An analysis of 12.7 million U.S. death certificates found that 6.9% of deaths among flight attendants and 6.7% among pilots were attributed to cancers linked to ionizing radiation. Cumulative exposure to cosmic radiation at high altitudes is a possible explanation, but the study does not prove that it caused the diseases.
Flight attendants andAir stewardess וPilots Ranked at the top of a ranking of 503 occupations in the United States in the rate of deaths from these types of cancer which have been linked in previous studies to exposure toionizing radiationThey even outpaced technologists inmedicine Nuclear, who work directly with radioactive materials for diagnostic and therapeutic purposes.
The finding emerges fromA study published in the journal JAMA Internal Medicine, but the researchers emphasize that this is a statistical relationship and not proof that cosmic radiation caused the cancer cases.
The research team, led by Dr. Vishal Patel of Harvard Medical School and Brigham and Women's Hospital, analyzed more than 12.7 million death certificates in the United States from 2020 to 2024. The death certificates were linked to each person's usual occupation.
The database included 14,190 pilots and 7,170 flight attendants. The researchers adjusted the results for age at death, gender, ethnicity, education, and marital status.
Not all types of cancer were included in the group.
The researchers focused on types of cancer that the scientific literature has linked to exposure to ionizing radiation: breast cancer, central nervous system tumors, multiple myeloma, leukemia—except chronic lymphocytic leukemia—lymphoma, thyroid cancer, prostate cancer, melanoma, and non-melanoma skin cancer.
After statistical adjustments, these cancers accounted for about 6.9% of all deaths among flight attendants and about 6.7% of deaths among pilots, the two highest rates among the 503 occupations examined.
Compared to all occupational groups, flight attendants had a 50% higher chance of dying from these cancers, and pilots had a 36% higher chance. This does not mean that half of aircrew will develop or die from cancer: it is a statistical ratio between the rate of specific deaths among flight attendants and the rate in other occupational groups.
Significant differences were found in mortality from breast, prostate, and central nervous system cancer, as well as melanoma. Pilots also had a higher rate of leukemia deaths.
The suspicious material comes from space, not the plane.
The passenger plane is not the source of the radiation. The possible cause lies in the radiation environment in which it flies.
The Earth is constantly bombarded with high-energy particles from the Sun and sources outside the Solar System. When the particles collide with atoms in the atmosphere, they create cascades of secondary particles. At sea level, the atmosphere provides a thick protective layer that blocks most of them.
Passenger planes typically cruise at an altitude of about 9–12 kilometers, above much of the atmospheric protective layer. The aircraft's aluminum body provides only limited protection from the high-energy particles.
The degree of exposure depends not only on altitude but also on the flight path, the duration of the flight, solar activity, and latitude. The Earth's magnetic field deflects some of the charged particles, but its protection is weaker near the poles. Therefore, long flights on northern routes may involve a greater dose of radiation than flights of similar length near the equator.
According to the American Institute for Occupational Safety and Health, air crews are exposed toCosmic radiation ionizing radiation on each flight. The estimate cited in the study is that pilots and flight attendants typically accumulate about 3–6 millisieverts per year, depending on the flight routes. For comparison, a passenger making ten round-trip flights across the United States per year would be expected to accumulate a dose of about 0.4 millisieverts from their flights.
Each single dose is small, but aircrew members repeat the exposure hundreds of times a year and over decades of work.
Ionizing radiation carries enough energy to knock electrons out of atoms and molecules. When this occurs inside a living cell, it can cause damage to DNA. Most damage is repaired or causes the cell to die, but sometimes mutations remain. The accumulation of such mutations is one of the processes that can lead to the development of cancer.
Both control groups reinforced the suspicion
The researchers also examined other workers related to the world ofaviation, including aircraft mechanics and aircraft components. These workers are exposed to aircraft, jet fuel, and industrial fluids, but do not accumulate thousands of hours at high altitudes. They do not have the same increased rate of cancer deaths that have been linked to radiation.
On the other hand, nuclear medicine technologists served as a positive control group because they work with known radiation sources. They did rank high, but came in 12th place—after air crews.
