Cosmic radiation and cancer

:: Cosmic radiation and cancer

Recently, several epidemiological studies have been carried out to investigate cancer mortality and cancer incidence among airline crew. Many exposure studies have been conducted to estimate and to measure the dose of cosmic radiation at flight altitudes of jet aircraft. The latter studies conclude that a typical annual radiation dose is between 3 and 6 mSv for a commercial pilot. Values up to 9 mSv have been estimated for a pilot flying some 600 h/year on polar flights at 10 km and above. Detailed assessment of individual flight history has showed that for all pilots the lifetime cumulative exposure was below 100 mSv. Results of the mortality studies and incidence studies are as yet inconclusive, although for most cohorts the total cancer (mortality and incidence) was not raised compared with the general population. For specific cancer sites, increased and decreased standardised mortality or incidence ratios were observed without a clear pattern. Leukaemia risk is not increased, with the exception of a study of Danish pilots, based on only 14 cases. A more consistent finding is an increased risk of breast cancer, which is also a cancer associated with radiation. The role of risk factors other than radiation, such as late first childbirth and low parity, may not always have been fully taken into account when evaluating these findings. Another consistent finding is an increase in skin cancer and melanoma. Whether this is related to leisure activities, occupational factors or a combination of both needs further investigation.

The overwhelming evidence does not point to a significant adverse health effect in terms of cancer, and the present regulation of aircrew as radiation workers sufficiently controls the occupational exposure. Very few passengers will ever accumulate radiation doses from cosmic radiation in the same magnitude as the staff and hence no particular precautions need to be taken.