Melanoma incidence in Australian commercial pilots, 2011-2016

Increased Peripheral Blood DNA Damage and Elevated Serum Levels of Melanoma Inhibitory Activity Protein: Clues to Excess Skin Cancer Risk in Airline Pilots?

Background and objective The risk of malignant melanoma (MM) and other forms of skin cancer appears to be higher in airline pilots (APs), potentially due to their exposure to ionizing and ultraviolet (UV) radiation. We explored the possibility of increased peripheral blood DNA damage and elevated serum levels of the melanoma inhibitory activity (MIA) protein - a serological marker for MM known to be stimulated by UV radiation - in this professional group. Methods This was a case-control study involving 40 male APs, each of whom was age- and tenure-matched (≥5 years of service) with 40 male office workers (OWs). We assessed DNA damage in the two professional groups by performing comet and micronucleus (MN) assays on peripheral blood. Serum levels of MIA protein were quantified using an immunoassay. Results The comet tail lengths and the frequency of MN were significantly higher in APs (4.57 ± 0.79 µm and 2.05 ± 0.26 per 1000 cells, respectively) than in OWs (3.81 ± 0.60 µm and 1.76 ± 0.31 per 1000 cells, respectively, both p<0.001). Furthermore, serum MIA levels were also significantly higher in APs (7.45 ± 0.95 ng/mL) than in OWs (5.78 ± 0.54 ng/mL, p<0.001). A significant positive correlation was found between comet tail lengths in APs and their serum MIA concentrations (r=0.68, p<0.01). Conclusions The increased burden of DNA damage and elevated serum MIA levels in APs may offer an explanation for their higher susceptibility to MM and other types of skin cancers.

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.

Measurements of UV—A Exposure of Commercial Pilots Using Genesis-UV Dosimeters

A number of studies suggest that pilots are at twice the risk of melanoma and keratinocyte skin cancers than the general population, and that they have a raised mortality from melanoma. No conclusive links with in-flight exposure to ionising radiationor circadian rhythm disruption due to the pilots’ shift work were found. Possible over-exposure to ultraviolet radiation (UVR) may be implicated as pilots may be exposed to higher UV-A levels at cruise altitude compared with those at ground levels. The direct method of making in-flight spectral measurements has been carried out on a limited number of flights, but this technique is challenging; the use of small wearable sensors may be more appropriate but there are a few issues that should be addressed for their use in cockpit measurements. While the spectral response of sensors for erythema effective values usually closely matches the corresponding weighting function, the response of UV-A sensors may not be spectrally flat, which, if not corrected to account for the transmission of the aircraft windshield, could potentially result in large errors. In this paper, the spectral correction method was applied to the UV-A sensor of the Genesis-UV unit to measure UVR exposure of commercial pilots on 312 flights to a range of destinations from four UK airports from September 2016 to August 2017.

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.