(b) The national or even international character of the problem is self-evident;

(c) Means for establishing regulations and enforcement may be peculiar to this case;

(d) For irradiation of the reproductive organs, total dose to an "effective population" is the significant parameter;

(e) It does not follow that there is no upper limit, on genetic grounds only, for exposure of an individual;

(f) For irradiation of other tissues-the somatic effects-a population average dose limit may be a useful index;

(g) Nevertheless, the matter is one of acceptable risk for each individual, and this calls for specific upper limits for classes of individuals;

(h) There may plausibly be a whole series of such limits, for example, a low one for children or those with certain defined infirmities, a moderate one for definable groups of "normal" adults; the occupational limits are essentially such a case; a relatively high limit for certain tasks voluntarily assumed or otherwise in the national interest, for example, space flight; a relatively high limit for virtually all where the stress of enemy attack substantially alters the risk balancing equations.

In a few concluding paragraphs let me try to identify and summarize some of the key points in the derivation and application of radiation standards.

1. The risk principle: We are taking calculated risks with a poor calculation in some cases. A most diligently executed research effort is needed to resolve this.

2. Technological growth: Positive use of radiation in more devices together with its occurrence as an unwanted side effect of other developments is expected to spread the chance of exposure.

3. Enforcement: There is no easy solution to how much control is needed on all users of radiation in order to limit the hazard created by less-responsible or less-informed users.

4. Subdivision of time: One pressing problem is to determine the true significance of time limits. Below a more or less agreed upon annual limit is an array of arbitrary time intervals used for control purposes-1 day, any consecutive 7 days, any consecutive 13 weeks, and so on. What significance do these now have?

5. Subdivision of space: There are specific limits for the body, the skin, the head, hands and forearm, feet and ankles, and, in the case of internal deposition, for an assortment of critical organs. Dose to these parts can be cataloged and compartmented far more easily on paper than in actual practice.

6. Subdivision of radiation type: In terms of the radiation energy absorbed, separate limits be established for all types of radiation. These can be stated in terms of a physical absorbed dose measured in rads. In the real case, people are exposed to a mixture of radiations. It is a matter of practical necessity for anyone keeping radiation. score on a large group to convert the component doses to a common scale such as RBE doses measured in rems. In the present state of knowledge, arbitrary values of radiobiological effectiveness-RBEhave to be assigned. Such values are almost certainly different for different end effects, and in some cases for the same effect produced

at different dose rates. The use of the term "rem" in code or regulation can be highly misleading unless it is suitably qualified by an arbitrary scale of relation.

7. Subdivision by radionuclide: Separate limits are provided for an increasing array of nuclides that may get into the body. Those that are bone seekers get preferential treatment in calculations, adding further to complications of dose addition. Also one can see intuitively that for some less radioactive nuclides, chemical toxicity may be as significant or more so than radiation toxicity, and two may have to be integrated.

Taking points 4, 5, 6, and 7 together, man gets so subdivided between time, space, radiation types and radionuclides that the basic integrating sense of standards is lost. This is a point of some significance, too, for that kind of standardization related to a national register of radiation exposure.

8. An informed public: Public acceptance of radiation standards is needed. This should follow public understanding of the broad principles involved. The details of the standards picture are so complex that even the full-time practioners get confused enough. Public acceptance of detail must hinge on what we have called the authority of knowledge, a belief that informed people are studying and reporting in knowledgeable, unbiased terms. I am hopeful, Mr. Chairman, that these hearings will make a major contribution to this public awareness. May I again thank you for the opportunity to participate. (The material referred to by Mr. Parker follows:)

TABLE I.-Estimated background radiations

1 This is taken as at sea level. The generally reported range is about 50 to 150 millirem per year. In a few areas it rises above 1 rem per year.

2 Measurements in specific buildings in Sweden; apparently such differences are usually not so pronounced.

3 Osteocyte dose.

4 Variations with building types and degree of ventilation.

RADIATION PROTECTION

TABLE II.-Summary of radiation overexposure instances in New York State,

1956-59 (13)

? Presumably localized.

NOTE.-Figure in parentheses refers to item in references, infra.

TABLE III.-30-year per capita doses in the United States from radiation sources

5-7

1 Taken here as the osteocyte dose to match table I. This principally affects the radium entry which would be 0.05 rem for mean marrow dose.

Additional studies on limited groups have given values on the order of 1.5 rems. (See references 10 and 11.)

3 No estimate.

NOTE.-Figures in parentheses refer to items in references, infra.

REFERENCES

1. Cantril, S. T., and H. M. Parker, "The Tolerance Dose," MDDC-1100, Jan. 5, 1945. 2. "Permissible Dose From External Sources of Ionizing Radiation," National Bureau of Standards Handbook 59, Sept. 24, 1954; addendum, "Maximum Permissible Radiation Exposures to Man," Apr. 15, 1958.

3. "X-ray Protection," National Bureau of Standards Handbook 60, Dec. 1, 1955.

4. "Safe Handling of Radioactive Isotopes," National Bureau of Standards Handbook 42, September 1949.

5. "Control and Removal of Radioactive Contamination in Laboratories," National Bureau of Standards Handbook 48, Dec. 15, 1951.

6. "Recommendations for Waste Disposal of Phosphorus 32 and Iodine 131 for Medical Users," National Bureau of Standards Handbook 49, Nov. 2, 1951.

7. "Safe Design and Use of Industrial Beta-Ray Sources," National Bureau of Standards Handbook 66, May 28, 1955.

