Estimating the health consequences of flight attendant work: comparing flight attendant health to the general population in a cross-sectional study

Cosmic Ionizing Radiation: A DNA Damaging Agent That May Underly Excess Cancer in Flight Crews

In the United States, the Federal Aviation Administration has officially classified flight crews (FC) consisting of commercial pilots, cabin crew, or flight attendants as "radiation workers" since 1994 due to the potential for cosmic ionizing radiation (CIR) exposure at cruising altitudes originating from solar activity and galactic sources. Several epidemiological studies have documented elevated incidence and mortality for several cancers in FC, but it has not yet been possible to establish whether this is attributable to CIR. CIR and its constituents are known to cause a myriad of DNA lesions, which can lead to carcinogenesis unless DNA repair mechanisms remove them. But critical knowledge gaps exist with regard to the dosimetry of CIR, the role of other genotoxic exposures among FC, and whether possible biological mechanisms underlying higher cancer rates observed in FC exist. This review summarizes our understanding of the role of DNA damage and repair responses relevant to exposure to CIR in FC. We aimed to stimulate new research directions and provide information that will be useful for guiding regulatory, public health, and medical decision-making to protect and mitigate the risks for those who travel by air.

Challenges and support needs in psychological and physical health among pilots: a qualitative study

Introduction

Physical and mental health problems among pilots affect their working state and impact flight safety. Although pilots' physical and mental health problems have become increasingly prominent, their health has not been taken seriously. This study aimed to clarify challenges and support needs related to psychological and physical health among pilots to inform development of a more scientific and comprehensive physical and mental health system for civil aviation pilots.

Methods

This qualitative study recruited pilots from nine civil aviation companies. Focus group interviews via an online conference platform were conducted in August 2022. Colaizzi analysis was used to derive themes from the data and explore pilots' experiences, challenges, and support needs.

Results

The main sub-themes capturing pilots' psychological and physical health challenges were: (1) imbalance between family life and work; (2) pressure from assessment and physical examination eligibility requirements; (3) pressure from worries about being infected with COVID-19; (4) nutrition deficiency during working hours; (5) changes in eating habits because of the COVID-19 pandemic; (6) sleep deprivation; (7) occupational diseases; (8) lack of support from the company in coping with stress; (9) pilots' yearly examination standards; (10) support with sports equipment; (11) respecting planned rest time; and (12) isolation periods.

Discussion

The interviewed pilots experienced major psychological pressure from various sources, and their physical health condition was concerning. We offer several suggestions that could be addressed to improve pilots' physical and mental health. However, more research is needed to compare standard health measures for pilots around the world in order to improve their physical and mental health and contribute to overall aviation safety.

Turkish airline cabin crew members' attitudes towards protection from infectious diseases in the context of their health responsibilities and health perceptions

INTRODUCTION

This paper investigated Turkish Airline cabin crew members' attitudes towards protection from infectious diseases in the context of their health responsibilities and health perceptions.

MATERIALS AND METHODS

The study adopted a descriptive research design. The sample consisted of 686 cabin crew members. Data were collected online using a sociodemographic characteristics questionnaire, a scale of attitudes towards infectious diseases, the Health Perception Scale(HPS), and the Health Responsibility subscale(HRS) of the Healthy Lifestyle Behaviors Scale(HLBS). The data were analyzed using the Statistical Package for Social Sciences (SPSS, v. 20.0). Number, percentage, mean, standard deviation, t-test, f test, and correlation were used for analysis.

RESULTS

Participants had a mean HPS and HRS score of 56.12 ± 8.22 and 24.50 ± 7.05, respectively. The difference between the participants' marital status, position in the workplace, age group, number of children, occupational experience, exposure to communicable diseases, training on prevention from communicable diseases, voluntary vaccination status, and HPS and HRS scores were statistically significant(p < .05).

CONCLUSION

There was a strong correlation between HPS and HRS scores(r = 0.664). Cabin crew members' health perceptions and health responsibilities were affected by numerous factors. Suggestions were made to cabin crew members pertaining to infectious diseases and ways of protecting from them.

Health consequences of exposure to aircraft contaminated air and fume events: a narrative review and medical protocol for the investigation of exposed aircrew and passengers

Thermally degraded engine oil and hydraulic fluid fumes contaminating aircraft cabin air conditioning systems have been well documented since the 1950s. Whilst organophosphates have been the main subject of interest, oil and hydraulic fumes in the air supply also contain ultrafine particles, numerous volatile organic hydrocarbons and thermally degraded products. We review the literature on the effects of fume events on aircrew health. Inhalation of these potentially toxic fumes is increasingly recognised to cause acute and long-term neurological, respiratory, cardiological and other symptoms. Cumulative exposure to regular small doses of toxic fumes is potentially damaging to health and may be exacerbated by a single higher-level exposure. Assessment is complex because of the limitations of considering the toxicity of individual substances in complex heated mixtures.There is a need for a systematic and consistent approach to diagnosis and treatment of persons who have been exposed to toxic fumes in aircraft cabins. The medical protocol presented in this paper has been written by internationally recognised experts and presents a consensus approach to the recognition, investigation and management of persons suffering from the toxic effects of inhaling thermally degraded engine oil and other fluids contaminating the air conditioning systems in aircraft, and includes actions and investigations for in-flight, immediately post-flight and late subsequent follow up.

