A comprehensive chemical analysis of pilot whale tissue spanning nearly four decades has revealed a more than 60 percent decline in legacy per- and polyfluoroalkyl substances (PFAS) in the North Atlantic. Published in PNAS, the study points to the measurable impact of global efforts to phase out these persistent pollutants – while also raising a new question: where are the newer PFAS going?
The study centers on archived liver samples from nearly 150 pilot whales harvested between 1986 and 2023 in the Faroe Islands. As apex predators, pilot whales serve as key bioindicators of persistent environmental pollutants, including PFAS.
To capture the full spectrum of fluorinated compounds – including newer PFAS that can evade targeted analyses – the team combined targeted mass spectrometry with combustion ion chromatography to quantify total extractable organofluorine (EOF). Comparing the two datasets allowed the researchers to infer the presence, and relative contribution, of unidentified fluorinated compounds.
The analysis showed that known legacy PFAS – particularly PFOS and related perfluorosulfonic acids – peaked in the early 2000s and had declined by over 60 percent by 2023. Importantly, EOF measurements tracked closely with those of legacy PFAS, suggesting that newer compounds are not accumulating in these oceanic food webs to the same extent.
The analysis showed that concentrations of well-known legacy PFAS – particularly PFOS and related perfluorosulfonic acids – peaked in the early 2000s and had declined by more than 60 percent by 2023. Importantly, EOF measurements closely tracked the decline in these legacy compounds, suggesting that newer PFAS are not accumulating in open-ocean food webs to the same extent.
Lead author Jennifer Sun emphasized the utility of this bulk fluorine-based method in the team’s press release: “We are now able to get a better handle on the total PFAS burden in tissues, even when we don’t know the exact identity of every compound.”
The researchers attribute the decline to global phase-outs and tighter regulations. However, the apparent absence of substantial accumulation of newer PFAS in these remote marine ecosystems raises fresh concerns about where these chemicals may be concentrating instead.
“While our results are good news for ocean contamination, it suggests newer PFAS may behave differently from the legacy ones,” said senior author Elsie Sunderland. “It underscores the need to place stronger regulations on ongoing PFAS production to mitigate future impacts.”
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