Cosmic radiation and cancer mortality among airline pilots: results from a European cohort study (ESCAPE)

Aircrew Health: A Systematic Review of Physical Agents as Occupational Risk Factors

The primary objective of this systematic review was to analyze the main physical agents representing risk factors for commercial aircrew, together with their consequences. The secondary objective was to identify the countries in which studies on the topic were conducted, as well as the quality of the publications available. Thirty-five articles, published between 1996 and 2020, were selected for the review, having met all inclusion criteria. The majority of studies were conducted in the United States, Germany, and Finland and had moderate or low methodological quality of evidence. The main risk factors for aircrew identified in publications were exposure to abnormal air pressure, cosmic radiation, noise, and vibrations. Hypobaric pressure was explored in response to demands for studies on this agent, a factor which may lead to otic and ear barotraumas, as well as acceleration of atherosclerosis of the carotid artery. However, there is a dearth of research exploring this phenomenon.

Incident skin melanoma in Danish male military pilots: a nested case-control study

OBJECTIVES

A growing body of research has reported that pilots have an increased risk of skin melanoma, which may be caused by occupational exposure to cosmic and solar ultraviolet A radiation in aircraft cockpits. However, the existing literature cannot rule out confounding, for example, that pilots may spend more leisure time in the sun compared with the general population, which therefore leaves the current evidence inconclusive. The present study aimed to provide more knowledge regarding this association.

METHODS

This nested case-control study included 199 male cases of skin melanoma diagnosed between 1990 and 2003, and 1126 male cancer-free controls identified from a large Danish military population. Among these individuals, 10 cases had ever worked as a pilot.Detailed information on military service and other held jobs together with socioeconomic and lifestyle characteristics, for example, leisure-time sun exposure habits, had been obtained from a structured questionnaire.

RESULTS

Adjusted results showed a positive association between work onboard aircraft and skin melanoma (OR=2.30, 95% CI: 1.06-4.97) and the risk was indicated only to be increased in pilots (OR=7.08, 95% CI: 2.51-19.93). A positive association between longer duration of employment as a pilot and skin melanoma was also observed (OR_{per year}=1.07, 95% CI: 1.01-1.14).

CONCLUSIONS

The findings from this study conducted among Danish military personnel suggest that pilots have an increased risk of skin melanoma after accounting for leisure-time sun exposure and socioeconomic status. Future large-scale studies focusing on the risk of skin melanoma in pilots, including detailed objective information on dimensions of exposure and potential confounders, are warranted.

Therapeutic potential of low dose ionizing radiation against cancer, dementia, and diabetes: evidences from epidemiological, clinical, and preclinical studies

The growing use of ionizing radiation (IR)-based diagnostic and treatment methods has been linked to increasing chronic diseases among patients and healthcare professionals. However, multiple factors such as IR dose, dose-rate, and duration of exposure influence the IR-induced chronic effects. The predicted links between low-dose ionizing radiation (LDIR) and health risks are controversial due to the non-availability of direct human studies. The studies pertaining to LDIR effects have importance in public health as exposure to background LDIR is routine. It has been anticipated that data from epidemiological and clinical reports and results of preclinical studies can resolve this controversy and help to clarify the notion of LDIR-associated health risks. Accumulating scientific literature shows reduced cancer risk, cancer-related deaths, curtailed neuro-impairments, improved neural functions, and reduced diabetes-related complications after LDIR exposure. In addition, it was found to alter evolutionarily conserved stress response pathways. However, the picture of molecular signaling pathways in LDIR responses is unclear. Besides, there is limited/no information on biomarkers of epidemiological LDIR exposure. Therefore, the present review discusses epidemiological, clinical, and preclinical studies on LDIR-induced positive effects in three chronic diseases (cancer, dementia, and diabetes) and their associated molecular mechanisms. The knowledge of LDIR response mechanisms may help to devise LDIR-based therapeutic modalities to stop disease progression. Modulation of these pathways may be helpful in developing radiation resistance among humans. However, more clinical evidence with additional biochemical, cellular, and molecular data and exploring the side effects of LDIR are the major areas of future research.

Prevalence of cataract among Australian commercial airline pilots

Because little is known about cataract in pilots, we estimated prevalence by anonymously ascertaining all commercial airline pilots diagnosed with cataract 2011-2016 using the electronic Medical Records System of the Australian Civil Aviation Safety Authority. Of 14,163 Australian male commercial pilots licensed in 2011, 1286 aged ≥60 had biennial eye examinations showing a cataract prevalence of 11.6%. Among 12,877 pilots aged <60, based on compulsory eye examinations only when first licensed, prevalence was 0.5%. There was no significant difference by ambient ultraviolet (UV) radiation levels in state of residence though lowest prevalence was seen in the low-UV state of Victoria. Most cataract in pilots ≥60 years was bilateral and of mild severity, while cataract in pilots <60 were more likely to be unilateral and of greater severity.

Cancer Incidence and Mortality Among Fighter Aviators in the United States Air Force

OBJECTIVE

This study sought to clarify cancer risk in fighter aviators.

METHODS

US Air Force officers who served between 1970 and 2004 were followed through 2018 for incidence and mortality of 10 cancers: colon and rectum; pancreas; melanoma skin; prostate; testis; urinary bladder; kidney and renal pelvis; brain and other nervous system; thyroid; and non-Hodgkin lymphoma. Fighter aviators were compared with other officers and the general US population.

RESULTS

Compared with other officers, male fighter aviators had greater adjusted odds of developing testis, melanoma skin, and prostate cancers; mortality odds were similar for all cancers. When compared with the US population, male fighter aviators were more likely to develop and die from melanoma skin cancer, prostate cancer, and non-Hodgkin lymphoma.

CONCLUSIONS

Military fighter aviation may be associated with slightly increased risk of certain cancers.

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Radiation in the Atmosphere—A Hazard to Aviation Safety?

