The Lesser Evil: Plutonium-239 or Uranium-235? A Study on F0 Atomic Bomb Survivors

Abstract

‘All models are wrong, but some models are useful.’ Radioactivity is a life-detrimental exposure that increases individuals’ susceptibility to cancer onset. The plasticity of the rate of aging _d(log μ(x))/dx_ has never been formally addressed, as it has been casually inferred as mortality rate _μ(x)_ or risk _log μ(x)_. The mortality schedule of irradiated F0 atomic bomb survivors in Hiroshima (U-235) and Nagasaki (Pu-239) at age exposure 40 - 45 (ATE45) can unveil the characteristics of hazard trajectories by isotope type and dosimetry. Based on the advantage derived from background radiation, an alternative population was employed during the comparative study. A dose-dependent relationship between radioactive isotope types and the rate of aging was presented in the frailty framework; _γ-Gompertz-Makeham_. A pseudo-benefit initial mortality risk by distance to the epicenter was also observed among 0-5mGy survivors, suggesting that selection for mortality was determined by stringency from impact and frailty from natural selection. Furthermore, the standardized mortality ratio suggests Pu-239 has a more drastic effect on age-specific mortality trajectory than U-235; 0-5mGy, _Pu-239_ 11%(M) 37%(F); _U-235_ 4%(M) 0.5%(F). Upon intense radiation exposure, variation in the human rate of aging exists within a 10-km radius from the epicenter, and gender sensitivity may be a significant contributor to mortality selection.