~3- CABINET PAPER—PRIVILEGED Property of the White House—For Authorized Persons Only 25 rems (units of radiation dose), immediately observabl Ve As acute whole body doses increase above approximately effects increase in severity with dose, beginning from barely detectable changes, to biological signs clearly indicating damage, to death at levels of a few hundred rema@, Delayed effects produced either by acute irradiation or by chronic irradiation are similar in kind, but the ability of the body to repair radiation damage is usually more effective in the case of chronic than acute irradiation, The delayed effects from radiation are in general indistinguishable from familiar pathological conditions usually present in the population. Delayed effects include genetic effects (effects transmitter to succeeding generations), increased incidence of tumors, |fife- span shortening, and growth and development changes. The child, the infant, and the unborn infant appear to be more sensitive to radiation than the adult. The various organs of the body differ in their sensitivity fo 8, Although ionizing radiation can induce genetic and somati aa radiation, effects (effects on the individual during his lifetime other than genetic effects), the evidence at the present time is insufficient to justify precise conclusions on the nature of the dose-effect relationship at low doses anddose rates, Moreover, the evidence is insufficient to prove either th¢ hypothesis of a "damage threshold" (a point below which fo damage occurs) or the hypothesis of "no threshold" in man at low doses, CABINET PAPER For Consideration