In May, I reported that Russian scientists at the Institute of Theoretical and Experimental Biophysics in Pushchino and the Institute of High-Energy Physics in Protvino, had investigated the chronic effects of the radiation to which we are exposed every time we fly in high altitude aircraft. They wanted to know if any putative damage to one’s DNA might be passed on to your future offspring. It’s an issue that girds the loins of air crew and other regular flyers alike.
At the time, the team simulated the radiation conditions in laboratory tests and reported some rather worrying results. I have now followed up with team leader Alsu Dyukina a few questions that arose.
How did you decide on what dose to use in the tests?
The dose received by our experimental mice were decided based on really date that with an annual norm of flights of 2000 h the rate of the equivalent dose of space radiation is 1.7-6 microsieverts per hour, which makes up a radiation dose of 7—50 millisieverts. Radiation doses received by pilots and flight attendants are often greater than those received by traditional radiation workers in the heavily regulated nuclear industry, but until recently, little attention was paid to occupationally exposed air crew.
According to a report of the Federal Aviation Administration, the average dose rate in the contiguous United States from cosmic and terrestrial radiation is 0.06 μSv/h. At an altitude of 10 km, which is common for domestic air travel, the dose rate from galactic cosmic radiation alone is 6 μSv/h.
What about solar activity, is that an issue?
During a solar maximum, the numbers and energies of the solar radiation particles increase enough to affect the cosmic radiation dose to air travellers.
Do you think there is cause for concern for would-be parents?
We think that we can extrapolate to possible damage to the offspring of pilots as it is known that the mice are more radio-resistant in comparison with the human. We believe that revealed by us such negative consequences as the changes in radiosensitivity and the absence of adaptive response in the progeny of parents irradiated with low doses of high-LET radiation are evidence of genetic instability, which is transmitted via the sex cells of the parents.
What can be done to protect air crews?
It is an established fact that an increase in altitude means an increase in radiation levels therefore to protect air crew and travellers should decrease the altitude of flights.
The International Federation of Air Line Pilots Associations (IFALPA) recognizes 20 mSv/yr as the cosmic radiation limit for airline flight crews as established by the National Council of Radiation of Protection and Euratom. It is further recognized that airline flight crew should be categorized as occupationally exposed radiation workers, likely to receive more than 1 mSv/y.
As cosmic radiation imposes a potential health risk to airline flight crews, it is highly recommended that national authorities make provisions for exposure assessment verification. Crew members should be made aware through extensive educational programs that high altitude flying exposes them to significantly higher ionizing radiation levels, with carcinogenic potential, than the general population and the scope of radiation protection legislation.
Crew members should be warned that radiation exposure above 1 mSv during the course of the entire pregnancy may cause an increased risk to the fetus. In addition, airlines will be required to organize the schedules of crew members with the objective of reducing the doses of highly exposed air crew, educate the crew about health risks, and give special protections to women who have declared pregnancy.
But, these are still low doses of radiation, right?
It is important to remember that little is known of the radiobiological effects of low dose ionizing radiation, much less that of low dose ionizing radiation of the type and quantity which airline pilots and cabin crew are exposed to at altitude.
What’s more in the last decade it was shown by many researchers that the damaging action of low doses is more efficiently determined when compared with the damage that might be expected at linear extrapolation of results from greater doses to low.
What is the bottom line on this study?
The studies will expand what is known about the health risks of cosmic radiation in the near future.
S. Zaichkina, O. Rozanova, G. Aptikaeva, A. Akhmadieva, H. Smirnova, S. Romanchenko, O. Vakhrusheva, S. Sorokina, A. Dyukina, & V. Peleshko (2009). Adaptive response and genetic instability induced in mice in vivo by low dose-rate radiation simulating high-altitude flight conditions Int. J. Low Radiation, 6 (1), 28-36