Harvard Study Examines Cancer Risk Among Airline Crew
A new Harvard-led study has drawn attention to the airline crew cancer risk associated with long-term exposure to cosmic radiation. Researchers examined millions of U.S. death certificates to compare mortality patterns among pilots, flight attendants and workers in hundreds of other occupations.
The study, published in JAMA Internal Medicine, analyzed about 13 million death certificates from 2020 through 2024. The records included the deaths of approximately 14,000 pilots and 7,000 flight attendants.
Researchers focused on radiation-associated cancers and examined whether airline workers showed higher mortality rates than expected.
Why Airline Workers Face More Cosmic Radiation
Airline crews spend many hours at high altitudes, where Earth’s atmosphere provides less protection from cosmic radiation.
Cosmic radiation comes from sources including the sun and deep space. Although everyone receives some exposure, the amount increases at cruising altitude.
Airline crew members can receive an estimated 3 to 6 millisieverts (mSv) or more of cosmic radiation each year, depending on their flight schedules and routes.
By comparison, a passenger who takes 10 cross-country round trips in a year could receive about 0.4 mSv.
As a result, frequent-flying crew members can receive substantially more annual cosmic radiation than typical passengers.
Cancer Risk May Increase With Years of Exposure
Researchers say occupational exposure can accumulate over a person’s career.
Lead researcher Anupam B. Jena, M.D., Ph.D., highlighted the importance of cumulative exposure. Pilots and flight attendants who spend many years in the profession may therefore experience greater lifetime exposure than occasional travelers.
However, radiation exposure represents only one potential factor in cancer risk. Lifestyle, genetics, age and other workplace or environmental exposures can also influence health outcomes.
Radiation-Associated Cancer Deaths Among Flight Attendants
The researchers examined several cancers that can be associated with radiation exposure.
Among flight attendants, radiation-associated cancer deaths accounted for about 6.9% of total deaths examined in the study.
The researchers reported elevated mortality patterns involving several cancers, including:
- Melanoma
- Central nervous system cancers
- Prostate cancer
- Breast cancer
The study did not include lung cancer in its radiation-associated analysis because smoking could strongly influence the results.
Pilots Also Showed Elevated Cancer Mortality
Pilots showed a similar pattern.
Radiation-associated cancers accounted for about 6.7% of deaths among pilots in the study.
Researchers identified higher mortality rates involving several cancer types, including:
- Central nervous system cancers
- Leukemia
- Melanoma
- Breast cancer
- Prostate cancer
These findings highlight the need to better understand occupational radiation exposure among aviation professionals.
How Cosmic Radiation Exposure Compares
The amount of cosmic radiation an aircraft crew member receives depends on several factors.
Flight altitude is important because radiation exposure generally increases as aircraft climb higher. Flight duration also matters, meaning long-haul crews can receive greater cumulative exposure.
Frequent flights can therefore add up over years of employment.
Passengers, meanwhile, generally spend far less time at cruising altitude. Someone who takes only occasional flights receives much less cumulative exposure than a professional who spends thousands of hours in the air.
What the Study Means for Pilots and Flight Attendants
The findings do not mean that every pilot or flight attendant will develop cancer because of cosmic radiation exposure.
Instead, the research highlights a potential occupational risk that deserves continued monitoring and investigation.
Airline workers routinely undergo repeated exposure over many years. Therefore, understanding the long-term effects could help researchers and aviation authorities develop better strategies for protecting crews.
The findings also reinforce the importance of studying occupational health risks among workers who regularly operate at high altitudes.
More Research Is Needed
The Harvard study provides important evidence about cancer mortality among airline workers, but researchers must consider the limitations of death-certificate data.
Such records can show patterns across large populations, but they cannot establish that cosmic radiation directly caused an individual’s cancer.
Other factors could also contribute to the observed differences.
Even so, the findings add to the growing evidence that airline crew cancer risk deserves closer attention, particularly because pilots and flight attendants can accumulate radiation exposure throughout long careers.