Circadian Disruption and Mental Health: The Chronotherapeutic Potential of Microbiome-Based and Dietary Strategies

Mental illness is alarmingly on the rise, and circadian disruptions linked to a modern lifestyle may largely explain this trend. Impaired circadian rhythms are associated with mental disorders. The evening chronotype, which is linked to circadian misalignment, is a risk factor for severe psychiatric symptoms and psychiatric metabolic comorbidities. Resynchronization of circadian rhythms commonly improves psychiatric symptoms. Furthermore, evidence indicates that preventing circadian misalignment may help reduce the risk of psychiatric disorders and the impact of neuro-immuno-metabolic disturbances in psychiatry. The gut microbiota exhibits diurnal rhythmicity, as largely governed by meal timing, which regulates the host's circadian rhythms. Temporal circadian regulation of feeding has emerged as a promising chronotherapeutic strategy to prevent and/or help with the treatment of mental illnesses, largely through the modulation of gut microbiota. Here, we provide an overview of the link between circadian disruption and mental illness. We summarize the connection between gut microbiota and circadian rhythms, supporting the idea that gut microbiota modulation may aid in preventing circadian misalignment and in the resynchronization of disrupted circadian rhythms. We describe diurnal microbiome rhythmicity and its related factors, highlighting the role of meal timing. Lastly, we emphasize the necessity and rationale for further research to develop effective and safe microbiome and dietary strategies based on chrononutrition to combat mental illness.

Fatigue and Sleep in Airline Cabin Crew: A Scoping Review

Airline cabin crew operate in dynamic work environments that are continuously changing, from unpredictable shift work hours to travelling through multiple time zones. These likely impact cabin crews' overall health and may affect their performance on safety-related tasks. Research on this population has been limited; therefore, the aim was to summarise the relevant literature regarding fatigue, sleepiness and mental health of cabin crew. This review followed the PRISMA-ScR guidelines and conducted a systematic search utilising five databases. The initial search identified 1223 studies, and through vigorous screening processes, 27 studies were selected for this review. Over half of the selected studies focused on international or long-haul flights, and a large proportion of the sample participants were women. Findings suggested a high prevalence of fatigue and sleepiness as well as unsatisfactory sleep quality with elevated susceptibility to sleep disorders. Factors identified with health outcomes were associated with flight operations (e.g., rosters) and individual differences (e.g., age and coping strategies). Regarding mental health, cabin crews are potentially at a greater risk for depression and anxiety compared to the general public. This review draws attention to the importance of using a standardised approach, such as validated measures for fair and consistent inferences.

Exploring relationships between health-related lifestyle habits and fatigue among flight attendants and trainees

BACKGROUND

Fatigue in flight attendants is an important issue concerning flight safety and occupational health. It is well known that work-related factors and certain lifestyle habits can cause fatigue. But very few studies have focused on the difference between having work experience flight attendants and no flight experience trainees.

OBJECTIVE

The present study was performed to compare and investigate the relationships between fatigue and health-related lifestyle habits among flight attendants and trainees.

METHODS

A questionnaire-based cross-sectional study with convenience sampling was conducted. A total of 107 flight attendants and 109 trainees were recruited in an international airline. The research was using a self-developed health-related lifestyle habits questionnaire and the Checklist Individual Strength (CIS) scale. The relationships between health-related lifestyle habits and fatigue were examined by Pearson's chi-square test and Fisher's exact test. Logistic regression was used to identify factors predicting fatigue among flight attendants and trainees.

RESULTS

Nearly half of the participants had fatigue and poor health-related lifestyle habits. Logistic regression showed that trainees with sleeping hours less than 7 hours, had a higher probability of fatigue than those who sleep more than 7 hours. In addition, the flight attendants with an irregular sleep pattern, unbalanced diet, sedentary leisure-time, no use relaxation technique, and an exercise frequency below once a week had a higher probability of fatigue.

CONCLUSION

The flight attendants' sleep patterns, diet, activity, and relaxation had a more significant impact on fatigue than trainees. Therefore, a healthy lifestyle is important in this population for good workplace performance.

