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Hazard screening of contaminated sites: bioavailable fractions and biological in vitro tools
Umeå University, Faculty of Science and Technology, Chemistry.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The environmental bioavailability of contaminants, rather than their total concentrations in the soil compartment play a decisive role for the risks associated with contaminated sites. Various soil constituents and abiotic conditions have strong influence on bioavailability, which may vary substantially between different locations. It is therefore necessary to site-specifically use tools that reflect the fractions of contaminants that are available to biota and pose the highest potential environmental risks. Bioassays provide integrated toxic responses which include effects from unknown contaminants or combinatory toxic effects from mixtures of contaminants. Thus, biological effect data greatly contribute to establish more realistic exposure and risk-scenarios at contaminated sites.

The work underlying this thesis presents possible techniques for high capacity screening for site-specific hazards at contaminated areas. By combining rapid water extractions and cell-based in vitro designs measures of the toxic potential in soils was obtained. Toxicologically bioavailable fractions of mixed metal pollution, including arsenic, were primarily investigated in this thesis. In two of the studies, environmental availability and toxicological bioavailability of arsenic was explored in CCA-contaminated soils. Application of cell-based in vitro screening techniques was also conducted at a metal contaminated industrial site to obtain spatial distribution of toxicity. Multivariate association techniques were employed in the interpretation of environmental exposure and cytotoxicity data.

It was shown that cell-based in vitro systems for both basal cytotoxicity and specific end-points targeting arsenic could assess the toxic potential from extracts obtained by several water-based extraction techniques including Pressurised Liquid Extraction (PLE). The cell-based in vitro systems were found to add important information on the site-specific differences in arsenics genotoxic potential from CCA-contaminated soils. The results highlight the importance of taking speciation and toxicological bioavailability into account in the risk analysis, rather than to base risk estimates on total load of contaminants. The presented screening approach was successfully applied at a metal polluted industrial site where spatial distribution of toxicity was obtained. PLE extraction also provided means for combined toxicological and chemical screening of explosives in soils from live-fire training ranges. Multivariate association techniques highly facilitated the interpretation of complex environmental data. The PLE was found to be a rapid extraction technique that has sufficient environmental relevance to be used in environmental impact analyses. It was also concluded that other cell-based in vitro systems that target specific toxic effects have large potential for being used in screening for a variety of environmental chemicals.

Keywords: Environmental availability, Environmental bioavailability, Toxicological bioavailability, mixture toxicity, hazard screening, contaminated soils, heavy metals, arsenic, CCA, explosives, soil extraction, water extracts, cell-based in vitro tests, cytotoxicity, genotoxicity, PLE, MVDA, PCA, PLS.

Abstract [sv]

Föroreningars biotillgänglighet snarare än deras totala koncentration i markmiljön styr den risk som kan förknippas med förorenade områden. Biotillgängligheten är ofta långt från 100% p.g.a. en rad olika bindningsytor och processer i jorden som reducerar biotillgängligheten. Således kan biotillgängligheten variera kraftigt mellan olika förorenade platser och även inom samma plats till följd av de specifika förhållanden som råder på respektive plats. Tillämpning av biologiska indikatorer som ger ett mått på den samlade giftigheten från biotillgängliga föroreningar är därför viktiga verktyg i platsspecifika exponerings- och farobedömningar. Många biologiska tester är ofta laborativt intensiva och dyra och lämpar sig mindre väl i testning av ett stort antal prover vilket är önskvärt om en tillräcklig geografisk täckning ska uppnås över ett förenat område. Testsystem som har kapacitet att hantera många prover till en rimlig kostnad är därför mycket användbart för screening i ett inledande skede av en miljöriskanalys av ett förorenat område.

Föreliggande avhandlingsarbete presenterar möjliga lösningar i att kombinera snabb vattenextraktionsmetodik med cellbaserade in vitro system för platsspecifik toxikologisk faroscreening av metallförorenade områden. Metodiken erbjuder hög kapacitet för många jordprover. Tillämpning av metodiken har gjorts mot huvudsakligen metallföroreningar, inklusive arsenik. I två delarbeten studerades två modelljordar från CCA-förorenade fastigheter avseende tillgänglighet och giftighet av framför allt arsenik. Vidare studerades om det med applicerad metodik gick att illustrera geografisk utbredning av toxicitet, mätt i cellbaserade in vitro system, som biotillgängliga föroreningar uppvisar på ett metallförorenat industriområde. Slutligen studerades lämpligheten i att använda PLE för kombinerad kemisk och toxikologisk screening av jordar från militära skjutfält som var förorenade med explosivämnen.

Cellbaserade in vitro system för mätning av både generell toxicitet och mer specifika effektmarkörer för arsenik visade sig användbara vid mätning från flera vattenbaserade extraktionsmetoder, inklusive PLE (trycksatt vätskeextraktion). Resultaten visade på PLEs tillämplighet som en snabb extraktionsmetod med bibehållen relevans för miljöanalyser. Applikation av cellbaserade in vitro system på vattenextrakt från förorenad jord gav värdefull information bl.a. om platsspecifik genotoxisk potential där specieringen av arsenik hade avgörande betydelse i en fallstudie med CCA-förorenade jordar. Vattenextraktion av jordprover kombinerat med cellbaserade in vitro system kunde också ge en geografisk bild av den omedelbara faran från biotillgängliga metallföroreningar inom ett industriområde. Vattenextraktion med PLE visade sig även användbart för screening av explosivämnen där extrakten direkt kunde användas för såväl kemisk karakterisering som för toxikologisk analys. Även andra typer av in vitro system än de som användes i detta arbete har stor framtida potential för tillämpning i faroscreening av ett stort antal olika typer av miljöföroreningar.

