Bioavailability Of PAHs Research Articles

Evaluation of polycyclic aromatic hydrocarbons bioavailability on Santos Bay (Brazil) through levels of biliary metabolites

This study evaluated the PAH bioavailability from Santos Bay (Brazil) in 4 species of fish, using PAH biliary metabolites. The collection was done monthly, between July and December, in three different regions of Santos Bay. The metabolites were analyzed through a high performance liquid chromatograph with fluorescence detectors. Total metabolites concentrations ranged from 65.5 to 589μgg−1 of bile, evidencing PAH bioavailability on Santos Bay. Levels of phenanthrene and benzo[a]pyrene metabolites were in the classification range of areas moderate contaminated. Those concentrations were lower in Nebris microps and higher in Sphoeroides testudineus (p<0.05). Naphthalene metabolites concentrations did not differ significantly among fish species and were in the classification range of low contaminated areas. There were no significant spatial and temporal differences in levels among sampled areas. These results are environmentally important given the high levels of urbanization and the absence of biomonitoring data in this area.

Sorption of Phenanthrene to Soybean and Wheat Roots and the Bioavailability of Sorbed Phenanthrene

The study of PAHs sorption and bioavailability to different crop roots could help to reveal the environmental behavior of PAHs in the ecosystem and evaluate the ecological risk of PAHs. However, there is little information about the differences in PAHs sorption to different roots and the bioavailability of the sorbed PAHs. In this paper, the experiments were conducted on the sorption/desorption of phenanthrene to soybean and wheat roots under different sorption times and different phenanthrene concentrations. The results showed that the trend of phenanthrene sorption in vivo was first increased and then decreased and finally reached a balance, which was related to the transport delay in vivo; the trend in dead and dried roots was first increased and then reached a balance. The greater specific surface area and the higher fat content, the faster the balance was. Freundlich isotherm was fitted better than Henry isotherm for dead and dried roots, Langmuir isotherm was best fitted in wheat roots. All of the fitted isotherms indicated that the distribution and the surface adsorption could control the phenanthrene sorption. Because of the special binding between living roots and phenanthrene, the fit effect was poor. The phenanthrene sorption capacity of soybean roots was higher than that of wheat, which was related to the high water content, fat content and membrane permeability. The phenanthrene sorbed on the roots was hard to desorb, and the desorption trends were wheat roots> soybean roots; living roots> dried roots> dead roots. The bioavailability of root-sorbed phenanthrene was consistent with the desorption results. Our results could provide data for the assessment of environmental risks of PAHs sorbed onto crop roots.

Activated carbon from kraft lignin: A sorbent for in situ remediation of contaminated sediments

Abstract A new type of activated carbon derived from Kraft lignin, separated from black liquor in the paper pulp process, was evaluated for its use as an alternative sorbent to commercial powdered activated carbons (AC) from anthracite ( AC COAL ) or coconut ( AC BIO ) for remediation in situ of contaminated sediments. Two types of kraft lignins (KL): (1) softwood (SKL), (2) hardwood (HKL) were first evaluated for their sorption to PAHs using assays in water with passive samplers (POMs). Results showed that without further chemical modifications the two kraft lignins tested had lower sorption coefficients than commercial AC COAL or AC BIO and are not good sorbents for remediation. Following these initial tests a new type of AC derived from softwood ( AC SKL ) was produced in the lab using activation with potassium hydroxide (KOH) (lignin:KOH, 1:3 by dry weight) and pyrolysis at 700 °C. Sorption properties of the new AC SKL was compared to the other ACs in water spiked with PAHs and in water with PAH-contaminated sediment. Sorption results were also compared to bioavailability measurements, using digestive fluid extraction (DFE) in vitro, a method that mimics the solubilization of contaminants that occurs in the gut of a sediment-ingesting invertebrate. AC SKL was found to have similar surface area, pore volume and sorption coefficients as AC COAL and AC BIO and thus offers a new potential sorbent for remediation, based on a more renewable biomass-derived source than AC from coal. Sediment amendment with 1% AC-SKL reduced the bioavailability of larger PAHs on average by 54% (measured by DFE), and reduced pore water concentrations of Σ PAH by 80% (measured with passive samplers). Our results show that a new type of AC based on softwood kraft lignin, a renewable and locally produced biomass material, could be used as an alternative sorbent for sediment and water remediation provided it is produced in sufficient amount and at a competitive price compared to other traditional ACs.