Cancer risks from cosmic radiation exposure in flight: A review

Aircrew (consisting of flight attendants, pilots, or flight engineers/navigators) are exposed to cosmic ionizing radiation (CIR) at flight altitude, which originates from solar activity and galactic sources. These exposures accumulate over time and are considerably higher for aircrew compared to the general population, and even higher compared to U.S. radiation workers. Many epidemiological studies on aircrew have observed higher rates of specific cancers compared to the general population. Despite high levels of CIR exposure and elevated rates of cancer in aircrew, a causal link between CIR and cancer has yet to be established. Many challenges still exist in effectively studying this relationship, not the least of which is evaluating CIR exposure separately from the constellation of factors that occur as part of the flight environment. This review concentrates on cancer incidence and mortality observed among aircrew in epidemiologic studies in relation to CIR exposure and limitation trends observed across the literature. The aim of this review is to provide an updated comprehensive summary of the literature that will support future research by identifying epidemiological challenges and highlighting existing increased cancer concerns in an occupation where CIR exposure is anticipated to increase in the future.

Research gaps and needs for preventing worker fatigue in the transportation and utilities industries

BACKGROUND

The transportation and utilities industries include establishments engaged in the movement of passengers and freight, or the provision of public power, water, and other services. Along with the warehousing industry, they make up the US National Occupational Research Agenda's Transportation, Warehousing and Utilities (TWU) industry sector. In 2018 the sector composed 5% of the US workforce, with approximately 8 million workers. TWU workers experienced 19% of all fatalities among U.S. workers in 2018 and 7% of total occupational injuries and illnesses.

METHODS

Around-the-clock operations, heavy workloads, long and irregular shifts, complicated schedules, and time pressures characterize work across the US TWU sector. However, there are considerable differences in worker priorities and concerns between TWU industries. Major areas of concern within the sector include disparities in work schedules; required training for employee fatigue awareness and prevention; physical and mental job demands; and safety culture.

RESULTS

Strategies for fatigue mitigation are critical to reduce the prevalence of injuries, safety-critical events, and crashes in TWU workers. Further research on the incidence and characterization of fatigue among TWU workers will guide the development of effective mitigation strategies. The influence of work scheduling on missed sleep opportunities and disrupted circadian rhythms should be determined. Evaluation of fatigue mitigation strategies can lead to the adoption of the most effective ones for each TWU industry.

CONCLUSION

Implementation of effective strategies is critical for the health, safety, wellbeing, and productivity of workers in the TWU sector.

Sleep Quality and Mental Health Consequences of COVID-19 Pandemic in the Aviation Community in Greece

OBJECTIVE

The aim of this study was to assess the mental health and sleep quality of aviation workers in Greece during the pandemic.

METHODS

A cross-sectional study of aviation workers in Greece was conducted.

RESULTS

Sleep disturbances were observed in 25.4% of our 548 participants, whereas 8.2% and 5.8% reported at least mild depressive and anxiety symptoms, respectively. The impact of the pandemic on their mental health was their primary concern, which increased for many active pilots according to their workload. Those infected mainly faced daily tiredness and fatigue. Smoking habits and high body mass index were a predisposition for more physical symptoms. Cabin crew and women generally yielded worse scores than the other groups.

CONCLUSION

Fear of infection could explain mental health issues, whereas physical symptoms of those infected could be attributed to long-COVID (coronavirus disease) syndrome. Flight attendants' lower ratings may be due to more occupational exposure.

Evaluation of fatigue and sleep problems in cabin crews during the early COVID-19 pandemic period

Background

The COVID-19 outbreak has affected the aviation sector. The anxiety and fear caused by this newly emerging virus, whose effects are not fully known in the short and long term, may also cause problems in terms of flight safety. We aimed to evaluate fatigue and sleep problems associated with fear of COVID-19 during the early pandemic period in cabin crew.

Methods

This is a cross-sectional survey study consisting of 45 questions in total. Participants were cabin crew members on flight duty. An online questionnaire was sent to 2092 cabin crew in February–April 2021 via TASSA Cabin Crew Member's Association. The survey included questions about socio-demographic characteristics, flight times, flight types and COVID test history, as well as the international physical activity questionnaire-short form (IPAQ-SF), fatigue severity scale (FSS), Jenkins sleep scale (JSS) and fear of COVID-19 scale (FCV-19S).

Results

Out of 316 survey results obtained (response rate, 15%), 225 (71%) were included in the study, with a mean age (SD) of 32.54 (4.91) years, and 124 (55.1%) were women. According to IPAQ-SF, 27.6% of cabin crew were found to be inactive, 54.7% minimally active and 17.7% very active. According to FSS, pathological fatigue was found in 43.6%. The FSS score of the inactive group was higher than the others (Kruskal Wallis, p < 0.001). As the number of people living in the same house or flight time in the last 1 month increase, the fear of COVID-19 also increases (Spearman, p = 0.01 r = 0.171, and p = 0.049 r = 0.131). In addition, there was direct correlation between fear of COVID-19 and fatigue and sleep problems (Spearman, p = 0.001 r = 0.218, and p < 0.001 r = 0.26, respectively).

