Perfluoroalkyl substances (PFAS) – also known as ‘forever chemicals’ – and microplastics are more toxic when combined than on their own.
Researchers from the University of Birmingham compared water fleas (Daphnia) unexposed to pollution with another group that had previously been exposed.
Daphnia genotypes with histories of chemical exposure reveal the compounded effect of pollutants exposure, the researchers explained.
Both groups were then exposed to microparticles of polyethylene terephthalate (PET), as well as PFOA and PFOS, two common PFAS which are typically used to provide water and grease resistance to consumer products.
The scientists observed a “markedly reduced number of offspring”, as well as developmental failure.
While 59% of the increased toxicity was attributed to the addition of the substances’ toxic effects, 41% was attributed to a synergy among the substances that makes them even more dangerous.
The authors believe this could be the result of enhanced affinity due to the differing charges of the chemicals.
Certain PFAS are intentionally added as ingredients in some cosmetic products, including lipsticks, eyeshadows, moisturisers, rouges, nail polish and enamel, blushers and cleansers.
These are used to condition and smooth the skin and hair, making them appear shiny, or to affect product consistency and texture.
Some PFAS may also be present in cosmetics unintentionally as the result of raw material impurities, or due to the breakdown of intentionally added PFAS ingredients that form other types of PFAS.
The European Union (EU) is currently in the process of restricting around 10,000 PFAS.
Measures to restrict intentionally-added microplastics in the Union, meanwhile, were adopted by the European Commission in 2023.
In cosmetics, intentionally-added microplastics include those used for exfoliation, and for obtaining a specific texture, fragrance or colour.
Read more: