Aircrew Members’ Perceived Risk to Cancer and Other Adverse Health Conditions from Cosmic Radiation Exposure

Abstract

Aircrew members are exposed to cosmic radiation from the sun and outer space throughout their careers. The goal of this study is to evaluate contributing factors to individual perceived risk from this cumulative exposure. A 22-question, self-administered online survey was utilized to assess flight experience, demographic information, and attitudes regarding individual risk from cosmic radiation exposure among flight crew members.

Both gender and base location were found to be statistically significant indicators of how aircrew members perceived their individual risk of exposure. Results suggest that female aircrew members are more concerned with their individual risk from cosmic radiation exposure than male crew members, especially in areas regarding reproductive health and pregnancy. Results also suggest that aircrew members perceive their individual risk from exposure to be higher when they have a greater background knowledge of cosmic radiation. A greater level of background knowledge of cosmic radiation exposure was reported in aircrew members based outside of the United States.

Additional research is needed to determine if current U.S. regulations offer adequate training and protection for aircrew members and if access to radiation information may affect other aspects of aircrew health and personal lives.

KEY WORDS: aircrew, cancer, cosmic radiation exposure, occupational exposure, reproductive health, risk perception

1. Introduction

Commercial airline travel continues to be one of the safest modes of transportation, although negative reports continue to rise as customers return to air travel after the pandemic (Bureau of Transportation Statistics, 2024). Public safety concerns about commercial airline travel increased in 2024 due to media coverage of a series of airplane malfunctions on the Boeing 737, 777, and 787 models (Cameron, 2024). Customer complaints about commercial air travel continue to increase year after year due to flight delays and cancellations, long lines, lack of customer service, and technology and booking malfunctions (Associate Press, 2024). As the commercial airline industry continues to increase the number and frequency of flights while finding new ways to control costs, flight attendants are experiencing an increase in workers’ compensation claims due to overexertion (strain) injuries as a result of lifting, falls, and struck-by injuries caused by in-flight turbulence and aisleway trip hazards. Injuries due to violence with irate passengers and health and psychological distress due to shift work and/or long flights or schedules are also increasing concerns (Johnson and Gilbert, 2024). For the past several years, the Federal Aviation Administration (FAA) commissioned a committee of experts to study the mental health of pilots and air traffic controllers. The FAA committee provided a 164-page final report in April 2024 that identified 24 recommendations to improve current mental health policies (Hoffman, 2024). One powerful finding in this report is that pilots are afraid to report concerns, symptoms, or treatment for mental health issues because it could affect their employment or standing with peers (FAA, 2024). This is just one example of undisclosed or “non-spoken” safety and health concerns among pilots and flight crews.

Despite aircrew members’ classification as occupationally exposed workers, there is little regulation for monitoring cosmic radiation exposure in the United States (International Commission on Radiological Protection, 1991). Furthermore, little is known about the health effects of cumulative small doses of cosmic radiation exposure. This lack of information is particularly problematic for female aircrew members, who may be given different guidance for how to safely support a pregnancy depending on the country they live in and by what rules their employer abides. Cosmic radiation is a naturally occurring mixture of various types of ionizing radiation, including galactic cosmic radiation (GCR) measured in millisievert (mSv), which originates outside of our solar system, and solar particle events (SPE), which originates from the sun (Bartlett, 2004). The International Commission on Radiological Protection’s (ICRP) recommended guideline for annual exposure to cosmic radiation is 20,000 mSv per year (based on a five-year average of 100,000 mSv). Aircrew members who travel at higher altitudes near the earth’s poles have less protection from atmospheric shielding and are exposed to higher levels of GCR (FAA n.d.; Scheibler et al., 2022). NASA researchers have also concluded that among occupational exposures, aircrew members are the most highly exposed (Wilson et al., n.d.).

Little is known regarding the effects of cumulative long-term cosmic radiation exposure or the effects on DNA from high-energy neutron exposure (Wilson et al., n.d.). The primary health concern to aircrew members regarding the effects of GCR is an increased risk of cancer (Scheibler et al., 2022). Studies examining male and female aircrew members have found an increased likelihood of malignant melanoma, breast cancer (in females), and brain cancer in individual cancer sites but haven’t been able to provide a clear association with cosmic radiation exposure (Wilkison and Wong, 2017; Rafnsson, 2000; Zeeb et al., 2012). Non-stochastic risks in terms of radiation exposure in pregnancy include miscarriage, mental deficit, congenital malformations, and growth restrictions, in which the risk of the effect is a function of dosage (Aspholm et al., 1999; Irgens et al., 2003; McCollough et al., 2007). Many agree that there is no demonstrative data correlating specific fetal harm (birth defects, neurological effects) at dose levels less than 20 mSv, but exposures of much less could cause miscarriages in the early stages of pregnancy (Barish, 2004). Increased rates of Down syndrome in infants from airline pilots and cabin attendants have been documented but have not been specifically linked to GCR exposure (Irgens et al., 2003). Increased risk of childhood cancer has not been documented at lower in-utero exposure levels, but physicians recommend a 1 mSv limit to their expecting patients (Barish, 2004).

The ICRP and the FAA currently describe aircrew members to be occupationally exposed workers (International Commission on Radiological Protection, 1991; White, 1994; Nicholas et al., 2000). ICRP guidance suggests that occupational workers, regardless of gender, should not be exposed to dosage levels exceeding 20mSv annually (Lochard et al., 2016). When a worker becomes pregnant, their fetus is considered a member of the public whose annual exposure limit is 1 mSv. The maternal abdomen provides no effective shielding to the fetus, so the equivalent dosage to the fetus is equal to its mother (Bartlett, 2004). FAA Report AM-92/2 reveals that a crewmember working 1,000 block hours (time the plane engine(s) is/are running) annually would likely receive less than half of the ICRP’s recommended limit of 20 mSv. The average airline pilot in the U.S. reports flying 75 hours a month, so a pregnant crewmember flying 70 block hours per month could reasonably exceed the recommended limit of 1 mSv during the pregnancy (Friedberg et al., 1992; Bureau of Labor Statistics, 2021). The National Commission on Radiation Protection (NCRP) guidelines describe an embryo or fetus of a pregnant worker as an individual whose dose is recommended to be monitored, and the FAA recommends that an unborn child not exceed doses of up to 0.5 mSv per month (Cool et al., 2019; Tobiska et al., 2015).

In the European Union (EU), member states are required to assess exposure, inform workers of health concerns, organize schedules to reduce doses of “highly exposed aircrew,” and apply special considerations to female aircrew members (Council of the European Union, 1996). In the United States, the FAA currently supports “as low as reasonably achievable” (ALARA) guidance as the basis for exposure management, but there are no current regulations requiring employer training or monitoring of long-term exposures (Federal Aviation Administration, 2014; White, 1994; Copeland, 2013). Recently, the National Aeronautics and Space Administration (NASA) began re-examining past exposure thresholds created for astronauts, as former exposure restrictions put on female astronauts were seen as discriminatory (Niiler, 2021). The perception that individual workers have over their own exposure can be more detrimental than the actual risk of harm from radiation exposure. Misconceptions instill fear among employees despite having radiation training, and actual psychological stress from perceived exposures highlights the importance of gaining a better understanding of exposed worker perceptions (Ghatan et al., 2016; Collett et al., 2020). Aircrew members’ perceptions, specifically, are largely under-researched due to the lack of information available regarding cumulative long-term exposures.

Historically, aviators and astronauts have been recognized as explorers—those who have a high-risk threshold due to inherently dangerous aspects of their careers (Slovic, 1996). This topic is increasingly important to understand as we subject aircrew members to flights with more cumulative GCR exposure and as more women get involved in aerospace careers. This study’s objective is to determine how aircrew members perceive their individual risks to cosmic radiation exposure.

2. Material and Methods

2.1 Data Collection and Survey Instrument

This study utilized a self-administered online survey to gather participant information. Survey data was collected from a group of aircrew members over the course of two weeks utilizing an online Qualtrics survey. This survey was available to Facebook groups, including Professional Jet Pilots, Female Aviators Sticking Together, Skywest Pilots Group, Skywest Pilots Official, and an SC Aviation employee email list. After a preliminary message was sent out, a list was compiled of interested aircrew members. These volunteers were then sent an anonymous link to the online Qualtrics survey. Aircrew members were informed of the voluntary nature of their participation and the benefit to our combined knowledge from their contribution. Aircrew members were given an anonymous link via email on January 26, a reminder email on February 2, and a thank you email on February 7. A total of 210 completed surveys were collected from aircrew members. The instrument used was a 22-item, self-administered online survey that asked participants questions relevant to demographic information, flight experience, cosmic radiation background knowledge, perceived risk, and known health experiences.

