71 Question 15 Natural radiation, in spite of its low level, is apparently harmful genetically. According to one estimate, one out of every 20 seriously defective (mentally or physically) children is the victim of natural radiation. Is that the best and accepted current estimate? If not, what percentage of seriously defective children is now considered to be the consequence of natural (not man-made) radiation? What is the applicable description of "seriously defective"? What studies form the basis of that estimate? Is there any concomitant estimate for fetal deaths and stillborn infants as a result of natural radiation? Answer 15 It is not clear where the estimate, "one out of every twenty seriously defective (mentally or physically) children is the victim of natural radiation," was derived. The estimate in question is not considered to be the currently accepted estimate or even an accurate estimate. To provide an estimate of the percentage of seriously defective children that are produced as a consequence of natural (not man-made) radiation would be an extremely complex exercise. At the present time there is no such estimate available and to ouwr knowledge there is no attempt to derive one. To define "seriously defective" as it applies to this problem is an arbitrary decision; however, it might be considered to be any mental or physical condition which markedly alters or prevents the affected individual from functioning in society and thus is dependent on society for his moaintemince.