Exposure of aircrew to cosmic radiation has been recognized as an occupational health risk for several decades. Based on the recommendations by the International Commission on Radiological Protection (ICRP), many countries and their aviation authorities, respectively have either stipulated legal radiation protection regulations, e.g., in the European Union or issued corresponding advisory circulars, e.g., in the United States of America. Additional sources of ionizing and non-ionizing radiation, e.g., due to weather phenomena have been identified and discussed in the scientific literature in recent years. This article gives an overview of the different generally recognized sources due to weather as well as space weather phenomena that contribute to radiation exposure in the atmosphere and the associated radiation effects that might pose a risk to aviation safety at large, including effects on human health and avionics. Furthermore, potential mitigation measures for several radiation sources and the prerequisites for their use are discussed.

The Risk of Cancer from CT Scans and Other Sources of Low-Dose Radiation: A Critical Appraisal of Methodologic Quality

INTRODUCTION

Concern exists that radiation exposure from computerized tomography (CT) will cause thousands of malignancies. Other experts share the same perspective regarding the risk from additional sources of low-dose ionizing radiation, such as the releases from Three Mile Island (1979; Pennsylvania USA) and Fukushima (2011; Okuma, Fukushima Prefecture, Japan) nuclear power plant disasters. If this premise is false, the fear of cancer leading patients and physicians to avoid CT scans and disaster responders to initiate forced evacuations is unfounded.

STUDY OBJECTIVE

This investigation provides a quantitative evaluation of the methodologic quality of studies to determine the evidentiary strength supporting or refuting a causal relationship between low-dose radiation and cancer. It will assess the number of higher quality studies that support or question the role of low-dose radiation in oncogenesis.

METHODS

This investigation is a systematic, methodologic review of articles published from 1975-2017 examining cancer risk from external low-dose x-ray and gamma radiation, defined as less than 200 millisievert (mSv). Following the PRISMA guidelines, the authors performed a search of the PubMed, Cochrane, Scopus, and Web of Science databases. Methodologies of selected articles were scored using the Newcastle Ottawa Scale (NOS) and a tool identifying 11 lower quality indicators. Manuscript methodologies were ranked as higher quality if they scored no lower than seven out of nine on the NOS and contained no more than two lower quality indicators. Investigators then characterized articles as supporting or not supporting a causal relationship between low-dose radiation and cancer.

RESULTS

Investigators identified 4,382 articles for initial review. A total of 62 articles met all inclusion/exclusion criteria and were evaluated in this study. Quantitative evaluation of the manuscripts' methodologic strengths found 25 studies met higher quality criteria while 37 studies met lower quality criteria. Of the 25 studies with higher quality methods, 21 out of 25 did not support cancer induction by low-dose radiation (P = .0003).

CONCLUSIONS

A clear preponderance of articles with higher quality methods found no increased risk of cancer from low-dose radiation. The evidence suggests that exposure to multiple CT scans and other sources of low-dose radiation with a cumulative dose up to 100 mSv (approximately 10 scans), and possibly as high as 200 mSv (approximately 20 scans), does not increase cancer risk.

The downfall of the linear non-threshold model

The linear non-threshold model (LNTM) is a theoretical dose-response function as a result of extrapolating the late effects of high-dose exposure to ionizing radiation to the low-dose range, but there is great uncertainty about its validity. The acceptance of LNTM as the dominant probabilistic model have survived to the present day and it is actually the cornerstone of current radiation protection policies. In the last decades, advances in molecular and evolutive biology, cancer immunology, and many epidemiological and animal studies have cast serious doubts about the reliability of the NLTM, as well as suggesting alternative models, like the hormetic theory. Considering the given evidences, a discussion between the involved scientific societies and the regulatory commissions is promtly required in order to to reach a redefiniton of theradiation protection basis, as it would be specially crucial in the medical field.

Cohort study of occupational cosmic radiation dose and cancer mortality in German aircrew, 1960–2014

Objectives

To determine cancer mortality compared with the general population and to examine dose-response relationships between cumulative occupational radiation dose and specific cancer outcomes in the German aircrew cohort.

Methods

For a cohort of 26 846 aircrew personnel, standardised mortality ratios (SMR) were calculated. Dose-response analyses were carried out using Poisson regression to assess dose-related cancer risks for the period 1960–2014. Exposure assessment comprises recently available dose register data for all cohort members and newly estimated retrospective cabin crew doses for 1960–2003.

Results

SMR for all-cause, specific cancer groups and most individual cancers were reduced in all aircrew groups. The only increases were seen for brain cancer in pilots (n=23, SMR 2.01, 95% CI 1.15 to 3.28) and for malignant melanoma (n=10, SMR 1.88, 95% CI 0.78 to 3.85). Breast cancer mortality among female cabin crew was similar to the general population (n=71, SMR 1.06, 95% CI 0.77 to 1.44). Overall median cumulative effective dose was 34.2 mSv (max: 116 mSv) for 1960–2014. No dose-response associations were seen in any of the models. For brain cancer, relative risks were elevated across dose categories. An indicative negative trend with increasing dose category was seen for large intestine cancer in female cabin crew (n=23).

Conclusions

There was no evidence for significant dose-response patterns for the considered cancer types. Interpretation of results remains difficult as cumulative dose is closely related to age. Future work should focus on investigating radiation jointly with other risk factors that may contribute to risks for specific cancers among aircrew.

Overview of Biological, Epidemiological, and Clinical Evidence of Radiation Hormesis

The effects of low-dose radiation are being increasingly investigated in biological, epidemiological, and clinical studies. Many recent studies have indicated the beneficial effects of low doses of radiation, whereas some studies have suggested harmful effects even at low doses. This review article introduces various studies reporting both the beneficial and harmful effects of low-dose radiation, with a critique on the extent to which respective studies are reliable. Epidemiological studies are inherently associated with large biases, and it should be evaluated whether the observed differences are due to radiation or other confounding factors. On the other hand, well-controlled laboratory studies may be more appropriate to evaluate the effects of low-dose radiation. Since the number of such laboratory studies is steadily increasing, it will be concluded in the near future whether low-dose radiation is harmful or beneficial and whether the linear-no-threshold (LNT) theory is appropriate. Many recent biological studies have suggested the induction of biopositive responses such as increases in immunity and antioxidants by low-dose radiation. Based on recent as well as classical studies, the LNT theory may be out of date, and low-dose radiation may have beneficial effects depending on the conditions; otherwise, it may have no effects.

