenol solutions used in the Boulton wood treatment process. When normalized against the pentachlorophenol (PCP) content, the octachlorodibenzo-p-dioxin level was 34% higher in the recirculating PCP solution than in the fresh PCP solution, and in the sludge it was 90% higher. A smaller concentration increase was observed for the heptachlorodibenzo-p-dioxin in the recirculating solution, but a similar increase was observed in the sludge.

Chlorophenols↗

A multimedia fugacity river model of pentachlorophenol in South Drainage Canal, China.

An investigation of Pentachlorophenol (PCP) in South Drainage Canal and Haihe Estuary, Tianjin, China was carried out from 1998 to 1999. PCP was found in each sample of the surface microlayer, subsurface water, sediment and air. The waste drainage from a PCP-producing plant was the main pollution source of PCP to Haihe Estuary. The enrichment phenomenon of PCP in the surface microlayer was reported for the first time. The maximum enrichment factor was 4.11. A multimedia (including air, the surface microlayer, water and sediment) fugacity river model was established and successfully applied to fate data for pentachlorophenol in South Drainage Canal. The results showed that under steady state, 97.09% of the loaded PCP was removed by advective outflow into Bohai Bay and 2.46% was by the biodegradation in the water phase. The residue of PCP in South Drainage Canal mainly distributed (99.56%) in the water phase. The discharge rate of PCP from South Drainage Canal to Bohai Bay was 53.4 kg/h.

Air↗

Role of sulfation in the formation of DNA adducts from N-hydroxy-2-acetylaminofluorene in rat liver in vivo. Inhibition of N-acetylated aminofluorene adduct formation by pentachlorophenol.

N-Hydroxy-2-acetylaminofluorene (N-OH-AAf) is metabolically converted into reactive N,O-esters which are capable of forming covalent adducts with DNA in rat liver in vivo. The effect of inhibiting one of the proposed pathways, N-O-sulfation, on DNA adduct formation was studied by using a specific sulfotransferase inhibitor, pentachlorophenol. Rats were pretreated with pentachlorophenol and, after 45 min, N-OH-AAF was administered. Four hours after dosing the animals were sacrificed and hepatic DNA was isolated. In DNA from control livers two acetylaminofluorene-and one aminofluorene-substituted deoxyguanosine adducts were found. The acetylaminofluorene derivatives, N-(deoxyguanosin-8-yl)-2--acetylaminofluorene and 3-(deoxyguanosin-N2-yl)-2acetylaminofluorene, accounted for 40% of the total binding in the hydrolyzed DNA. The aminofluorene adduct, N-(deoxyguanosin-8-yl)-2-aminofluorene, accounted for the remainder. In rats that were pretreated with pentacholorphenol, total DNA binding was decreased by 26%. The same three adducts were found, but the acetylaminofluorene adducts were now only 13% of the total, while the aminofluorene adduct accounted for 87%. The absolute amount of aminofluorene adduct was not altered as compared to control rats. These data demonstrate the involvement of N-O-sulfation in carcinogen-DNA binding and indicate that at least 70% of the acetylaminofluorene bound to deoxyguanosine in rat liver DNA, in vivo, is formed through N-O-sulfation of N-OH-AAF.

2-Acetylaminofluorene↗

Degradation of pentachlorophenol by Phanerochaete chrysosporium: intermediates and reactions involved.

Under nitrogen-limiting, secondary metabolic conditions, the lignin-degrading basidiomycete Phanerochaete chrysosporium rapidly degrades pentachlorophenol. The pathway for the degradation of pentachlorophenol has been elucidated by the characterization of fungal metabolites and oxidation products generated by purified lignin peroxidase (LiP) and manganese peroxidase (MnP). The multi-step pathway is initiated by a LiP- or MnP-catalysed oxidative dechlorination reaction to produce tetrachloro-1,4-benzoquinone. Under primary or secondary metabolic conditions, the quinone is further degraded by two parallel pathways with cross-links. The quinone is reduced to tetrachlorodihydroxybenzene, which can undergo four successive reductive dechlorinations to produce 1,4-hydroquinone, and the latter is o-hydroxylated to form the final aromatic metabolite, 1,2,4-trihydroxybenzene. Alternatively, the tetrachloro-1,4-benzoquinone is converted, either enzymically or nonenzymically, to 2,3,5-trichlorotrihydroxybenzene, which undergoes successive reductive dechlorinations to produce 1,2,4-trihydroxybenzene. Finally, at several points, hydroxylation reactions convert chlorinated dihydroxybenzenes to chlorinated trihydroxybenzenes, linking the two pathways at each of these steps. Presumably, the 1,2,4-trihydroxybenzene produced in each pathway is ring-cleaved with subsequent degradation to CO2. In contrast to the oxidative dechlorination step, the reductive dechlorinations and hydroxylations occur during both primary and secondary metabolic growth. Apparently, all five chlorine atoms are removed from the substrate prior to ring cleavage.

