Nicknamed “forever chemicals”, perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been the subjects of controversy over their longevity and potential harms to health and the environment. Now, a new study published in the Journal of Environmental Science and Technology Letters says they are also found in makeup without being mentioned in the ingredients list.

“These are products that are applied around the eyes and mouth with the potential for absorption through the skin or at the tear duct, as well as possible inhalation or ingestion,” study author Graham Peaslee, professor of physics at the University of Notre Dame, said in a statement. “PFAS is a persistent chemical – when it gets into the bloodstream, it stays there and accumulates. There’s also the additional risk of environmental contamination associated with the manufacture and disposal of these products, which could affect many more people.”

We still don’t have the full picture of how PFAS can impact health, and much of the evidence of their adverse effects come from animal studies that may or may not translate to humans. These studies have implicated PFAS in reproductive, developmental, liver, kidney, and immunological effects, as well as the formation of tumors.

A large part of our knowledge of their effects on humans comes from epidemiological studies on populations exposed to PFAS, for example via contaminated drinking water. According to the US Environmental Protection Agency (EPA), the most consistent finding of these studies is increased cholesterol levels, with more limited findings pointing to low infant birth weight, thyroid hormone disruption, immune system effects – and for a specific type of PFAS called PFOA, cancer.

In this new study, researchers tested 231 cosmetic products for the element fluorine (not to be confused with fluoride, the ion of fluorine that’s good for your teeth). The products were bought from locations in the US and Canada between 2016 and 2020.

Professor Peaslee explained to IFLScience that products with high levels of fluorine are likely to contain PFAS. Certain clays and minerals present in cosmetics also contain fluorine, which could lead to a high-fluorine product with no PFAS present. However, manufacturers can also treat natural minerals with PFAS to imbue certain desirable properties, further complicating the testing process.

Targeted analysis for PFAS was carried out on 29 of the products, all of which were found to contain at least four PFAS. Professor Peaslee stated that “The three main categories we observed include perfluorinated alkyl phosphates (PAPs), fluorotelomer alcohols, and fluoromethacrylates. Each of these may have health concerns directly in the human body, but all three of these types of PFAS have peer-reviewed publications that they can break down in the body (PAPs and fluorotelomer alcohols) or in sunlight (fluoromethacrylates) into known toxic PFAS, such as PFOA in some cases. There are known disease correlations with PFOA, while most of the C6 PFAS are still undergoing animal studies to evaluate their toxicity.”

The categories with the highest numbers of high-fluorine products were foundations (63 percent), eye products (58 percent), mascaras (47 percent), and lip products (55 percent). Over three-quarters of waterproof mascaras and nearly two-thirds of liquid lipsticks contained high fluorine concentrations.

"Lipstick wearers may inadvertently eat several pounds of lipstick in their lifetimes," said Peaslee in a statement. "But unlike food, chemicals in lipstick and other makeup and personal care products are almost entirely unregulated in the U.S. and Canada. As a result, millions of people are unknowingly wearing PFAS and other harmful chemicals on their faces and bodies daily."

The researchers found that products advertised as “long-lasting” or resistant to water and oil were more likely to have high fluorine levels. This is most likely due to the properties of PFAS that have led to their use in non-stick pans and water repellent fabrics. This family of over 4,700 chemicals has been in use since the 1940s, giving products grease, water, oil, and heat-proof properties.

According to the FDA, PFAS are added intentionally to cosmetics to "condition and smooth the skin, making it appear shiny, or to affect product consistency and texture," or can be present due to raw material impurities. However, none of the cosmetics tested had PFAS listed anywhere on their ingredients labels, which the study authors say points to a gap in US and Canadian laws around labeling.

“We measured products from all the major brands and a good number of smaller brands as well. As long as we had enough products from a manufacturer to test, we always found at least one of the products with high fluorine, and one of their products without fluorine. So I don't think we can call out any company for being fluorine-free or entirely PFAS-laden,” Professor Peaslee said. 

“This paper merely identifies a potential source of exposure to PFAS, but does not mean that the consumer should have to do anything more than to read the labels on products they buy. Unfortunately, in North America it appears the labeling may not be complete – and it is up to the industry to make sure that it is labeling their products correctly.”