The pilots and flight attendants who help us travel through the sky might be taking on more danger than advertised. Research out today finds that people with these jobs have a noticeably greater risk of dying from certain cancers, likely due to higher exposure levels of cosmic radiation that originate from outer space.
Scientists with Harvard Medical School and others compared death certificate data across hundreds of different occupations. Airline pilots and attendants were significantly more likely to die from cancers related to radiation exposure than other professions, they found, even compared to jobs where people have to intentionally spend time near radiation, like nuclear technologists. This research suggests much more should be done to safeguard these employees from the harmful effects of cosmic rays, particularly in the U.S., the authors say.
“These findings support consideration of occupational radiation protections for aircrew members commensurate with their exposure levels,” they wrote in their paper, published Monday in JAMA Internal Medicine.
Dangerous flying
Aircrew employees like pilots and flight attendants are already known to have the highest average exposure to ionizing radiation of any occupation in the U.S., with most of this coming from the greater amounts of cosmic rays seen at higher altitudes. Ionizing radiation can trigger the kind of harmful mutations in our cells that can turn them cancerous. However, it’s proven surprisingly difficult to establish whether the added radiation exposure that aircrew employees face actually translates to more cancer deaths, according to lead author Vishal Patel.
“Prior studies have generally been cohort studies assembled one airline, one country, or one cancer site at a time,” Patel, a physician and health care policy researcher at Harvard, told Gizmodo. “They tend to be limited by small numbers of deaths and by the choice of comparison group—aircrew are healthier, better educated, and more affluent than the general population, so whichever comparison you pick does a lot of the work.”
This study takes a different approach, one that only became possible in recent years. In 2020, U.S. death certificates began to routinely link deceased people to their usual occupation. This change made it much easier for the researchers to compare radiation-related cancer deaths across many different jobs using just one large source of data. These cancers include lymphoma as well as breast, thyroid, and prostate cancers, to list a few.
The team also included other comparisons to check against their hypothesis, such as cancers not linked to radiation. And they singled out two professions in particular to act as a sort of positive and negative control against pilots and flight attendants: nuclear technologists, who are regularly exposed to different sources of ionizing radiation, and ground aircrew members, who only share some of the same environments as flight aircrew employees.
Overall, the team analyzed 12.7 million deaths between 2020 and 2024 across 503 occupations; this included roughly 14,000 pilots and 7,000 flight attendants. After adjusting for relevant factors like marital status, education, and people’s age at death, the researchers found that these two jobs ranked first and second in having the greatest share of deaths from radiation-related cancers; 6.9% of attendants and 6.7% of pilots died of such cancers.
Though the team’s findings only demonstrate a correlation between occupation and these specific cancers, their other analyses bolster a causative explanation, according to Patel.
“The checks held. Aircrew ranked near the middle of all 503 occupations for cancers not thought to be radiation-related—so this isn’t a general excess of cancer deaths, it is specific to radiation-related cancers. Aircraft mechanics and assemblers, who work around aircraft, jet fuel, and hydraulic fluids but never accumulate flight hours, showed no elevation—so it isn’t the chemical environment of aviation,” he explained. “And nuclear technologists, who are exposed to radiation from entirely different sources, ranked 12th, which is what you’d expect if ionizing radiation is doing the work.”
Patel does note that their work can’t completely rule out other factors common to aircrew employees that might be raising their cancer risk, particularly the frequent disruption of their circadian rhythm from flying long-haul and overnight flights. Oh, and in case you’re wondering, even a relatively busy flyer (10 cross-country flights a year) isn’t being exposed to anywhere near the radiation levels seen with these occupations, according to the authors.
Implications for flight crew
This research clearly indicates that pilots and flight attendants need better protection from ionizing radiation while on the job, though trying to build inherently more protective airplanes won’t work, Patel says.
“Shielding is the intuitive answer and it’s the wrong one. At altitude you’re dealing with high-energy galactic cosmic rays and the secondary particles they produce when they hit the airframe—adding mass can generate more secondary neutrons than it absorbs. Aircraft cannot be practically shielded against this,” he said.
That said, many people who work near radiation, like nuclear technologists, are afforded multiple forms of protections to limit their exposure that aren’t commonplace today among U.S. aircrew. These include wearing dosimeters that actively track their radiation levels, documentation of their cumulative doses, and established regulatory limits on how much radiation they should be exposed to at most while working. We also know which kinds of flights will bombard aircrew with the most radiation.
“Dose rate rises steeply with altitude and is meaningfully higher at high latitudes, where the Earth’s magnetic field offers less deflection. So polar and ultra-long-haul routes carry the highest doses, and the practical levers are scheduling ones—capping cumulative annual flight hours, rotating crews off the highest-dose routes rather than assigning the same people repeatedly, adjusting assignments during pregnancy, and rerouting or descending during solar particle events, which can briefly raise dose rates by a large factor,” Patel said. “None of that requires new technology.”
Patel adds that while the Federal Aviation Administration does formally recognize that aircrew are occupationally exposed to ionizing radiation, the U.S. currently sets no dose limits nor mandates monitoring of these employees—regulations that aircrew in the European Union have had for years, along with schedule adjustments during pregnancy.
The team hopes further research can shore up their findings, such as studies looking at whether a pilot’s estimated cumulative radiation dose is linked to a higher cancer risk. But these stewards of the sky already deserve better from their job, the authors argue, and it shouldn’t take much effort to start now. “A reasonable first step would be individual dose estimation with records that follow a crew member across employers over a career,” Patel said.
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