Estimated radiation exposure of German commercial airline cabin crew in the years 1960-2003 modeled using dose registry data for 2004-2015

Exposure to ionizing radiation of cosmic origin is an occupational risk factor in commercial aircrew. In a historic cohort of 26,774 German aircrew, radiation exposure was previously estimated only for cockpit crew using a job-exposure matrix (JEM). Here, a new method for retrospectively estimating cabin crew dose is developed. The German Federal Radiation Registry (SSR) documents individual monthly effective doses for all aircrew. SSR-provided doses on 12,941 aircrew from 2004 to 2015 were used to model cabin crew dose as a function of age, sex, job category, solar activity, and male pilots' dose; the mean annual effective dose was 2.25 mSv (range 0.01-6.39 mSv). In addition to an inverse association with solar activity, exposure followed age- and sex-dependent patterns related to individual career development and life phases. JEM-derived annual cockpit crew doses agreed with SSR-provided doses for 2004 (correlation 0.90, 0.40 mSv root mean squared error), while the estimated average annual effective dose for cabin crew had a prediction error of 0.16 mSv, equaling 7.2% of average annual dose. Past average annual cabin crew dose can be modeled by exploiting systematic external influences as well as individual behavioral determinants of radiation exposure, thereby enabling future dose-response analyses of the full aircrew cohort including measurement error information.

COMPREHENSIVE DATA CONCERNING COSMIC RADIATION DOSES AT GROUND LEVEL AND IN-FLIGHTS FOR TURKEY

Cosmic radiation doses of individuals living in 81 cities in Turkey were estimated by using CARI-6 software. Annual cosmic radiation doses of individuals were found to be between 308 and 736 µSv y^-1 at ground level. The population-weighted annual effective dose from cosmic radiation was determined to be 387 µSv y^-1 for Turkey. Cosmic radiation doses on-board for 137 (60 domestic and 77 international) flights varied from 1.2 to 83 µSv. It was estimated that six or over long-route round-trip air travels may cause cosmic radiation dose above the permissible limit for member of the public, i.e. 1 mSv y^-1 According to the assumption of flights throughout 800 h on each route, cosmic radiation doses were found to be between 1.0 and 4.8 mSv for aircrew.

Cancer incidence among male military and civil pilots and flight attendants: an analysis on published data

Flight personnel are exposed to cosmic ionizing radiation, chemicals (fuel, jet engine exhausts, cabin air pollutants), electromagnetic fields from cockpit instruments, and disrupted sleep patterns. Only recently has cancer risk among these workers been investigated. With the aim of increasing the precision of risk estimates of cancer incidence, follow-up studies reporting a standardized incidence ratio for cancer among male flight attendants, civil and military pilots were obtained from online databases and analysed. A meta-analysis was performed by applying a random effect model, obtaining a meta-standardized incidence ratio (SIR), and 95% confidence interval (CI). In male cabin attendants, and civil and military pilots, meta-SIRs were 3.42 (CI=1.94-6.06), 2.18 (1.69-2.80), 1.43 (1.09-1.87) for melanoma; and 7.46 (3.52-15.89), 1.88 (1.23-2.88), 1.80 (1.25-2.58) for other skin cancer, respectively. These tumors share as risk factors, ionizing radiation, recreational sun exposure and socioeconomic status. The meta-SIRs are not adjusted for confounding; the magnitude of risk for melanoma decreased when we corrected for socioeconomic status. In civil pilots, meta-SIR was 1.47 (1.06-2.05) for prostate cancer. Age (civil pilots are older than military pilots and cabin attendants) and disrupted sleep pattern (entailing hyposecretion of melatonin, which has been reported to suppress proliferative effects of androgen on prostate cancer cells) might be involved. In male cabin attendants, meta-SIR was 21.5 (2.25-205.8) for Kaposi’s sarcoma and 2.49 (1.03-6.03) for non-Hodgkin’s lymphoma. AIDS, which was the most frequent single cause of death in this occupational category, likely explains the excess of the latter two tumors.

Harderian Gland Tumorigenesis: Low-Dose and LET Response

Increased cancer risk remains a primary concern for travel into deep space and may preclude manned missions to Mars due to large uncertainties that currently exist in estimating cancer risk from the spectrum of radiations found in space with the very limited available human epidemiological radiation-induced cancer data. Existing data on human risk of cancer from X-ray and gamma-ray exposure must be scaled to the many types and fluences of radiations found in space using radiation quality factors and dose-rate modification factors, and assuming linearity of response since the shapes of the dose responses at low doses below 100 mSv are unknown. The goal of this work was to reduce uncertainties in the relative biological effect (RBE) and linear energy transfer (LET) relationship for space-relevant doses of charged-particle radiation-induced carcinogenesis. The historical data from the studies of Fry et al. and Alpen et al. for Harderian gland (HG) tumors in the female CB6F1 strain of mouse represent the most complete set of experimental observations, including dose dependence, available on a specific radiation-induced tumor in an experimental animal using heavy ion beams that are found in the cosmic radiation spectrum. However, these data lack complete information on low-dose responses below 0.1 Gy, and for chronic low-dose-rate exposures, and there are gaps in the LET region between 25 and 190 keV/μm. In this study, we used the historical HG tumorigenesis data as reference, and obtained HG tumor data for 260 MeV/u silicon (LET ∼70 keV/μm) and 1,000 MeV/u titanium (LET ∼100 keV/μm) to fill existing gaps of data in this LET range to improve our understanding of the dose-response curve at low doses, to test for deviations from linearity and to provide RBE estimates. Animals were also exposed to five daily fractions of 0.026 or 0.052 Gy of 1,000 MeV/u titanium ions to simulate chronic exposure, and HG tumorigenesis from this fractionated study were compared to the results from single 0.13 or 0.26 Gy acute titanium exposures. Theoretical modeling of the data show that a nontargeted effect model provides a better fit than the targeted effect model, providing important information at space-relevant doses of heavy ions.

Cosmic radiation and cancer: is there a link?

