New research shows that 15 different PFAS (perfluoroalkyl substances) or toxic “forever chemicals” can permeate the skin barrier and reach the body’s bloodstream. Researchers say their study, published in Environment Internationalis the most comprehensive assessment showing that PFAS can be absorbed through the skin.

The researchers investigated 17 different PFAS. The compounds selected correspond to chemicals regulated by the EU’s Drinking Water Directive and are among those most widely used and most widely studied for their toxic effects.

Of the 17 PFAS tested, 15 substances showed substantial dermal absorption of at least 5% of the exposure dose. At the exposure doses examined, absorption into the bloodstream of the most regulated PFAS (perfluoro octanoic acid (PFOA)) was 13.5% with a further 38% of the applied dose retained within the skin for potential longer-term uptake into the circulation.  

For the dermal absorption studies, researchers used 3D human skin equivalent models. PFAS had already been shown to enter the body through other routes, such as inhalation or ingestion via food or drinking water.  

Lead author of the study, Dr Oddný Ragnarsdóttir carried out the research while studying for her PhD at the University of Birmingham. She explained: “The ability of these chemicals to be absorbed through skin has previously been dismissed because the molecules are ionised. The electrical charge that gives them the ability to repel water and stains was thought to also make them incapable of crossing the skin membrane. 

“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.” 

The amount of the chemical absorbed seemed to correlate with the length of the carbon chain within the molecule. Substances with longer carbon chains showed lower levels of absorption, while compounds with shorter chains that were introduced to replace longer carbon chain PFAS like PFOA, were more easily absorbed.

You can explore more about PFAS in the Dermalorian Podcast episode “Some Things Last Forever: PFAS and Dermatology” with Michelle Hure, MD.