Chromatographic Evidence of Lipophilic PFAS in Killer Whale Blubber

While most known per- and polyfluoroalkyl substances (PFAS) bioaccumulate by binding to proteins or partitioning to phospholipids, leading to prevalence in liver and blood, the recent discovery of high concentrations of unidentified extractable organofluorine (EOF) in the blubber of a killer whale (Orcinus orca) from Greenland suggests that some fluorinated substances preferentially bioaccumulate in storage lipids. To further investigate, researchers examined blubber from four killer whales (three from Greenland, one from Sweden) via gas chromatography-atmospheric pressure chemical ionization-ion mobility mass spectrometry (GC-APCI-IMS). To the best of the team’s knowledge, this is the first study to identify lipophilic (occurring preferentially in storage lipids) highly fluorinated PFAS in wildlife.A paper based on their research was published in Environmental Science & Technology Letters (1).

PFAS are chemicals that contain fully fluorinated methyl (−CF₃) or methylene (−CF₂−) (2). These anthropogenic compounds have extensive industrial and consumer uses; more than 10,000 PFAS are known to exist in the world to date, from low-molecular weight water-soluble substances to high molecular weight, hydrophobic polymers (2,3). Previous PFAS research has focused primarily on perfluoroalkyl acids (PFAAs) and precursors, the most notorious of these being perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). These are highly water-soluble surfactants with low pK_as which accumulate in protein- and phospholipid-rich tissues (for example, in the liver or blood) rather than storage lipids like other persistent organic pollutants (4-6).

The first empirical evidence of large quantities of unidentified extractable organic fluorine (EOF) in the blubber of a marine mammal was recently reported (7). A combination of combustion ion chromatography (CIC) and mass spectrometry-based target analyses were applied for that study to eight different tissues of a killer whale from East Greenland. While the distribution of known PFAS in tissues aligned with previous findings (with wet weight concentrations decreasing in the order: liver > blood > kidney ≈ lung ≈ ovary > muscle ≈ skin ≈ blubber), unknown EOF concentrations were highest in blubber. These results could not be explained by inorganic fluorine (which was removed during the extraction procedure) or targeted PFAS. Considering that blubber can account for up to 50% of the entire body mass of some species of cetaceans at certain life stages (8,9), the researchers associated with (1) hypothesized that overlooking chemicals in this compartment may significantly underestimate overall exposure to organofluorines (10).

Using collision cross sections, the research team prioritized features believed to be highly fluorinated and then selected five for manual annotation. Custom synthesized standards verified the presence of 10:2 and 12:2 fluorotelomer methylsulfone, 10:2 and 12:2 fluorotelomer chloromethylsulfone, and 6:2 bisfluorotelomer sulfone in all blubber samples from Greenland, at concentrations ranging from <0.4 to 72.5 ng/g, explaining 34-75% of blubber EOF, but none in the Swedish sample. None of these substances were observable in liver, suggesting preferential accumulation in storage lipids (1).

While a considerable portion of EOF continues to be unexplained and over 300 features prioritized as possible PFAS remain unidentified, the researchers believe that continued investigation is essential. This study offers valuable insights into the EOF composition of lipid-rich tissues and underscores the importance of including nonpolar PFAS in fluorine mass balance studies and environmental exposure assessments (1).

References

1. Lauria, M. Z.; Shi, X.; Haque, F. et al. Discovery of Fluorotelomer Sulfones in the Blubber of Greenland Killer Whales (Orcinus orca). Environ. Sci. Technol. Lett. 2025, 12 (9), 1218-1224. DOI: 10.1021/acs.estlett.5c00516
2. Reconciling Terminology of the Universe of Per- and Polyfluoroalkyl Substances: Recommendations and Practical Guidance, OECD Series on Risk Management of Chemicals, OECD Publishing, 2021. DOI:10.1787/e458e796-en
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