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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Routes of human exposure to per- and polyfluorinated compounds (PFCs) in Winnipeg homes

Nikoobakht, Neda 28 July 2014 (has links)
Per and polyfluorinated compounds (PFCs) include a large group of chemicals which are known to be toxic, bioaccumulative and resistant to hydrolysis, photolysis, microbial degradation and metabolism. However, human exposure pathways and toxic effects to humans are still widely unknown and more data is needed over time. The concentrations of 7 PFCs were measured in indoor air from homes in Winnipeg, Manitoba using gas chromatography-mass spectrometry. 16 PFCs were measured in house dust from Winnipeg, Manitoba using on-line solid phase extraction coupled with liquid chromatography mass spectrometry. For commonly detected PFCs in indoor air and dust, concentrations were found at pg/m3 and ng/g levels, respectively, similar to that observed in other recent studies. Appropriate statistical tests and principal component analysis were used to evaluate possible associations between PFC concentrations and home characteristics. PFCs in indoor air and dust were associated with each other and home characteristics but not with indoor ambient temperature nor type of room (child room or the most used room). Furthermore PFCs did not show significant association with infant wheezing. None of the neutral PFCs in indoor air showed an association with seasonal temperature variation, except 8:2 FTOH and MeFOSE that had significantly higher concentrations in winter than summer.
2

Atmospheric Chemistry of Polyfluorinated Compounds: Long-lived Greenhouse Gases and Sources of Perfluorinated Acids

Young, Cora Jean Louise 15 September 2011 (has links)
Fluorinated compounds are environmentally persistent and have been demonstrated to bioaccumulate and contribute to climate change. The focus of this work was to better understand the atmospheric chemistry of poly- and per-fluorinated compounds in order to appreciate their impacts on the environment. Several fluorinated compounds exist for which data on climate impacts do not exist. Radiative efficiencies (REs) and atmospheric lifetimes of two new long-lived greenhouse gases (LLGHGs) were determined using smog chamber techniques: perfluoropolyethers and perfluoroalkyl amines. Through this, it was observed that RE was not directly related to the number of carbon-fluorine bonds. A structure-activity relationship was created to allow the determination of RE solely from the chemical structure of the compound. Also, a novel method was developed to detect polyfluorinated LLGHGs in the atmosphere. Using carbotrap, thermal desorption and cryogenic extraction coupled to GC-MS, atmospheric measurements can be made for a number of previously undetected compounds. A perfluoroalkyl amine was detected in the atmosphere using this technique, which is the compound with the highest RE ever detected in the atmosphere. Perfluorocarboxylic acids (PFCAs) are water soluble and non-volatile, suggesting they are not susceptible to long-range transport. A hypothesis was derived to explain the ubiquitous distribution of these compounds involving atmospheric formation of PFCAs from volatile precursors. Using smog chamber techniques with offline analysis, perfluorobutenes and fluorotelomer iodides were shown to yield PFCAs from atmospheric oxidation. Dehydrofluorination of perfluorinated alcohols (PFOHs) is poorly understood in the mechanism of PFCA atmospheric formation. Using density functional techniques, overtone-induced photolysis was shown to lead to dehydrofluorination of PFOHs. In the presence of water, this mechanism could be a sink of PFOHs in the atmosphere. Confirmation of the importance of volatile precursors was derived from examination of snow from High Arctic ice caps. This provided the first empirical evidence of atmospheric deposition. Through the analytes observed, fluxes and temporal trends, it was concluded that atmospheric oxidation of volatile precursors is an important source of PFCAs to the Arctic.
3

Atmospheric Chemistry of Polyfluorinated Compounds: Long-lived Greenhouse Gases and Sources of Perfluorinated Acids

