Bioavailability Of Pentachlorophenol Research Articles

The Bioaccessibility and Bioavailability of Pentachlorophenol in Five Animal-Derived Foods Measured by Simulated Gastrointestinal Digestion.

Pentachlorophenol (PCP) is a ubiquitous emerging persistent organic pollutant detected in the environment and foodstuffs. Despite the dietary intake of PCP being performed using surveillance data, the assessment does not consider the bioaccessibility and bioavailability of PCP. Pork, beef, pork liver, chicken and freshwater fish Ctenopharyngodon Idella-fortified by three levels of PCP were processed by RIVM and the Caco-2 cell model after steaming, boiling and pan-frying, and PCP in foods and digestive juices were detected using isotope dilution-UPLC-MS/MS. The culinary treatment and food matrix were significantly influenced (p < 0.05) in terms of the bioaccessibility and bioavailability of PCP. Pan-frying was a significant factor (p < 0.05) influencing the digestion and absorption of PCP in foods, with the following bioaccessibility: pork (81.37-90.36%), beef (72.09-83.63%), pork liver (69.11-78.07%), chicken (63.43-75.52%) and freshwater fish (60.27-72.14%). The bioavailability was as follows: pork (49.39-63.41%), beef (40.32-53.43%), pork liver (33.63-47.11%), chicken (30.63-40.83%) and freshwater fish (17.14-27.09%). Pork and beef with higher fat content were a key factor in facilitating the notable PCP bioaccessibility and bioavailability (p < 0.05). Further, the exposure of PCP to the population was significantly reduced by 42.70-98.46% after the consideration of bioaccessibility and bioavailability, with no potential health risk. It can improve the accuracy of risk assessment for PCP.

Effects of carboxylated multi-walled carbon nanotubes on bioconcentration of pentachlorophenol and hepatic damages in goldfish.

Carboxylated multi-walled carbon nanotubes (MWCNT-COOH) exerts strong adsorption capacity for pentachlorophenol (PCP) and they inevitably co-occur in the environment, but few studies have characterized the effects of MWCNT-COOH on the bioavailability of PCP and its oxidative and tissue damages to fish. In this work, we assessed the PCP accumulation in different organs and the induced oxidative and tissue damages of goldfish following 50-d in vivo exposure to PCP alone or co-exposure with MWCNT-COOH. Our results indicated that PCP bioaccumulation in goldfish liver, gill, muscle, intestine and gut contents was inhibited after co-exposure with MWCNT-COOH in uptake phase. PCP exposure alone and co-exposure with MWCNT-COOH evoked severe oxidative and tissue damages in goldfish bodies, as indicated by significant inhibition of activities of antioxidant enzymes, remarkable decrease in glutathione level, simultaneous elevation of malondialdehyde content, and obvious histological damages to liver and gill. The decreased accumulation of PCP in the presence of MWCNT-COOH led to the reduction of PCP-induced toxicity to liver tissues, as confirmed by the alleviation of hepatic oxidative damages. However, co-exposure groups had higher concentrations of PCP in the tissues than PCP treatment alone (p < 0.05 each) in the depuration phase, revealing that MWCNT-COOH-bound pollutants might pose higher risk once desorbed from the nanoparticles. These results provided substantial information regarding the combined effects of PCP and MWCNT-COOH on aquatic species, which helps to deeply understand the potential ecological risks of the emerging pollutants.

