People who fly for a living could face a higher risk of certain types of cancers, a new Harvard study suggests.
Flight attendants and pilots in the U.S. face the highest risk of radiation-related cancer deaths out of a list of more than 500 occupations, the researchers concluded.
"As you get high up in the atmosphere, you're exposed to ionizing radiation from the sun. It's called cosmic radiation," study author Anupam B. Jena, M.D., Ph.D., told Fox News Digital.
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The finding was based on analysis of data from the National Vital Statistics System, specifically, nearly 13 million U.S. death certificates between 2020 and 2024. Out of those records, 14,000 were pilots and 7,000 were flight attendants.
Across all occupations, the team analyzed mortality from radiation-related cancers, including breast cancer, multiple myeloma, leukemia (except chronic lymphocytic leukemia), lymphoma, central nervous system cancers, thyroid cancer, prostate cancer, melanoma and non-melanoma skin cancers.
They did not include lung cancer to prevent confounding the results with any smoking-related risk.
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Pilots and flight attendants were found to have "statistically significantly" higher mortality rates linked to breast cancer, central nervous system cancers, prostate cancers and melanoma. Pilots were also more likely to die from leukemia.
Among all flight attendant deaths, 6.9% were linked to radiation-related cancers, as were 6.7% of pilots’ deaths. This was higher than the rates for any other occupations, the researchers found.
For cancers not related to radiation, the rates were comparable to other occupations.
"It's not just lifestyle factors or factors about these individuals that are making them more likely to develop cancer at large," Jena added.
The study was published Aug. 17 in JAMA Internal Medicine.
"The risk increase is meaningful enough for the group," Jena said. "Our study doesn't speak to the individual pilot or flight attendant, but more so to the two groups as a whole."
Each year, airline workers receive about 3 to 6 millisieverts of cosmic radiation, compared to 0.4 millisieverts for someone who takes 10 round-trip cross-country flights, according to the Centers for Disease Control and Prevention.
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That means airline workers may receive roughly eight to 15 times the annual cosmic radiation exposure of someone taking 10 cross-country round trips.
"It is thought that this would be a cumulative risk, so the more time that you're exposed to that cosmic radiation, the greater the increase in risk that you might experience," Jena pointed out.
The findings could also raise questions about whether U.S. pilots and flight attendants should receive additional or earlier cancer screenings.
"I think the level of screening may need to be higher," Jena said, noting that approaches differ between the U.S. and other countries.
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"Just making sure that these individuals are screened regularly, that they may be screened earlier in life than other folks — I think that's totally on the table."
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For people who fly frequently for business or pleasure, Jena said the findings should be less concerning, noting that very few passengers accumulate flight time comparable to pilots and flight attendants.
He added, "This is really sort of a consideration for people who spend their life in the air."
The study has several limitations. Because it was observational, the findings cannot establish that cosmic radiation caused the elevated cancer mortality among pilots and flight attendants, only that the two were associated.
The researchers also did not have access to data on individual workers’ radiation exposure, which means they could not determine whether those with greater exposure faced greater risks.
Other occupational or lifestyle factors could also potentially contribute to the findings.