PFAS Can Be Absorbed Through the Skin, Study Finds

Per- and poly-fluoroalkyl substances ( PFAS ) have long been scrutinized for harming both the planet and the public . Resistant to water and oil, and impossible to break down in the environment or the body, forever chemicals have been linked to cancer, reproductive issues and immune system damage, among a myriad of other health concerns .

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In an effort to curb exposure to PFAS, the Environmental Protection Agency (EPA) limited the amount of forever chemicals allowed in drinking water —marking the first time that the standards had been finalized for a new chemical since 1996—earlier this year.

PFAS build up in the human body mainly through the consumption of contaminated food and water, followed by indoor air and dust inhalation. But now, researchers have discovered evidence that that PFAS can be absorbed through the skin—something long questioned but previously disputed by the federal government organization, the Agency for Toxic Substances and Disease Registry (ATSDR).

In a study titled “Dermal bioavailability of perfluoroalkyl substances using in vitro 3D human skin equivalent models” published by Environment International, a team of researchers have proven for the first time that forever chemicals can, in fact, permeate the skin’s barrier and enter the bloodstream .

Lead author of the study Oddný Ragnarsdóttir carried out this research while studying for her doctorate at the University of Birmingham.

“The ability of these chemicals to be absorbed through skin has previously been dismissed because the molecules are ionized; the electrical charge that gives them the ability to repel water and stains was thought to make them incapable of crossing the skin membrane ,” Ragnarsdóttir said in a statement. “Our research shows that this theory does not always hold true and that, in fact, uptake through the skin could be a significant source of exposure to these harmful chemicals.”

Ragnarsdóttir, along with co-authors Mohamed Abou-Elwafa Abdallah and Stuart Harrad, investigated 17 different PFAS, focusing on the most prevalent and widely studied forever chemicals, in particular those regulated by the European Union’s Drinking Water Directive. The team used 3D human skin equivalent models to test how much of each chemical was absorbed, unabsorbed, or retained in the skin.

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“Our study provides first insight into significance of the dermal route as a pathway of exposure to a wide range of forever chemicals,” said Abdallah, co-author of the study. “Given the large number of existing PFAS, it is important that future studies aim to assess the risk of broad ranges of these toxic chemicals, rather than focusing on one chemical at a time.”

Of those 17 PFAS tested, 15 showed substantial (at least 5 percent of the exposure dose) dermal absorption. For PFOA —the most regulated of the lot—that absorption jumped to 13.5 percent, with 38 percent remaining in the skin and potentially entering circulation later. The amount absorbed appeared to depend on the length of the carbon chain within the molecule. The researchers found that substances with longer carbon chains showed lower absorption levels, while the compounds with shorter chains (which are used to replace longer ones like PFOA) were more easily absorbed.

PFOA is a globally banned, highly fluorinated compound with low surface tension, useful for making water-resistant products like raincoats and swimsuits. According to a 2023 study by Arnika, IPEN and 13 IPEN member groups and partners, PFOA was the most common PFAS found in outdoor jackets.

A year later, another study by the group reached the same conclusion, with PFOA being the most common chemical in the coats tested. Since the long-chain compound has been allegedly phased out, however, textile manufacturers have used side-chain fluorinated polymers based on fluorotelomer alcohols (FTOHs) and short-chain PFAS like perfluorobutanesulfonate (PFBS) to achieve the same results.

“This study helps us to understand how important exposure to these chemicals via the skin might be and also which chemical structures might be most easily absorbed,” said co-author Harrad. “This is important because we see a shift in the industry toward chemicals with shorter chain lengths because these are believed to be less toxic—however, the trade-off might be that we absorb more of them, so we need to know more about the risks involved.”

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