Cosmic radiation can cause genetic and cytogenetic damage. Certain occupations including airline pilots and cabin crew are acknowledged to have a greater exposure to cosmic radiation. In a systematic search of MEDLINE, performed from 1990 to 2014, we analyzed clinical studies using the keywords: cosmic radiation, cancer, chromosome aberration, pilots and astronauts. Increased incidence of skin cancers among airline cabin crew has been reported in a number of studies and appears to be the most consistent finding. However, as with other cancers, it is unclear whether increased exposure to cosmic radiation is a factor in the increased incidence or whether this can be explained by lifestyle factors. Further research is needed to clarify the risk of cancer in relation to cosmic radiation.

Concepts and challenges in cancer risk prediction for the space radiation environment

Cancer is an important long-term risk for astronauts exposed to protons and high-energy charged particles during travel and residence on asteroids, the moon, and other planets. NASA's Biomedical Critical Path Roadmap defines the carcinogenic risks of radiation exposure as one of four type I risks. A type I risk represents a demonstrated, serious problem with no countermeasure concepts, and may be a potential "show-stopper" for long duration spaceflight. Estimating the carcinogenic risks for humans who will be exposed to heavy ions during deep space exploration has very large uncertainties at present. There are no human data that address risk from extended exposure to complex radiation fields. The overarching goal in this area to improve risk modeling is to provide biological insight and mechanistic analysis of radiation quality effects on carcinogenesis. Understanding mechanisms will provide routes to modeling and predicting risk and designing countermeasures. This white paper reviews broad issues related to experimental models and concepts in space radiation carcinogenesis as well as the current state of the field to place into context recent findings and concepts derived from the NASA Space Radiation Program.

The risk of melanoma in airline pilots and cabin crew: a meta-analysis

IMPORTANCE

Airline pilots and cabin crew are occupationally exposed to higher levels of cosmic and UV radiation than the general population, but their risk of developing melanoma is not yet established.

OBJECTIVE

To assess the risk of melanoma in pilots and airline crew.

DATA SOURCES

PubMed (1966 to October 30, 2013), Web of Science (1898 to January 27, 2014), and Scopus (1823 to January 27, 2014).

STUDY SELECTION

All studies were included that reported a standardized incidence ratio (SIR), standardized mortality ratio (SMR), or data on expected and observed cases of melanoma or death caused by melanoma that could be used to calculate an SIR or SMR in any flight-based occupation.

DATA EXTRACTION AND SYNTHESIS

Primary random-effect meta-analyses were used to summarize SIR and SMR for melanoma in any flight-based occupation. Heterogeneity was assessed using the χ2 test and I2 statistic. To assess the potential bias of small studies, we used funnel plots, the Begg rank correlation test, and the Egger weighted linear regression test.

MAIN OUTCOMES AND MEASURES

Summary SIR and SMR of melanoma in pilots and cabin crew.

RESULTS

Of the 3527 citations retrieved, 19 studies were included, with more than 266 431 participants. The overall summary SIR of participants in any flight-based occupation was 2.21 (95% CI, 1.76-2.77; P < .001; 14 records). The summary SIR for pilots was 2.22 (95% CI, 1.67-2.93; P = .001; 12 records). The summary SIR for cabin crew was 2.09 (95% CI, 1.67-2.62; P = .45; 2 records). The overall summary SMR of participants in any flight-based occupation was 1.42 (95% CI, 0.89-2.26; P = .002; 6 records). The summary SMR for pilots was 1.83 (95% CI, 1.27-2.63, P = .33; 4 records). The summary SMR for cabin crew was 0.90 (95% CI, 0.80-1.01; P = .97; 2 records).

CONCLUSIONS AND RELEVANCE

Pilots and cabin crew have approximately twice the incidence of melanoma compared with the general population. Further research on mechanisms and optimal occupational protection is needed.

Mortality among a cohort of U.S. commercial airline cockpit crew

BACKGROUND

We evaluated mortality among 5,964 former U.S. commercial cockpit crew (pilots and flight engineers). The outcomes of a priori interest were non-chronic lymphocytic leukemia, central nervous system (CNS) cancer (including brain), and malignant melanoma.

METHODS

Vital status was ascertained through 2008. Life table and Cox regression analyses were conducted. Cumulative exposure to cosmic radiation was estimated from work history data.

RESULTS

Compared to the U.S. general population, mortality from all causes, all cancer, and cardiovascular diseases was decreased, but mortality from aircraft accidents was highly elevated. Mortality was elevated for malignant melanoma but not for non-chronic lymphocytic leukemia. CNS cancer mortality increased with an increase in cumulative radiation dose.

CONCLUSIONS

Cockpit crew had a low all-cause, all-cancer, and cardiovascular disease mortality but elevated aircraft accident mortality. Further studies are needed to clarify the risk of CNS and other radiation-associated cancers in relation to cosmic radiation and other workplace exposures.

The incidence of venous thromboembolism in commercial airline pilots: a cohort study of 2630 pilots

BACKGROUND

Airline pilots may be at increased risk of venous thromboembolism (VTE) because air travel has recently been established as a risk factor for VTE.

OBJECTIVES

The aim of this study was to assess the risk of VTE in a cohort of Dutch airline pilots.

PATIENTS/METHODS

Airline pilots who had been active members of the Dutch aviation society (VNV) were questioned for the occurrence of VTE, presence of risk factors for VTE and number of flight hours per year and rank. Incidence rates among pilots were compared with those of the general Dutch population and with a population of frequently flying employees of multinational organizations.

RESULTS AND CONCLUSIONS

A total of 2630 male pilots were followed-up for a total of 20420 person-years (py). Six venous thromboses were reported, yielding an incidence rate of 0.3 per 1000 py. The standardized morbidity ratio, comparing these pilots with the general Dutch population adjusted for age, was 0.8. Compared with the international employee cohort, the standardized morbidity ratio was 0.7 when all employees were included and 0.6 when only the frequently travelling employees were included. The incidence rate did not increase with number of flight hours per year and did not clearly vary by rank. We conclude that the risk of VTE is not increased amongst airline pilots.

Incidence of colorectal neoplasms among male pilots

AIM: To assess the prevalence of colorectal neoplasms (adenomas, advanced adenomas and colorectal cancers) among Israeli military and commercial airline pilots.