Conclusion

This study shows that fatigue and sleep problems increase as the fear of COVID-19 increases in cabin crew during the early pandemic period. Consequently, precautions and further studies are needed, as fatigue and sleep disorders may primarily be related to the anxiety, fear and uncertainty surrounding the COVID-19 pandemic.

Flight attendant occupational nutrition and lifestyle factors associated with COVID-19 incidence

In the era of COVID-19, essential workers are plagued with unforeseen and obfuscated challenges. Flight attendants are a unique subgroup of essential workers who face a multitude of health risks attributed to occupational exposures that are accentuated by the COVID-19 pandemic. Such risks can be ameliorated with strategies that target factors which enhance COVID-19 risk, including modifiable factors of diet and lifestyle. The aim of this cross-sectional study is to detect occupational dietary and lifestyle factors which could increase COVID-19 incidence amongst flight attendants. To identify potential risk factors, a questionnaire was administered to eighty-four flight attendants and examined the participants’ diet and lifestyle, and COVID-19 incidence. Descriptive statistics and logistic regression indicated that the participants’ perceived dietary quality at work (p = 0.003), sleep disruptions which impacted their consumption of a healthy diet (p = 0.013), job tenure (OR: 0.67, 95% CI: 0.46:0.98) and frequency of reported cold/flu (OR: 1.49, 95% CI: 1.014–2.189) were all factors associated with confirmed/suspected COVID-19 incidence. This study also revealed that a lack of infrastructure for food storage and time limitations are considerable occupational barriers for flight attendants to consume healthy foods. Additional investigation can further elucidate these relationships and related solutions to mitigate COVID-19 risk in the future.

Occupational risk of organophosphates and other chemical and radiative exposure in the aircraft cabin: A systematic review

Occupational exposure to oil fumes, organophosphates, halogenated flame retardants, and other volatile and semi-volatile contaminants is a concern within the aviation industry. There is no current consensus on the risk attributed to exposure to these chemical classes within the aircraft cabin. Contaminant concentrations rarely exceed conventional air quality guidelines, but concerns have been raised about these guidelines' applicability within the aircraft environment. This systematic review, the largest and most comprehensive completed to date on the subject matter, aims to synthesize the existing research related to chemical and other exposures inside the aircraft cabin to determine the occupational risk that may be attributed said exposure, as well as, determine knowledge gaps in source, pathway, and receptor that may exist. The Science Direct, Scopus, and Web of Science databases were queried with five search terms generating 138 manuscripts that met acceptance criteria and screening. Several potential areas requiring future examination were identified: Potable water on aircraft should be examined as a potential source of pollutant exposure, as should air conditioning expansion turbines. Historical exposure should also be more fully explored, and non-targeted analysis could provide valuable information to comprehend the aircraft cabin exposome. Occupational risk under typical flight scenarios appears to be limited for most healthy individuals. Contaminants of concern were demonstrated to be extant within the cabin, however the concentrations under normal circumstances do not appear to be individually responsible for the symptomologies that are present in impacted individuals. Questions remain regarding those that are more vulnerable or susceptible to exposure. Additionally, establishing the effects of chronic low dose exposure and exposure to contaminant mixtures has not been satisfied. The risk of acute exposure in mitigable fume events is substantial, and technological solutions or the replacement of compounds of concern for safer alternatives should be a priority.

Delayed Meal Timing, a Breakfast Skipping Model, Increased Hepatic Lipid Accumulation and Adipose Tissue Weight by Disintegrating Circadian Oscillation in Rats Fed a High-Cholesterol Diet

Background: To investigate whether shifted timing of eating, breakfast skipping, induces alterations in the circadian clock and abnormal lipid metabolism, we have established a delayed meal timing (DMT) protocol for rats, which started eating food 4 h delay. In the present study, control and DMT rats were fed a high-cholesterol diet during zeitgeber time (ZT) 12-24 and ZT 16-4, respectively. The DMT protocol increased the hepatic lipids and epididymal adipose tissue weight without changes in food intake and body weight. The surge in body temperature was delayed by 4 h in the DMT group, suggesting that energy expenditure was decreased in response to DMT. The peaks of the diurnal rhythm of serum non-esterified fatty acids and insulin were delayed by 2 and 4 h due to DMT, respectively. The oscillation peaks of hepatic de novo fatty acid synthesis gene expression was delayed by 4 h in response to DMT, whereas the peak of hepatic clock genes were 2 h delayed or not by DMT. Although metabolic oscillation is considered to be controlled by clock genes, the disintegration rhythms between the clock genes and lipid metabolism-related genes were not observed in rats fed a high-fat diet in our previous study. These data suggest that the circadian rhythm of de novo fatty acid metabolism is regulated by timing of eating, but is not directly controlled by clock genes. The present study suggests that breakfast skipping would complicate fatty liver and body fat accumulation.