Benzoquinones↗

Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams.

The biodegradation, photolysis, and adsorption of pentachlorophenol (PCP) in outdoor, aquatic environments were examined with man-made channels built by the U.S. Environmental Protection Agency at a field station on the Mississippi River near Monticello, Minn. Four channels were used, each channel being approximately 520 m long and receiving river water that flowed through the channels for about 10 h before reentering the river. The channels were dosed continuously during the summer of 1982 with various concentrations of PCP (approximately 0, 48, 144, and 432 micrograms/liter). We monitored the biotic and abiotic degradation of PCP in these channels for approximately 16 weeks. Photolysis of PCP was rapid at the water surface, but greatly attenuated with depth. Depending on sunlight conditions, photolysis accounted for a 5 to 28% decline in initial PCP concentration. Adsorption of PCP by sediment and uptake by biota accounted for less than 15% and probably less than 5% in unacclimated water. Microbial degradation of PCP became significant about 3 weeks after the initiation of dosing and eventually became the primary mechanism of PCP removal, accounting for a 26 to 46% (dose-dependent) decline in initial PCP. Most of the PCP-mineralizing microorganisms that developed in the channels were either attached to surfaces (e.g., rocks and macrophytes) or associated with surface sediments. Total bacterial numbers (direct microscopic counts) in the various channels were not affected significantly by PCP concentrations of micrograms per liter. Numerous strains of bacteria able to grow at the expense of PCP were isolated from the adapted channels. The experiments reported here will help predict the responses of flowing aquatic ecosystems to contamination by biocides such as pentachlorophenol.

Adsorption↗

Effects of pentachlorophenol and some of its known and possible metabolites on fungi.

The fungicidal activity of pentachlorophenol and its derivatives against 16 species of fungi representing 14 genera was tested. In relation to pentachlorophenol, no increase in fungistatic activity was found for pentachloroanisole, pentachloronitrobenzene, hexachlorobenzene, pentachlorophenyl acetate, o- and p-chloranil, the three isomeric chlorophenols, 2,6-dichlorophenol, the three isomeric tetrachlorobenzenediols, the three isomeric tetrachlorodimethoxybenzenes, the three isomeric tetrachlorobenzenediol diacetates, and all of the isomeric mono-, di-, tri-, and tetrachloroanisoles, except for 2,3,5-trichloroanisole with Geotrichum candidadum PC 67 and for 2,3,5,6-tetrachloroanisole with Mucor circinelloides PC 1. Increasing fungistatic activities were seen with 3,5-dichlorophenol, four trichlorophenols, and 2,3,4,5-tetrachlorophenol for all of the strains, with four dichlorophenols, 2,4,6-trichlorophenol, and two tetrachlorophenols for some strains, and with 2,3,6-trichlorophenol for only one strain (M. circinelloides PC 1).

Chlorophenols↗

31P nuclear magnetic resonance studies of effects of some chlorophenols on Escherichia coli and a pentachlorophenol-degrading bacterium.

A Flavobacterium sp. that mineralizes pentachlorophenol degrades some, but not all, of the other chlorinated phenols. Whole-cell 31P nuclear magnetic resonance was used to compare and observe transmembrane pH gradients and nucleotide pools in the Flavobacterium sp. and Escherichia coli after pentachlorophenol and 3,4,5-trichlorophenol were added to the cell suspensions. The data suggest that those chlorinated phenols which are not degraded by the Flavobacterium sp. may be resistant to degradation because they act as proton dissipators.