METHODS: Initial screening colonoscopy was performed on average-risk (no symptoms and no family history) airline pilots at the Integrated Cancer Prevention Center (ICPC) in the Tel-Aviv Medical Center. Visualized polyps were excised and sent for pathological examination. Advanced adenoma was defined as a lesion >10 mm in diameter, with high-grade dysplasia or villous histology. The results were compared with those of an age- and gender-matched random sample of healthy adults undergoing routine screening at the ICPC.

RESULTS: There were 270 pilots (mean age 55.2 ± 7.4 years) and 1150 controls (mean age 55.7 ± 7.8 years). The prevalence of colorectal neoplasms was 15.9% among the pilots and 20.6% among the controls (P = 0.097, χ² test). There were significantly more hyperplastic polyps among pilots (15.5% vs 9.4%, P = 0.004) and a trend towards fewer adenomas (14.8% vs 20.3% P = 0.06). The prevalence of advanced lesions among pilots and control groups was 5.9% and 4.7%, respectively (P = 0.49), and the prevalence of cancer was 0.7% and 0.69%, respectively (P = 0.93).

CONCLUSION: There tends to be a lower colorectal adenoma, advanced adenoma and cancer prevalence but a higher hyperplastic polyp prevalence among pilots than the general population.

Mortality from cancer and other causes in commercial airline crews: a joint analysis of cohorts from 10 countries

BACKGROUND

Commercial airline crew is one of the occupational groups with the highest exposures to ionising radiation. Crew members are also exposed to other physical risk factors and subject to potential disruption of circadian rhythms.

METHODS

This study analyses mortality in a pooled cohort of 93 771 crew members from 10 countries. The cohort was followed for a mean of 21.7 years (2.0 million person-years), during which 5508 deaths occurred.

RESULTS

The overall mortality was strongly reduced in male cockpit (SMR 0.56) and female cabin crews (SMR 0.73). The mortality from radiation-related cancers was also reduced in male cockpit crew (SMR 0.73), but not in female or male cabin crews (SMR 1.01 and 1.00, respectively). The mortality from female breast cancer (SMR 1.06), leukaemia and brain cancer was similar to that of the general population. The mortality from malignant melanoma was elevated, and significantly so in male cockpit crew (SMR 1.57). The mortality from cardiovascular diseases was strongly reduced (SMR 0.46). On the other hand, the mortality from aircraft accidents was exceedingly high (SMR 33.9), as was that from AIDS in male cabin crew (SMR 14.0).

CONCLUSIONS

This large study with highly complete follow-up shows a reduced overall mortality in male cockpit and female cabin crews, an increased mortality of aircraft accidents and an increased mortality in malignant skin melanoma in cockpit crew. Further analysis after longer follow-up is recommended.

Rotating night-shift work and lung cancer risk among female nurses in the United States

The risk of lung cancer among night-shift workers is unknown. Over 20 years of follow-up (1988-2008), we documented 1,455 incident lung cancers among 78,612 women in the Nurses' Health Study. To examine the relationship between rotating night-shift work and lung cancer risk, we used multivariate Cox proportional hazard models adjusted for detailed smoking characteristics and other risk factors. We observed a 28% increased risk of lung cancer among women with 15 or more years spent working rotating night shifts (multivariate relative risk (RR) = 1.28, 95% confidence interval (CI): 1.07, 1.53; Ptrend = 0.03) compared with women who did not work any night shifts. This association was strongest for small-cell lung carcinomas (multivariate RR = 1.56, 95% CI: 0.99, 2.47; Ptrend = 0.03) and was not observed for adenocarcinomas of the lung (multivariate RR = 0.91, 95% CI: 0.67, 1.24; Ptrend = 0.40). Further, the increased risk associated with 15 or more years of rotating night-shift work was limited to current smokers (RR = 1.61, 95% CI: 1.21, 2.13; Ptrend < 0.001), with no association seen in nonsmokers (Pinteraction = 0.03). These results suggest that there are modestly increased risks of lung cancer associated with extended periods of night-shift work among smokers but not among nonsmokers. Though it is possible that this observation was residually confounded by smoking, our findings could also provide evidence of circadian disruption as a "second hit" in the etiology of smoking-related lung tumors.

Exposure assessment at 30 000 feet: challenges and future directions

Few studies of cancer mortality and incidence among flight crew have included a detailed assessment of both occupational exposures and lifestyle factors that may influence the risk of cancer. In this issue, Kojo et al. (Risk factors for skin cancer among Finnish airline cabin crew. Ann Occup. Hyg 2013; 57: 695-704) evaluated the relative contributions of ultraviolet and cosmic radiation to the incidence of skin cancer in Finnish flight attendants. This is a useful contribution, yet the reason flight crew members have an increased risk of skin cancer compared with the general population remains unclear. Good policy decisions for flight crew will depend on continued and emerging effective collaborations to increase study power and improve exposure assessment in future flight crew health studies. Improving the assessment of occupational exposures and non-occupational factors will cost additional time and effort, which are well spent if the role of exposures can be clarified in larger studies.

Occupational cosmic radiation exposure in Portuguese airline pilots: study of a possible correlation with oxidative biological markers

Several studies have sought to understand the health effects of occupational exposure to cosmic radiation. However, only few biologic markers or associations with disease outcomes have so far been identified. In the present study, 22 long- and 26 medium-haul male Portuguese airline pilots and 36 factory workers who did not fly regularly were investigated. The two groups were comparable in age and diet, were non-smokers, never treated with ionizing radiation and other factors. Cosmic radiation exposure in pilots was quantified based on direct monitoring of 51 flights within Europe, and from Europe to North and South America, and to Africa. Indirect dose estimates in pilots were performed based on the SIEVERT (Système informatisé d'évaluation par vol de l'exposition au rayonnement cosmique dans les transports aériens) software for 6,039 medium- and 1,366 long-haul flights. Medium-haul pilots had a higher cosmic radiation dose rate than long-haul pilots, that is, 3.3 ± 0.2 μSv/h and 2.7 ± 0.3 μSv/h, respectively. Biological tests for oxidative stress on blood and urine, as appropriate, at two time periods separated by 1 year, included measurements of antioxidant capacity, total protein, ferritin, hemoglobin, creatinine and 8-hydroxy-2-deoxyguanosine (8OHdG). Principal components analysis was used to discriminate between the exposed and unexposed groups based on all the biological tests. According to this analysis, creatinine and 8OHdG levels were different for the pilots and the unexposed group, but no distinctions could be made among the medium- and the long-haul pilots. While hemoglobin levels seem to be comparable between the studied groups, they were directly correlated with ferritin values, which were lower for the airline pilots.