Cabin crew health and fitness-to-fly: Opportunities for re-evaluation amid COVID-19

Aircrew fitness-to-fly is among the elements that make aviation the safest form of long-distance transport. The health of cabin crew is a crucial determinant in carrying out safety-related duties. 'Fitness-to-fly' is associated with defined workplace conditions, for which airlines have a legal duty to ensure fitness for employment. We explored the literature on fitness-to-fly to obtain a pragmatic assessment of the challenges for aeromedical examinations. Regulations promulgated by aviation regulatory authorities and airline-internal policies have similar status and meaning, yet there is no harmonised approach internationally, and an inability to conform periodic medical assessments to actual operational fitness. The COVID-19 pandemic has highlighted the need to better understand fitness-to-fly criteria. Fitness-to-fly measures are mainly based on self-reported data and there is a need for a 'safety' factor for self-reports. Aeromedical evaluations should evolve from meeting medical standards to include pandemics as an element of the overall risk of aircraft operations. Re-evaluating criteria for fitness-to-fly assessment will further the goal of linking research to the actual needs of public health decisionmakers. If airlines are to resume operations at pre-pandemic levels, they must demonstrate to the public and public health agencies that fitness-to-fly assessment is appropriate and effective.

Disrupted circadian rhythms and mental health

During the evolution of life, the temporal rhythm of our rotating planet was internalized in the form of circadian rhythms. Circadian rhythms are ~24h internal manifestations that drive daily patterns of physiology and behavior. These rhythms are entrained (synchronized) to the external environment, primarily by the light-dark cycle, and precisely controlled via molecular clocks located within the suprachiasmatic nucleus of the hypothalamus. Misalignment and/or disruption of circadian rhythms can have detrimental consequences for human health. Indeed, studies suggest strong associations between mental health and circadian rhythms. However, direct interactions between mood regulation and the circadian system are just beginning to be uncovered and appreciated. This chapter examines the relationship between disruption of circadian rhythms and mental health. The primary focus will be outlining the association between circadian disruption, in the form of night shift work, exposure to light at night, jet lag, and social jet lag, and psychiatric illness (i.e., anxiety, major depressive disorder, bipolar disorder, and schizophrenia). Additionally, we review animal models of disrupted circadian rhythms, which provide further evidence in support of a strong association between circadian disruption and affective responses. Finally, we discuss future directions for the field and suggest areas of study that require further investigation.

Interplay Between Air Travel, Genome Integrity, and COVID-19 Risk vis-a-vis Flight Crew

During air travel, flight crew (flight attendants, pilots) can be exposed to numerous flight-related environmental DNA damaging agents that may be at the root of an excess risk of cancer and other diseases. This already complex mix of exposures is now joined by SARS-CoV-2, the virus that causes COVID-19. The complex exposures experienced during air travel present a challenge to public health research, but also provide an opportunity to consider new strategies for understanding and countering their health effects. In this article, we focus on threats to genomic integrity that occur during air travel and discuss how these threats and our ability to respond to them may influence the risk of SARS-CoV-2 infection and the development of range of severity of the symptoms. We also discuss how the virus itself may lead to compromised genome integrity. We argue that dauntingly complex public health problems, such as the challenge of protecting flight crews from COVID-19, must be met with interdisciplinary research teams that include epidemiologists, engineers, and mechanistic biologists.

Fatigue Management Health Education Intervention Effects on Flight Attendants

BACKGROUND: This study explored the impact of a fatigue management health education intervention (FMI) on flight attendants fatigue management knowledge, attitudes, behavioral intention, self-efficacy, and fatigue intensity.METHODS: A quasi-experimental pretest-posttest design was used. The sample included 70 flight attendants of an international airline company in Taiwan. The experimental group (N 34) received an FMI, while the control group (N 36) had no intervention. Fatigue management knowledge, attitude, behavior intention, self-efficacy, and fatigue intensity were assessed at baseline and 1 wk later. Single-factor analysis of covariance and Jensen Neman methods were used to assess the differences in outcomes between the two groups.RESULTS: Attitude and self-efficacy in the experimental group were significantly improved after the FMI [standardized mean difference (SMD), 0.96; 1.98]. The intervention also reduced their fatigue intensity (SMD 6.05) and both knowledge and behavioral intention scores were increased in more than 80% of subjects in the experimental group.DISCUSSION: FMI can effectively improve fatigue management knowledge, attitudes, behavioral intention, and self-efficacy and reduce fatigue intensity in flight attendants.Hu CJ, Lee FP, Hong RM. Fatigue management health education intervention effects on flight attendants. Aerosp Med Hum Perform. 2020; 91(12):911917.