Biotransformation↗

Mechanisms of cadmium resistance in anaerobic bacterial enrichments degrading pentachlorophenol.

The mechanisms of heavy-metal resistance used by adapted sulfidogenic and methanogenic enrichments degrading pentachlorophenol in the presence of cadmium (Cd) were studied. The enrichment cultures adapted to and readily tolerated bioavailable Cd concentrations up to 50 ppm while degrading an equal concentration of pentachlorophenol. Both cultures removed >95% of the Cd from solution. Transmission electron micrographs revealed (i). the presence of electron-dense particles surrounding the cells in the sulfidogenic enrichments and (ii). the unusual clumping of cells and the presence of an exopolymer in the methanogenic enrichments. Energy dispersive X-ray analysis showed that the sulfidogenic enrichments removed Cd by extracellular precipitation of cadmium sulfide, while the methanogenic enrichment culture removed Cd by extracellular sequestration of Cd into the exopolymer.

Bacteria, Anaerobic↗

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.

Chlorobenzenes↗

Biological activity of pentachlorophenol on the digestive gland cells of the freshwater mussel Unio tumidus.

Many chlorinated phenols and their derivatives are used extensively as insecticides, fungicides and herbicides by industrial and agricultural users throughout the world. Among these substances, pentachlorophenol (PCP) is a broad-spectrum biocide, which is still used as a wood preservative. In this paper, the digestive gland cells were used to assess the effect of PCP in the range of concentrations 3.75-75 microM (0.01-0.2 ppm) on oxidative DNA damage, fluidity changes and peroxidation activity in the plasma membrane. The toxic property of PCP on DNA strand breakage was studied using the comet assay. The results showed that pentachlorophenol in the range of 37.5-75 microM contributed to these lesions. To demonstrate the changes in the fluidity of plasma membrane we used the spectrofluorimetric method using two fluorescence probes: 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 12-(9-anthroyloxy) stearic acid (12-AS). It was shown that PC did not influence the surface of plasma membrane but contributed to the increase in the fluidity of the internal region of the lipid bilayer in the range of concentrations 18.75-75 microM (0.05-0.2 ppm). We also examined the effect of PCP on the lipid peroxidation. To imply its peroxidation properties the spectrophotometry method was used to measure the level of malondialdehyde (MDA), one of the endpoints of the peroxidation of polyunsaturated fatty acids. The obtained results showed that PCP in the used doses did not initiate the formation of lipid peroxides. Thus, our investigation indicates that PCP can behave as a prooxidant agent but its action depends on the used doses and parameters chosen for the research.

Animals↗

Reproductive effects in mink (Mustela vison) exposed to the pesticides Lindane, Carbofuran and Pentachlorophenol in a multigeneration study.

The mammalian reproductive system is sensitive to exposure to endocrine disrupting chemicals, particularly during sexual maturation. The purpose of this study was to examine reproductive function in second and third generation male and female mink exposed to pesticides from conception to maturity. The mink were fed untreated feed or feed treated with Lindane (1 mg kg-1 day-1), Carbofuran (0.05 mg kg-1 day-1) or Pentachlorophenol (1 mg kg-1 day-1) from the time they were weaned. The second generation mink had also been exposed to the pesticides in utero and from their mother's milk as their mothers were similarly fed pesticides, from 3 weeks before breeding. The third generation mink were the offspring of mink (second generation females) who had themselves undergone long-term exposure to pesticides from conception onwards. Blood samples and endocrine tissues were obtained at necropsy from both generations of mink. No overt signs of toxicity were seen. The pesticides did not affect the percentage of mink mated. Lindane treatment reduced the proportion of mated mink that subsequently whelped (P < 0.1) and the litter size of mink that whelped (P < 0.05). Testis size was reduced in the Lindane-treated, third generation males (P < 0.05). Serum concentrations of cortisol, testosterone and oestradiol were not affected by any pesticide treatment; however, thyroxine concentration was reduced by Pentachlorophenol (P < 0.05). In conclusion, exposure of mink to Lindane from conception resulted in a decrease in reproductive efficiency when they were subsequently mated, leading to a 60% reduction in the number of kits born.

Adrenal Glands↗