Additionally, pilots and flight attendants did not appear to be similarly prominent in mortality from cancers not classified as radiation-related, placing both groups near the middle of the occupational rankings. This pattern reinforces the hypothesis that exposure at altitude plays a role, but does not yet prove a causal relationship.
The study did not measure the radiation dose of each worker.
The main limitation is that the researchers did not know how many years each person worked on an air crew, how many hours they flew each year, at what altitudes and on what routes, and what their cumulative radiation dose was.
A death certificate usually lists a person's primary occupation, but does not describe their full employment history. The listing of occupation and cause of death may also contain errors.
The study looked at the proportion of specific types of cancer in total deaths, and did not follow a healthy population to measure who developed cancer over the years. Therefore, it is impossible to conclude from it what the absolute risk of a pilot or flight attendant developing the disease is.
There are other possible factors as well. Working nights, crossing time zones, and chronic disruption of the circadian rhythm can all affect health. Pilots may also be exposed to ultraviolet radiation that penetrates through some cockpit windows. In an explanatory article accompanying the study Australian radiation researchers have noted that air crews are exposed to a combination of several possible carcinogens, which are difficult to separate.
And what is happening in Israel?
In Israel, professional standards for protecting air crews from cosmic radiation were formulated as early as 2014. They include exposure assessment, consideration of radiation doses when planning flight hours and routes, informing employees, maintaining records, and special restrictions for pregnant workers.
According to the Occupational Safety and Health Administration, the radiation dose calculated at that time for an Israeli aircrew member performing 1,000 flight hours on typical routes was 2–4 millisieverts. The recommendations stated that the annual dose should be limited to 6 millisieverts and the radiation dose to the fetus of a pregnant worker to at least 1 millisievert. However, when the recommendations were published, it was clarified that they were a professional procedure and not a full legal obligation.
In the United States, the Federal Aviation Administration recognizes aircrews as workers occupationally exposed to ionizing radiation, but there is no personal monitoring requirement or federal dose limit equivalent to that applicable to some other radiation workers. In June 2026, it read National Academy of Sciences of the United States Change this situation, track cumulative exposure, and provide teams with better information and protection.
The occasional traveler has no reason to avoid flying.
Cosmic radiation does not distinguish between pilot, flight attendant, and passenger. The important factor is the cumulative dose. A person who flies dozens of long flights each year, especially on northern routes, will receive a higher dose than a person who flies once or twice a year.
However, there is no specific number of flights from which exposure suddenly becomes dangerous. For most occasional travelers, the additional radiation exposure is small and is not a reason to avoid flying. The main significance of the findings concerns air crews and people who fly unusually frequently over many years.
The researchers conclude that the combination of high occupational exposure, a unique mortality pattern, and a lack of adequate monitoring warrants a reexamination of aircrew protection. The next step will need to include studies that follow workers for years and link flight routes and personal radiation doses to morbidity and mortality.
Questions and Answers
Did the study prove that cosmic radiation caused cancer in air crews? No. The study found a statistical association between aircrew employment and mortality from radiation-related cancers. It did not measure personal radiation dose and cannot prove cause and effect.
Why is radiation exposure greater during a flight? At flight altitude, the atmosphere above the aircraft is much thinner and therefore blocks fewer high-energy particles from space. Exposure increases with altitude and is also affected by latitude, flight duration, and solar activity.
Should frequent flyers stop flying? The study does not indicate a specific threshold for the number of flights and does not recommend avoiding flying. The exposure on each flight is small, but it accumulates for those who spend many hours in the air over years.
How can the exposure of air crews be reduced? By calculating the cumulative dose, planning work arrangements so that the employee does not take many long or polar flights, monitoring particle events from the sun, and special adjustments during pregnancy. More of the topic in Hayadan:
- Radiation and microgravity caused changes in the liver that resemble accelerated aging
- Cosmic radiation, bit flipping, and Airbus aircraft shutdowns
- Will astronauts' kidneys survive a round trip to Mars?
- Artemis II and the health challenge of cosmic radiation
- Strong cosmic radiation could endanger astronauts flying to Mars
For the original publication: Opening the original publication