Does intermittent exposure to high altitude increase the risk of cardiovascular disease in workers? A systematic narrative review

OBJECTIVE

Several working groups (eg, miners, flight crews and soldiers) are subjected to chronic intermittent hypoxic exposure. The cardiovascular implications have been studied but not systematically reviewed with focus on possible negative health implications. The aim of the present review was to systematically evaluate the hypothesis that intermittent hypoxic exposure causes cardiovascular stress detrimental to health in workers.

DESIGN

Systematic review.

DATA SOURCES

Electronic database search of PubMed, Scopus and Web of Science up to April 2020.

ELIGIBILITY CRITERIA

Studies of workers ≥18 years repeatedly subjected to months to years of irregular intermittent hypoxia, lasting from a few hours (eg, flight crews), one or a few days (eg, soldiers), or several days to weeks (eg, miners working at high altitude), written in English and evaluating the effect of intermittent hypoxia on cardiovascular disease were included. Animal studies, books, book chapters, personal communication and abstracts were excluded. The primary outcome measure was changes in standardised mortality ratio.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed risk of bias using the Cochrane Collaboration's tool.

RESULTS

119 articles were identified initially, 31 of which met the inclusion criteria. Of these, 17 were retrospective cohort mortality studies (irregular short-term intermittent hypoxia), and 14 studies were observational (long-term intermittent hypoxia). The population of irregular short-term intermittent hypoxia users (flight crew) showed a lower mortality by cardiovascular disease. Long-term intermittent hypoxia over several years such as in miners or soldiers may produce increased levels of cardiac disorders (12 studies), though this is probably confounded by factors such as obesity and socioeconomic status.

CONCLUSION

This systematic narrative review found that cardiovascular disease mortality in flight crews is lower than average, whereas miners and soldiers exposed to intermittent hypoxia experience increased risks of cardiovascular diseases. The impact of socioeconomic status and lifestyle appears of importance.

PROSPERO REGISTRY NUMBER

CRD42020171301.

The Effect of Loving-Kindness Meditation on Flight Attendants' Spirituality, Mindfulness and Subjective Well-Being

Background: This study investigated: (1) the effects of the loving-kindness meditation (LKM) on mindfulness, subjective well-being (SWB), and spirituality and (2) the relationships between mindfulness, spirituality, and SWB. Methods: 98 flight attendants from Xiamen Airlines in China were recruited and randomly assigned to the LKM training group (n = 49) or the waiting control group (n = 49). The LKM training group underwent an 8-week LKM training intervention, and the control group did not undergo intervention. The three main variables (SWB, mindfulness, and spirituality) were measured both before (pre-test) and after (post-test) the LKM training intervention. Results: In the experimental group, SWB and spirituality increased significantly. In the control group, no significant differences were observed for the three variables between the pre-test and post-test. Conclusions: Our results indicated that LKM may help to improve SWB and spirituality. However, the mechanisms which underlie the effects of the LKM on mindfulness, spirituality, SWB, and other psychological constructs require further elucidation.

Circadian rhythm disruption and mental health

Circadian rhythms are internal manifestations of the solar day that permit adaptations to predictable environmental temporal changes. These ~24-h rhythms are controlled by molecular clockworks within the brain that are reset daily to precisely 24 h by exposure to the light-dark cycle. Information from the master clock in the mammalian hypothalamus conveys temporal information to the entire body via humoral and neural communication. A bidirectional relationship exists between mood disorders and circadian rhythms. Mood disorders are often associated with disrupted circadian clock-controlled responses, such as sleep and cortisol secretion, whereas disruption of circadian rhythms via jet lag, night-shift work, or exposure to artificial light at night, can precipitate or exacerbate affective symptoms in susceptible individuals. Evidence suggests strong associations between circadian rhythms and mental health, but only recently have studies begun to discover the direct interactions between the circadian system and mood regulation. This review provides an overview of disrupted circadian rhythms and the relationship to behavioral health and psychiatry. The focus of this review is delineating the role of disruption of circadian rhythms on mood disorders using human night shift studies, as well as jet lag studies to identify links. We also review animal models of disrupted circadian rhythms on affective responses. Lastly, we propose low-cost behavioral and lifestyle changes to improve circadian rhythms and presumably behavioral health.

Sleep and female reproduction

PURPOSE OF REVIEW

Sleep disturbances are increasing in prevalence in North America. There is growing evidence that poor sleep quality and short sleep duration may adversely affect circadian rhythms, which in turn may affect female reproduction. The objective of this review is to evaluate recent literature on the association between sleep disturbances and female reproduction.

