PFAS, or per- or polyfluoroalkyl substances, are ubiquitous in modern life. First produced at the end of World War II, these chemicals are in everything from furniture and cosmetics to food packaging, non-stick pans and clothing. They have also infiltrated our water, soil, and food, making PFAS a major concern for human and ecological health.
Beginning in the early 2000s, some of the most common and well-studied PFAS were phased out through a combination of industry shifts and international regulations. A new study from Harvard has found that since that phaseout, North Atlantic pilot whales have 60% lower concentrations of these chemicals in their bodies.
The study, published in Proceedings of the National Academy of Sciences, overcomes a long-standing challenge in the detection and measurement of PFAS concentrations. While older, so-called legacy PFAS are well understood and easy to detect, newer generations of chemicals are harder to pinpoint.
"With legacy PFAS, we know a lot more about their environmental transport and impacts on organisms," said lead author Jennifer Sun, a recent Ph.D. graduate and current postdoctoral fellow. "But we have a lot less information about what is going on with many newer compounds that have been produced to replace the phased-out legacy PFAS."
Senior author Elsie Sunderland , the Fred Kavli Professor of Environmental Chemistry in the John A. Paulson School of Engineering and Applied Sciences, has likened the PFAS problem to whack-a-mole : Once researchers understand the exposure and health implications of one chemical, a new one is developed.
To overcome that challenge, the researchers took a new approach: Instead of measuring individual PFAS, they measured bulk organofluorine, which captures the fluorine in most PFAS compounds. They used these measurements as a proxy for total concentrations of PFAS, including newer types of PFAS that are harder to identify on their own.
Armed with this approach, the researchers studied whale tissue samples in collaboration with longtime research partners in the North Atlantic Ocean's Faroe Islands, who maintain a unique, long-term archive of pilot whale tissues. As apex predators, the whales are considered sentinels of marine pollution because their bodies retain chemical exposures for long periods, and they exist in the outer ocean, demonstrating how far harmful compounds can travel into the environment. The researchers found that overall organofluorine levels were primarily made up of four legacy PFAS that all peaked in the mid-2010s and had declined by more than 60% by 2023.
"Production phase-outs, which were initially voluntary and later driven by regulation, have been quite effective at reducing concentrations of these chemicals in near-source communities as well as more remote ecosystems, which I think is very positive and important to emphasize," said Sun.
Surprisingly, this reduction comes at a time when global production of new PFAS is actually on the rise, which begs the question: if most of the newer PFAS aren't accumulating in ocean ecosystems like the legacy ones, where are they accumulating?
"Generally, the ocean is thought to be the terminal sink for human pollution on land. But we are not seeing substantial accumulation of the newest PFAS in the open ocean. So, where are they?" Sunderland asked. "While our results are good news for ocean contamination, it suggests newer PFAS may behave differently from the legacy ones. It underscores the need to place stronger regulations on ongoing PFAS production to mitigate future impacts."
The paper's co-authors were Euna Kim, Heidi Pickard, Bjarni Mikkelsen, Katrin Hoydal, Halla Reinert and Colin Thackray. The research was supported by the National Science Foundation (ICER-2108452) and the National Institutes of Environmental Health Sciences Superfund Research Program (P42Es027706).