Effects of Source and Concentration on Relative Oral Bioavailability of Benzo(a)pyrene from Soil.

The objective of this study was to examine the influence of soil composition, PAH concentration, and source material type on PAH bioavailability using an approach capable of measuring uptake at low, environmentally relevant PAH concentrations (down to 1 ppm). Contaminated soil samples were constructed using PAHs from three source materials-solvent, soot, and fuel oil-to which 3H-benzo(a)pyrene (3H-BaP; total BaP concentrations of 1, 10, and 100 ppm) was added in a mixture of PAHs. The soils were weathered for 8 weeks using weekly wet-dry cycles. Each soil was administered as a single dose to rats, and blood samples were taken over 6 days. Relative oral bioavailability (RBA) of the BaP from soil was estimated by comparing the area under the curve (AUC) for 3H concentration versus time in blood with the AUC observed from the same PAH mixture dosed in a food matrix. The extent to which BaP RBA was diminished in soil versus food varied among the source materials, but little or no difference was observed among the soil types examined unless carbon amendments were added. These results suggest that the type of PAH source material can have a strong influence on PAH oral bioavailability.

Natural attenuation of fluorene and pyrene in contaminated soils and assisted with hydroxypropyl-β-cyclodextrin. Effect of co-contamination

The objectives of this study were to investigate the mutual effect of the PAHs fluorene and pyrene on their respective biodegradation and dissipation processes in an agricultural soil, and to determine the effect of hydroxypropyl-β-cyclodextrin (HPBCD), used to increase the bioavailability of PAHs, on such processes. Fluorene dissipation was primarily due to abiotic processes, although a small contribution from biodegradation was also observed. Therefore, fluorene dissipation did not increase with HPBCD and its presence did not significantly alter the dehydrogenase activity. In contrast to fluorene, pyrene dissipation depended primarily on biotic factors, with endogenous soil microorganisms capable of degrading pyrene, with large increases in dehydrogenase activity. HPBCD increased biodegradation rate of pyrene. The co-contamination of soil with both PAHs did not affect fluorene evolution, but significantly inhibited pyrene biodegradation. The different abilities of soil bacterial consortia to catabolize these PAHs are discussed. Additionally, the possibility that the abiotic loss of fluorene through volatilization had a significant effect on the microbial community biodegradation of both fluorene and pyrene is examined.

Oral Bioavailability, Bioaccessibility, and Dermal Absorption of PAHs from Soil-State of the Science.

This article reviews the state of the science regarding oral bioavailability, bioaccessibility, and dermal absorption of carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in soil by humans, and discusses how chemical interactions may control the extent of absorption. Derived from natural and anthropomorphic origins, PAHs occur in a limited number of solid and fluid matrices (i.e., PAH sources) with defined physical characteristics and PAH compositions. Existing studies provide a strong basis for establishing that oral bioavailability of cPAHs from soil is less than from diet, and an assumption of 100% relative bioavailability likely overestimates exposure to cPAHs upon ingestion of PAH-contaminated soil. For both the oral bioavailability and dermal absorption studies, the aggregate data do not provide a broad understanding of how different PAH source materials, PAH concentrations, or soil chemistries influence the absorption of cPAHs from soil. This article summarizes the existing studies, identifies data gaps, and provides recommendations for the direction of future research to support new default or site-specific bioavailability adjustments for use in human health risk assessment.

