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though it is not detectable. It is generally agreed that the effect that may actually occur will not exceed the amount predicted by this assumption.

7.4 To clarify the most critical problem areas concerning quantitative relationships of the effects of irradiation on man, it is recommended that special attention be given to the following research efforts:

1. Increasing epidemiological studies on humans who have been exposed to radiation especially in doses sufficient to offer some probability that deleterious effects can be found. 2. Continuing studies on the mechanism of radiation damage and of the interaction of radiation with matter at the cellular level and at the molecular level.

3. Studies designed to determine more adequately the relationship between damage and dose at low total dose and low dose rates. Included should be more precise information at higher levels from which the relationships at lower levels may be inferred.

7.5 The various current sources of radiation exposure to the U. S. population are discussed in Section III. It should be noted that the radiation exposure to patients by practitioners of the healing arts is in the same order as natural background, when averaged over the population. The average exposure to the U. S. population from activities of the nuclear energy industry, under current practices, is less than that from background by a substantial factor.

7.6 If the presence of a threshold for radiation damage could be established by adequate scientific evidence, and if this threshold were above the background level and sufficiently high to represent a reasonable working level, it would serve as a relatively simple basis for the establishment of radiation protection standards. However, with the accumulation of quantitative information concerning radiation effects in both animals and humans, and some increased understanding of the mechanisms of radiation injury, the possibility that somatic effects as well as genetic effects might have no threshold appeared acceptable, as a conservative assumption, to increasing numbers of scientists. On the basis of this conservative assumption, radiation protection standards must be established by a process of balancing biological risk and the benefits derived from radiation use. Such a balance cannot be made on the basis of a precise mathematical formula but must be a matter of informed judgment. Several approaches towards the evaluation of the risk are discussed in Section IV. These approaches, together with the evaluation of benefits and useful applications by the agencies, have been used in the formulation of the recommendations in this staff report.

7.7 Under the working assumptions used, there can be no single "permissible" or "acceptable" level of exposure, without regard to the reasons for permitting the exposure. The radiation dose to the population which is appropriate to the benefits derived will vary widely depending upon the importance of the reason for exposing the population to a radiation dose. For example, once weapons testing in the atmosphere has taken place, the dose to be permitted in lieu of such alternatives as depriving the population of essential foodstuffs might also be quite different from levels used in the planning phases. As another example, for radiation workers, emergency situations will almost certainly arise which make exposures in excess of those applicable to normal operations desirable.

7.8 Also, under the assumptions used, it is noted that all exposures should be kept as far below any arbitrarily selected levels as practicable. There should not be any man-made radiation exposure without the expectation of benefit resulting from such exposure. Activities resulting in man-made radiation exposure should be authorized for useful applications provided the recommendations set forth in this staff report are followed. Within this context, any numerical recommendations should be considered as guides, and the need is for a series of levels, each of which might be appropriate to a particular action under certain circumstances.

7.9 The term "maximum permissible dose" is used by the NCRP and ICRP for the radiation worker. However, this term in often misunderstood. The words "maximum" and "permissible" both have unfortunate connotations not intended by either the NCRP or the ICRP. This report introduces the use of the term Radiation Protection Guide (RPG). This term is defined as, the radiation dose which should not be exceeded without careful consideration of the reasons for doing so; every effort should be made to encourage the maintenance of radiation doses as far below this guide as practicable.

7.10 There can, of course, be quite different numerical values for the Radiation Protection Guide, depending upon the circumstances. It seems useful, however, to recommend Guides which appear appropriate for normal peacetime operations. It is recognized that our present knowledge does not provide a firm basis within a factor of two or three for the selection of any particular numerical value in preference to another value. Nevertheless, on the basis set forth in Section V, the following Radiation Protection Guides are recommended for normal peacetime operations:

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1Minor variations here from certain other recommendations are not considered significant in light of present uncertainties.

2See Section V for reasons why these values differ from those applicable to radiation workers.

'See Paragraph 5.5 (1) for applicability of these levels.

7.11 Recommendations are not made concerning the Radiation Protection Guides for individual organ doses to the population, other than the gonads. Unfortunately, the complexities of establishing guides applicable to radiation exposure of all body organs preclude their inclusion in the report at this time. However, current protection guides used by the agencies appear appropriate on an interim basis.

7.12 These guides are not intended to apply to radiation exposure resulting from natural background or the purposeful exposure of patients by practitioners of the healing arts.

7.13 The Federal agencies should apply these Radiation Protection Guides with judgment and discretion, to assure that 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 staff report.

7.14 This staff report also introduces the term Radioactivity Concentration Guide (RCG) defined as: the concentration of radioactivity in the environment which is determined to result in organ doses equal to the Radiation Protection Guide. Within this definition, Radioactivity Concentration Guide can be established only after the Radiation Protection Guide is decided upon. Any given Radioactivity Concentration Guide is applicable only for the circumstances under which use of its corresponding Radiation Protection Guide is appropriate.