Place, publisher, year, edition, pages
Umeå: Kemi , 2007. , 56 p.
Keyword [en]
Hazard screening, bioavailability, metal pollution, in vitro cytotoxicity, water extraction, CCA, arsenic genotoxicity, genotoxicity, Contaminated soil
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:umu:diva-1148ISBN: 978-91-7264-329-1 (print)OAI: oai:DiVA.org:umu-1148DiVA: diva2:140370
Public defence
2007-06-05, KB3A9, KBC-huset, Umeå Universitet 90187, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2007-05-15 Created: 2007-05-15 Last updated: 2009-12-03Bibliographically approved
List of papers
1. Assessment of contaminants availability in CCA-soils: guidance from soil extraction methods
Open this publication in new window or tab >>Assessment of contaminants availability in CCA-soils: guidance from soil extraction methods
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Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2390 (URN)
Available from: 2007-05-15 Created: 2007-05-15 Last updated: 2010-01-13Bibliographically approved
2. Arsenic chemical species-dependent genotoxic potential in water extracts from two CCA-contaminated soils measured by DNA-repair deficient CHO-cells
Open this publication in new window or tab >>Arsenic chemical species-dependent genotoxic potential in water extracts from two CCA-contaminated soils measured by DNA-repair deficient CHO-cells
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2009 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 407, no 14, 4253-4260 p.Article in journal (Refereed) Published
Abstract [en]

Two soils with similar contamination levels from wood preservatives containing Chromium (Cr), Copper (Cu) and Arsenic (As) (CCA), were assessed for their general toxicity and genotoxicity. A set of water-based extraction methods, including pressurized liquid extraction (PLE), and batch leaching in milli-Q water and a weak CaCl2-solution, was used to produce soil extracts containing available fractions of contaminants. In addition, to obtain indications of the contaminants' bioavailability and toxic potential the genotoxicity of the extracts was estimated by testing their ability to inhibit the growth of wildtype Chinese hamster ovary cells (CHO-cells) and three genetically modified pheno-types that are deficient in different DNA-repair mechanisms. Total extractable arsenic concentrations in the extracts were comparable between the sites. However, the genotoxic potential was clearly higher in soil R extracts. The differences in genotoxic responses were related to differences in inorganic arsenic speciation. The ratio of trivalent arsenic (AsIII) to pentavalent arsenic (AsV) was higher in all soil extracts from soil R, regardless of the leaching method used. The results of the various combinations of soil extraction techniques and assays using the CHO-cell lines reflected important differences in arsenic speciation in the two soils and possible synergistic effects in CCA-related exposure. They also indicate that speciation and combinatory effects are factors that should be taken into account when assessing risks at former wood impregnation sites contaminated by CCA-agents.

Place, publisher, year, edition, pages
Elsevier B.V., 2009
Keyword
CCA, Arsenic speciation, CHO-cells, DNA-repair, Genotoxicity
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-22138 (URN)10.1016/j.scitotenv.2009.02.036 (DOI)19361837 (PubMedID)
Available from: 2009-04-24 Created: 2009-04-24 Last updated: 2017-12-13Bibliographically approved
3. Environmental Hazard Screening of a Metal-polluted Site Using Pressurized Liquid Extraction and Two In Vitro Bioassays
Open this publication in new window or tab >>Environmental Hazard Screening of a Metal-polluted Site Using Pressurized Liquid Extraction and Two In Vitro Bioassays
2007 (English)In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 36, no 6, 494-501 p.Article in journal (Refereed) Published
Abstract [en]

Rapid screening methods can improve the cost effectiveness, throughput, and quality of risk assessments of contaminated sites. In the present case study, the objective was to evaluate a combination of pressurized liquid extraction and 2 in vitro bioassays for the hazard assessment of surface soil sampled from 46 points across a pyrotechnical industrial site. Pressurized liquid extraction was used to rapidly produce soil-water extracts compatible with 2 high-capacity bioassays. Hazard assessment using combined toxicological and chemical screening revealed zones with relatively high potential risks of metal pollution. Multivariate data analysis provided indications that significant inhibition in the bioassays was correlated with levels of metals in the extracts, suggesting an elevated toxic potential from certain metals. Low pH and high concentrations of dissolved organic carbon were associated with increased cytotoxicity of extracts, indicating that these factors influence metal bioavailability. The cytotoxicity observed was more strongly correlated to metal concentrations in the extracts than in the soil, suggesting that measurements of total metal concentrations in soils do not provide good indications of the soil's potential toxicity.

Identifiers
urn:nbn:se:umu:diva-16868 (URN)doi:10.1579/0044-7447(2007)36[494:EHSOAM]2.0.CO;2 (DOI)
Available from: 2007-10-18 Created: 2007-10-18 Last updated: 2017-12-14Bibliographically approved
4. Pressurized liquid extraction with water as a tool for chemical and toxicological screening of soil samples at army live-fire training ranges
Open this publication in new window or tab >>Pressurized liquid extraction with water as a tool for chemical and toxicological screening of soil samples at army live-fire training ranges
2007 In: Journal of Hazardous Materials, ISSN 0304-3894, Vol. 142, no 1-2, 418-424 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-2393 (URN)
Available from: 2007-05-15 Created: 2007-05-15Bibliographically approved

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