Occupational cancer in Britain. Statistical methodology

An approach using the attributable fraction (AF) has been developed to estimate the current burden of occupational cancer in Britain. The AF combines the relative risk (RR) associated with exposure with the proportion exposed. For each cancer–exposure pairing, the RR is selected from key epidemiological literature such as an industry, or population-based study, meta-analysis or review. The CARcinogen EXposure (CAREX) database provides point estimates for the number of workers exposed to a range of carcinogens; alternative sources are national surveys such as the Labour Force Survey and Census of Employment. The number of workers exposed are split between high and low exposure levels matched to appropriate RRs from the literature. The relevant period for cancer development during which exposure occurred is defined as the risk exposure period (REP). Estimation of the numbers ever exposed over the REP takes into account the changes in the number of people employed in primary and manufacturing industry and service sectors in Britain where appropriate, and adjustment is made for staff turnover over the period and for life expectancy. National estimates of the population ever of working age during the REP are used for the proportion denominator. Strategies have been developed to combine exposure AFs correctly while avoiding double counting and minimising bias. The AFs are applied to national cancer deaths and registrations to obtain occupation-attributable cancer numbers. The methods are adaptable for other diseases and other geographies, and are also adaptable to more sophisticated modelling if better exposure and dose–response data are available.

Developing an action plan for patient radiation safety in adult cardiovascular medicine. Proceedings from the Duke University Clinical Research Institute/American College of Cardiology Foundation/American Heart Association Think Tank Held on February 28, 2011

Technological advances and increased utilization of medical testing and procedures have prompted greater attention to ensuring the patient safety of radiation use in the practice of adult cardiovascular medicine. In response, representatives from cardiovascular imaging societies, private payers, government and nongovernmental agencies, industry, medical physicists, and patient representatives met to develop goals and strategies toward this end; this report provides an overview of the discussions. This expert "think tank" reached consensus on several broad directions including: the need for broad collaboration across a large number of diverse stakeholders; clarification of the relationship between medical radiation and stochastic events; required education of ordering and providing physicians, and creation of a culture of safety; development of infrastructure to support robust dose assessment and longitudinal tracking; continued close attention to patient selection by balancing the benefit of cardiovascular testing and procedures against carefully minimized radiation exposures; collation, dissemination, and implementation of best practices; and robust education, not only across the healthcare community but also to patients, the public, and media. Finally, because patient radiation safety in cardiovascular imaging is complex, any proposed actions need to be carefully vetted (and monitored) for possible unintended consequences.

Cancer incidence in professional flight crew and air traffic control officers: disentangling the effect of occupational versus lifestyle exposures

Flight crew are occupationally exposed to several potentially carcinogenic hazards; however, previous investigations have been hampered by lack of information on lifestyle exposures. The authors identified, through the United Kingdom Civil Aviation Authority medical records, a cohort of 16,329 flight crew and 3,165 air traffic control officers (ATCOs) and assembled data on their occupational and lifestyle exposures. Standardised incidence ratios (SIRs) were estimated to compare cancer incidence in each occupation to that of the general population; internal analyses were conducted by fitting Cox regression models. All-cancer incidence was 20-29% lower in each occupation than in the general population, mainly due to a lower incidence of smoking-related cancers [SIR (95% CI) = 0.33 (0.27-0.38) and 0.42 (0.28-0.60) for flight crew and ATCOs, respectively], consistent with their much lower prevalence of smoking. Skin melanoma rates were increased in both flight crew (SIR = 1.87; 95% CI = 1.45-2.38) and ATCOs (2.66; 1.55-4.25), with rates among the former increasing with increasing number of flight hours (p-trend = 0.02). However, internal analyses revealed no differences in skin melanoma rates between flight crew and ATCOs (hazard ratio: 0.78, 95% CI = 0.37-1.66) and identified skin that burns easily when exposed to sunlight (p = 0.001) and sunbathing to get a tan (p = 0.07) as the strongest risk predictors of skin melanoma in both occupations. The similar site-specific cancer risks between the two occupational groups argue against risks among flight crew being driven by occupation-specific exposures. The skin melanoma excess reflects sun-related behaviour rather than cosmic radiation exposure.

RAD51 plays a crucial role in halting cell death program induced by ionizing radiation in bovine oocytes

Reproductive health of humans and animals exposed to daily irradiants from solar/cosmic particles remains largely understudied. We evaluated the sensitivities of bovine and mouse oocytes to bombardment by krypton-78 (1 Gy) or ultraviolet B (UV-B; 100 microjoules). Mouse oocytes responded to irradiation by undergoing massive activation of caspases, rapid loss of energy without cytochrome-c release, and subsequent necrotic death. In contrast, bovine oocytes became positive for annexin-V, exhibited cytochrome-c release, and displayed mild activation of caspases and downstream DNAses but with the absence of a complete cell death program; therefore, cytoplasmic fragmentation was never observed. However, massive cytoplasmic fragmentation and increased DNA damage were induced experimentally by both inhibiting RAD51 and increasing caspase 3 activity before irradiation. Microinjection of recombinant human RAD51 prior to irradiation markedly decreased both cytoplasmic fragmentation and DNA damage in both bovine and mouse oocytes. RAD51 response to damaged DNA occurred faster in bovine oocytes than in mouse oocytes. Therefore, we conclude that upon exposure to irradiation, bovine oocytes create a physiologically indeterminate state of partial cell death, attributed to rapid induction of DNA repair and low activation of caspases. The persistence of these damaged cells may represent an adaptive mechanism with potential implications for livestock productivity and long-term health risks associated with human activity in space.