RECENT FINDINGS

There is accumulating evidence that sleep quality and duration are important for female reproduction, but epidemiologic research is limited. Recent studies provide suggestive evidence that sleep disorders are associated with increased menstrual irregularity, subfertility/infertility, and poor pregnancy and birth outcomes. Mechanisms underlying these associations are likely to be multifactorial and complex. In addition to genetics, circadian disruption may impact reproductive outcomes through dysregulation of the hypothalamic-pituitary-adrenal axis, insulin resistance, oxidative stress, and systemic inflammation. Recommendations for future studies include: use of prospective study designs; assessment of populations not already experiencing reproductive disorders; more detailed and accurate assessments of sleep such as validated self-reported measures or objective sleep measures (e.g. actigraphy); comprehensive assessment of potential confounders and mediators; and elucidation of biologic mechanisms.

SUMMARY

There is a growing body of literature showing evidence that sleep disturbances influence female reproduction, although further epidemiologic research is needed.

The Impact of Workplace Harassment on Health in a Working Cohort

Background: Workplace abuse, including sexual harassment, is frequently experienced worldwide and is related to adverse mental health outcomes, and injuries. Flight attendants are an understudied occupational group and are susceptible to harassment due to working in a feminized, client-facing occupation with few protections or sanctioned responses against aggressive behaviors.

Objective: We investigated the relationship between workplace abuse and health in a cohort of cabin crew. We also aimed to characterize perpetrator profiles.

Methods: We conducted our study among 4,459U.S. and Canada-based participants from the Harvard Flight Attendant Health Study using multivariate logistic regression. Our exposures of interest were episodes of workplace abuse in the past year. We evaluated several mental and physical health outcomes, including depression, fatigue, musculoskeletal injuries, and general workplace injuries.

Results: We report that exposures to verbal abuse, sexual harassment, and sexual assault are common among cabin crew, with 63, 26, and 2% of respondents, respectively, reporting harassment in the past year alone. Workplace abuse was associated with depression, sleep disturbances, and musculoskeletal injuries among male and female crew, with a trend toward increasing odds ratios (ORs) given a higher frequency of events. For example, sexual harassment was related to an increased odds for depression (OR = 1.91, 95% confidence interval [CI]: 1.51–2.30), which increased in a dose response-like manner among women reporting harassment once (OR = 1.44, 95% CI: 0.93–1.95), 2–3 times (OR = 1.83, 95% CI: 1.29–2.38), and 4 or more times (OR = 4.12, 95% CI: 3.18–5.06). We found that passengers were the primary perpetrators of abuse.

Conclusions: Our study is the first to comprehensively characterize workplace abuse and harassment and its relation to health in a largely female customer-facing workforce. The strong associations with health outcomes observed in our study highlights the question of how workplace policies can be altered to mitigate prevalent abuses. Clinicians could also consider how jobs with high emotional labor demands may predispose people to adverse health outcomes, educate patients regarding their psychological/physical responses and coping strategies, and be aware of signs of distress in patients working in such occupations in order to direct them to the appropriate treatments and therapies.

Legacy health effects among never smokers exposed to occupational secondhand smoke

OBJECTIVES

Secondhand tobacco smoke (SHTS) is a tremendous public health hazard, leading to morbidity and premature mortality worldwide, with racial and ethnic minorities and those of lower socioeconomic status disproportionately affected. Flight attendants were historically exposed to high levels of SHTS in the aircraft cabin. The health effects of active smoking are known to persist for up to a lifetime, but the legacy effects of SHTS exposure have not been well characterized.

DESIGN

We aimed to evaluate the legacy health effects of occupational SHTS exposure among never smoking workers using the resources of the Harvard Flight Attendant Health Study, a large study of cabin crew health. We evaluated associations between SHTS exposure and a range of diagnoses using multivariate logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs), employing a case-control sampling method and applying the bootstrap method to increase accuracy and precision of results.

RESULTS

We found no evidence of positive associations between SHTS and any cancer, but observed associations between SHTS and cardiac outcomes, including myocardial infarction (OR = 140, 95% CI: 1·04, 3·27) and peripheral artery disease (OR = 1·27, 95% CI: 1·00, 1·97). We also found associations between SHTS exposure and repeated pneumonia (OR = 1·06, 95% CI: 1·02, 1·10).

CONCLUSIONS

Our study reports associations between legacy SHTS exposure going back decades and severe cardiac and respiratory health outcomes. Given the high prevalence of ongoing and historical SHTS exposure, our findings, if confirmed, have important implications for smoking cessation efforts, health education, and clinical guidelines.

Vascular Aging Is Accelerated in Flight Attendants With Occupational Secondhand Smoke Exposure

OBJECTIVE

To determine whether early vascular aging may be present in flight attendants with remote in-cabin secondhand smoke (SHS) exposure.

