10 RADIATION STANDARDS, INCLUDING FALLOUT annual exposure, at least in the nuclear industry, is considerably less than 5 rem. From the standpoint of population genetics it is not the dose to the individual, but the total dose to the entire population before the end of the reproductive years that is important. On this basis, oceupational radiation exposure contributes only a vanishingly small fraction to thetotal genetically significant exposure. The doses received by radiation workers may be as much as 10 times those received from environmental sources, but radiation workers constitute such a small fraction of the whole population that the effect on population genetics is very small indeed. (d@) Medical and dental sources: The radiation exposure received by patients undergoing medical and dental diagnosis and therapy is to be distinguished from that received by the physicians, nurses, and technicians who administer to the patients. The latter type of exposure is properly classed as occupational and has already been discussed. The exposurereceived by the patient is quite different, as I shall now show. Medical and dental exposures seldom involve the whole body. They are almost always restricted to a small portion of the body, and in particular the reproductive organs are spared whenever possible. Like occupational exposure, medical and dental exposure is accepted knowingly and willingly by the person exposed to obtain information or effects necessary for good health. Considerable progress has been made in recent years in achieving these ends with smaller exposures to the patient. The standards recommended by the National Com- mittee on Radiation Protection have played a large part in this progress. ost estimates of the population exposure to medical and dental sources of radiation indicate that the average from these sources is about equal to that from natural sources. Thus medical and dental exposure is one of the two major contributors to the total population exposure. Although I feel that good standards for the medical and dental application of radiation and radioactive isotopes should be established and encouraged as widely as possible, I cannot see how these applications can be made the subject of legal regulations in the way that occupational exposures are regulated. This concludes my statement. I hope that it may prove of some value to you in the decisions you are called upon to make. Representative Price. Thank you, Dr. Whipple. Doctor, on page 8 you state that man can reduce his exposure from natural sources by living in a tent on a seacoast. How much would this reduce his normal exposure ? Dr. Wuierte. I suppose it might reduce it 10, 20 percent, perhaps to as low as three-quarters of what I have given as the national average. The fellow living in the granite house on the mountains may havefive times the national average. Representative Price. You also state on that page that there is not much the individual can do about exposure from manmade environmental sources. What should the individual do, instead of moving way, as a practical view ? Dr. Wuurete. In the practical view, in my view of the practical matter, I can see no reason fortrying to influenceit. setaecseaeaapsacriaieeRhiertisog,