A new study warns that more than half of popular cosmetics sold in the United States and Canada may contain high levels of a toxic chemical called polyfluoroalkyls (PFAS).

Researchers from the University of Notre Dame tested more than 200 products including concealers, foundation, eye products, eyebrows and lip products, and found evidence of PFAS in about half (52%) of them.

Alarmingly, previous research has linked some PFAS to a range of health problems, including kidney and testicular cancer, high blood pressure, thyroid disease, low birth weight, and immunotoxicity in children.

Professor Graham Beasley, who led the study, said PFAS is a persistent chemical – when it enters the bloodstream, it stays there and builds up. There is also an additional risk of environmental contamination associated with the manufacture and disposal of these products, which can affect many people.

PFAS is a large, complex and ever-expanding group of manufactured chemicals that are widely used to make various types of everyday products, according to the National Institute of Environmental Health Sciences.

“For example, it prevents food from sticking to cooking utensils, makes clothes and carpets stain-resistant, and creates more effective extinguishing foam. PFAS is used in industries such as aviation, automobiles, construction and electronics,” the researchers explained.

In the study, the team tested more than 200 cosmetic products for fluorine – an indication of the use of PFAS in the product.

Their analysis revealed that 56 percent of foundation and eye products, 48 ​​percent of lip products and 47 percent of mascara, contained high levels of fluorine.

In particular, products advertised as “long lasting” and “wear-resistant” were found to contain high levels, which is not surprising, according to the team, given that PFAS is often used to resist water.

Alarmingly, 29 products were further tested and found to contain up to 13 PFAS – however only one of these listed PFAS as an ingredient.