2.2 Measures

2.2.1 Risk Perspective

Risk perspective was assessed with four statements and their following Likert scale responses. These four statements were: “I feel that I am more at risk from cosmic radiation exposure than the non-flying public;” “I feel I have a higher risk of getting cancer than an average person due to exposures in my job;” “I am concerned about cosmic radiation’s impact on my fertility/virility;” “I am concerned about cosmic radiation’s impact on my future offspring’s health.” Participants could choose between “strongly agree,” “somewhat agree,” “somewhat disagree,” or “strongly disagree” for each statement.

2.2.2 Known Health Experiences

Known crew member health experiences were collected using four “yes or no” questions embodying main health concerns often attributed to radiation. Participants could answer “yes” or “no” to: “I have confirmation of someone in my field who has been diagnosed with cancer;” “I have confirmation of someone in my field who has had reproductive health problems;” “I have confirmation of someone in my field who has had difficulty having a healthy pregnancy;” “I have confirmation of someone in my field that has had health concerns due to cosmic radiation exposure.”

2.2.3 Radiation Knowledge

Participant radiation knowledge was assessed using five “yes or no” questions regarding the level of background knowledge or radiation exposure training that the participants underwent. The five statements were: “I would classify myself as a radiation-exposed worker;” “My employer has a maximum allowable cosmic radiation exposure limit for employees;” “My employer has written procedures on cosmic radiation exposure avoidance;” “I have monitored my individual cosmic radiation exposures;” “I have made a change in flight routing/altitude due to radiation exposure concerns.”

2.3 Statistical Analyses

Descriptive statistics and a two-tailed T-test (assumed unequal variances) were performed in Microsoft Excel version 2107, comparing crew members’ gender with the groups’ risk perspective mean score to determine the effect that gender has on their perception of individual risk. Additionally, each question regarding crew member background knowledge was compared to crew members’ risk perspective answers to determine if access to monitoring materials correlated with participant risk perspective.

Known health experiences were assessed by asking crew members four “yes or no” questions; a “2” was entered for “yes,” and a “1” was recorded as “no.” The average of the calculated total responses for each question was then compared with answers gathered depending on gender and base location.

3. Results

3.1 Demographic Profile of Study Subjects

An initial pool of 232 potential crew members was created through email solicitation. A total of 210 surveys were received. An approximate participation rate was 90.5%, but a true rate could not be determined because the research survey link was shareable among crew members. Two crew members did not disclose their gender. A total of 152 crew members identified as male, and 56 identified as female.

The reported age range among males and females was similar, with most respondents in both groups ranging from 26-40 years old (61.5%). U.S.-based participants comprised 89.4% of respondents, and 10.6% were internationally based. Two crew members didn’t disclose their base location. A larger percentage of male crew members were U.S.-based than female crew (96.7% American men vs. 69.6% American women) (see Table 1). A sample disproportionate to the world demographics of female aircrew members responded to this survey. Approximately 26.7% of crew members surveyed identified as female, although the world average percentage of female commercial aircrew is closer to 7% (Women in Aviation International, 2021).

The most reported cruise altitude was 27,000-41,000 ft. (81.3%), and 23 crew members reported flying even higher at 41,000 ft. or higher (11%). A majority of crew members reported that they “never” utilized polar routes (91.4%), but 18 crew members reported utilizing polar routes at least “sometimes” (8.6%). A greater percentage of female aircrew members (17.9%) indicated that they utilized polar routes at least “sometimes” when compared to the male aircrew members (8.6%) (see Table 2). The average calendar year of commercial pilot certification was reported to be about 2008 (2007.8), with an associated average of approximately 12 years of professional flight experience at the time the survey was distributed. Average reported annual flight hours were 499.8 hours (SD = 116.9). The average reported percentage of trips that were perceived as a “long haul” (more than 4 hours flight time or 2,000 nautical miles) was 22.9% (SD = 27.6%) (see Table 2).

3.2 Aircrew Radiation Perceptions, Knowledge, and Experiences

Roughly 95% of crew members felt that they were more at risk from cosmic radiation than the general non-flying public. Majority of crew members (88.1%) felt they have a higher risk of getting cancer than the non-flying public. Nearly half (45.7%) of crew members indicated they were concerned about cosmic radiation’s impact on their fertility or virility, and 42.9% of crew members were concerned about their future offspring’s health (see Table 3).

