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|Title: ||Exploring Sources of Human and Environmental Fluorochemical Contamination|
|Authors: ||D'eon, Jessica C.|
|Advisor: ||Mabury, Scott A.|
|Keywords: ||Environmental Chemistry|
|Issue Date: ||5-Sep-2012|
|Abstract: ||Perfluorinated carboxylates (PFCAs) and perfluorinated sulfonates (PFSAs) are found almost ubiquitously in the environment, however their direct production and use is limited. The focus of this thesis was to explore connections between observed contamination with the manufacture and/or use of commercial fluorochemical materials. Perfluorinated sulfonamides (PFSAms) are semi-volatile materials used in the manufacture of commercial fluorochemicals. Investigations into the atmospheric fate of a model PFSAm found atmospheric lifetimes that allow transport to remote environments, potentially through a novel N–dealkylation product. A suite of PFCAs, as well as the PFSA from loss of the amide moiety, were also observed. This investigation demonstrated that PFSAm atmospheric oxidation will contribute to PFCA and PFSA contamination in remote locations, including the Arctic.
The perfluorinated phosphonates (PFPAs) were used as defoaming additives in pesticide formulations. Using novel extraction and analysis methods, widespread PFPA contamination was detected in Canadian surface waters and wastewater treatment plant (WWTP) effluent. As fully fluorinated acids, the PFPAs are a new class of perfluorinated acid discovered in the environment. Uptake and elimination parameters determined in the rat demonstrate the potential for human PFPA exposure, as these chemicals are bioavailable.
Processes governing the pharmacokinetics and disposition of perfluorinated acids in the body are poorly understood. Novel heteronuclear nuclear magnetic resonance experiments identified human serum albumin as the major site of interaction. Competitive binding experiments found the PFCAs displaced the endogenous human serum albumin ligand, 13C1-oleic acid, at lower concentrations than established ligands. The strong association observed between the PFCAs and human serum albumin may inform observed human toxic endpoints and long elimination half-lives.
The polyfluoroalkyl phosphates (PAPs) are used in food-contact paper packaging. High PAP concentrations were discovered in human sera, waste paper fibres and WWTP sludge, establishing human exposure to these chemicals. Biotransformation from PAP to PFCA was investigated in a rat model. The serum kinetics and PFCA products observed, suggest PAP exposure may be a significant source of human PFCA contamination.
The concerted approach of environmental monitoring with investigations of atmospheric and biological fate allowed strong associations to be made between commercial fluorochemical sources and observed contamination.|
|Appears in Collections:||Doctoral|
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