. * be about fivefold larger. Added to these would be a smaller number caused by chromosoma] defects and recessive diseases. (c) Risk Relative to Current Prevalence of Serious Disabilities. In addition to those in (b) caused by single-gene defects and chromosome aberrations are con- genital abnormalities and constitutional dis- eases which are partly genetic. It is estimated that the total incidence from all these including those in (b) above, would be between 1100 and 27,000 per year at equilibrium (again, based on 3.6 million births). This would be about 0.75% at equilibrium, or 0.1% in the first generation. (a) The Risk in Terms of Overall II]-Health. The most tangible measureof total genetic damage is probably “ill-health” which includes but is not limited to the above categories. It is thought that between 5% and 50% ofill-health is proportional to the mutation rate. Using a value of 20% and a doubling dose of 20 rem, we can calculate that 5 rem per generation would eventually lead to an increase of 5% in theillhealth of the population. Using estimates of the financial costs of ill-health, such effects can be measured in dollarsif this is needed for costbenefit analysis. Until recently, it has been taken for granted that genetic risks from exposure of populations to ionizing radiation near background levels were of much greater import than were somatic risks. However, this assumption can no longer be made if linear non-threshold relationships are accepted as a basis for estimating cancer risks Based on knowledge of mecha- nisms (admittedly incomplete) it must be stated that tumor induction as a result of radiation. injury to one or a fewcells of the body cannot be excluded. Risk estimates have been made based on this premise and using linear extrapolation from the data from the A-bomb survivors of Hiroshima and Nagasaki, from certain groups of patients irradiated therapeutically, and from groups occupationally exposed. Such calculations based on these data from irradiat- ed humansJead to the prediction that addition- al exposure of the U. §. population of 5 rem per _ 80 years could cause from roughly 3,000 to 15,000 cancer deaths annually, depending on the assumptions used in the calculations. The Committee considers the most likely estimate to be approximately 6,000 cancer deaths annually, an increase of about 2% in the spontaneous cancer death rate which is an increase of about 0.3% in the overall death rate from «!! causes. Given the estimates for genetic and somatic risk, the question arises as to howthis infor- mation can be used as a basis for radiation protection guidance. Logically the guidance or standards should be related to risk. Whethe: we regard a risk as acceptable or not depends on howavoidable it is, and, to the extent not avoidable, how it compares with the risks of alternative options and those normally accepted bysociety. There is reason to expect that over the next few decades, the dose commitmentsfor all manmade sources of radiation except medica) should not exceed more than a few millirems average annual dose to the entire U. S. popula- tion. The present guides of 170 mrem/yr grew out of an effort to balance societal needs against genetic risks. It appears that these needs can be met with far lower average expo- sures and lower genetic and somatic risk than permitted by the current Radiation Protection Guide. To this extent, the current Guide is unnecessarily high. The exposures from medical and dental uses should be subject to the samerationale. To the extent that such exposures can be reduced without impairing benefits, they are also unnecessarily high. It is not within the scope of this Committee to propose numerical limits of radiation exposure. It is apparent that sound decisions require technical, economic and sociological considera- tions of a complex nature. However, we can state some general principles, many of which are well-recognized and in use, and some of which may represent a departure from present practice. a) No exposure to ionizing radiation should be permitted without the expectation of a commensurate benefit. b) The public must be protected from radia- tion but not to the extent that the degree cf protection provided results in the substitution of a worse hazard for the radiation avoided. Additionally there should not be attempted the reduction of small risks even further at the cost: of large sums of money that spent otherwise, would clearly produce greater benefit. DOE ARCHIVES TOOT Tb