Commercial flight crews, including both pilots and flight attendants, face a significantly higher risk of dying from radiation-related cancers than workers who directly handle radioactive materials on the ground, according to new research.

Cosmic radiation originates from outer space. Only a fraction of these high-energy particles reaches the Earth's surface, but human exposure increases substantially for individuals who fly frequently at high altitudes.

In the past, only limited evidence from small-scale studies suggested that atmospheric radiation exposure might lead to elevated cancer mortality rates among frequent flyers, particularly commercial pilots and cabin crew. The new research "brings important new evidence to bear on this question," wrote two independent Australian radiation specialists who were not involved in the study in an accompanying commentary.

The newly published study, which appeared Monday in JAMA Internal Medicine, evaluated national records drawn from over 12 million death certificates that included detailed occupational data. Authors focused specifically on mortality rates from cancers known to be linked to radiation exposure, such as leukemia, lymphoma, multiple myeloma, as well as cancers of the skin, breast, thyroid, prostate, and central nervous system.

Across more than 500 different occupations evaluated, researchers found that flight attendants recorded the highest percentage of deaths attributed to radiation-related cancers, while pilots ranked second. For both of these aviation professions, the statistical odds of dying were noticeably elevated across every specific type of radiation-linked cancer.

Neither occupational group demonstrated higher-than-average mortality rates for cancers that are not associated with radiation exposure, noted commentary authors Catherine Olsen and Ken Karipidis. This finding "supports the hypothesis that occupational radiation exposure, rather than lifestyle or socioeconomic factors, underlies the observed excess," they explained in their analysis.

The study's authors determined that flight attendants had roughly 50% higher odds of dying from a radiation-related cancer compared to the general working population, while commercial pilots faced approximately 36% higher odds.

When measuring absolute statistical risk, roughly 6.9% of flight attendant deaths were caused by these specific cancers — representing nearly 1 in 14 deaths. Among pilots, the figure reached 6.7%, compared to just 5% within the general working population, according to lead author Dr. Vishal Patel of Harvard Medical School.

The researchers acknowledged several inherent limitations in their findings. They were unable to quantify the precise amount of atmospheric or external radiation exposure received by individual pilots and flight attendants. Additionally, there remains a possibility that occupations were misclassified on a small fraction of the death certificates analyzed.

The study also could not measure another potentially significant contributor unique to aviation careers: elevated cancer risks triggered by chronic disruption of the human biological clock, caused by regular jet lag, crossing multiple time zones, and working irregular schedules.

While the Federal Aviation Administration acknowledges that commercial aircrews are routinely exposed to ionizing radiation during flight, federal regulations do not establish dose limits or require regular monitoring, the researchers highlighted.

"You can't manage an exposure you've decided not to measure," Patel stated in an email statement.

Sara Nelson, leader of a union representing 55,000 flight attendants, stated that the study confirms the urgent need to address workplace radiation hazards seriously, an issue the labor union has raised for years.

"The risk is known, but crew are not educated or informed. And, no one is taking responsibility," said Nelson, president of the Association of Flight Attendants-CWA.

Routine annual skin examinations may be recommended for everyone working aboard high-altitude flights, while female crew members should consider earlier or more frequent mammograms, Olsen and Karipidis suggested. Physicians providing care to pilots and flight attendants ought to maintain a "heightened index of suspicion" for potential cancers when assessing these patients, they concluded.