Anti-fog sprays and cloths that have become popular to help keep eyewear from fogging up while wearing a face mask can expose users to carcinogens.
That’s the warning from experts led by Duke University, who found that these treatments may contain carcinogenic perfluorinated and polyfluorinated alkylated substances (PFAS).
The team subjected four anti-fog sprays and five anti-fog cloths — all of which received top ratings on Amazon — to high-resolution mass spectrometry.
Specifically, chemical analysis revealed that all nine products contained so-called fluorotelomer alcohols (FTOHs) and fluorotelomer ethoxylates (FTEOs).
These are two types of PFAS that have, until now, largely slipped under the radar, meaning scientists aren’t sure what health effects they may have.
However, research has suggested that once inhaled or absorbed through the skin, FTOHs may well break down in the body into other long-lived, toxic forms of PFAS.
These can include perfluorooctanoic acid (PFOA), which – along with perfluorooctane sulfonic acid (PFOS) – has been linked to disorders like cancer.
Anti-fog sprays (pictured) and cloths that have become popular to prevent glasses from fogging up when wearing a face mask can expose users to carcinogens
The study was carried out by environmental scientist Nicholas Herkert of Duke University in North Carolina and his colleagues.
“Our tests show that the sprays contain up to 20.7 milligrams of PFAS per milliliter of solution, which is quite a high concentration,” Dr. Herkert said.
“If we were to assume that FTOHs and FTEOs have similar toxicity to PFOA and PFOS, then spraying these bottles would expose you to PFAS at levels several orders of magnitude higher than you would receive from drinking a liter of water that contains PFAS at the current EPA health advisory limit for safe drinking, which is 70 nanograms per liter.
The idea for the study came after environmental chemist Heather Stapleton – also from Duke University – looked at the ingredient list on a bottle of anti-fog spray the researcher had bought for her 9-year-old daughter.
“Ironically, it was advertised as safe and non-toxic. It said to spray it on your glasses and use your fingers to rub it in,’ Prof Stapleton said, noting that the other eight products the team tested didn’t even mention their ingredients.
“It’s troubling to think that the products people use daily to protect themselves during the pandemic may put them at a different risk.”
Dr. Herkert also noted that the FTEOs used in the four popular spray mixes they analyzed showed significant toxicity in their lab tests that damaged cells and converted them to fat.
“FTOHs and FTEOs could be metabolic disruptors, but the only way to find out is through in vivo testing on whole organisms,” he explained.
“We only did in vitro (lab box) tests.”
Further studies will be needed to flesh out these initial results, the team said, with the next logical step being to analyze a wider selection of anti-fog products and assess the impact of the chemicals used on living organisms. .

“It’s troubling to think that the products people use daily to protect themselves during the pandemic may put them at a different risk,” said paper author and environmental chemist Heather Stapleton of Duke University.
“Because of COVID, more people than ever — including many medical professionals and other first responders — are using these sprays and wipes to keep their glasses from fogging up while wearing masks or face shields,” added Professor Stapleton.
“They deserve to know what’s in the products they use,” she concluded.
The full results of the study have been published in the journal Environmental Science and Technology Letters.