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- Lam, Monika M., 1987-
(författare)
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Characterization of PAC-contaminated soil with the focus on availability, leachability and biological activities
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Current risk assessments of polycyclic aromatic compounds (PACs)-contaminated soil are often based on the 16 priority PAHs and do not consider availability of PACs in soil sufficiently. This may lead to uncertainties of the assessment, since important contaminants can be overlooked and only a small fraction of contaminants is available for the uptake for organisms. The overall aim of this thesis was to develop a refined and enhanced analytical approach based on both chemical and bioassay analysis coupled to passive sampling with polyoxymethylene (POM) and leaching tests that can provide a more comprehensive picture of chemical pollution at PAC-contaminated sites. To achieve this, bioassay-specific relative potency factors (REPs) of PACs were determined for the H4IIE-luc bioassay, detecting AhR-mediated activity, and for the VM7luc4E2 transactivation assay, detecting ER-mediated activity for the use in potency-balance analysis. Results of uptake-experiments of PACs in earthworms and POM suggested that POM is a suitable tool to study availability of AhR and ER agonists in soil. Availability and mobility of PACs in soil were investigated by the use of POM and leaching tests. The results of potency-balance analysis showed that in soil samples, in POM-fractions or in leachates, a large fraction of AhR- or ER-agonists remained unexplained, despite the use of a large number of REPs. In addition, coupling of chemical and biological analysis to passive sampling or leaching tests revealed that only a small fraction of the total mass of PACs in the soil is available or leachable in soil. The results suggests that the use of only the total concentration in soil while ignoring unknown toxicants will lead to great uncertainties in the risk assessment. Therefore, effect-based screening using bioassays, taking availability and mobility of compounds into account, as well as a widened chemical analysis should be included in modern hazard- and risk assessment of PAH contaminated soils.
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| 3. |
- Lam, Monika M., 1987-, et al.
(författare)
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Methylated PACs Are More Potent than Their Parent Compounds : A Study on AhR-mediated Activity, Degradability and Mixture Interactions in the H4IIE-luc Assay
- 2018
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Ingår i: Environmental Toxicology and Chemistry. - : John Wiley & Sons. - 0730-7268 .- 1552-8618. ; 37:5, s. 1409-1419
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-six polycyclic aromatic compounds (PACs; including native polycyclic aromatic hydrocarbons [PAHs], hydroxylated PAHs, alkylated and oxygenated PAHs, and [alkylated] heterocyclic compounds) were investigated for their aryl hydrocarbon receptor (AhR)-mediated potencies in the H4IIE-luc bioassay. Potential degradabilities of PACs were investigated by use of various durations of exposure (24, 48, or 72 h), and various mixtures of PACs including PAHs, alkylated and oxygenated PAHs, and heterocyclic compounds were tested for their joint AhR-mediated potency. Additive behaviors of PACs in mixtures were studied by comparing observed mixture potencies with mixture potencies predicted by use of the concentration addition model. Methylated derivatives were more potent than their parent compounds in the H4IIE-luc assay. A time-dependent decrease in relative potency was observed for all AhR-active compounds, which may be indicative of in vitro biotransformation. Monomethylated compounds seemed to be more rapidly transformed than analogous unsubstituted compounds. In addition, the results showed that the predictive power of the concentration addition model increased with the number of compounds, suggesting additivity in multicomponent mixtures. Due to the greater potency of methylated derivatives and their ubiquitous occurrence, there is a need for further research on the toxicity and mixture behavior of these environmentally and toxicologically relevant compounds.
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| 4. |
- Lam, Monika M., 1987-, et al.
(författare)
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Methylated polycyclic aromatic hydrocarbons and/or their metabolites are important contributors to the overall estrogenic activity of polycyclic aromatic hydrocarbon-contaminated soils
- 2018
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Ingår i: Environmental Toxicology and Chemistry. - : John Wiley & Sons. - 0730-7268 .- 1552-8618. ; 37:2, s. 385-397
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Tidskriftsartikel (refereegranskat)abstract
- In the present study 42 polycyclic aromatic compounds (PACs) were investigated for their estrogenic potential using the VM7Luc4E2 transactivation assay. Relative potencies were determined for mass-balance analysis. In addition, compounds were tested in combination with the estrogen receptor (ER) antagonist vertical bar C vertical bar 182,780 (vertical bar C vertical bar) and the aryl hydrocarbon receptor antagonist/CYP1A1 inhibitor a-naphthoflavone. Luciferase induction and CYP1A1-dependent ethoxyresorufin-O-deethylase (EROD) activity were measured to assess whether the estrogenic activity was elicited by the compound itself and/or by its metabolites. Relative potencies ranged between 10(-7) and 10(-4). The ability of ICI to decrease luciferase activity stimulated by all compounds indicated that the induction responses were ER-dependent. The aryl hydrocarbon receptor antagonist/CYP1A1 inhibitor a-naphthoflavone decreased luciferase induction and EROD activity by several compounds, including the methylated chrysenes, suggesting that metabolites of these chemicals contributed to ER activation. Several PACs, such as acridine and its derivatives, appear to directly activate the ER. Furthermore, extracts of soils from industrial areas were examined using this bioassay, and estrogenic activity was detected in all soil samples. Mass-balance analysis using a combination of relative potencies and chemical analysis of the samples suggested that polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs, such as 1-and 3-methylchrysene, are important contributors to the overall estrogenic activity. However, these results revealed that a considerable proportion of the estrogenic activity in the soil remained unexplained, indicating the presence of other significant estrogenic compounds.
