The claim: Long-term mask-wearing may cause advanced-stage lung cancer, one study shows
It is well-known by now masks can help prevent the spread of the novel coronavirus. New data from the U.S. Centers for Disease Control and Prevention recommends even better prevention with double masking. But one social media post claims wearing a mask may cause serious harm in the long run.
“Long-Term Mask Use May Contribute to Advanced Stage Lung Cancer, Study Finds,” asserts a Jan. 29 article from BlackListed News, an independent news platform known to publish pseudoscience and conspiracy-related content.
How exactly this alarming condition arises is through the “inhalation of harmful microbes” into the lung that has been “cultivated through prolonged mask-wearing,” writer Phillip Schneider claims.
He also provides quotes from lead author Dr Leopoldo Segal, director of New York University Langone’s Lung Microbiome Program, explaining the scientific basis for these microbes’ destructive effect, and ties the study’s discovery to the larger trend of purported evidence against mask-wearing.
BlackListed News did not return USA TODAY’s request for comment.
Fact check: Masks encouraged on federal lands if distancing isn’t possible
Oral bacteria can lead to poor lung cancer prognosis and progression
The human body is a host to millions of different kinds of microorganisms inhabiting both the skin surface and deep within various organs, such as the gastrointestinal tract. These bacteria, viruses, fungi and other life forms – the microbiome – play a key role in maintaining health and preventing disease. Shifts in the microbiome because of ageing, long-term dieting, stress or pharmaceutical drugs have been linked to conditions like obesity, depression and autoimmune diseases, among many others.
They can even contribute to cancer, as some emerging research has found. Segal’s study particularly looked at how the microbiome within the lungs – previously believed a sterile, microorganism-free environment – plays into the development of lung cancer, a disease afflicting over 2 million people worldwide and responsible for nearly 1.8 million deaths in 2018, according to the World Health Organization.
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The study analyzed the lung microbiomes of 83 untreated adult patients with lung cancer and found that patients with advanced-stage lung cancer (stage III to IV) “had greater enrichment of oral commensals in the lung than those who had the early-stage disease (stages 1-3a),” stated a November news release on the study from the American Association for Cancer Research. Oral commensals are simply oral bacteria.
Some of those bacteria are the same ones typically found in the respiratory tract’s lower airways, such as Prevotella and Veillonella, both of which can cause oral infections and mingle with Streptococcus to form dental plaque (in the case of Veillonella).
These oral bacteria were found to be associated with “decreased survival, even after adjusting for tumour stage.” Veillonella, Prevotella and Streptococcus, in particular, were associated with poor prognosis. All three, plus another bacteria making up the mouth’s normal flora, Rothia, were associated with tumour progression.
The study did report that one limitation to its findings – aside from the study size being too small to allow for patient stratification into subgroups – was that since lung microbiomes were sampled before patients undergoing their respective cancer treatments, “changes resulting from treatment could not be assessed.”
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No correlation of long-term mask-wearing with lung cancer
USA TODAY reviewed the study’s paper published online this month: Nowhere is long-term mask-wearing mentioned or even alluded to.
Segal and another author, Dr James Tsay of NYU’s Grossman School of Medicine, told Reuters their study did not involve long-term mask-wearing, and that, “currently there is no scientific evidence to this misinterpretation of our result.”
The study’s participants were individuals recruited from NYU’s Lung Cancer Biomarker Center between March 2013 and October 2018, before the pandemic. Tsay stated that “since mask-wearing was not common during our study period, it is highly unlikely it is one of the reasons that contribute to our findings.”
“The main source of these bacteria to the lung is the mouth and oropharynx (the part of the pharynx that is behind the mouth) itself,” said Segal, explaining these oral bacteria are in “pretty much every individual” and how much is present depends on oral hygiene and food intake.
