Toxic PFAS absorbed through skin at levels higher than previously thought

Researches have found that PFAS can be absorbed through the skin from a range of products, including makeup. Photograph: fstop123/Getty Images/iStockphoto

New research “for the first time proves” toxic PFAS forever chemicals are absorbed through human skin, and at levels much higher than previously thought.

Though modeling and research has suggested the dangerous chemicals are absorbed through skin, University of Birmingham researchers say they used lab-grown tissue that mimics human skin to determine how much of a dose of PFAS compounds can be absorbed.

The paper shows “uptake through the skin could be a significant source of exposure to these harmful chemicals”, said lead author Oddný Ragnarsdóttir.

PFAS are a class of about 16,000 compounds used to make products resistant to water, stains and heat. They are called “forever chemicals” because they do not naturally break down and have been found to accumulate in humans. The chemicals are linked to cancer, birth defects, liver disease, thyroid disease, plummeting sperm counts and a range of other serious health problems.

Humans are most commonly exposed to them through water and diet, but researchers in recent years are increasingly looking into inhalation and dermal absorption. The latter is especially a concern because of the wide range of products containing PFAS that come into contact with skin. Among them are bandages, waterproof clothing, makeup, personal care products, upholstery, baby products and guitar strings.

Researchers applied samples of 17 different PFAS compounds to the three-dimensional tissue model and were able to measure the proportion of the chemicals that were absorbed.

The skin took in “substantial” amounts of 15 PFAS, including 13.5% of PFOA, one of the most toxic and common kinds of the chemical. The skin absorbed a further 38% of the PFOA dose with a longer application. US regulators have found that virtually no level of exposure to PFOA in drinking water is safe.

PFOA is a relatively larger compound, and smaller “short-chain” PFAS that industry now more commonly produces and claims are safer were absorbed at higher levels – up to nearly 60% of one short chain compound dose was absorbed by the skin.

“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,” said study co-author Stuart Harrad.

Some scientists and industry officials have claimed PFAS used in personal care products or makeup won’t be absorbed because the molecules are ionised so they can repel water.

“Our research shows that this theory does not always hold true,” Ragnarsdóttir said.