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.

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.

Effects of a healthy lifestyle intervention and COVID-19-adjusted training curriculum on firefighter recruits.

There are knowledge gaps regarding healthy lifestyle (HLS) interventions in fire academy settings and also concerning the impacts of the pandemic on training. We enrolled fire recruits from two fire academies (A and B) in New England in early 2019 as the historical control group, and recruits from academies in New England (B) and Florida (C), respectively, during the pandemic as the intervention group. The three academies have similar training environments and curricula. The exposures of interest were a combination of (1) an HLS intervention and (2) impacts of the pandemic on training curricula and environs (i.e. social distancing, masking, reduced class size, etc.). We examined the health/fitness changes throughout training. The follow-up rate was 78%, leaving 92 recruits in the historical control group and 55 in the intervention group. The results show an HLS intervention improved the effects of fire academy training on recruits healthy behaviors (MEDI-lifestyle score, 0.5 ± 1.4 vs. - 0.3 ± 1.7), systolic blood pressure (- 7.2 ± 10.0 vs. 2.9 ± 12.9 mmHg), and mental health (Beck Depression score, - 0.45 ± 1.14 vs. - 0.01 ± 1.05) (all P < 0.05). The associations remained significant after multivariable adjustments. Moreover, a 1-point MEDI-lifestyle increment during academy training is associated with about 2% decrement in blood pressures over time, after multivariable adjustments (P < 0.05). Nonetheless, the impacts of pandemic restrictions on academy procedures compromised physical fitness training, namely in percent body fat, push-ups, and pull-ups.

The Effects of Fire Academy Training and Probationary Firefighter Status on Select Basic Health and Fitness Measurements.

PURPOSE: This study aimed to investigate changes in firefighter recruits' select health and fitness measurements, from academy training to the early probationary firefighter period. METHODS: Firefighter recruits from two New England fire academies were followed up prospectively from enrollment at the academy to graduation after 15- to 16-wk training programs, and then for an average of 8 months as probationary firefighters. The participants' demographic, lifestyle, and mental health information was collected using a questionnaire. Body mass index, percent body fat, blood pressure, and push-ups were also measured at each time point. Furthermore, the academies tested the recruits on selected fitness measures (push-ups, pull-ups, and 1.5-mile running time) at academy entry, midtraining, and at graduation. RESULTS: Ninety-two recruits consented and were included in the analyses. The recruits' percent body fat significantly decreased (median, 21.0%-18.2%) from baseline to graduation, and push-up capacity significantly improved (median, 34-53 per minute) in the same period, along with pull-ups and 1.5-mile running time. However, the recruits' blood pressure, both systolic and diastolic, increased significantly by an average of 3 mm Hg during the training. Those completing probationary follow-up (45/92 recruits) showed that most health/fitness improvements declined after graduation. From academy graduation to probationary follow-up, recruits' physical activity decreased and TV screen time increased significantly, leading to a lower healthy lifestyle score (median, 4-3). After multivariate adjustments, the recruits' diastolic blood pressure increased by 2 mm Hg per measuring time throughout the study period. CONCLUSIONS: Fire academy training improved recruits' select health and fitness measurements, but the benefits dissipated as probationary firefighters, and blood pressures increased throughout the study period. Further interventions regarding blood pressure and to maintain training benefits after joining fire departments are warranted.

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.