Hypolipidemic potential of perillaldehyde-loaded self-nanoemulsifying delivery system in high-fat diet induced hyperlipidemic mice: Formulation, in vitro and in vivo evaluation

This study reports the hypolipidemic effects of perillaldehyde-loaded self-nanoemulsifying delivery system (PAH-SNEDS) developed with D-optimal experimental design based on a three component system: 40% w/w drug-oil phase, X1 (a mixture of perillaldehyde-isopropyl myristate/medium chain triglyceride, 1:1, w/w); 48% surfactant, X2 (Kolliphor EL); and 12% co-surfactant, X3 (PEG 200). The design space was navigated using a linear model to produce spherical and homogenous droplets which were observed under TEM, with mean size, polydispersity index (PDI) and zeta potential of 32.8±0.1nm, 0.270±0.029 and −10.14±0.66mV, respectively. PAH-SNEDS demonstrated significant increase in dissolution in vitro compared to the free PAH, and further yielded an oral relative bioavailability of about 206.18% in vivo which suggested a promising formulation design for potential liquid bioactive compounds. Oral administration of PAH-SNEDS (240mg/kg per body weight) in high-fat induced hyperlipidemia in mice, also significantly decreased serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) while increasing high-density lipoprotein cholesterol (HDL-C) level. The improved bioavailability and functional application of PAH via SNEDDS suggested a suitable approach to promote hypolipidemic effect of the drug. Perillaldehyde, therefore, promises to be a useful bioactive compound to prevent high-fat diet induced hyperlipidemia.

Using in vitro bioaccessibility to refine estimates of human exposure to PAHs via incidental soil ingestion

PAH bioaccessibility in contaminated soil was determined using the organic physiologically based extraction test with the inclusion of a sorption sink. Silicone cord was incorporated into the assay in order to overcome the limited capacity of the in vitro medium to accommodate desorbable PAHs. Initially, silicone cord sorption efficacy was determined by assessing sorption kinetics using PAH-spiked sand (phenanthrene, pyrene and benzo[a]pyrene; 10–1000mgkg−1). Irrespective of PAH and concentration, >95% of the initial PAH mass partitioned into the silicone cord within 12h although rates were lower at higher concentration and with increasing hydrophobicity. When PAH bioaccessibility was assessed in contaminated soil (n=18), contamination source (i.e. pyrogenic versus petrogenic) influenced PAH bioaccessibility. Individual PAH bioaccessibility ranged up to 81.7±2.7% although mean values ranged from 2.1 (acenaphthalene) to 20.8% (benzo[k]fluoranthene) with upper 95% confidence intervals of the means of 4.5 and 28.3% respectively. Although a PAH in vivo–in vitro correlation is yet to be established, bioaccessibility approaches incorporating sorption sinks represent a robust approach for estimating PAH bioavailability as the desorbable fraction may be a conservative measure of the absorbable fraction.

Using linoleic acid embedded cellulose acetate membranes to in situ monitor polycyclic aromatic hydrocarbons in lakes and predict their bioavailability to submerged macrophytes.

To date no passive sampler has been used to predict bioavailability of contaminants to macrophytes. Here a novel passive sampler, linoleic acid embedded cellulose acetate membrane (LAECAM), was developed and used to in situ measure the freely dissolved concentrations of ten polycyclic aromatic hydrocarbons in the sediment porewaters and the water columns of two lakes in both winter and summer and predict their bioavailability to the shoots of resident submerged macrophytes (Potamogeton malainus, Myriophyllum spicata, Najas minor All., and Vallisneria natans (Lour.) Hara). PAH sampling by LAECAMs could reach equilibrium within 21 days. The influence of temperature on LAECAM-water partition coefficients was 0.0008-0.0116 log units/°C. The method of LAECAM was comparable with the active sampling methods of liquid-liquid extraction combined with fDOC adjustment, centrifugation/solid-phase extraction (SPE), and filtration/SPE but had several advantages. After lipid normalization, concentrations of the PAHs in LAECAMs were not significantly different from those in the macrophytes. In contrast, concentrations of the PAHs in the triolein containing passive sampler (TECAM) deployed simultaneously with LAECAM were much higher. The results suggest that linoleic acid is more suitable than triolein as the model lipid for passive samplers to predict bioavailability of PAHs to submerged macrophytes.

