Cancer at Altitude
Could cancer be an occupational hazard?

Sky-high levels of cosmic ionizing radiation exposure can be a major health concern for flight attendants. Despite the fact that flight attendants are exposed to several known carcinogens in the cabin environment, few studies have quantified the cancer-causing risks, and researchers say they are one of the most understudied cohorts.

Recently published research from the Harvard T.H. Chan School of Public Health found flight attendants have higher rates of several types of cancer than the general population. According to the study, increased cancer occurrences were related to flight crew tenure and the accumulation of hazardous exposures over time.

Led by research associate Irina Mordukhovich, the group of Harvard researchers surveyed participants of the Harvard Flight Attendant Health Study at airports and through online and mailed-in surveys. More than 5,300 flight attendants answered questions about their flight schedules and disclosed any diagnoses of cancer. The study compared the prevalence of their self-reported cancer diagnoses to an existing cohort from the Centers For Disease Control and Prevention’s National Health and Nutrition Examination Survey, which is ongoing.

To date, the Harvard Flight Attendant Health Study is the largest and most comprehensive study conducted on cancer prevalence among flight attendants, and the first to reveal a higher rate of non-melanoma skin cancers in this occupation. Mordukhovich found a higher prevalence of breast, melanoma, uterine, thyroid, gastrointestinal, and cervical cancers compared to the general public.

“Our study showed, not precise, but elevated associations for all the cancers we looked at,” Mordukhovich says. “Breast and skin cancers are the ones that show up consistently, although I think it’s possible that you have a lot of associations that are just not being seen in the literature because they’re not as common,” she adds. Researchers suggest that it’s difficult to study cancers that are more rare and fatal. The findings are particularly alarming considering flight attendants are healthier than the general population on average. “The fact that we’re seeing the higher cancer rates given the fact that it’s a healthy worker population by definition, and the fact that they have this profile of reduced obesity and healthier behaviors is striking,” Mordukhovich says.

In the U.S., [flight crew members are] actually the most highly exposed radiation workers, and yet there are no regulations around their exposure at all.

This observational study, however, does not prove cause and effect. “We see this association and know the exposure that flight attendants have that are either confirmed or probable carcinogens, which are ionizing radiation, circadian rhythm destruction, different chemical contaminants in the cabin, and possibly U.V. radiation,” Mordukhovich says.  

Everyone is exposed to radiation daily from natural and man-made sources, and it is well-known that radiation can cause cancer. However, it is less obvious that flight attendants and pilots are considered “radiation workers” because of their exposure to cosmic ionizing radiation at altitude.

“In the U.S., they’re actually the most highly exposed radiation workers, and yet there are no regulations around their exposure at all,” says Mordukhovich. “In the European Union and Air Canada, their levels are monitored and their schedules are adjusted if the radiation levels are going above a certain point.” Thirty hours of flying is equivalent in radiation exposure to that of about one chest X-ray. That level of exposure may not be concerning to passengers who fly minimally, but flight crew members are exposed to dangerous levels of radiation over time, which may be detrimental to their health.

Mordukhovich hopes her research and future longitudinal studies will help create regulations. “In general, with any sort of changes that have happened in the occupational environment, it usually takes a lot of research, a lot of advocacy, and a lot of time to make these changes,” she says, noting that laws against in-flight smoking still took about 30 years to pass, despite advocacy efforts. “I think the ionizing radiation piece is just like everything else—it’s expensive, it’s burdensome, and there’s not a precedent for that in this country.  So, there’s just a lot of pushback and resistance, but it’s something that the unions are advocating for [currently].”


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