More than half (67.1%) of crew members classified themselves as radiation-exposed workers, despite only 21.0% of crew members indicating that their employers have written radiation avoidance procedures and 19.5% of crew members indicating that their employers have a maximum allowable exposure limit. Only 10% of crew members indicated that they have monitored their individual cosmic radiation exposure, and 14.3% indicated that they had made a change in flight routing or altitude due to exposure concerns (see Table 3).

Slightly more than half of crew members (55.5%) indicated they had confirmation of someone in their field who had been diagnosed with cancer. A majority of crew members answered “no” to having confirmation of someone with reproductive health problems (83.7%), difficult pregnancies (83.7%), or general health concerns due to cosmic radiation (75.6%) (see Table 3).

3.3 Effect of Gender

T-tests on gender and risk perception indicated female crew members had greater concern about risk from cosmic radiation (p<.05), more concern about cosmic radiation’s impact on their fertility (p<.005), and more concern for their future offspring’s health (p<.01) than their male counterparts indicated. The difference in concern for cancer among males and females was not significant (p = 0.12) (see Table 4).

Gender influenced the percentage of crew members who answered “yes” to each of the “health experience” questions. Female aircrew answered “yes” at a higher percentage than male aircrew, with the greatest difference seen in reproductive problems (32.1% vs. 10.5%) and pregnancy difficulties (32.1% vs. 10.5%). Reproductive health problems and pregnancy difficulties were both found to be highly significant among respondent groups. Known cancer diagnosis (p = 0.07) and health concerns due to GCR (p = 0.26) were not significant between male and female crew members (see Table 5).

3.4 Effect of Base Location

Internationally-based crew members were significantly more likely to indicate that they were more at risk from exposure than the general public (p<.005), more concerned with radiation’s impact on their fertility/virility (p<.05), and more concerned about radiation exposure’s impact on their future offspring (p<.05) (see Table 6).

Internationally-based crew members were more likely to indicate that they classified themselves as radiation workers, had an employer-set maximum exposure limit, had written avoidance procedures, had individually monitored their exposure, and had made a change in their flight path due to radiation concerns (see Table 7).

Crew members who considered themselves to be radiation-exposed workers were more likely to perceive that they were more at risk from cosmic radiation exposure than the non-flying public (p<.001), felt they were at higher risk of getting cancer (p<.002), were more concerned about GCR impact on their fertility/virility (p<.003), and were more concerned about the health of their future offspring (p<.004) than those who did not consider themselves to be “radiation-exposed workers.” Crew members whose employers had a maximum exposure limit felt they were more at risk from exposure (p<.001), had higher chances of getting cancer (p<.002), were more concerned about cosmic radiation’s impact on their fertility/virility (p<.005), and were more concerned about their future offspring’s health (p<.004) than those who did not have a maximum exposure limit at their work (see Table 8). Having written procedures regarding GCR exposure from their employer affected the way that crew members felt about their personal risk from radiation exposure and their chances of getting cancer. Crew members who had written procedures at their work felt that they were more at risk from cosmic radiation exposure (p<.001) and were more likely to feel they had a higher risk of getting cancer (p<.05). The relationship between having written procedures and an indication of fertility difficulties (p=.076) and offspring concerns (p=0.11) was insignificant.

Crew members who had monitored their individual exposures were more likely to indicate they were at greater risk from exposure than the general public (p<.005), more likely to get cancer (p<.005), more concerned with radiation’s impact on their fertility/virility (p<.001), and more concerned about radiation exposure’s impact on their future offspring (p<.002). Crew members who indicated they had changed their route of flight due to GCR exposure concerns were more likely to indicate that they felt more at risk than the general public (p<.001), more at risk for cancer (p<.005), fertility/virility implications (p<.05), and were more concerned about their future offspring’s health (p<.005) (see Table 8).

All things considered, internationally-based crew members were more likely to indicate that they had greater knowledge or experience with cosmic radiation exposure in each survey parameter. Radiation knowledge in each question was correlated with increased perceived risk, and internationally-based crew members indicated that they felt more risk from radiation exposure than U.S.-based crew members.

