Dangerous ‘forever chemicals’ absorb through human skin, study finds

Toxic “forever chemicals” can be absorbed through human skin, a study has confirmed for the first time.

It was previously thought that PFAS, perfluoroalkyl substances, which are found in a wide range of household products, were unable to permeate the skin barrier.

But a study of 17 commonly used varieties of PFAS found that most of them were able to enter the bloodstream through the skin after 36 hours of exposure.

PFAS are so-called “forever chemicals” because they do not break down naturally in the environment, but are valued for their moisture-repellent properties.

They have been used for decades in items such as waterproof clothing, non-stick pans and cosmetics.

They have been found in drinking water, soils and dust, and have been linked to immune system disruption, impaired liver function and decreased birth weight.

Substantial absorption

The study from researchers at the University of Birmingham applied samples of each chemical to laboratory grown tissue that mimics human skin.

Of the 17 PFAS tested, the researchers found that 15 showed “substantial” absorption into the skin, meaning at least 5 per cent of the dose was absorbed.

It found that the absorption into the bloodstream of perfluorooctanoic acid (PFO), which is commonly used for food packaging, was 13.5 per cent of the dose, with a further 38 per cent retained within the skin.

Dr Oddný Ragnarsdóttir, the lead author of the study, said: “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 study also found that more modern PFAS, which have shorter carbon chains, may be more easily absorbed, despite having been introduced by the industry because they were believed to be less toxic.

Overturning assumptions

Prof Stuart Harrad, of the University of Birmingham’s School of Geography, Earth and Environmental Sciences and the study’s co-author, added: “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. 

“This is important because we see a shift in industry towards 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.”

Prof Harrad added that the study would help inform regulators around what PFAS concentration levels would lead to levels that would be absorbed easily through the skin.

But he said more research would be needed to find out what the impact of the chemicals is after they have permeated the skin barrier.

Dr David Megson, a reader in Chemistry and Environmental Forensics from Manchester Metropolitan University, said the research had overturned previous assumptions that it would be difficult for PFAS to penetrate the skin barrier.

“This is especially concerning given that PFAS are widely used within our clothes and many cosmetic products,” he said. “Most of the population are unknowingly covering themselves in PFAS every day when they get dressed and apply their makeup, these toxic chemicals are slowly leaching into us and may be leading to a wide range of adverse health effects.”