Young, Cora Jean Louise 15 September 2011 (has links)
Fluorinated compounds are environmentally persistent and have been demonstrated to bioaccumulate and contribute to climate change. The focus of this work was to better understand the atmospheric chemistry of poly- and per-fluorinated compounds in order to appreciate their impacts on the environment. Several fluorinated compounds exist for which data on climate impacts do not exist. Radiative efficiencies (REs) and atmospheric lifetimes of two new long-lived greenhouse gases (LLGHGs) were determined using smog chamber techniques: perfluoropolyethers and perfluoroalkyl amines. Through this, it was observed that RE was not directly related to the number of carbon-fluorine bonds. A structure-activity relationship was created to allow the determination of RE solely from the chemical structure of the compound. Also, a novel method was developed to detect polyfluorinated LLGHGs in the atmosphere. Using carbotrap, thermal desorption and cryogenic extraction coupled to GC-MS, atmospheric measurements can be made for a number of previously undetected compounds. A perfluoroalkyl amine was detected in the atmosphere using this technique, which is the compound with the highest RE ever detected in the atmosphere. Perfluorocarboxylic acids (PFCAs) are water soluble and non-volatile, suggesting they are not susceptible to long-range transport. A hypothesis was derived to explain the ubiquitous distribution of these compounds involving atmospheric formation of PFCAs from volatile precursors. Using smog chamber techniques with offline analysis, perfluorobutenes and fluorotelomer iodides were shown to yield PFCAs from atmospheric oxidation. Dehydrofluorination of perfluorinated alcohols (PFOHs) is poorly understood in the mechanism of PFCA atmospheric formation. Using density functional techniques, overtone-induced photolysis was shown to lead to dehydrofluorination of PFOHs. In the presence of water, this mechanism could be a sink of PFOHs in the atmosphere. Confirmation of the importance of volatile precursors was derived from examination of snow from High Arctic ice caps. This provided the first empirical evidence of atmospheric deposition. Through the analytes observed, fluxes and temporal trends, it was concluded that atmospheric oxidation of volatile precursors is an important source of PFCAs to the Arctic.
4

Occupational exposure to fluorinated ski wax

Nilsson, Helena January 2012 (has links)
Per- and polyfluorinated substances (PFAS) are used in the production of ski wax to reduce the friction between the snow and the ski. In this occupational study of ski wax technicians’ exposure to PFAS and particulate aerosol we have collected whole blood (wb) (n =94), air (n =84) and aerosol (n =159) samples at World Cup events from 2007-2011. We have analysed the blood, air and aerosol with respect to 13 perfluorocarboxylic acids (PFCAs), 4 perfluorosulfonic acids (PFSAs), 3 fluorotelomer alcohols (FTOHs), 3 fluorotelomer acids (FTCAs) and 3 unsaturated fluorotelomer acids (FTUCAs). Further, we assessed the exposure to 3 particulate aerosol fractions (inhalable, respirable and total aerosol) in air. In comparison to a general population, several of the PFCA blood levels are elevated in the technicians’, primarily  erfluorooctanoate (PFOA) and perfluorononate (PFNA) with concentrations up to 628 and 163 ng/mL wb, respectively. Further,  we detected FTUCAs and FTCAs in the blood, suggesting biotransformation of FTOHs to PFCAs. The metabolites 5:3 and 7:3 FTCA were detected in all blood samples at levels up to 6.1 and 3.9 ng/mL wb. Levels of perfluorohexadecanoic acid PFHxDA) and perfluorooctadecanoic acid (PFOcDA) were detected in the technician’s blood at mean concentration up to 4.22 ng/mL wb and 4.25 ng/mL wb. The FTOH levels in air of the wax cabin during work ranged up to 997 000 ng/m3 (average=114 000 ng/m3 ) and PFOA up to 4 890 ng/m3 (average= 526 ng/m3 . FTOHs were not detected in aerosols but PFOA showed average levels of 12 000 ng/m3 (range=1 230- 46 900 ng/m3 ). The occupational exposure limit (OEL) of 2 mg/m3 was exceeded in 37% of the personal measurements with aerosol  concentrations up to 15 mg/m3 . Keywords : Perfluorinated, polyfluorinated, FIS, occupational exposure, ski wax,  iotransformation, metabolism, fluorotelomer alcohol, fluorotelomer acid, aerosol, dust, UPLC/MS-MS, GC/MS-MS
5

