Employees in one very common profession at higher cancer risk than even nuclear workers. Harvard study examines 13 million death records

A job that involves spending much of the working life in the sky may carry a cancer risk that is not immediately obvious. A new Harvard Medical School study has found that flight attendants and pilots had the highest and second-highest proportions of radiation-related cancer deaths among more than 500 occupations studied, even ranking above nuclear technologists.

The research, published in JAMA Internal Medicine, examined nearly 13 million US death certificates recorded between 2020 and 2024. The records covered 503 occupations, including about 14,000 pilots and 7,000 flight attendants.

Flight attendants and pilots stood out in the study

The analysis found that about 6.9% of deaths among flight attendants and 6.7% of deaths among pilots were linked to cancers classified as radiation-related. These were the highest proportions among all the occupations included in the research.


The researchers also found significantly higher death rates from breast cancer, central nervous system cancers, prostate cancer and melanoma among both groups. Pilots additionally had a higher rate of deaths from leukemia.

The study, led by Vishal Patel, a clinical fellow in surgery at Brigham and Women’s Hospital, adjusted for factors including age, sex, race, ethnicity, education and marital status. It also compared aircrew with ground-based aviation workers. Aircraft mechanics and assemblers did not show higher rates of radiation-related cancer deaths.

Nuclear technologists, despite working around radiation from non-cosmic sources, ranked 12th in the analysis, according to Harvard Medical School.

The reason has to do with flying at high altitude

The concern for pilots and cabin crew is mainly cosmic radiation, which comes from space and reaches aircraft at higher levels than it does people on the ground. The atmosphere gives us some protection, but that protection is reduced at commercial flight altitudes.

The CDC says aircrew are exposed to cosmic ionizing radiation on every flight, with exposure depending on factors such as flight duration, altitude and route.

According to estimates cited by Harvard, aircrew receive around 3 to 6 millisieverts of cosmic radiation each year. An average passenger taking 10 cross-country round trips in a year receives about 0.4 millisieverts, making the occupational exposure considerably higher.

Harvard senior author Anupam Jena explained the basic reason for the exposure, saying, "As you get high up in the atmosphere, you're exposed to ionizing radiation from the sun. It's called cosmic radiation," in comments to Fox News Digital.

The findings do not prove radiation caused the cancers

The researchers were careful about what the study can and cannot show. It found an association between working as aircrew and radiation-related cancer mortality, but it does not prove that cosmic radiation itself caused the deaths.

Other factors linked to the profession may also play a role, including disrupted sleep, working across time zones and other occupational exposures. The researchers also did not have individual radiation-dose records for each worker.

The study excluded lung cancer from its radiation-related cancer analysis because smoking could have made the results harder to interpret.

Researchers raise questions about protection

The findings have also brought attention to the way aircrew radiation exposure is handled in the US. The Federal Aviation Administration recognises pilots and flight attendants as occupationally exposed to ionizing radiation, but they are not covered by federal radiation dose limits or mandatory monitoring requirements in the same way as some other radiation-exposed workers.

Jena and his colleagues said the results support considering stronger occupational radiation protections for US aircrew that match their level of exposure.

For people who fly occasionally, the findings are a different matter. The researchers focused on people who spend thousands of hours flying as part of their careers, rather than ordinary passengers who take flights from time to time.

The study therefore does not mean that flying itself is a major cancer threat to regular travellers. Instead, it adds to the evidence that the long-term health effects of repeated cosmic radiation exposure among pilots and flight attendants need closer attention and further research.