Comedian Kristina Wong formed an online community of “Aunties” to make homemade skull caps and face coverings for health care workers.


The claim: The chemicals in your face mask are giving you lung cancer

As health officials around the country encourage mask-wearing to slow the spread of COVID-19, a Facebook post is claiming masks can give wearers cancer. 

“THAT MASK IS GIVING YOU LUNG CANCER,” reads the Oct. 15 Facebook post, written by Guy Crittenden. As a source, Crittenden cites his time as former editor of the Canadian trade publication HazMat Management, which in part focuses on issues related to occupational safety and waste management. 

He also asserted his claims are backed up by “OSHA mask experts” Tammy Clark and Kristen Meghan, two women with backgrounds in environmental health and safety who appeared on anti-vaccine personality Del Bigtree’s webcast “The HighWire.” The two women spoke out against face masks, though notably did not address the supposed cancer-causing chemicals Crittenden’s post mentions. Bigtree has used his program to push various COVID-related conspiracy theories.

Crittenden’s post been shared across a number of platforms, with Pennsylvania State Rep. Russ Diamond sharing a link to it via The Human News Network, a website that claims to “carry the load vacated by the Fake Media.” 

Crittenden claims wearing masks causes oxygen deprivation (experts say it doesn’t) and that chemicals used on masks will give wearers cancer.

Masks won’t lead to lung cancer. But USA TODAY found that other claims about chemicals and face masks may be true but require some context.

More: Fact check: What’s true and what’s false about face masks?

Ethylene oxide used to sterilize masks?

One of the chemicals Crittenden mentions is ethylene oxide, a “known carcinogen” he claims is used to sterilize surgical masks.

According to the World Health Organization, ethylene oxide is a “potent neurotoxin, a known human carcinogen, a potential reproductive hazard, and an allergic sensitizer” that can cause health problems with acute overexposure and chronic exposure. Lymphoma and leukemia are the cancers most commonly linked to occupational exposure to ethylene oxide, although stomach and breast cancers may also be associated, according to the National Cancer Institute. 

At the same time, “ethylene oxide sterilization is an important sterilization method that manufacturers widely use to keep medical devices safe,” according to the U.S. Food and Drug Administration. Ethylene oxide may sometimes be the only method of effectively sterilizing equipment that would otherwise be damaged in other sterilization processes, the FDA notes.

Video: COVID updates: CDC releases new guidance on mask wearing

About 50% of all sterile medical devices in the U.S. are sterilized with ethylene oxide, according to the FDA. The FDA encourages medical device makers to follow consensus standards to ensure residual levels of ethylene oxide are within safe limits. 

There are a limited number of online listings where manufacturers claim their masks are sterilized with ethylene oxide, also known as oxirane. However, according to the FDA, face masks sold to consumers (including cloth masks) are generally not sold as sterile, and surgical masks are not typically provided as sterile. 

When surgical masks are sold for use by health care professionals, they may sometimes be packaged in bulk for terminal sterilization — when products are sterilized in their final packaging — and will be labeled as sterile, the spokesperson explained. If sterilized, face masks or surgical masks would likely be sterilized using ethylene oxide.

As with other medical devices sterilized using ethylene oxide, FDA guidance helps ensure any remaining levels are within safe limits. 

More: Parents face holiday flight nightmare if kids can’t keep masks on. But airlines take a hard line.

Early on in the pandemic, Illinois-based medical supplies manufacturer and distributor Medline Industries sought FDA approval to resterilize used masks using ethylene oxide. Crucially, however, the Occupational Safety and Health Administration recommends against using ethylene oxide for resterilizing single-use filtering face piece respirators — masks like N95s — due to risks associated with the chemical. 3M, which manufactures masks and personal protective equipment, also warns against using ethylene oxide to decontaminate masks because wearers could breathe in residual amounts.

What about Teflon?

