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Uncertainty, variability and environmental risk analysis
Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The negative effects of hazardous substances and possible measures that can be taken are evaluated in the environmental risk analysis process, consisting of risk assessment, risk communication and risk management. Uncertainty due to lack of knowledge and natural variability are always present in this process. The aim of this thesis is to evaluate some tools as well as discuss the management of uncertainty and variability, as it is necessary to treat them both in a reliable and transparent way to gain regulatory acceptance in decision making.

The catalytic effects of various metals on the formation of chlorinated aromatic compounds during the heating of fly ash were investigated (paper I). Copper showed a positive catalytic effect, while cobalt, chromium and vanadium showed a catalytic effect for degradation. Knowledge of the catalytic effects may facilitate the choice and design of combustion processes to decrease emissions, but it also provides valuable information to identify and characterize the hazard.

Exposure factors of importance in risk assessment (physiological parameters, time use factors and food consumption) were collected and evaluated (paper II). Interindividual variability was characterized by mean, standard deviation, skewness, kurtosis and multiple percentiles, while uncertainty in these parameters was estimated with confidence intervals.

How these statistical parameters can be applied was shown in two exposure assessments (papers III and IV). Probability bounds analysis was used as a probabilistic approach, which enables separate propagation of uncertainty and variability even in cases where the availability of data is limited. In paper III it was determined that the exposure cannot be expected to cause any negative health effects for recreational users of a public bathing place. Paper IV concluded that the uncertainty interval in the estimated exposure increased when accounting for possible changes in climate-sensitive model variables. Risk managers often need to rely on precaution and an increased uncertainty may therefore have implications for risk management decisions.

Paper V focuses on risk management and a questionnaire was sent to employees at all Swedish County Administrative Boards working with contaminated land. It was concluded that the gender, age and work experience of the employees, as well as the funding source of the risk assessment, all have an impact on the reviewing of risk assessments. Gender was the most significant factor, and it also affected the perception of knowledge.

Abstract [sv]

Negativa effekter orsakade av skadliga ämnen och möjliga åtgärder bedöms och utvärderas i en miljöriskanalys, som kan delas i riskbedömning, riskkommunikation och riskhantering. Osäkerhet som beror på kunskapsbrist samt naturlig variabilitet finns alltid närvarande i denna process. Syftet med avhandlingen är att utvärdera några tillvägagångssätt samt diskutera hur osäkerhet och variabilitet hanteras då det är nödvändigt att båda hanteras trovärdigt och transparent för att riskbedömningen ska vara användbar för beslutsfattande.

Metallers katalytiska effekt på bildning av klorerade aromatiska ämnen under upphettning av flygaska undersöktes (artikel I). Koppar visade en positiv katalytisk effekt medan kobolt, krom och vanadin istället katalyserade nedbrytningen. Kunskap om katalytisk potential för bildning av skadliga ämnen är viktigt vid val och design av förbränningsprocesser för att minska utsläppen, men det är också ett exempel på hur en fara kan identifieras och karaktäriseras.

Information om exponeringsfaktorer som är viktiga i riskbedömning (fysiologiska parametrar, tidsanvändning och livsmedelskonsumtion) samlades in och analyserades (artikel II). Interindividuell variabilitet karaktäriserades av medel, standardavvikelse, skevhet, kurtosis (toppighet) och multipla percentiler medan osäkerhet i dessa parametrar skattades med konfidensintervall.

Hur dessa statistiska parametrar kan tillämpas i exponeringsbedömningar visas i artikel III och IV. Probability bounds analysis användes som probabilistisk metod, vilket gör det möjligt att separera osäkerhet och variabilitet i bedömningen även när tillgången på data är begränsad. Exponeringsbedömningen i artikel III visade att vid nu rådande föroreningshalter i sediment i en badsjö så medför inte bad någon hälsofara. I artikel IV visades att osäkerhetsintervallet i den skattade exponeringen ökar när hänsyn tas till förändringar i klimatkänsliga modellvariabler. Riskhanterare måste ta hänsyn till försiktighetsprincipen och en ökad osäkerhet kan därmed få konsekvenser för riskhanteringsbesluten.

Artikel V fokuserar på riskhantering och en enkät skickades till alla anställda som arbetar med förorenad mark på länsstyrelserna i Sverige. Det konstaterades att anställdas kön, ålder och erfarenhet har en inverkan på granskningsprocessen av riskbedömningar. Kön var den mest signifikanta variabeln, vilken också påverkade perceptionen av kunskap. Skillnader i de anställdas svar kunde också ses beroende på om riskbedömningen finansierades av statliga bidrag eller av en ansvarig verksamhetsutövare.

Place, publisher, year, edition, pages
Växjö, Kalmar: Linnaeus University Press , 2011.
Series
Linnaeus University Dissertations, 35/2011
Keyword [en]
Contaminated land, exposure assessment, exposure factors, risk analysis, risk perception, uncertainty, variability, probabilistic risk assessment
National Category
Natural Sciences
Research subject
Natural Science, Environmental Science
Identifiers
URN: urn:nbn:se:lnu:diva-11193ISBN: 978-91-86491-63-5OAI: oai:DiVA.org:lnu-11193DiVA: diva2:405602
Public defence
2011-03-18, A137, Landgången 4, Kalmar, 09:30 (Swedish)
Opponent
Supervisors
Available from: 2011-03-23 Created: 2011-03-23 Last updated: 2011-03-24Bibliographically approved
List of papers
1. Catalytic effects by metal oxides on the formation and degradation of chlorinated aromatic compounds in fly ash.
Open this publication in new window or tab >>Catalytic effects by metal oxides on the formation and degradation of chlorinated aromatic compounds in fly ash.
2008 (English)In: Chemosphere, ISSN 0045-6535, Vol. 71, no 6, 1135-43 p.Article in journal (Refereed) Published
Abstract [en]