Influence and interactions of multi-factors on the bioavailability of PAHs in compost amended contaminated soils

Compost amendment to contaminated soils is a potential approach for waste recycling and soil remediation. The relative importance and interactions of multiple factors on PAH bioavailability in soils were investigated using conjoint analysis and five-way analysis of variance. Results indicated that soil type and contact time were the two most significant factors influencing the PAH bioavailability in amended soils. The other two factors (compost type and ratio of compost addition) were less important but their interactions with other factors were significant. Specifically the 4-factor interactions showed that compost addition stimulated the degradation of high molecular PAHs at the initial stage (3month) by enhancing the competitive sorption within PAH groups. Such findings suggest that a realistic decision-making towards hydrocarbon bioavailability assessment should consider interactions among various factors. Further to this, this study demonstrated that compost amendment can enhance the removal of recalcitrant hydrocarbons such as PAHs in contaminated soils.

In vivo measurement, in vitro estimation and fugacity prediction of PAH bioavailability in post-remediated creosote-contaminated soil

In this study, PAH bioavailability was assessed in creosote-contaminated soil following bioremediation in order to determine potential human health exposure to residual PAHs from incidental soil ingestion. Following 1000days of enhanced natural attenuation (ENA), a residual PAH concentration of 871±8mgkg−1 (∑16 USEPA priority PAHs in the <250μm soil particle size fraction) was present in the soil. However, when bioavailability was assessed to elucidate potential human exposure using an in vivo mouse model, the upper-bound estimates of PAH absolute bioavailability were in excess of 65% irrespective of the molecular weight of the PAH. These results indicate that a significant proportion of the residual PAH fraction following ENA may be available for absorption following soil ingestion. In contrast, when PAH bioavailability was estimated/predicted using an in vitro surrogate assay (FOREhST assay) and fugacity modelling, PAH bioavailability was up to 2000 times lower compared to measured in vivo values depending on the methodology used.

Evaluation five years after a Refinary Oil Spill in freshwater wetland - Paraná State, Southern of Brazil

In order to evaluate the Getúlio Vargas refinery oil spill - 2000, Paraná State - Brazil the presence of PAHs in the sediment, PAHs bioavailability through bile chemical analysis and biochemical and morphological biomarkers were investigated in a native fish species Hyphessobrycon reticulates. The histophatological parameters were also considered to another native species Phalloceros caudimaculatus. Sediment analysis showed the presence of 5-6 rings PAHs on the surface layer and 2-3 rings PAHs in the deepest sediment showing that oil is still accumulated in sediment, and its bioavailability is confirmed by the accumulation of PAHs in bile. Lipid peroxidation, catalase (CAT), GST and cholinesterase activities indicated respectively oxidative stress in liver of H. reticulatus and neurotoxicity, also evidenced by genotoxic and histopathological damages. Despite of the occurrence of other pollutants not identified in the current study, the data presented here may suggest that 5 years after the accident animals as fish can be still affected by hydrocarbons and PAHs presented in the sediment. Concluding, studies must be done to confirm that with a more sophisticated chemical analysis, but this work is the only study realized after the accident. We strongly suggest a new study to compare and verify if still there is risk to biota.

PAH effects on meio- and microbial benthic communities strongly depend on bioavailability

The effects of anthropogenic pollutants in dissimilar habitats can vary depending on differences in bioavailability. The factors determining bioavailability are not yet fully understood. This study was performed to evaluate whether analysis of total PAH concentrations in sediments is a satisfactory measurement to indicate environmental effects or if bioavailability is needed to be taken into account. We have here performed a 60-day experiment, where nominal PAH concentrations of 1300μg/kg sediment were added to three different marine sediments. Meiofaunal and microbial communities were analyzed for alterations in community response at 30 and 60 days.Results showed that bioavailability of PAHs varied between the three different sediments. Nonetheless, the petroleum addition gave rise to significant negative effects on all three sediments at both time points. The two direct measurements of toxicity on the microbial community, potential nitrification and denitrification, displayed a lower effect of the PAH addition in the muddy sediment at both time points, compared to the other two sediment types. No effects were seen in the analysis of meiofaunal community structure. Measurements of PAH bioavailability in the three sediment types concurred with the results from the microbial community, revealing a lower bioavailability in the muddy sediment compared to the other two sediment types, 34% compared to sandy and 18% compared to organic at day 0. At day 60 it was 61% lower compared to sandy and 20% lower compared to organic. The negative effects of the PAH addition on the microbial nitrogen cycle were in six out of eight cases best correlated to the amount of alkylated bioavailable PAH in the sediments, and thus microbial nitrogen cycle is a possible good indicator for assessing PAH-induced stress.The results presented here have implications for risk analysis studies of petroleum-contaminated marine sediments; consequently, sediment characteristics and its effects on bioavailability are important to include. In addition, these results add to the understanding that bioavailability measurements of PAHs are a more correct assessment compared to measurements of total PAH concentrations, and need to be included when estimating effects of PAHs in marine benthic communities.