Impact of chlorophenols on microbiota of an unpolluted acidic soil: microbial resistance and biodegradation

The impact of 2-monochlorophenol (MCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) on the microbial community of an acidic forest soil was studied under controlled laboratory conditions by spiking microcosms with the pollutants at concentrations ranging from 0.1 to 5000 mg kg(-1). A decrease in the cumulative respirometric values and changes in the bacterial and fungal community composition were detected at 1000 mg MCP kg(-1), 100 mg TCP kg(-1) and 100 and 1000 mg PCP kg(-1). However, drastic effects on the microbial community were revealed only at higher concentrations of MCP and TCP, although the toxicity of PCP was expected to be stronger. The acidic condition of the soil presumably reduces bioavailability of PCP, leading to less pronounced effects than the other pollutants. This finding highlights the consideration of pollutant bioavailability in each environment to adequately assess contamination effects. Twenty-two different chlorophenol-resistant and potentially degrading microorganisms were isolated from highly polluted microcosms. The most resistant isolates were related to Burkholderia arboris, Bacillus circulans, Paenibacillus taichungensis, Luteibacter rhizovicina and Janibacter melonis. These isolates also showed the capacity to reduce the concentration of TCP or PCP between 15% and 35% after 5 days of incubation (initial concentration of 50 mg L(-1)). The isolate related to B. circulans is an atypical case of a member of the Firmicutes group for which chlorophenol-degrading capacities have been described.

Soil monitoring of pentachlorophenol by bioavailability and ecotoxicity measurements

Several approaches to monitor the bioavailability and ecotoxicity of pentachlorophenol (PCP) in sterile and non sterile soils as a function of aging are reported. Porapak resins and water were used to assess the bioaccessibility and the bioavailability of PCP in soil. Aging effects were observed mainly after 240 d of aging. Actual bioavailability, measured as PCP bioaccumulation in earthworms, decreased more markedly with time. The ecotoxicological biomarker neutral red retention time (NRRT) displayed a dose dependent effect but no aging effects after exposing the earthworms to polluted soils. Nevertheless, mortality of earthworms increased after 240 d at 150 mg kg(-1) contamination. In contrast, the luminescent biosensor Pseudomonas fluorescens pUCD607 evidenced in non sterilized samples a slight reduction of ecotoxicity in time related to the degradation of the molecule. Once again, results highlight the necessity to study the fate of soil pollutants with different chemical and biological approaches. Different PCP degradation pathways and/or the different sensitivity of earthworms and bacteria could explain the different behaviours observed.

Bioavailability and toxicity of pentachlorophenol in contaminated soil evaluated on coelomocytes of Eisenia andrei (Annelida: Lumbricidae)

Pentachlorophenol (PCP) is widely distributed and highly persistent in soil, and represents a threat to the health of ecosystems. The present study aimed to assess the toxicity and bioavailability of PCP in soils as a function of different aging periods with the attempt to select a good toxicological assay for Eisenia andrei Bouché (Annelida: Lumbricidae). The experiments were performed on soil contaminated with PCP at 15 and 150 ppm. After different aging periods (20, 60 and 120 days from spiking), bioavailability and toxicity were evaluated on E. andrei kept for 7 and 14 days in treated soils. The actual bioavailability decreased in relation to the aging for both PCP concentrations. No membrane damage was observed on coelomocytes collected by ethanol extrusion. Modifications in distribution of coelomocyte subpopulations were detected by flow cytometry on samples aged for 60 and 120 days at 150 ppm PCP contamination. The reduction of lysosomal membrane stability, measured by neutral red retention time, was observed in all treatments. Worm mortality increased with aging in soils spiked with 150 ppm of PCP. In conclusion, aging did not seem to reduce PCP cytotoxicity. This is the first report on in vivo toxicity of PCP evaluated on coelomocytes of E. andrei using different assays.

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 C soil and log C worm, 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.

Bioavailability of pentachlorophenol to acclimatised bacteria under batch and flow-through conditions.