Polychlorinated benzenes, dibenzo-p-dioxins (PCDD), and dibenzofurans (PCDF) may be formed below the combustion temperature in fly ash from municipal solid waste incinerators (MSWI). Copper catalyzes this formation, possibly by the Deacon reaction. Many other elements are also Deacon catalysts or promoters, and here we report results from a statistically designed experiment with 15 metal oxides added to fly ash and heated at 300 degrees C for 2h in an air atmosphere. A resolution IV fractional factorial design with four replicates was completed in 36 runs with the oxides of magnesium, yttrium, titanium, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, and tin. All samples were analyzed for chlorinated benzenes and the results were evaluated by analysis of variance. The addition of copper significantly increased the amounts of the chlorinated benzenes, while cobalt, chromium and vanadium decreased the net formation. The oxides of zinc and iron seemed to have a slightly positive and negative effect respectively. The findings in this study seem to corroborate our previously reported results regarding the different catalytic effects of copper and chromium, and lack of a significant effect by nickel. Besides chromium, it also identifies cobalt and vanadium as potent catalysts for oxidative degradation of the chlorinated aromatic compounds found in MSWI fly ash.

Place, publisher, year, edition, pages
Oxford: Pergamnon Press, 2008
Keyword
Persistent organic pollutant, Organic compounds, Oxidation, Thermal degradation, Metal Oxides, Catalytic reaction, Factorial design, Reaction mechanism, Dioxin derivatives, Organic chlorine compounds, Pollutant formation, Fly ash, Incineration plant, Urban waste, Solid waste
National Category
Environmental Sciences
Research subject
Environmental Science, Environmental Chemistry
Identifiers
urn:nbn:se:hik:diva-1481 (URN)10.1016/j.chemosphere.2007.10.033 (DOI)18061236 (PubMedID)
Available from: 2009-04-28 Created: 2009-04-28 Last updated: 2016-11-15Bibliographically approved
2. Variability and uncertainty in Swedish exposure factors for use in quantitative exposure assessments
Open this publication in new window or tab >>Variability and uncertainty in Swedish exposure factors for use in quantitative exposure assessments
2011 (English)In: Risk Analysis, ISSN 0272-4332, E-ISSN 1539-6924, Vol. 31, no 1, 108-119 p.Article in journal (Refereed) Published
Abstract [en]

Information of exposure factors used in quantitative risk assessments has previously been compiled and reported for U.S. and European populations. However, due to the advancement of science and knowledge, these reports are in continuous need of updating with new data. Equally important is the change over time of many exposure factors related to both physiological characteristics and human behavior. Body weight, skin surface, time use, and dietary habits are some of the most obvious examples covered here. A wealth of data is available from literature not primarily gathered for the purpose of risk assessment. Here we review a number of key exposure factors and compare these factors between northern Europe—here represented by Sweden—and the United States. Many previous compilations of exposure factor data focus on interindividual variability and variability between sexes and age groups, while uncertainty is mainly dealt with in a qualitative way. In this article variability is assessed along with uncertainty. As estimates of central tendency and interindividual variability, mean, standard deviation, skewness, kurtosis, and multiple percentiles were calculated, while uncertainty was characterized using 95% confidence intervals for these parameters. The presented statistics are appropriate for use in deterministic analyses using point estimates for each input parameter as well as in probabilistic assessments.

Keyword
Body weight;exposure factors, food ingestion, skin surface area, time use, uncertainty, variability
National Category
Natural Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:lnu:diva-6546 (URN)10.1111/j.1539-6924.2010.01464.x (DOI)
Available from: 2010-06-26 Created: 2010-06-26 Last updated: 2016-11-15Bibliographically approved
3. Exposure to contaminated sediments during recreational activities at a public bathing place
Open this publication in new window or tab >>Exposure to contaminated sediments during recreational activities at a public bathing place
2009 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 171, no 1-3, 200-207 p.Article in journal (Refereed) Published
Abstract [en]

More and more time is spent on recreational activities, but few risk assessments focus specifically on these situations and exposure factor data are often scarce. To assess exposure to contaminants at a public bathing place in an urban environment, we have compiled literature data, conducted observation studies, and analyzed water and sediment samples. The levels of anthropogenic contaminants are high in urban environments and traffic frequently plays an important role. In this study, to characterize variability and uncertainty, the deterministic exposure calculations for metal pollutants were supplemented by a probability bounds analysis for the polycyclic aromatic hydrocarbons (PAH). The results from these calculations show that oral intake is the major exposure route for metals, while skin absorption, with present assumptions, is more important for the PAH. The presently measured levels of contaminants, at this public bathing place, cannot be anticipated to cause any significant adverse influence on public health.

Place, publisher, year, edition, pages
Elsevier, 2009
National Category
Natural Sciences
Research subject
Natural Science, Environmental Science
Identifiers
urn:nbn:se:hik:diva-2237 (URN)10.1016/j.jhazmat.2009.05.128 (DOI)
Available from: 2009-09-26 Created: 2009-09-26 Last updated: 2016-11-15Bibliographically approved

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