The group of female participants comprised a greater percentage of internationally-based women (30.4%) than the male group (3.3%) (see Table 1). Although being based outside the U.S. correlated with higher feelings on average risk from cosmic radiation exposure, regardless of base location, female crew members had similar perceived risk levels of developing cancer, their fertility concerns, and their concern for the health of their future offspring. When asked if crew members were more at risk from cosmic radiation exposure than the non-flying public, U.S.-based females were slightly less concerned, on average, than females based outside the U.S. (p<.05). The concern for cancer (p = 0.87), fertility (p = 0.18), and offspring (p = 0.26) between U.S. females and internationally-based females was insignificant (see Table 9).

4. Discussion

Although both male and female aircrew members in this study had concern for their individual exposure to cosmic radiation, females reported significantly more concern in all areas other than the risk of cancer, including overall risk, fertility, and the health of their future offspring. This gender-risk effect has been examined following industrial accidents, such as the Fukushima nuclear disaster in 2011, where there was a reluctance in males to acknowledge danger when it impeded their ability to provide for their families (Morioka, 2014). While this disaster was a source of acute radiation exposure, compelling parallels exist in the comparison of male and female parents interviewed afterward. The NCRP describes risk perception as not only the data we examine from health effects but the perceived benefits from that exposure (Slovic, 1996). When mothers were interviewed following the Fukushima disaster, physical well-being was expressed as a greater threat than in fathers, whose concern was their own economic stability (Morioka, 2014). This gender-risk effect may carry varying results in cultures where occupations (and benefits gained) are divided more evenly between genders.

How we perceive our personal risk is also determined by the culture around us and how the magnitude of those risks is presented to us (Slovic, 1996). A greater percentage of female aircrew indicated that they had more knowledge of members in their field who had either reproductive health problems (p<.005) or difficulty having a healthy pregnancy (p<.005) than their male counterparts. This may be due to the ability of women in many cultures to discuss pregnancy details more comfortably with other women than men would to discuss potential reproductive problems with other men. Regardless of where the knowledge comes from, this difference in the information received may contribute to how aircrew members perceive their own risk from exposure. In experiencing pregnancy, women have more to lose from myriad possible pregnancy complications than their male counterparts, which may inherently increase their perceived risk.

The relationship between radiation knowledge and risk perception has been studied in several practices, typically in professional medical training. Adequate training among students has been found to decrease risk perception, but perceptions have also varied among different professional vantage points (Yoshida et al., 2020, Hyde et al., 2016). Despite having received ionizing radiation training, occupational patterns have emerged suggesting that exposure risk beliefs are socially constructed (Hyde et al., 2016). Past research suggests that increased radiation education decreases subject risk perception, but only if the training given is adequate and understood properly (Yoshida et al., 2019). Conversely, aircrew members in this study who received more radiation exposure guidance felt, on average, more at risk from radiation exposure. Like results published by Pepin et al. (2023), this study suggests that radiation exposure training given to aircrew members is either inadequate in an effort to calm aircrew perceptions or that cultural beliefs have a stronger impact on aircrew perceptions than evidence-based training.

One of the key challenges in gathering a representative sample of surveys among the aircrew member population was a lack of representation of female aircrew members in the field. Despite offering this survey online, there was still a much larger respondent pool based in the U.S. than based outside of the U.S., misrepresenting the world population of aircrew. Although the participants sampled had a greater proportion of female aircrew than representative of the actual population of aircrew (roughly 7% worldwide), the data gathered was from a relatively small sample size, also leading to possible misrepresentation. Finally, this survey was self-administered, so responses could have been collected from unqualified or unrequested participants. The effect of different cultural protections in pregnancy was not examined in this study. Outside of having access to information about radiation exposure, there may be more cultural pressure in some countries to take time off during pregnancy. Family structure and societal norms may also influence risk perception, depending on the aircrew member’s responsibility for their household’s financial security. This information is important to understand as more women are launching aerospace careers and will require adequate information to care for themselves.

5. Conclusions and Recommendations

This study provides a compelling example of an occupation with varying degrees of exposure risk perception. The results corroborate that female aircrew members are more concerned about individual health effects from cosmic radiation exposure than their male counterparts. Furthermore, when cosmic radiation exposure is perceived as a tangible risk, crew members feel more concerned about their individual risk of exposure. This relationship contradicts current research, displaying the need for better understanding of radiation exposure among the aviation industry. The total and long-term effects of this increased risk perception among female aircrew members is unknown. Further research is needed to determine the impact of these beliefs among female aircrew members, the causes of these beliefs, and the possible effects of monitoring exposures in the U.S.

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