Perfluorinated Compounds in the Australian Environment: Sources, Fate and Human Exposure

Jack Thompson (2011). Perfluorinated Compounds in the Australian Environment: Sources, Fate and Human Exposure PhD Thesis, School of Medicine, The University of Queensland.

       
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s41794825_phd_final_thesis.pdf final and complete thesis application/pdf 22.45MB 13
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Author Jack Thompson
Thesis Title Perfluorinated Compounds in the Australian Environment: Sources, Fate and Human Exposure
School, Centre or Institute School of Medicine
Institution The University of Queensland
Publication date 2011-12
Thesis type PhD Thesis
Supervisor Proffessor Jochen Mueller
Geoff Eaglesham
Michael Bartkow
Total pages 142
Total colour pages 18
Total black and white pages 124
Language eng
Subjects 039901 Environmental Chemistry (incl. Atmospheric Chemistry)
050299 Environmental Science and Management not elsewhere classified
050206 Environmental Monitoring
Abstract/Summary Perfluorinated compounds (PFCs) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are anthropogenic chemicals produced since the 1950’s for various commercial and industrial applications, including stain-proofing and polymer production. In the past 10 – 15 years PFCs have come under increasing scrutiny as apparently ubiquitous and persistent environmental pollutants. They have been found to accumulate in humans and wildlife. To date no conclusive evidence has been found linking PFCs to any adverse health effects in humans. However a number of toxicological responses have been reported in animals and in cell assays following exposure to these chemicals. The aim of this thesis was to obtain robust data regarding the presence of these compounds in the Australian environment, providing ‘baseline’ concentrations against which to assess in future the effect of product discontinuation and increased regulation. This thesis also aimed to assess the extent to which the Australian population is exposed to PFCs, and the potential sources of this exposure. This work contributes to the growing global database on PFCs in the environment, and lessens the knowledge gap with regards to the Australian environment, and more broadly the Southern Hemisphere in general. A complete investigation of all possible sources of PFCs in Australia, their environmental transport and fate would be impossible within the scope of a single PhD thesis. Instead several studies were undertaken to investigate a particular aspect of the broader issue. Human exposure was investigated in terms of daily intakes of the two most prominent PFCs, PFOS and PFOA. These were estimated for the Australian population using pharmacokinetic modelling. This provided average intake estimates of 0.80 & 1.5 ng/kg bw/day for PFOA and PFOS respectively (Chapter 2). Next, drinking water was investigated as a possible contributor to this exposure. Analysis of samples from 34 locations across Australia showed drinking water is most likely a small contributor to daily PFOS and PFOA intakes, accounting on average for around 2% (Chapter 3). However PFCs were present at trace levels, with at least one PFC being quantifiable in 76% of the samples. PFOS and PFOA were the most frequently detected with overall averages of 1.6 and 0.99 ng/L respectively, well below the provisional drinking water guidelines available internationally. Having established the presence of these compounds in drinking water, a next step was to examine their fate during water treatment. This was done to understand the behaviour of PFCs in state of the art water treatment facilities in Australia, their removal efficiencies, and the likelihood of any contamination stemming from the treatment process itself. PFCs were measured at two advanced water treatment plants throughout the various stages of treatment (Chapter 4). At one facility, with ozone oxidation and sorption processes operating, PFC concentrations remained relatively stable throughout treatment and were present in the finished water. At the second facility all the PFCs were rejected by the reverse-osmosis membranes and concentrated in the brine waste stream. This removed the PFCs from the finished water, but raised the issue of environmentally responsible management of this waste stream. Looking at the broader environment, a mixed media study of the Homebush area in Sydney was undertaken (Chapter 5). PFCs were measured in water, sediment, fish, oysters and bird eggs from the area. The lowest concentrations were found in sediment (<1.0 – 6.2 ng/g PFOS) and the highest in fish livers (47 – 107 ng/g PFOS). The broadest range of PFCs was detected in the water samples. The concentrations in all media were comparable with those from international studies, and demonstrate the presence of local PFC contamination rather than global transport. Finally a sixth study was undertaken with the aim of exploring the differences typically seen in male and female human body burdens (Chapter 6). Menstruation is considered a possible mechanism for lowering the serum concentrations in adult females relative to males. To investigate the significance of ongoing blood loss on body burden, pooled serum samples were analysed taken from people regularly undergoing venesection. This provided an experimental population with which to examine the PFC decreases occurring via blood loss. The experimental results supported the hypothesis that blood loss does reduce the PFC body burden, and by extension menstruation remains a likely determinant of the sex related differences. This thesis demonstrates overall that there are low yet measurable concentrations of PFCs in the Australian environment, and a portion of these are entering the bodies of the human and animal population. Given the current knowledge on biological effects of PFCs, there is no suggestion of any immediate health or eco-toxicological risks. However little is known regarding the effect of long term low dose exposure, and this warrants further study. The persistence of these compounds in the environment means we may continue to be exposed for decades after their production and use has ceased.
Keyword perfluorinated alkyl compounds
PFOS
PFOA
Australian environment
Human exposure
Additional Notes 18 colour pages in total. These are: 37, 50, 54, 64, 65, 66, 70, 73, 74, 75, 76, 96, 104, 105, 119, 121, 129, 131

 
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Created: Tue, 22 May 2012, 20:45:38 EST by Jack Thompson on behalf of Library - Information Access Service