Some school uniforms were found to have high levels of potentially harmful PFAS chemicals

High levels of chemicals called per-and polyfluoroalky substances (PFAS) were detected in water-proof or stain-resistant school uniforms in the United States and Canada, according to a new study published Wednesday in the Journal of Environmental Science and Technology.

PFAS chemicals, often called “forever chemicals” because of their slow breakdown, are widely used for their non-stick properties. They are ubiquitous and found in a range of everyday products such as non-stick cookware, stain and water repellants on carpets, food packaging and personal care products such as shampoos and cosmetic products.

Researchers studied more than 72 products from nine different brands, finding that school uniforms had high amounts of these potentially harmful chemicals. The highest levels were detected in clothing that was labeled as 100% cotton or cotton/spandex.

Due to widespread use and their slow breakdown, these chemicals can build up in humans and the environment over time. Current scientific research suggests that exposure to high levels of certain PFAS may cause a range of health problems, from delays in development in children to increased risk of some cancers, with the highest risk associated with drinking or eating contaminated food over an extended time. Scientists, however, are continuing to learn about the health effects of exposure to different types and levels of PFAS.

Researchers are especially concerned about possible high exposure, especially for children.

"Our findings are concerning as school uniforms are worn directly on the skin for about eight hours per day by children, who are particularly vulnerable to harmful chemicals," said Dr. Arlene Blum, a study co-author and the executive director of the Green Science Policy Institute.

It's not clear if PFAS chemicals cause health problems if exposed on the skin, but researchers who led the study said that they may end up in children’s bodies through skin absorption, eating with unwashed hands, hand-to-mouth behaviors and mouthing of fabric by younger children.

"These chemicals are not well studied. We still have a lot to learn and we are not sure what harmful effects, if any, these chemicals have by skin exposure and clothing," said Dr. Stephanie Widmer, a medical toxicologist and an emergency medicine physician.

According to the study, the PFAS levels in some uniforms exceeded the tolerable daily intake set by European regulators. In the United States, regulators have yet to set similar allowable limits for clothing. But given these concerns, bills in New York and California that require the phasing out of PFAS in textiles, including school uniforms, by Jan. 1, 2025, were passed by state lawmakers.

The Centers for Disease Control and Prevention said exposure to PFAS chemicals may be associated with increased cholesterol levels, changes in liver enzymes, decreases in infant birth weights, decreased vaccine response in kids, increased risk of birth complications in pregnant women and increased risk of some cancers.

“The reality is the health concerns that have been reported in association with PFAS cannot be ignored, and while we are learning more about PFAS and their potential dangers, we should all try to limit our exposures as much as reasonably possible," said Widmer.

Added Blum: "Concerned parents should check if any of their children’s uniforms are labeled 'stain-resistant.' If so, they should ask school administrators to update their uniform policies and when purchasing new uniforms, specify PFAS-free uniform options."

ABC News' Youri Benadjaoud contributed to this report.

Khushali Jhaveri, MD, a board-certified internal medicine physician, is a hematology/oncology fellow at Moffitt Cancer Center and is a member of the ABC News Medical Unit.