Consider now the question of residual low level radiation from one war acting on succeeding generations, causing a new equilibrium for mutation rate. On the basis of residual activity present, according to the Hunter-Ballou tables, the only significant background gamma radiation after 20 years will be contributed by the’ element cesium-137, with a 37 year half-life, which decays to barium-137, with a 2.5 minute half-life, which emits a 0.7 mev gamma ray. Only gamma radiation is considered since practically no beta radiation will reach the germinal cells. It is of interest to calculate the amount of fission yield which would have to be released in order to double the natural background radiation dose-rate due to the uniform distribution of artificial radioactive materials at some future time, e.g., 20 years. Assume: 1. Beckground radiation = 0.0125x10"> r/nr = 0.3 m/2h hours. 2. Cesium-137 is the long-lived isotope with a strong gamma which will be the main contributor to increasing the background. 70 curies of cesium-157 are formed per KT fission yield. 3. Area of earth = ex10° square miles. 4, One megacurie of cesium-137 per square mile will give a radiation dose of 4 r/hr at three feet above ground. 5. Thus : Uniform world-wide distribution of the isotope. a- 70 curies of cestum-197 _ 5.52107! curies cesim-137/ 3 exl0” b. square miles I, = te. mi>fer This is the equation for radioactive decay for a single isotope in which I. t = 0.0125x107> r/hr I = radiation dose rate due to cesivum~-137 at H+l hour eA 0.69 for t = 20 years... I= se ° et 95°