In an email to USA TODAY, Schneider, the author of the BlackListed News article, acknowledged it was his personal view “this study suggests that prolonged mask-wearing may breed microbes which contribute to advanced-stage lung cancer.” Schneider did not say whether he verified his inference with the study’s authors but did add a clarification to the article on his website. This revision has not been made to the original BlackListed News article.
Fact check: Masks encouraged on federal lands if distancing isn’t possible
No evidence mask-wearing poses danger to health
Claims regarding whether face masks work against COVID-19, are detrimental to health (causing oxygen reduction or excessive blood carbon dioxide levels) or violate constitutional amendments have been debunked numerous times.
The claim in November alleging people were arriving in intensive care units sick with pneumonia from mask-wearing has also been debunked.
While bacteria and other microorganisms can collect on the inside of a mask, microbiologist Patrick Grant of Florida Atlantic University told CBS Florida affiliate CBS12 that whatever collects does not have the potential to harm unless it is allowed to build up; borrowing someone else’s mask is also ill-advised.
The CDC recommends storing cloth masks properly – either in plastic bags for damp masks, paper bags for dry or clean ones – and washing regularly, making sure to dry thoroughly. Disposable masks should be thrown away after one use.
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Our rating: False
The claim that long-term mask-wearing was found by one study to contribute to advanced-stage lung cancer is FALSE, based on our research. The study, headed by Dr Leopoldo Segal, director of NYU’s Lung Microbiome Program, found patients with advanced-stage lung cancer had greater amounts of oral bacteria in the lungs compared to early-stage patients. The presence of these bacteria was associated with decreased survival, poor prognosis and tumour progression. Nowhere is the impact of long-term mask-wearing or the relationship with lung cancer mentioned or alluded to. The writer of the article making the claim stated that the relationship was his personal view. There is no evidence to suggest masks, the only effective means to prevent COVID-19 transmission, instead cause disease.
Our fact-check sources:
Centres for Disease Control and Prevention, Feb. 10, “Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021”
Media Bias/Fact Check, accessed Feb. 16, “Blacklisted News”
Nature, Jan. 29, 2020, “The complex relationship between drugs and the microbiome”
The New York Times, Sept. 10, 2019, “Seeking an Obesity Cure, Researchers Turn to the Gut Microbiome”
Science Magazine, May 7, 2020, “Meet the ‘psychobiotic: the gut bacteria that may alter how you think, feel, and act”
Nature, Jan. 29, 2020, “Could a bacteria-stuffed pill cure autoimmune diseases?”
Nature, Jan. 29, 2020, “Fighting cancer with microbes”
The Journal of Immunology, June 15, 2016, “The Lung Microbiome, Immunity, and the Pathogenesis of Chronic Lung Disease”
The World Health Organization, Sept. 12, 2018, “Cancer”
American Association for Cancer Research, Nov. 11, 2020, “The Lung Microbiome May Affect Lung Cancer Pathogenesis and Prognosis”
American Journal of Respiratory and Critical Care Medicine, June 2, 2011, “Topographical continuity of bacterial populations in the healthy human respiratory tract”
Journal of Bacteriology, June 3, 2015, “Interaction between Streptococcus spp. and Veillonella tobetsu ensis in the Early Stages of Oral Biofilm Formation”
Journal of Microbiological Methods, Jan. 10, 2017, “Isolation and identification methods of Rothia species in oral cavities”
Cancer Discovery, Feb. 1, “Lower Airway Dysbiosis Affects Lung Cancer Progression”
Reuters, Feb. 4, “Fact check: No evidence linking masks to oral bacteria and to lung cancer; article refers to the study that did not involve masks”
USA TODAY, Jul. 27, 2020, “Fact check: What’s true and what’s false about face masks?”
CBS12, Nov. 20, 2020, “Bacteria is growing on your mask”
U.S. Centers for Disease Control and Prevention, Oct. 28, 2020, “How to Store and Wash Masks”
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This article originally appeared on USA TODAY: Fact check: Long-term face mask-wearing does not cause lung cancer