7.15 As discussed in Section VI, reasonably accurate estimates can be made of the amount of internally deposited radioactive material resulting in any particular organ dose. However, the establishment of guides as to the amount of material which, when taken into the body, will yield such organ doses is fraught with many uncertainties. Further extension of the estimation to indicate the equivalent amount of environmental contamination is even more uncertain. The potential errors are even greater with inhaled contamination than with ingested materials. Extension to individual portions of the environment further compounds the possible errors.

7.16 This staff report, therefore, does not contain specific numerical recommendations for Radioactivity Concentration Guides. However, concentration guides now used by the agencies appear appropriate on an interim basis. Where appropriate radioactivity concentration guides are not available, and where Radiation Protection Guides for specific organs are provided in this staff report, the latter Guides can be used by the Federal agencies as a starting point for the derivation of radioactivity concentration guides applicable to their particular problems. The Federal Radiation Council has also initiated action directed towards the development of additional Guides for radiation protection.

7.17 Particular attention is directed to the possibly different ratios of intake to uptake for adults and children. There is no simple numerical relationship between Radioactivity Concentration Guides for the worker and for the general population, even if such a simple relationship is adopted for Radiation Protection Guides.

7.18 With particular relationship to the establishment of Radioactivity Concentration Guides, the following research needs (in addition to those listed in paragraph 7.4) are pointed

Out:

1. Efforts to design design better and less expensive radiation monitoring instruments and methods.

2. Extensive studies to determine the relationship between concentration of radioactivity in food, air and water, and the ultimate disposition of these by the body.

3. Studies designed to elucidate the relationship between the intake of radionuclides in various chemical forms and their subsequent uptake. Presently, many compounds of a given radionuclide are treated as though they were the same compound.

4. Studies to elucidate the difference between children and adults in their uptake and disposition of radioactivity and their radiation sensitivity.

58016--U.S.Dept.of Comm--DC--1960

APPENDIX 7

FEDERAL RADIATION COUNCIL LETTER OF JULY 8, 1960 TO AGENCY HEADS

FEDERAL RADIATION COUNCIL

EXECUTIVE OFFICE BUILDING

WASHINGTON 25, D.C.

July 8, 1960

Dear Mr. Secretary:

In the May 18, 1960 issue of the Federal Register there was published a Memorandum for the President from the Chairman of the Federal Radiation Council containing seven recommendations which were approved by the President for the guidance of Federal agencies on radiation protection standards. This action was pursuant to Executive Order 10831 and Public Law 86-373 which entablished the Federal Radiation Council to "advise the President with respect to radiation matters, directly or indirectly affecting health, including guidance for all Federal agencies in the formulation of radiation standards.

The Memorandum for the President and the Staff Report of the Federal Radiation Council, "Background Material for the Development of Radiation Protection Standards," copies of which are enclosed for your convenience, discuss in detail the method by which the recommendations of the Federal Radiation Council were developed. It was pointed out that the formulation of radiation protection standards involves a balancing of the risks to man of exposure to ionizing radiation against the benefits to be derived from the many important usages to which radiation is applied. The staff of the Council, in addition to conducting a careful review of the current information on the hazards of ionizing radiation, consulted with staff members of many si the Federal agencies concerned with radiation protection in order to define the problem areas to be provided for in recommended protection standards.

In order to provide continuing advice to the President on radiation protection standards, the Federal Radiation Council must have information from which it can determine the extent to which its recommendations represent an appropriate balance between the requirements of health protection and the beneficial uses of radiation and atomic energy. To this end, your assistance is requested.

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Specifically, the Federal Radiation Council would like a report on radiation protection activities to be conducted by the Department of Agriculture under the Radiation Protection Guidance for Federal Agencies promulgated by the President. In particular, the Council would like to be informed on the operating standards developed by your agency and if any deviations from the Guides are planned under the provisions of Recommendation 7 which states:

"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 recom-
mendations in this paper."

On the basis of the reports received from the agencies, it is the plan of the Council to develop a regular mechanism for receiving such reports and we would welcome your suggestions on this matter. In order to expedite the development of a routine pattern, the Council would appreciate receving the report from your agency by August 1, 1960. Any questions you may have about this report may be directed to the Secretary of the Federal Radiation Council, Dr. Donald R. Chadwick, code 113 - extention 2505.

Sincerely yours,

Arthur S. Flemming
Chairman

The Honorable Ezra Taft Benson

Secretary of Agriculture

Washington 25, D. C.

Identical ltrs sent to heads of the attached list of Federal agencies cc: The Honorable Chet Holifield, Chairman, Spec. Subcomm, JCAE The Honorable Clinton P. Anderson, Chairman, JCAE

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