According to an American study, a significant presence of chemicals called “Forever Chemicals” that could cause health problems such as asthma, obesity or infertility have been found in school uniforms in the United States and Canada.

“Forever chemicals” are substances that the body breaks down very slowly. The substances in question are known as perfluorinated (PerFluoroAlkyl-PFAS) and are often used to make stain or water repellent clothing.

These products are found in greater quantities in 100% cotton uniforms, while synthetic materials are less common, according to a study published in Environmental Science and Technology Letters.

Children’s exposure to its chemicals could increase their risk of long-term health problems, scientists say.

But the researchers said their study was small, based on 72 product samples, and they didn’t yet know if the products got into children’s bodies.

“But we know that perfluorides pose a health risk, so the idea of ​​children in the uniforms releasing these substances is worrying,” said Dr. Martha Venier from the University of Indiana told the BBC.

Perfluors can be found in textiles, food packaging or in foam concentrates, the foam contained in fire extinguishers. They are known for their non-stick and water-repellent properties.

These chemicals have long worried scientists because they do not degrade under normal environmental conditions.

Perfluors number in the thousands and persist in soil and water. However, they can also accumulate in the human body when ingested.

Scientists are drawing the most attention to exposure, especially among young people, as their lower weight poses a greater risk.

About 20% of children in Canada and the United States wear uniforms.