|MadSci Network: Biophysics|
There is no need to suspect whether radiation exposure can induce sterility. It is clearly proven based on many radiological accidents involving localized exposures to gonads region. Permanent sterility was observed in many cases when the doses involved were in the range of 6 Gy. It is also known that the required dose will be less at least by 2 to 3 times for densely ionizing radiations such as neutrons and heavy charged particles, which are usually encountered by astronauts in space missions. However, the range of dose in Apollo 11 mission as claimed by NASA is in the range of 1.73 mGy (173 mrad), which is far less a dose for induction of sterility. The fear of large doses during the mission was very much there due to possible solar events but no such events occurred during the mission.
The issue about radiation hazard may not be about the sterility, but may be due to enforced fear about genetic effects. Over the years, the genetic risk of radiation seems to be blown out of proportion. Analysis and follow-up of about 76,626 children born to atomic bomb survivors exposed various level of radiation doses has not yielded any concrete conclusion that radiation can induce genetic defects in human being. Although no increase in incidences were observed, it is still difficult to believe that radiation poses no genetic risk. International Commission for Radiological Protection in its report no 60 (ICRP60) published in 1991 has estimated a genetic risk of 1% per Sv of radiation for general public. However the estimate is based on the results from experiments on laboratory animals. Many recent studies reveal that the estimated risk by ICRP60 is far excess than the reality. In the proposed draft of ICRP and recent studies reveal at least 4 times less genetic risk. DNA defects by radiation are usually very severe in nature and germ cells carrying such damages may not yield successful fertilization and live births.
Keeping aside the scientific arguments, one can clearly see that astronauts were selected in the age group such that the complication about their progeny would not exist. All the members of Apollo missions were in their late 30’s and early 40’s. That means they were in their near non- reproductive age, although not biologically but more so by social statistics. Although it is not documented about ethical issues about reproduction, probably by choice, these astronauts decided not to reproduce after the mission to avoid any possible complications, and it was easy to take this decision because of their age group.
Further information about dose details and methods of dose estimation can
be obtained in the following site :
Documents about genetic risks:
1. International Commission for Radiological Protection in its report no. 60 (ICRP60) published in 1991
2. Journal: Mutation Research Vol 453 (2000) page 183 – 197. Authors: K. Sankaranarayanan and R. Chakraborty
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