Scientists from Stockholm University and the Swedish Museum of Natural history, in collaboration with partners in Greenland and Canada, have identified a previously undocumented class of PFAS* in the blubber of killer whales.

The new study, published in Environmental Science and Technology Letters, reveals the presence of five fluorotelomer sulfones – highly fluorinated, lipophilic (fat-loving) chemicals never before reported in wildlife. Unlike well studied PFAS, which typically accumulate in protein-rich tissues such as liver and blood, these new substances accumulate in fat-rich blubber.

“This is the first time that highly fluorinated PFAS have been shown to preferentially accumulate in fat,” says lead author Mélanie Lauria, formerly a doctoral student at the Department of Environmental Science at Stockholm University and currently at the Swiss Federal Institute of Aquatic Science and Technology (EAWAG).

“It challenges the long-held assumption that PFAS primarily bind to proteins and accumulate in the liver or blood. Research has so far focused on a subgroup of PFAS that is “charged” or “polar”, and therefore interact mainly with proteins. The results of this study show that we have overlooked PFAS that are neutral and can interact and accumulate in neutral fats such as blubber.”

Using advanced mass spectrometry techniques, the researchers analysed tissue samples from killer whales sampled in Greenland and Sweden. The newly identified compounds accounted for up to 75 percent of fluorine-containing substances in blubber, but were undetectable in liver tissue – evidence of their fat-loving nature.

“These findings suggest that we may be underestimating the PFAS body burden in marine mammals. Blubber can represent up to half of a marine mammal’s body mass, so neglecting fat-soluble PFAS could significantly undermine the accuracy of exposure assessments,” says co-author Jonathan Benskin, professor at the Department of Environmental Science, Stockholm University.

According to the authors, monitoring efforts should be expanded to include fat-soluble PFAS in order to better understand the full extent of PFAS exposure in Arctic ecosystems.

The study raises new questions about chemical exposure in apex predators, with implications for environmental and human health – particularly in Arctic regions where marine mammals are part of traditional diets.

The research was funded by the European Union’s Horizon 2020 program and supported by Indigenous communities in Greenland, who facilitated the legal sampling of whales through subsistence hunting.

*PFAS stands for poly- and perfluorinated alkyl substances and is a collective term for a large group of organic compounds with a carbon chain where hydrogen atoms are completely (perfluorinated carbon chain) or partially (polyfluorinated carbon chain) replaced by fluorine atoms.

The article “Discovery of Fluorotelomer Sulfones in the Blubber of Greenland Killer Whales (Orcinus orca)” is published in Environmental Science and Technology Letters.
https://pubs.acs.org/doi/10.1021/acs.estlett.5c00516