Predicting PAHs bioavailability for earthworms by mild solvents and Tenax extraction

The total concentration of organic contaminants in soil often overestimates their environmental risk, it is thus important to establish time- and cost-efficient chemical techniques for predicting their bioavailability. In the present study, three chemical extractions, namely: Tenax extraction, butanol extraction and HPCD extraction, were conducted to predict PAHs bioavailability in soil for earthworms. The results showed that earthworm accumulations had less correlation with total concentrations except for PAHs of low molecular weight (R2–3 PAHs). Fractions extracted by butanol/HPCD correlated to earthworm accumulated PAHs of low molecular weight (R2–3 PAHs), but not to earthworm accumulated PAHs of high molecular weight (R5–6 PAHs). Tenax 6h-extracted PAHs had significantly linear correlations with earthworm accumulated R2–3 PAHs, R4 PAHs as well as R5–6 PAHs (associated R2 were 0.96, 0.98 and 0.97, respectively). Furthermore, Tenax 6h-extracted concentrations were comparable to earthworm accumulations for R2–3, R4 as well as R5–6 PAHs. These observations verified that Tenax 6h extraction is better than butanol and HPCD extractions to predict earthworm accumulation of PAHs in soil. Tenax 6h extraction can serve as a good technique to assess PAHs bioavailability for earthworms.

Benefit of ecotoxicological bioassays in the evaluation of a biological treatment of PAHs polluted soil

The performance of a biological treatment of a PAH-contaminated soil was evaluated with respect to its physicochemical and ecotoxicological properties. After six months, the biological treatment led to an significant reduction of 2- and 3-ring PAHs and to a lesser extent to 4-ring PAHs. As a consequence a significant decrease of the acute ecotoxicity was observed passing from highly ecotoxic before treatment to non-ecotoxic according to Lactuca sativa seedling and growth inhibition test and Eisenia fetida mortality test. This could be related to the bioavailability of PAHs. Indeed, tests performed on aqueous leachates of the soil showed a strong decrease of 2- and 3-ring PAHs correlated with a significant reduction of acute and chronic ecotoxicity responses. The biological treatment led to the mutagenicity reduction and the genotoxicity disappearance in the leachate. Thus, bioassays are complementary to chemical analyses to evaluate the efficiency of a bioremediation process and to evaluate the bioavailability of the organic pollutants as the total concentration of a contaminant is not the only criterion to consider. The comparison of the ecotoxic responses allowed us to underline the best sensitivity of the earthworm, Microtox, Alga and Ames bioassays among the tested set. These bioassays could thus be good candidates to build a toxicity evaluation procedure for PAHs contaminated/ remediated soils.

Monitoring PAH contamination in water: Comparison of biological and physico-chemical tools

The suitability of biological methods and chemical-based passive samplers to determine exposure to PAHs was tested by deploying zebra mussels and SPMDs along the Seine River over 11months. The concentration of 13 PAHs was analyzed every month in both water and mussels. The sum of the PAH concentrations in mussels, initially at 299nggdry wt−1, reached 2654, 3972 and 3727ngg−1 at the end of exposure in the three sampling points taken through the river. The respective SPMD-available concentrations of TPAHs reached 9, 52 and 34ngL−1. Results showed seasonal variations of total PAH concentrations in the mussels, characterized by a decrease during spawning. The non-achievement of steady state concentration that was observed in mussels may be accounted for by the temporal variation of environmental concentrations. Thus, a bioaccumulation model based on kinetic rather than simple equilibrium partitioning was found to be more appropriate to describe PAH content in mussels. Moreover, biodynamic kinetic modeling proved useful to better understand the uptake and loss processes of pyrene. It clearly shows that these processes are markedly influenced by the biological state of the zebra mussels. The most realistic hypothesis is that the temporal variation of the biodynamic parameters may originate from a decrease of the mussels' metabolization of PAHs during spawning. Since SPMD passive samplers cannot integrate such biological factors, they are poor predictors of PAH bioavailability in mussels.