Patent som källa för att analysera användning och förekomst av per- och polyfluorerade alkylsubstanser (PFAS)

Dillström, Filip January 2017 (has links)
No description available.
6

Tre kommuners arbete med PFAS i dricksvatten : En kvalitativ intervjustudie om svårigheter och möjligheter

Petersson, Emilia, Nilsson, Emma January 2020 (has links)
Today there are many uncertainties in the form of a lack of knowledge about perfluorinated and polyfluorinated substances (PFAS) regarding long-term risks to health and the environment, there is no efficacy data for many environments. The fluorocarbon bond is the strongest chemical bond, which means that PFAS can be transported long distances, for example through water streams and into the atmosphere. If surface water and groundwater are contaminated by PFAS, people are at risk of exposure to PFAS through the drinking water. It is therefore important to investigate and identify what difficulties and opportunities the municipalities see in their work to influence and reduce the occurrence of PFAS in drinking water with PFAS in water revenues and drinking water. The purpose of the study is to map what Halmstad, Linköping and Uppsala municipality see for difficulties and opportunities in their work on influencing and reducing the occurrence of PFAS in drinking water and how the result relates to scientific research about national environmental management. We have chosen to do a qualitative interview with an analysis of the interview using previous research on national environmental management about actions, cooperation and policy, directives, guidelines, and legislation. Some of the conclusions the study came to where that the municipalities see similar difficulties and opportunities in working with PFAS and have similar ways of working with PFAS. But there are still some differences and similarities in what they see for difficulties and opportunities in their work with PFAS. Difficulties that have been identified are inadequate or unclear guidelines, directives, legislation and insufficient limit values. It is also a difficulty that the municipalities do not know where all sources of PFAS pollution come from. Opportunities that have been identified are collaborations, knowing where certain parts of PFAS's pollution come from. One possibility that exists is to influence certain polluting activities by means of distribution routes, to submit activities to improve purification methods and to set requirements for sampling and remediation. / Det finns idag många osäkerheter i form av bristande kunskap om perfluorerade och polyfluorerade ämnen (PFAS) när det gäller långsiktiga risker mot hälsa och miljö, det saknas effektdata för många miljöer. Fluor-kol-bindningen är den starkaste kemiska bindningen vilket leder till att PFAS kan transporteras långa vägar, genom till exempel vattenströmmar och i atmosfären. Om ytvatten och grundvatten blir förorenat av PFAS så riskerar människor att exponeras för PFAS genom dricksvattnet. Det är därför av vikt att undersöka och identifiera vad för svårigheter och möjligheter kommunerna ser med sitt arbete med att påverka och minska förekomsten av PFAS i dricksvatten med PFAS i vattentäkter och dricksvatten. Syftet med studien är att kartlägga vad Halmstad, Linköping och Uppsala kommun, ser för svårigheter och möjligheter i sitt arbete med att påverka och minska förekomsten av PFAS i dricksvatten och hur resultatet förhåller sig till vetenskaplig forskning om nationell miljömanagement. Vi har valt att göra en kvalitativ intervju med en analys av intervjun med hjälp av tidigare forskning om nationell miljömanagement med avseende på åtgärder, samarbete och direktiv, riktlinjer och lagstiftning. Några av slutsatserna studien kom fram till var att kommunerna ser liknande svårigheter och möjligheter i arbetet med PFAS och har liknande sätt att arbeta med PFAS på. Men det finns ändå en del skillnader och likheter i vad de ser för svårigheter och möjligheter i deras arbete med PFAS. Svårigheter som har identifierats är otillräckliga eller otydliga riktlinjer, direktiv, lagstiftning och otillräckliga gränsvärden. Det är även en svårighet att kommunerna inte vet vart alla källor av PFAS-föroreningar kommer från. Möjligheter som har identifierats är samarbeten, att veta vart vissa delar av PFAS föroreningar kommer från. En möjlighet som finns är att påverka vissa förorenande verksamheter genom spridningsvägar, förelägga verksamheter att förbättra reningsmetoder och sätta krav på provtagning och sanering.

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