Epidemiological investigations of aircrew: an occupational group with low-level cosmic radiation exposure

Aircrew and passengers are exposed to low-level cosmic ionising radiation. Annual effective doses for flight crew have been estimated to be in the order of 2-5 mSv and can attain 75 mSv at career end. Epidemiological studies in this occupational group have been conducted over the last 15-20 years, usually with a focus on radiation-associated cancer. These studies are summarised in this note. Overall cancer risk was not elevated in most studies and subpopulations analysed, while malignant melanoma, other skin cancers and breast cancer in female aircrew have shown elevated incidence, with lesser risk elevations in terms of mortality. In some studies, including the large German cohort, brain cancer risk appears elevated. Cardiovascular mortality risks were generally very low. Dose information for pilots was usually derived from calculation procedures based on routine licence information, types of aircraft and routes/hours flown, but not on direct measurements. However, dose estimates have shown high validity when compared with measured values. No clear-cut dose-response patterns pointing to a higher risk for those with higher cumulative doses were found. Studies on other health outcomes have shown mixed results. Overall, aircrew are a highly selected group with many specific characteristics and exposures that might also influence cancers or other health outcomes. Radiation-associated health effects have not been clearly established in the studies available so far.

Cause-specific mortality among a cohort of U.S. flight attendants

BACKGROUND

We evaluated mortality among 11,311 former U.S. flight attendants. The primary a priori outcomes of interest were breast cancer and melanoma.

METHODS

Vital status was ascertained through 2007, and life table analyses was conducted. Cumulative exposure to cosmic radiation and circadian rhythm disruption were estimated from work history data and historical published flight schedules.

RESULTS

All-cause mortality was less than expected among women but was elevated among men, primarily due to elevated HIV-related disease mortality. Mortality from breast cancer among women and melanoma was neither significantly elevated nor related to metrics of exposure. Mortality was elevated for non-Hodgkin's lymphoma among men; for alcoholism, drowning, and intentional self-harm among women; and for railway, water, and air transportation accidents.

CONCLUSIONS

We found no evidence of increased breast cancer or melanoma mortality. Limitations include reliance on mortality data and limited power resulting from few melanoma deaths and relatively short employment durations.

SCCT guidelines on radiation dose and dose-optimization strategies in cardiovascular CT

Over the last few years, computed tomography (CT) has developed into a standard clinical test for a variety of cardiovascular conditions. The emergence of cardiovascular CT during a period of dramatic increase in radiation exposure to the population from medical procedures and heightened concern about the subsequent potential cancer risk has led to intense scrutiny of the radiation burden of this new technique. This has hastened the development and implementation of dose reduction tools and prompted closer monitoring of patient dose. In an effort to aid the cardiovascular CT community in incorporating patient-centered radiation dose optimization and monitoring strategies into standard practice, the Society of Cardiovascular Computed Tomography has produced a guideline document to review available data and provide recommendations regarding interpretation of radiation dose indices and predictors of risk, appropriate use of scanner acquisition modes and settings, development of algorithms for dose optimization, and establishment of procedures for dose monitoring.

Cause-specific mortality in professional flight crew and air traffic control officers: findings from two UK population-based cohorts of over 20,000 subjects

OBJECTIVE

Flight crew are exposed to several potential occupational hazards. This study compares mortality rates in UK flight crew to those in air traffic control officers (ATCOs) and the general population.

METHODS

A total of 19,489 flight crew and ATCOs were identified from the UK Civil Aviation Authority medical records and followed to the end of 2006. Consented access to medical records and questionnaire data provided information on demographic, behavioral, clinical, and occupational variables. Standardized mortality ratios (SMR) were estimated for these two occupational groups using the UK general population. Adjusted mortality hazard ratios (HR) for flight crew versus ATCOs were estimated via Cox regression models.

RESULTS

A total of 577 deaths occurred during follow-up. Relative to the general population, both flight crew (SMR 0.32; 95% CI 0.30, 0.35) and ATCOs (0.39; 0.32, 0.47) had lower all-cause mortality, mainly due to marked reductions in mortality from neoplasms and cardiovascular diseases, although flight crew had higher mortality from aircraft accidents (SMR 42.8; 27.9, 65.6). There were no differences in all-cause mortality (HR 0.99; 95% CI 0.79, 1.25), or in mortality from any major cause, between the two occupational groups after adjustment for health-related variables, again except for those from aircraft accidents. The latter ratios, however, declined with increasing number of hours.

CONCLUSIONS

The low all-cause mortality observed in both occupational groups relative to the general population is consistent with a strong "healthy worker effect" and their low prevalence of smoking and other risk factors. Mortality among flight crew did not appear to be influenced by occupational exposures, except for a rise in mortality from aircraft accidents.

Rotating night shifts and risk of skin cancer in the nurses' health study

Night shift work is associated with increased risk of several cancers, but the risk of skin cancer among night shift workers is unknown. We documented 10,799 incident skin cancers in 68,336 women in the Nurses' Health Study from June 1988 to June 2006 and examined the relationship between rotating night shifts and skin cancer. We used Cox proportional hazard models, adjusted for confounding variables (phenotypic and established risk factors of skin cancer), and performed stratified analysis to explore the modifying effect of hair color. Working 10 years or more on rotating night shifts was associated with a 14% decreased risk of skin cancer compared with never working night shifts (age-standardized incidence rate: 976 per 100,000 person-years (PY) vs 1070 per 100,000 PY, respectively; adjusted hazard ratios = 0.86, 95% confidence interval = 0.81 to 0.92, P(trend) < .001). This association was strongest for cutaneous melanoma; working 10 years or more of rotating night shifts was associated with 44% decreased risk of melanoma, after adjustment for melanoma risk factors (age-standardized incidence rate: 20 per 100,000 PY vs 35 per 100,000 PY, respectively; adjusted hazard ratios = 0.56, 95% confidence interval = 0.36 to 0.87, P(trend) = .005). Hair color, a surrogate for an individual's susceptibility to skin cancer, was a statistically significant effect modifier for the observed associations; darker-haired women had the lowest risk (P(interaction) = .02).