Crittenden also claims single-use surgical masks contain polytetrafluoroethylene (PTFE), known by the brand name Teflon. PTFE is used in some masks, although polypropylene is the material most commonly used to make medical face masks and N95-style respirator masks.

The American Cancer Society does not report any cancer risk tied directly to PTFE, but did note perfluorooctanoic acid (PFOA), a chemical used to make Teflon prior to 2015, has been classified as “possibly carcinogenic to humans.” However, the American Cancer Society also stated PFOA burns off in the process of making Teflon and is not present in significant amounts in the final products.

In an email to USA TODAY, Crittenden expressed concerns about the chemicals that have since replaced PFOA and suggested they carry similar risks. According to the FDA, the science surrounding the use of these chemicals is still developing.

More: Fact check: CDC report doesn’t show mask-wearers are more likely to contract COVID-19

“I might not be able to find a medical paper from, say, the (The New England Journal of Medicine) that specifically says ‘this mask gives people cancer,’” Crittenden wrote. “It’s more like a conviction-based on circumstantial evidence.”

PTFE itself can cause coughing and flu-like symptoms through polymer fume fever, a rare disease caused by overheating the material — for example, when cooking with nonstick pans — to about 500°F (for reference, the normal range for frying meat is between 400°F to 470°F). 

Full Fact, which fact-checked a claim similar to Crittenden’s, concluded there is “no evidence that anyone would suffer from (polymer fume fever) as a result of the normal wearing of a mask made with Teflon unless they were inhaling fumes from the burning of the mask.”

Our ruling: Partly false 

We rate this claim as PARTLY FALSE, based on our research. It is false to state that a mask will give its wearer lung cancer. Crittenden correctly states some masks include PTFE, but misleads readers about potential health risks associated with this material, especially when it comes to chemicals remaining in the finished product. Similarly, ethylene oxide is a known carcinogen, but it’s not used to sterilize masks as widely as the original post claims.

Our fact-check resources

  • Guy Crittenden, Oct. 15 Facebook Post 
  • The HighWire with Del Bigtree: “The COVID Defection Begins”
  • CBS, April 14: “Anti-vaxxers spread fear about future coronavirus vaccine”
  • PA State Rep. Russ Diamond, Oct. 26 Facebook Post
  • Human News Network, Oct. 21, “Is Your Mask Giving You Lung Cancer?”
  • USA TODAY, Oct. 17: “Fact check: Experts say face masks don’t cause oxygen deprivation, neurological damage”
  • World Health Organization: “Sterilizing units, ethylene oxide”
  • National Cancer Institute: “Ethylene Oxide” 
  • U.S. Food and Drug Administration: “Ethylene Oxide Sterilization for Medical Devices”
  • U.S. Food and Drug Administration: “Submission and Review of Sterility Information in Premarket Notification (510(k)) Submissions for Devices Labeled as Sterile”
  • Chicago Tribune, April 29: “After meeting with Trump, Medline wants FDA approval to sterilize N95 masks with ethylene oxide. Two other federal agencies are against it, citing cancer risks for health care workers.”
  • Occupational Safety and Health Administration: “Enforcement Guidance on Decontamination of Filtering Facepiece Respirators in Healthcare During the Coronavirus Disease 2019 (COVID-19) Pandemic”
  • 3M: “Decontamination of 3M Filtering Facepiece Respirators, such as N95 Respirators, in the United States – Considerations”
  • Solvay: “Materials for Covid-19 PPE and Medical Equipment”
  • American Chemical Society Public Health Emergency Collection: “Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging”
  • The BMJ: “Polymer fume fever”
  • Teflon: “The Facts about Polymer Fume Exposure”
  • American Cancer Society: “Perfluorooctanoic Acid (PFOA), Teflon, and Related Chemicals”
  • Full Fact, Oct. 26: “Teflon in masks does not pose a health risk, unless you get it extremely hot”
  • U.S. Food and Drug Administration: “Per and Polyfluoroalkyl Substances (PFAS)”

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Our fact check work is supported in part by a grant from Facebook.

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