Cc. National Council on Radiation Protection and Measurements* (NCRP) The NCRP position is that the rational use of radiation should conform to levels of safety to users and the public which are at least as stringent as those achieved for other powerful agents. Continuing and chronic exposure attributable to peaceful uses of ionizing radiation are assumed. The NCRP has adopted the assumption of no-threshold dose-effects relationship and uses the term ''dose limits'' in providing guidance on population exposures. All radiation exposures are to be kept as low as practicable. The numerical values of exposure as pre- sented are to be interpreted as recommendations, not regulations. Use of the no-threshold concept involves the thesis that there is no exposure limit free from some degree of risk. To establish criteria, NCRP uses the concept of ''acceptable risk" (where the risk is compensated by a demonstrable benefit) broken down to fit classes of individuals or population groups exposed for various purposes to different quantities of radiation. Numerical recommendations for dose limits are necessarily arbitrary because of their mixed technical value-judgement foundation. The dose limits for individual members of the public and for the average population recommended by NCRP represent a level of risk considered to be so small compared with other hazards of life, and so well offset by perceptible benefits when used as intended, that public appro- bation will be achieved when the informed public review process is completed. For peaceful uses of radiation, NCRP provides yearly numerical dose limits for individual members of the public, considering possible somatic effects, and strongly advocates maintenance of lowest practicable exposure levels, especially for infants and the unborn, NCRP also recommends yearly dose limits for the average population based upon somatic and genetic considerations and recommends the samme value as ICRP of 5 rems in 30 years for gonadal exposure of the U.S. population. Table IfI contains a summary of recommended values. NCRP Report No. 39 en- titled, ‘Basic Radiation Protection Criteria, '' dated January 15, 1971, contains the most recent updating of NCRP recommendations for protection of the public. “Formerly known as the National Committee on Radiation Protection and Measurements, I-—5