Comparative Analysis of Organofluorine Mass Balance and Per- and Polyfluoroalkyl Substances in Marine and Terrestrial Environments

Abstract

Abstract Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic pollutants. Several PFAS are highly persistent and associated with various adverse health effects and environmental concerns. In response to these concerns, restrictions have been placed on some legacy compounds, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Consequently, new PFAS compounds have emerged; however, information on the risk of these compounds to human health and the environment is unknown. In this thesis, combustion ion chromatography (CIC) and high-resolution continuous source-graphite furnace molecular absorption spectrometry (HR-GFMAS) were employed to assess the level of all extractable organic fluorine (EOF) in various tissues of whales stranded in Scotland. A comparison between CIC and HR-GFMAS revealed that both methods give results within one order of magnitude, with CIC consistently slightly lower concentrations. The EOF was then related to the sum of all quantified PFAS, analysed by targeted HPLC-MS/MS analysis. A mass balance study was conducted in the blubber, brain, kidney, liver and muscle of pilot whales aged 1 to 35 years. The findings showed that the majority of the EOF was unidentified in all whale samples. For instance, target analytes were unable to explain more than 80% of the extractable organofluorine (EOF) in brain and blubber samples. Due to the detection of perfluoroalkyl substances (PFAS) in marine environments, further work was conducted to explore the impact of these compounds in other environments; in this case, plant uptake was explored. Plant systems are a potentially importatant route of human exposure to these compounds due to the human consumption of crop plants. As a result, the study of PFAS accumulation in crops provides valuable information, particularly in light of the introduction of new PFAS substitutes that have been promoted as safer alternatives. Research in this area is needed because previous concerns regarding GenX accumulation have been raised. A greenhouse experiment using wheat and rice under different growing conditions was conducted to gain insight into the conditions influencing GenX uptake in plants. Moreover, a mass balance analysis was performed on both sample media to estimate the fractions that could be analysed using targeted LC-MS/MS, thereby improving our understanding of PFAS behaviour in plants. The findings revealed that GenX had the ability to accumulate in both rice and wheat shoots, and under non-flooded rice accumulates higher concentrations of GenX compared growing under flooded conditions. It was found that GenX contributed between 78 to 97% of the extractable organic fluorine in flooded rice shoots. Despite the limitations of organofluorine mass balance analysis, it is vital to recognize and address potential health and environmental risks associated with unidentified organofluorine compounds. Considering the scarcity of naturally occurring organofluorine compounds, this analytical approach is crucial in estimating the overall exposure and impacts of per- and polyfluoroalkyl substances (PFAS).