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| 6. |
- Larsson, Maria, 1975-, et al.
(författare)
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Occurrence and leachability of polycyclic aromatic compounds in contaminated soils : Chemical and bioanalytical characterization
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 622-623, s. 1476-1484
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Tidskriftsartikel (refereegranskat)abstract
- An important concern regarding sites contaminated with polycyclic aromatic compounds (PACs) is the risk of groundwater contamination by release of the compounds from soils. The goal of this study was to investigate the occurrence and leachability of 77 PACs including polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic compounds (NSO-PACs) among total aryl hydrocarbon receptor (AhR) agonists in soils from historical contaminated sites. A novel approach combining chemical and bioanalytical methods in combination with characterization of leachability by use of a column leaching test was used. Similar profiles of relative concentrations of PACs were observed in all soils, with parent PAHs accounting for 71 to 90% of total concentrations in soils. Contribution of oxy-PAHs, alkyl-PAHs and N-PACs ranged from 2 to 9%, 3 to 9% and 1 to 14%, respectively. Although the contributions of groups of PACs were small, some compounds were found in similar or greater concentrations than parent PAHs. Leachable fractions of 77 PACs from soils were small and ranged from 0.002 to 0.54%. Polar PACs were shown to be more leachable than parent PAHs. The contribution of analyzed PACS to overall AhR-mediated activities in soils and leachates suggests presence of other AhR agonists in soils, and a potential risk. Only a small fraction of AhR agonists was available in soils, indicating an overestimation of the risk if only total initial concentrations in soils would be considered in risk assessment. The results of the study strongly support that focus on 16US EPA PAHs may result in inadequate assessment of risk and hazard of PACs in complex environmental samples.
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| 7. |
- Titaley, Ivan, 1990-, et al.
(författare)
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Characterization of polycyclic aromatic compounds in historically contaminated soil by targeted and non-targeted chemical analysis combined with in vitro bioassay
- 2021
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 289
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Tidskriftsartikel (refereegranskat)abstract
- Soil samples from a contaminated site in Sweden were analyzed to identify the presence of 78 polycyclic aromatic compounds (PACs) using gas chromatography coupled with mass spectrometry (GC-MS). The target analysis revealed large contributions not only from polycyclic aromatic hydrocarbons (PAHs), but also from alkylated- and oxygenated-PAHs (alkyl- and oxy-PAHs, respectively), and N-heterocyclics (NPACs). PAC profiles indicated primarily pyrogenic sources, although contribution of petrogenic sources was also observed in one sample as indicated by a high ratio of alkylated naphthalene compared to naphthalene. The aryl hydrocarbon receptor (AhR)-activity of the soil extracts was assessed using the H4IIe-pGudluc 1.1 cells bioassay. When compared with the calculated total AhR-activity of the PACs in the target list, 35–97% of the observed bioassay activity could be explained by 62 PACs with relative potency factors (REPs). The samples were further screened using GC coupled with Orbitrap™ high resolution MS (GC-HRMS) to investigate the presence of other PACs that could potentially contribute to the AhR-activity of the extracts. 114 unique candidate compounds were tentatively identified and divided into four groups based on their AhR-activity and environmental occurrence. Twelve substances satisfied all the criteria, and these compounds are suggested to be included in regular screening in future studies, although their identities were not confirmed by standards in this study. High unexplained bio-TEQ fractions in three of the samples may be explained by tentatively identified compounds (n = 35) with high potential of being toxic. This study demonstrates the benefit of combining targeted and non-targeted chemical analysis with bioassay analysis to assess the diversity and effects of PACs at contaminated sites. The applied prioritization strategy revealed a number of tentatively identified compounds, which likely contributed to the overall bioactivity of the soil extracts.
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