The effect of concentrations and properties of phenanthrene, pyrene, and benzo(a)pyrene on desorption in contaminated soil aged for 1 year

Purpose The choice and timing of microorganisms added to soils for bioremediation is affected by the dominant bioavailable contaminants in the soil. However, changes to the concentration of bioavailable PAHs in soil are not clear, especially when several PAHs coexist. This study investigated the effects of PAH concentration and chemical properties on desorption in meadow brown soil after a 1-year aging period, which could reflect changes of PAH bioavailability during bioremediation.

Modern approaches to assessment of PAHs bioavailability in soil for environmental toxicology research

The efficiency of TENAX beads sorption method enabling to separate the bioavailable fraction of PAHs in the soil has been estimated. Due to the method the PAHs effects on soil biota have been explored. Laboratory investigations have ascertained possibility of application of TENAX beads sorption for soil quality assessment.

Influence of mature compost amendment on total and bioavailable polycyclic aromatic hydrocarbons in contaminated soils

A laboratory microcosm study was carried out to assess the influence of compost amendment on the degradation and bioavailability of PAHs in contaminated soils. Three soils, contaminated with diesel, coal ash and coal tar, respectively, were amended with two composts made from contrasting feedstock (green waste and predominantly meat waste) at two different rates (250 and 750tha−1) and incubated for 8months. During this period the treatments were sampled for PAH analysis after 0, 3, 6 and 8months. Total and bioavailable fractions were obtained by sequential ultrasonic solvent extraction and hydroxypropyl-β-cyclodextrin extraction, respectively, and PAHs were identified and quantified by GC–MS. Bioavailability decrease due to sorption was only observed at the first 3months in the diesel spiked soil. After 8months, compost addition resulted in over 90% loss of total PAHs irrespective of soil types. Desorption and degradation contributed to 30% and 70%, respectively, of the PAH loss in the spiked soil, while PAH loss in the other two soils resulted from 40% enhanced desorption and 60% enhanced degradation. Compost type and application rates had little influence on PAH bioavailability, but higher PAH removal was observed at higher initial concentration during the early stage of incubation. The bioavailable fraction of PAH was inversely correlated to the number of benzene rings and the octanol–water partition coefficient. Further degradation was not likely after 8-month although over 30% of the residual PAHs were bioavailable, which highlighted the application of bioavailability concept during remediation activities.

Concentrations of Heavy Metals (Cu, Cd, Zn and Ni) and PAHs in Perna viridis Collected from Seaport and Non-seaport Waters in the Straits of Johore

In this study, the ranges of pollutants found in the soft tissues of Perna viridis collected from Kg. Masai and Kg. Sg. Melayu, both located in the Straits of Johore, were 0.85-1.58 μg/g dry weight (dw) for Cd, 5.52-12.2 μg/g dw for Cu, 5.66-8.93 μg/g dw for Ni and 63.4-72.3 μg/g dw for Zn, and 36.4-244 ng/g dry weight for ∑PAHs. Significantly (p < 0.05) higher concentrations of Cd, Cu, Ni, Zn and ∑PAHs in the mussels were found in the water of a seaport site at Kg. Masai than a non-seaport site at Kg. Sg. Melayu population. The ratios of low molecular weight/high molecular weight hydrocarbons (2.94-3.42) and fluoranthene/pyrene (0.43-0.45) in mussels from both sites indicated the origin of the PAHs to be mainly petrogenic. This study has demonstrated the utility of using the soft tissues of P. viridis as a biomonitor of PAH contamination and bioavailability in the coastal waters of Peninsular Malaysia.