The introduction of new chemicals requires detailed study by specialists
Researchers used laboratory-grown human skin samples to find out whether PFAS can enter our bloodstream through skin contact. The experiment confirmed that various common chemicals can be absorbed into the human body.
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Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that have been renowned since the 1950s for their resistance to heat, stains, oil, grease and water. As such, they are widely used in the manufacture of pots and pans, as well as in food packaging, furniture, adhesives and clothing.
Research results indicate the likelihood that these chemicals may contribute to various diseases. But although they have not yet been proven to directly cause these health problems, there is growing evidence regarding their use, which has led to their ban or regulation in many countries.
It is common knowledge that PFAS can enter the body through several routes. The most obvious of them is entering the body with food, as well as with air. However, it is generally believed that PFAS cannot penetrate the skin barrier, although there is a link between the use of personal care products and the levels of these chemicals in a person's blood.
Now, researchers from the University of Birmingham have provided the most comprehensive assessment to date of PFAS absorption into human skin. They confirm that most of these chemicals can indeed enter the body in this way.
«The ability of these chemicals to penetrate the skin has not previously been considered, since the molecules are ionized, — explained researcher Oddni Ragnarsdottir.
It was believed that the electrical charge that gives them the ability to repel water and stains also makes them unable to penetrate the skin membrane.
“Our study shows that this theory is not necessarily true and that in fact dermal absorption may be a significant source of exposure to these harmful chemicals,” she adds.
Ragnarsdottir and her colleagues studied 17 different types of PFAS. Importantly, these chemicals correspond to those regulated by the EU Drinking Water Directive.
To safely test whether skin could absorb these chemicals without resorting to animal studies, the team used 3D multilayer tissue models equivalent to human skin. The scientists then applied samples of each PFAS to see what proportion was absorbed, not absorbed, or persisted in the skin models.
Of the 17 chemicals tested, 15 showed significant absorption through the skin, representing at least 5 percent of the radiation dose. Worryingly, the radiation dose measured for perfluorooctanoic acid, the most regulated PFAS, was 13.5 percent, with another 38 percent of the administered dose retained on the skin.
Amount of the chemical absorbed, according to the analysis correlated with the length of its carbon chain. Chemicals with longer carbon chains had lower absorption levels, while chemicals with shorter chains were absorbed more easily. For example, perfluoropentanoic acid was four times more easily absorbed than perfluorooctanoic acid.
“This study helps us understand how important skin exposure to these chemicals may be, and which chemical structures are most easily absorbed,” — explained Stuart Harrad.
The experiment is important because scientists are seeing a shift in industry towards shorter chain-length chemicals because they are thought to be less toxic, but the trade-off may be that we are consuming more of them, so we need to be more aware of the risks involved.
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