Per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals”, have been detected in various environments worldwide, from Arctic ice and polar bears to penguin colonies in Tasmania, and even in rainwater, sea spray, and dust from the International Space Station. These persistent chemicals have also been found in the blood and breast milk of people globally. However, the pathways through which PFAS enter the human body are not yet fully understood.
Potential Exposure Pathways for PFAS
While ingesting contaminated food, water, and other products containing PFAS, as well as breathing in PFAS-contaminated air particles, are known exposure pathways, recent research has revealed that dermal exposure – the absorption of PFAS through the skin – could be another significant route for these chemicals to enter the human body.
PFAS are present in numerous consumer products, including skincare items, cosmetics, and waterproof clothing. These compounds are often referred to as “forever chemicals” due to their persistence in the environment and the human body, where they can remain for many years.
Study Reveals PFAS Absorption Through Human Skin
A new study conducted by environmental chemists has shown, for the first time, that many PFAS compounds can be absorbed through human skin, contrary to previous beliefs about the skin acting as a barrier. The researchers investigated the dermal permeation of 17 different PFAS chemicals using 3D models of lab-grown human skin tissue that mimic the properties of real human skin.
Health Effects of PFAS Exposure
Once absorbed into the body, PFAS can have various health effects. Some PFAS disrupt hormone systems and can lower the immune response to childhood vaccinations against diseases such as diphtheria. Other concerning effects include lowered birth weight in newborns and changes in liver function. One particular PFAS, perfluorooctanoic acid (PFOA), has recently been designated as “carcinogenic to humans” by the International Agency for Research on Cancer.
Differences in Absorption Between Short and Long-Chain PFAS
The study results showed that short-chain PFAS, which contain fewer carbon molecules, were absorbed by the skin more readily than long-chain PFAS. For example, 58% of the applied dose of perfluoropentanoic acid (a PFAS with five carbon molecules) was absorbed by the end of the 36-hour exposure period. In contrast, only 13% of the applied dose of PFOA (a PFAS with eight carbon molecules) had permeated through the skin during the same time period.
Time Required for PFAS Absorption
The researchers also observed that skin permeation took some time to occur for the PFAS included in the study. However, given that these compounds are found in products used daily, frequent contact could lead to substantial exposure over time.
Implications for Industry and Regulation
The study’s findings help to understand the importance of dermal exposure to PFAS and indicate which chemical structures might be most easily absorbed. This is particularly relevant as the industry shifts towards chemicals with shorter chain lengths, assuming they are less toxic or persistent. However, the trade-off might be that humans absorb more of these short-chain PFAS, as these smaller chemicals are more easily transported through the skin barrier.
Manufacturers and regulators must ensure that the risks involved are thoroughly understood before bringing PFAS-containing products to market. The study’s results highlight the need for further research and stricter regulations to protect human health from the potential dangers of PFAS exposure.