Working during normal sleep hours, high physical job demands and exposure to cosmic radiation may put pregnant flight attendants at higher risk for miscarriage, according to a new study out of the United States.
“What’s notable about our study is this was the first time each flight worked by a flight attendant was examined for potential reproductive health hazards,” said lead investigator Barbara Grajewski. “This gives us a much more specific estimate of the exposures these workers face on the job every day.”
For this study, investigators analyzed 840 pregnancies among 673 female flight attendants and examined company records of two million single flights flown by these women. From these data, researchers estimated a marker of circadian disruption — working during normal sleeping hours — and exposure to cosmic and solar particle event radiation for each flight, and assessed the physical demands of the job.
Using the airline records, researchers estimated each flight attendant’s chronic sleep disturbance during the first trimester of pregnancy. They added up the time the flight attendants were working in the air when they would normally be asleep at home. Results indicated that flight attendants who flew more than 15 hours during normal sleep hours in the first trimester were at increased risk for miscarriage.
To estimate the flight attendants’ exposure to background cosmic radiation, researchers used the CARI software program from the U.S. Federal Aviation Administration, which is designed to provide radiation dose estimates for past flights. Additionally, researchers from the National Institute for Occupational Safety and Health (NIOSH) in the U.S. collaborated with National Aeronautics and Space Administration (NASA) to compare the flight attendants’ flights with NAIRAS data — a model that estimates radiation exposure to commercial airline crew from solar particle events.
Analysis of exposure to background cosmic and solar particle event radiation suggested that exposure to 0.1mGy or more may be associated with increased risk of miscarriage. Solar particle events were infrequent, but during one of the solar particle events studied, radiation dose reached 0.45 mGy on a single flight. These data suggest that if a pregnant flight attendant works on a flight that travels through a solar particle event, she could be exposed to more radiation than is recommended during pregnancy.
From a questionnaire administered to the flight attendants, researchers found that early miscarriage was about two times as likely for a pregnant flight attendant with high physical job demands compared to those without high physical job demands. High physical job demands included standing and walking for more than eight hours per day and bending at the waist more than 25 times per day.
“Our study shows that flight crew exposures are unique; exposure to cosmic radiation and circadian disruption are linked very closely on many flights,” said Grajewski. “This is the first study that has separated these two exposures to determine which is potentially linked to miscarriage. This information supports the need for clearer guidelines and additional research on potential reproductive risks for flight attendants.”