Irina Mordukhovich, corresponding author of the study, said the research is one of "the largest and most comprehensive studies of cancer among cabin crew to date". That exposure may not be concerning for people taking individual flights, but for people whose jobs involve flying, that risk may have a negative effect on their health, as the study results suggest.
The study, which was conducted by researchers at Harvard T.H. Chan School of Public Health in Boston, Massachusetts, surveyed 5,366 USA flight crew members and found that slightly over 15 per cent of them reported having been diagnosed with cancer.
The researchers studied the data from a survey conducted from 2013 to 2014 as part of the Flight Attendant Health Study, which was first launched in 2007.
Unions for flight attendants at Southwest and American airlines identified crew fatigue as a top health issue that needs to be addressed, something the pending FAA reauthorization bill could do with required minimum rest times. "The E.U. already evaluates radiation exposure among flight attendants, which our findings show may be an important step toward lowering cancer risk among this work population", Eileen McNeely, a fellow study author also of Harvard TH Chan, said in a university statement.
"Having fewer children and having children later in life are known risk factors for breast cancer", Pinkerton, who wasn't involved in the current study, said by email.
One of those carcinogens is cosmic ionizing radiation, which is elevated at higher altitudes, Mordukhovich told Live Science.
Air crews have the largest average annual effective dose of all radiation-exposed workers in the USA, according to 2009 findings by the National Council on Radiation Protection and Measurements.
Scientists have long suspected that flight attendants' cancer risk might be affected by their exposure to naturally occurring radiation at high altitudes, shift work, time zone changes that disrupt sleep cycles, and poor cabin air quality, researchers note in Environmental Health.
Although it's still not a proven link, the researchers writing in Environmental Health think US airlines could do more to protect flight attendants from the perils of radiation and abnormal sleep patterns. They are, for example, less likely to smoke or be overweight, and have lower rates of heart disease. "Consistent with previous studies, we report a higher lifetime prevalence of breast, melanoma and non-melanoma skin cancers among flight crew relative to the general population". (The risk for pilots may be similar, but this study focused specifically on flight attendants.) The Association of Flight Attendants did not provide comment in time for publication.
Any current or former U.S. flight attendant was eligible to participate.