Understanding the exposure of UK and Antarctic wildlife to per- and polyfluoroalkyl substances (PFAS).

Bailes, Imogen and Sweetman, Andrew (2026) Understanding the exposure of UK and Antarctic wildlife to per- and polyfluoroalkyl substances (PFAS). PhD thesis, Lancaster University.

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Abstract

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals of global concern due to their extreme persistence, bioaccumulative properties, potential toxicity and ability to undergo long-range transport. Despite regulatory efforts and phase-outs of legacy compounds, PFAS continue to be detected worldwide, including in remote regions. Replacement compounds, i.e., substitutes for restricted PFAS, are also being increasingly detected in the environment, raising questions about the potential risk they pose. This thesis aimed to characterise the occurrence, profiles, and drivers of legacy and replacement PFAS accumulation in wildlife, from both the UK (close to source) and Antarctica (far from source). In the Southern Ocean, analysis of sub-Antarctic seabirds revealed the bioaccumulation of both legacy PFAS (notably PFOS and long-chain PFCAs) and replacement compounds (e.g., ADONA, GenX, short-chain PFAAs, PFECAs), confirming long-range transport and ongoing exposure. Varying migration strategies between species revealed similar PFAS profiles throughout the South Atlantic basin due to long-range transport. Furthermore, trophic level appeared to influence concentrations to a greater extent than geographic distribution, suggesting wildlife are not protected from contamination by the limited oceanic transfer through the Antarctic Circumpolar Current, as has been previously suggested. This thesis presents the most comprehensive dataset to date of UK-stranded marine mammals (n = 206, across 17 species, 2006–2024), which showed high variability in PFAS burdens, which is broadly explained by trophic ecology, maternal transfer, and habitat use. PFAS concentrations exceeded toxicity thresholds in several individuals, highlighting potential health risks. Profiles varied between species but mainly comprised PFOS and long-chain PFCAs. Replacement PFAS were also detected, some at high detection frequencies, demonstrating the continued environmental persistence of restricted substances alongside the emergence of unregulated replacements. Non-target analyses identified several previously unreported PFAS in marine mammals, underscoring the value of complementary analytical approaches. Together, these findings provide clear evidence that both legacy and replacement PFAS are globally pervasive, accumulating in wildlife from industrialised coastlines (UK) to the most remote polar regions (Antarctica). The results highlight the importance of trophic ecology in exposure and accumulation, the persistence of PFOS despite phase-outs, and the need for long-term, multi-species biomonitoring to understand trends of both legacy and replacement PFAS. This work contributes to understanding the environmental fate and transport of PFAS and supports the need for strengthened global restrictions, improved monitoring frameworks, and research linking contaminant burdens with ecological and health outcomes.