PFAS, or perfluoroalkyl substances, are a group of synthetic chemicals widely used in various industries and consumer products due to their water- and stain-repellent properties. These forever chemicals have gained notoriety for their persistence in the environment and potential health risks. While previous research has focused on PFAS exposure through ingestion and inhalation, a new study from the University of Birmingham has shed light on another significant route of exposure: absorption through the skin.
The research team, led by Dr. Oddný Ragnarsdóttir, conducted a comprehensive assessment of PFAS absorption into human skin. Their findings, published in the journal Environment International, challenge the long-held belief that these chemicals cannot penetrate the skin barrier due to their ionized nature. The study examined 17 different PFAS compounds that are among the most widely used and studied for their toxic effects.
To investigate skin absorption, the researchers used 3D human skin equivalent models, which are laboratory-grown tissues designed to mimic the properties of normal human skin. These models allowed the team to measure the proportions of each PFAS compound that were absorbed, unabsorbed, or retained within the skin layers. The results were striking: 15 out of the 17 tested PFAS showed substantial dermal absorption, with at least 5% of the exposure dose being absorbed.
One of the most regulated PFAS, perfluoro octanoic acid, PFOA, demonstrated a 13.5% absorption rate into the bloodstream at the tested exposure doses. Additionally, 38% of the applied PFOA dose was retained within the skin, potentially allowing for longer-term uptake into circulation. The study also revealed an interesting correlation between absorption rates and the length of the carbon chain within the PFAS molecules. Compounds with shorter carbon chains, which were introduced as replacements for longer-chain PFAS like PFOA, showed higher absorption rates. For instance, perfluoro pentanoic acid was absorbed at a rate four times higher than PFOA, reaching 59%.
These findings have significant implications for public health and regulatory policies. Professor Stuart Harrad, a co-author of the study, emphasized the importance of understanding how different chemical structures affect absorption rates. He noted that while industry has been shifting towards shorter-chain PFAS due to their perceived lower toxicity, the trade-off might be increased absorption through the skin. This highlights the need for further research into the risks associated with these replacement chemicals.
The study's results also raise concerns about the widespread use of PFAS in personal care products and clothing items that come into direct contact with the skin. Previous studies have shown links between the use of such products and PFAS concentrations in human blood and breast milk. With this new evidence of dermal absorption, the potential for cumulative exposure through multiple routes becomes even more apparent.
Dr. Mohamed Abdallah, another co-author of the study, emphasized the importance of assessing the risks of a broad range of PFAS rather than focusing on individual chemicals. Given the large number of existing PFAS compounds and their varying properties, comprehensive studies like this one are crucial for understanding the full scope of potential health impacts and informing future regulatory decisions.
This groundbreaking research underscores the need for continued vigilance and investigation into the health effects of PFAS exposure. As our understanding of these persistent chemicals grows, it becomes increasingly clear that a multifaceted approach to risk assessment and regulation is necessary to protect public health and the environment from the far-reaching impacts of forever chemicals.