METHODS

Twenty-six flight attendants with a history of in-cabin SHS exposure prior to the airline smoking bans were recruited. Pulse wave analysis, peripheral arterial tonometry, and brachial artery reactivity testing evaluated their arterial compliance and endothelial function.

RESULTS

Flight attendants with remote in-cabin SHS exposure have normal blood pressure, pulse wave velocity, and reactive hyperemia index, but abnormal pulse pressure, augmentation index, flow-mediated dilation, and hyperemic mean flow ratio.

CONCLUSION

These preliminary findings suggest that flight attendants with remote in-cabin SHS exposure have preclinical signs of accelerated vascular aging and raise new questions about the relationship between remote SHS exposure and vascular health.

Rhythms of life: circadian disruption and brain disorders across the lifespan

Many processes in the human body - including brain function - are regulated over the 24-hour cycle, and there are strong associations between disrupted circadian rhythms (for example, sleep-wake cycles) and disorders of the CNS. Brain disorders such as autism, depression and Parkinson disease typically develop at certain stages of life, and circadian rhythms are important during each stage of life for the regulation of processes that may influence the development of these disorders. Here, we describe circadian disruptions observed in various brain disorders throughout the human lifespan and highlight emerging evidence suggesting these disruptions affect the brain. Currently, much of the evidence linking brain disorders and circadian dysfunction is correlational, and so whether and what kind of causal relationships might exist are unclear. We therefore identify remaining questions that may direct future research towards a better understanding of the links between circadian disruption and CNS disorders.

Delayed first active-phase meal, a breakfast-skipping model, led to increased body weight and shifted the circadian oscillation of the hepatic clock and lipid metabolism-related genes in rats fed a high-fat diet

The circadian clock is closely related to human health, such as metabolic syndrome and cardiovascular disease. Our previous study revealed that irregular feeding induced abnormal lipid metabolism with disruption of the hepatic circadian clock. We hypothesized that breakfast skipping induces lipid abnormalities, such as adiposity, by altering the hepatic circadian oscillation of clock and lipid metabolism-related genes. Here, we established a delayed first active-phase meal (DFAM) protocol as a breakfast-skipping model. Briefly, rats were fed a high-fat diet during zeitgeber time (ZT) 12-24 in a control group and ZT 16-4 in the DFAM group. The DFAM group showed increased body weight gain and perirenal adipose tissue weight without a change in total food intake. The circadian oscillations of hepatic clock and de novo fatty acid synthesis genes were delayed by 2-4 h because of DFAM. The peaks of serum insulin, a synchronizer for the liver clock, bile acids, and non-esterified fatty acid (NEFA) were delayed by 4-6 h because of DFAM. Moreover, DFAM delayed the surge in body temperature by 4 h and may have contributed to the increase in body weight gain and adipose tissue weight because of decreased energy expenditure. These data indicated a potential molecular mechanism by which breakfast skipping induces abnormal lipid metabolism, which is related to the altered circadian oscillation of hepatic gene expression. The results also suggested that the delayed peaks of serum NEFA, bile acids, and insulin entrain the circadian rhythm of hepatic clock and lipid metabolism-related genes.

Cancer prevalence among flight attendants compared to the general population

BACKGROUND

Flight attendants are an understudied occupational group, despite undergoing a wide range of adverse job-related exposures, including to known carcinogens. In our study, we aimed to characterize the prevalence of cancer diagnoses among U.S. cabin crew relative to the general population.

METHODS

In 2014-2015, we surveyed participants of the Harvard Flight Attendant Health Study. We compared the prevalence of their self-reported cancer diagnoses to a contemporaneous cohort in the National Health and Nutrition Examination Survey (NHANES 2013-2014) using age-weighted standardized prevalence ratios (SPRs). We also analyzed associations between job tenure and the prevalence of selected cancers, using logistic regression and adjusting for potential confounders.

RESULTS

Compared to NHANES participants with a similar socioeconomic status (n = 2729), flight attendants (n = 5366) had a higher prevalence of every cancer we examined, especially breast cancer, melanoma, and non-melanoma skin cancer among females. SPR for these conditions were 1.51 (95% CI: 1.02, 2.24), 2.27 (95% CI: 1.27, 4.06), and 4.09 (95% CI: 2.70, 6.20), respectively. Job tenure was positively related to non-melanoma skin cancer among females, with borderline associations for melanoma and non-melanoma skin cancers among males. Consistent with previous studies, we observed associations between job tenure and breast cancer among women who had three or more children.

CONCLUSIONS

We observed higher rates of specific cancers in flight attendants compared the general population, some of which were related to job tenure. Our results should be interpreted in light of self-reported health information and a cross-sectional study design. Future longitudinal studies should evaluate associations between specific exposures and cancers among cabin crew.