8. "Report of the United Nations Scientific Committee on the Effects of Atomic Radiations," United Nations, New York, 1958.

9. Laughlin, J. S., and I. Pullman, "Gonadal Dose Received in the Medical Use of X-rays, sec. II of "Genetic Radiation Dose Received by the Population of the United States," a report prepared for the Genetics Panel of the National Academy of Sciences Study of the Biological Effects of Atomic Radiation, Nov. 19, 1956, Washington, D.C.

10. Norwood, W. D., J. W. Healy, E. E. Donaldson, W. C. Roesch, and C. W. Kirklin, "The Gonadal Radiation Dose Received by the People of a Small American City Due to the Diagnostic Use of Roentgen Rays," American Journal of Roent., Radium Therapy and Nuclear Med. LXXXII, 6, 1081–1097, December 1959.

11. Brown, R. F., J. Heslep, and W. Eads, "Number and Distribution of Roentgenologic Examinations for 100,000 People," Radiology, 74, 3, 353-363, March 1960.

12. "Recommendations of the International Commission on Radiological Protection," Sept. 9, 1958, Pergamon Press, 1959.

13. Kleinfeld, M., and A. P. Abrahams, "Administrative Experience With Occupational Overexposure to Radiation," Industrial Hygiene Review, New York State Department of Labor, 2, 2, 7-12, December 1959.

Representative HOLIFIELD. Thank you, Mr. Parker, for your statement and the material you have contributed with it.

You have used the words "criteria" and "standards" all through your presentation. Do you use them as meaning the same thing, or is there a difference between "criteria" and "standards"?

Mr. PARKER. In the sense that I have used them in the provided material, I have not differentiated. I have used the two words in a sense to be responsive to the kind of language that I believe Dr. Taylor will use more thoroughly, in the sense that what we have called standards are not standards in the engineering sense with which many of us tend to be familiar, in which there is a concept of go-no-go gage. They are rather general guides to about the right kind or what might be described as reasonable amounts of radiation exposure. One notices the use of the term "guide" is becoming increasingly popular.

Representative HOLIFIELD. Is that because the technical knowledge does not allow you to define in exact mathematical terms the standards?

Mr. PARKER. It is partly due to that, Mr. Holifield, and partly because mathematics carried to the third decimal place very likely need never come into the kind of topic that we are talking about. If it turns out to be true that the effects go by a no-threshold curve of some kind, we are always into the area of balancing some potential damaging effects against some potential gain. This is not something I believe which goes by close mathematics.

Representative HOLIFIELD. When you use the word "guide," do you use it in the same way that the Federal Radiation Council uses it in their reports?

Mr. PARKER. The report from the Council reached us somewhat at the last minute, and we perhaps read this in rather cursory fashion so far, Mr. Holifield. It would seem that there is a slight twist in the terminology which I am sure will be brought out more fully later on. I would say this: Dr. Taylor, I believe, would say to you that the

standards we have are guides for practice. If I understood the background material from the Federal Radiation Council, it says rather directly that the radiation protection guide is five rems per year, that is, a dose. This is a slightly different use of the language. I am sure they are not meant to be inconsistent, but they may be distorted later. Representative HOLIFIELD. I notice in item 7 it says the Federal agencies apply these radiation protection guides with judgment and discretion to assure that a reasonable probability is achieved in the attainment of the desired goal of protecting man from the undesirable effects of radiation. The guides may be exceeded only after the Federal agency having jurisdiction over the matter has carefully considered the reason for doing so in light of the recommendations in this paper.

This will be in the Federal Register, and this will have the effect of a rule, you might say, and yet within the very terminology of the statement you have elastic terms such as judgment and discretion and reasonable probability. They certainly are not exact semantics. They vary in degree. So in essence you are not setting up a guide because that discretion that might be used might vary with the individual and his background and technical competence. All of this would restrict honesty and integrity on the part of the individual. Is that not true? Mr. PARKER. Indeed, it is true, Mr. Holifield. I think you touch on the basic problem of converting what we may describe as intelligent practices in the use of radiation into firm code and regulation. There do seem to be areas in which this will be a major national problem. I am sure the Federal Radiation Council has given considerable thought to this.

Representative HOLIFIELD. So we have to approach this in a way that the doctor approaches a diagnosis, is that not true? He exercises his own technical competence and his background of experience and observation. He uses what we hope is prudent judgment in making a diagnosis. It may later turn out to be right or wrong.

Mr. PARKER. Yes, sir. I believe this it what I have tried to characterize as value judgments on the part of all people concerned in the material submitted.

Representative HOLIFIELD. Are there any questions, Mr. Price?

Representative PRICE. Mr. Chairman, I would like to ask a question relative to the first of your summarizing points on page 9 of your statement, namely, the risk principle. You say we are taking a calculated risk with a poor calculation in some cases. Could you cite an example of exactly what you are talking about there?

Mr. PARKER. It would be difficult to cite an example in which the calculation was good in the mathematical sense. I perhaps believe that the question is not phrased in so specific a term as that. There are areas connected with both the genetic effects of radiation at low dose levels and in the somatic effect-for the effect of the same radiation on the remaining body tissues-in which we do not know responsibly what the actual effects are. We have a concept, I believe, of the general nature of these things. The details depend on the resolution of the application of the kind of model curves that I presented earlier, Mr. Price. Until we have a better and agreed technical appraisal of what the damage, long range, is, we must have in our terms of refer