Delayed effects of chronic low-dose high linear energy transfer (LET) radiation on mice in vivo

In the present work, the delayed effects of chronic high linear energy transfer (LET) radiation in polychromatic erythrocytes (PCEs) of mice bone marrow were investigated in vivo. Irradiation of the two-month-old SHK white mongrel random-bred male mice was performed in the radiation field behind the concrete shield of the accelerator of 70 GeV protons to accumulate doses of 0.005-0.16 Gy. The dependence of the biological response on dose, adaptive response (AR) and genomic instability (GI) in F(1) and F(2) generations from males irradiated with doses of 0.005 and 0.16 Gy and from males exposed to combined action of immunomodulator-bendazol hydrochloride (BH) and of 0.16 Gy irradiation, were examined using the micronucleus formation test. The data demonstrated that irradiation of mice with these doses lead to an increase in the level of cytogenetic damage and induces no AR. With analysis of the bone marrow radiosensitivity to 1.5 Gy of X rays and the capacity to AR it was found that the chronic high-LET irradiation of parents induced the GI at least two generations. The combined exposure to BH and the dose of 0.16 Gy induces no AR in F(0) generation but induces AR in F(1) and F(2) offspring.

Review and evaluation of updated research on the health effects associated with low-dose ionising radiation

While radiation health risks at low doses have traditionally been estimated from high-dose studies, we have reviewed recent literature and concluded that the mechanisms of action for many biological endpoints may be different at low doses from those observed at high doses; that acute doses <100 mSv may be too small to allow epidemiological detection of excess cancers given the background of naturally occurring cancers; that low-dose radiation research should use holistic approaches such as systems-based methods to develop models that define the shape of the dose-response relationship; and that these results should be combined with the latest epidemiology to produce a comprehensive understanding of radiation effects that addresses both damage, likely with a linear effect, and response, possibly with non-linear consequences. Continued research is needed to understand how radiobiology and epidemiology advances should be used to effectively model radiation worker risks.

Occupation and cancer in Britain

Background:

Prioritising control measures for occupationally related cancers should be evidence based. We estimated the current burden of cancer in Britain attributable to past occupational exposures for International Agency for Research on Cancer (IARC) group 1 (established) and 2A (probable) carcinogens.

Methods:

We calculated attributable fractions and numbers for cancer mortality and incidence using risk estimates from the literature and national data sources to estimate proportions exposed.

Results:

5.3% (8019) cancer deaths were attributable to occupation in 2005 (men, 8.2% (6362); women, 2.3% (1657)). Attributable incidence estimates are 13 679 (4.0%) cancer registrations (men, 10 063 (5.7%); women, 3616 (2.2%)). Occupational attributable fractions are over 2% for mesothelioma, sinonasal, lung, nasopharynx, breast, non-melanoma skin cancer, bladder, oesophagus, soft tissue sarcoma, larynx and stomach cancers. Asbestos, shift work, mineral oils, solar radiation, silica, diesel engine exhaust, coal tars and pitches, occupation as a painter or welder, dioxins, environmental tobacco smoke, radon, tetrachloroethylene, arsenic and strong inorganic mists each contribute 100 or more registrations. Industries and occupations with high cancer registrations include construction, metal working, personal and household services, mining, land transport, printing/publishing, retail/hotels/restaurants, public administration/defence, farming and several manufacturing sectors. 56% of cancer registrations in men are attributable to work in the construction industry (mainly mesotheliomas, lung, stomach, bladder and non-melanoma skin cancers) and 54% of cancer registrations in women are attributable to shift work (breast cancer).

Conclusion:

This project is the first to quantify in detail the burden of cancer and mortality due to occupation specifically for Britain. It highlights the impact of occupational exposures, together with the occupational circumstances and industrial areas where exposures to carcinogenic agents occurred in the past, on population cancer morbidity and mortality; this can be compared with the impact of other causes of cancer. Risk reduction strategies should focus on those workplaces where such exposures are still occurring.

Cancer mortality among German aircrew: second follow-up

Aircrew members are exposed to cosmic radiation and other specific occupational factors. In a previous analysis of a large cohort of German aircrew, no increase in cancer mortality or dose-related effects was observed. In the present study, the follow-up of this cohort of 6,017 cockpit and 20,757 cabin crew members was extended by 6 years to 2003. Among male cockpit crew, the resulting all-cancer standardized mortality ratio (SMR) (n = 127) is 0.6 (95% CI 0.5-0.8), while for brain tumors it is 2.1 (95% CI 1.0-3.9). The cancer risk is significantly raised (RR = 2.2, 95% CI 1.2-4.1) among cockpit crew members employed 30 years or more compared to those employed less than 10 years. Among both female and male cabin crew, the all-cancer SMR and that for most individual cancers are close to 1. The SMR for breast cancer among female crew is 1.2 (95% CI 0.8-1.8). Non-Hodgkin's Lymphoma among male cabin crew is increased (SMR 4.2; 95% CI 1.3-10.8). However, cancers associated with radiation exposure are not raised in the cohort. It is concluded that among cockpit crew cancer mortality is low, particularly for lung cancer. The positive trend of all cancer with duration of employment persists. The increased brain cancer SMR among cockpit crew requires replication in other cohorts. For cabin crew, cancer mortality is generally close to population rates. Cosmic radiation dose estimates will allow more detailed assessments, as will a pooling of updated aircrew studies currently in planning.

ACR Colon Cancer Committee white paper: status of CT colonography 2009

PURPOSE

To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC).

METHODS

Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness.

RESULTS

Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort.

CONCLUSION

Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

Epidemiological studies of cancer in aircrew

Exposure to cosmic ionising radiation, in addition to other specific occupational risks, is of concern to aircrew members. Epidemiological studies provide an objective way to assess the health of this occupational group. We systematically reviewed the epidemiological literature on health of aircrew members since 1990, focusing on cancer as the endpoint of interest. Sixty-five relevant publications were identified and reviewed. Whereas overall cancer incidence and mortality was generally lower than in the comparison population, consistently elevated risks were reported for breast cancer incidence in female aircrew members and for melanoma in both male and female aircrew members. Brain cancer was increased in some studies among pilots. Occasionally trends of increasing cancer mortality or incidence with increasing estimated radiation dose were reported. Ionising radiation is considered to contribute little if at all to the elevated risks for cancers among aircrew, whereas excess ultraviolet radiation is a probable cause of the increased melanoma risk.