gms | German Medical Science

Introduction: Commercial airline pilots are exposed to cosmic radiation and other specific occupational factors, potentially increasing cancer mortality. The first results of cohort studies among commercial airline crew were published in the early 1990s, the German cohort being one of the largest. The cohorts were quite young at the time, and there were few deaths. The results of an extended follow-up of the German cohort are presented here.

Material and methods: In a cohort of 6000 German male commercial airline pilots, a mortality follow-up for the years 1960-2004 was performed. Occupational exposure data were collected for this period, and dose estimates computed. The mortality in the cohort was compared to national reference rates using Standardised Mortality Ratios (SMR). Poisson regression was used to compare mortality between subgroups of the cohort with different exposure, applying a 10-year latency period. A group of cancers thought to be radiogenic was defined a priori. Analyses were restricted to groups of cancers with at least 20 cases.

Results: Overall, 418 deaths, including 129 cancer deaths, occurred in the cohort. The median cumulative effective dose was 30 mSv, with a maximum of 74 mSv. The mortality from all causes, cardiovascular diseases and all cancers was significantly lower than in the German population: SMR=0.51 (95% confidence interval (CI): 0.46-0.56), 0.48 (95% CI: 0.37-0.63) and 0.62 (95% CI: 0.49-0.79), respectively. Total mortality decreased with increasing radiation doses (rate ratio (RR) per 10 mSv: 0.89; 95% CI: 0.82-0.96). In contrast, a non-significant increase of cancer mortality was observed (RR per 10 mSv: 1.11; 95% CI: 0.97-1.27). This increase was driven by the group of non-radiogenic cancers; no significant increase was observed for radiogenic cancers.

Discussion: The total, cardiovascular and cancer mortality of cockpit crew are low, as are cumulative doses. A negative trend of all cause mortality with radiation dose was observed, and a positive trend of all cancer mortality, restricted to non-radiogenic cancers. This may partly be due to a healthy worker survivor effect, as well as to exposure to other, unrecorded occupational risk factors correlated with duration of employment and thus with radiation dose. More information is expected from a pooled analysis of updated international aircrew studies.