Biodegradation of organic contaminants in multi-phase systems, such as soils and aquifers, is often limited by the extent and the rate of contaminant sorption onto the solid matrix. However, information about biodegradation in complex matrices is largely limited to studies of closed systems under batch conditions in which potential bioavailability is characterised by the aqueous-phase concentration of a contaminant. There is little knowledge regarding the influence of flow-through conditions on the availability of contaminants to microbes (contaminant bioavailability). Thus, the aim of this study was to assess and compare contaminant bioavailability, in the presence of a sorptive medium, under both batch and flow-through conditions. Accordingly, experiments were designed in which pentachlorophenol (PCP) was introduced into a mixture of inoculated silica sand and a PCP-retaining resin, under either batch or flow-through (columns) conditions. The results indicated that an increase in the amount of resin (0.1-0.2 g) clearly lowered PCP availability to microbes after 170 h under batch conditions (30 and 45% respectively); whereas, the initial decrease in bioavailability observed under flow-through conditions (45 and 70% respectively) was reversed and no longer observable after 170 h. This increase in PCP availability was linked to an improvement in the contaminant biodegradation capacity from 0.03 to 0.13 mg x l(-1) x h(-1) over 200 h.

ORAL BIOAVAILABILITY OF PENTACHLOROPHENOL FROM SOILS OF VARYING CHARACTERISTICS USING A RAT MODEL

Evidence accumulated during the last two decades suggests that only a fraction of any chemical in soil is available to organisms, and soil-related effects on bioavailability should be considered in optimizing soil remediation cleanup levels. In the current study, the absolute and relative bioavailabilities of pentachlorophenol (PCP) from freshly spiked and environmentally aged soils varying in organic carbon content, clay content, and pH were examined using a rat model. PCP is a broad-spectrum biocide widely used as a wood preservative, and thus is ubiquitous in the environment. Soils and corn oil containing equivalent levels of PCP were administered to male Sprague-Dawley rats by gavage at 2 dose levels: 100 and 200 μg/kg body weight. Equivalent doses were also given intravenously. The areas under the plasma concentration of PCP versus time curves were calculated, and absolute and relative bioavailabilities of PCP from each soil were determined. At a dose of 100 μg/kg body weight, the absolute bioavailabilities of PCP across soils ranged from 36% to 65%, and the relative bioavailabilities ranged from 48% to 82%. At the higher dose level (200 μg/kg body weight), absolute and relative bioavailability ranges were somewhat higher at 46% to 77% and 52% to 87%, respectively. All soils decreased absolute PCP bioavailability significantly at both dose levels and relative bioavailability at the lower PCP dose level. At the higher dose level, only one of the two field-contaminated soils decreased the relative PCP bioavailability. The data indicate that PCP-soil interactions do significantly decrease the oral bioavailability of PCP from soil, but no obvious correlation was observed between soil properties and bioavailabilities.

Responses of the soil decomposer community and decomposition processes to the combined stress of pentachlorophenol and acid precipitation

The combined effects of contamination by pentachlorophenol (PCP) and acid precipitation on soil decomposer communities and decomposition processes were studied. Intact soil cores were taken from a coniferous forest in central Finland, enclosed in plastic tube microcosms and dug into the ground. The total set of microcosms was divided in four treatments: (1) contamination with PCP, (2) PCP and two irrigations with strong acid solution, (3) PCP and five irrigations with weak acid solution, and (4) control: irrigations with deionized water. The applications began 8 weeks after initial burial and were completed over a further period of 9 weeks. The microcosms were sampled after 18, 51 and 59 weeks. Soil pH did not decrease consistently with acid deposition. PCP concentrations were not affected by acid deposition. All acid and/or PCP-treated soils contained more NH + 4–N than the control soil at the first and second samplings, but there were no differences at the last sampling. There were more enchytraeids in the controls than in other treatments from the second sampling date onwards, that is, after the winter. Collembolan population density was not affected by the treatments while numbers of oribatid, prostigmatid and astigmatid mites were reduced in the stressed soils, but only on the first sampling date. Most of the observed effects on decomposers and nitrogen mineralization were attributable to PCP, but acid deposition may also have been involved through possible effects on the bioavailability of PCP. The imposed anthropogenic stresses, together with winter conditions, were detrimental for enchytraeids. By the end of the experiment decomposer communities together with mosses had mainly recovered.

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.