To Örebro University

Per- and polyfluoroalkyl substances (PFASs) are anthropogenic contaminants of emerging concern, because many are highly persistent to degradation and have been linked to adverse effects in humans as well as their ubiquitous spread in aquatic environments. This thesis investigated distribution of PFASs and organofluorine in freshwater environments impacted by PFAS point sources. The main focus was to study potential transfer of PFASs from freshwater systems to riparian zones via emergent aquatic insects as well as potential impacts on riparian invertebrate consumers.

Comprehensive sets of samples, such as aquatic insect larvae, emergent aquatic insects, terrestrial invertebrate consumers and water were collected from mainly two sites in Sweden, Ronneby Airport and Kvarntorp industrial area. Homologue and branched isomer profiles, estimates of mass discharges, bioaccumulation factors, stable isotope analysis of carbon and nitrogen as well as organofluorine mass balance and suspect screening analysis were used to characterize the distribution of PFASs in these freshwater environments including their aquatic and terrestrial invertebrate food webs.

Results revealed elevated PFAS concentrations in emergent aquatic insects and riparian invertebrate consumers, especially in spiders. Calculated biodriven transfers indicated that impact on riparian insectivores could be substantial on a local and seasonal scale. Furthermore, PFAS concentrations in terrestrial consumers were related to aquatic-based diet and trophic levels, indicating that biomagnification was a major pathway of uptake for some PFASs. Organofluorine mass balance could be closed for most aquatic and for some terrestrial invertebrates from the Ronneby site by target PFAS analysis, whereas a fraction of ~50% in surface water was unidentified organofluorine. Most new PFASs, tentatively identified by suspect screening, were found in water samples and given that contamination occurred decades ago suggested that those PFASs, mainly perfluoroalkyl sulfonamide-based PFASs, are highly water soluble and persistent.

Per- and polyfluoroalkyl substances (PFAS) have been linked to a range of negative health and environmental effects. Regulations limiting and/or banning the use of some of the legacy compounds have been introduced. Consequently, the production and use of PFAS has diversified. The risks posed by these newly introduced PFAS to both the environment and humans may be underestimated if they are not evaluated in current monitoring programs. Organofluorine mass balance analysis has been used in previous studies to estimate the overall exposure to PFAS since naturally occurring organofluorine compounds are rare in nature.

In this thesis, the organofluorine mass balance analysis was performed on a variety of samples, from surface water to sewage and human blood. The results indicated the ubiquitous presence of unidentified organofluorines in all environmental compartments and human samples, for example, more than 50 % of extractable organofluorine (EOF) in human samples could not be accounted for by an extended list of target analytes. Until these compounds are identified, it is not possible to assess the risks they pose and it could lead to misguided policy decisions.

To tackle the increasingly complex analytical picture and ensure more comprehensive screening, a workflow using EOF as an initial metric to identify pollution hot-spots was proposed. The wider adoption of organofluorine mass balance analysis would also require a better understanding of the analytical instrumentation used for this type of work. Experiments carried out here demonstrated the robustness of combustion ion chromatography in EOF analysis and highlighted areas in need of improvement.

While organofluorine mass balance analysis has its drawbacks, the potential health and environmental risks posed by the unidentified organofluorine compounds cannot be underestimated.