06 Feb Pregnant Flight Attendants May Have Increased Risk of Miscarriage
MedicalResearch.com Interview with:
Barbara Grajewski, Ph.D., M.S., Epidemiologist
Elizabeth Whelan, Ph.D., Branch Chief
Christina Lawson, Ph.D., Epidemiologist
Division of Surveillance, Hazard Evaluations and Field Studies
National Institute for Occupational Safety and Health
Centers for Disease Control and Prevention
Medical Research: What is the background for this study?
Response: The study, published January 5 online ahead of print in the journal Epidemiology, looked at potential workplace reproductive hazards for flight attendants. While in flight, flight attendants are exposed to cosmic radiation from space and, periodically, can be exposed to radiation from solar particle events. Flight attendants can also experience circadian disruption (disruption to the body’s internal time clock) from traveling across time zones and from working during hours when they would normally be asleep.
For this study, we analyzed 840 pregnancies among 673 female flight attendants and examined company records of 2 million single flights flown by these women. From these data, we estimated a marker of circadian disruption—working during normal sleeping hours—and exposure to cosmic and solar particle event radiation for each flight. This gives us a much more specific estimate of the exposures these workers face on the job every day. We also assessed the physical demands of the job, such as standing and walking for more than 8 hours a day and bending at the waist more than 25 times a day. Cosmic radiation and circadian disruption among flight attendants are linked very closely on many flights and are very difficult to look at separately when trying to understand what causes miscarriage. This is the first study that has attempted to separate these two exposures to determine which is potentially linked to miscarriage. This study is also an improvement over other studies in its assessment of cosmic radiation for each individual flight flown and from documentation of solar particle events. Earlier studies have looked at how many years a flight attendant has worked or other ways to estimate exposures that are not as specific.
Medical Research: What are the main findings?
Response: Working during normal sleep hours, exposure to cosmic radiation and high physical job demands may put pregnant flight attendants at higher risk for miscarriage.
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. 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 0.44 mGy on a single flight. These data suggest that if a pregnant flight attendant were to work on a flight that travels through a solar particle event, she could be exposed to more radiation than is considered safe during pregnancy. Finally, from a questionnaire administered to the flight attendants, we found that early miscarriage (in the first trimester) was about 2 times as likely for a pregnant flight attendant with high physical job demands compared to those without high physical job demands.
Medical Research: What should clinicians and patients take away from your report?
Response: Flight attendants may want to consult their healthcare professional about the potential for occupational hazards if they are pregnant or considering pregnancy. Our results may also apply to those women who fly frequently for business or pleasure.
Information from this study supports the need for clearer guidelines and additional research on potential reproductive risks for flight attendants.
Medical Research: What recommendations do you have for future research as a result of this study?
Response: It will take a larger study of pregnant flight attendants and rigorous exposure assessment to get beyond our findings with better focus. It might be possible to improve the study’s insights by adding biomarker and monitoring methods, such as sleep and light monitors, which have come a long way in the last few years
Grajewski B, Whelan EA, Lawson CC, Hein MJ, Waters MA, Anderson JL, MacDonald LA, Mertens CJ, Tseng C, Cassinelli RT, Luo L
Epidemiology. 2015 Mar;26(2): 192–203.