Trans-Scale Insights into Variability in Radiation Cancer Risk Across Tissues, Individuals, and Species.

Diversity is evident in various aspects of life and the human population. The current radiological protection system considers the diversity in disease susceptibility and incorporates some of it to provide a unified risk model for the human population. This paper focuses on variability in cancer risk among cells/tissues, individuals, and animal species. At the cell/tissue level, radiation cancer risk per unit dose varies among tissues, as indicated by epidemiological and animal studies. This variation is most likely due to the epigenetics of cells. At the individual level, radiation risks vary considerably depending on physiological, environmental, and genetic factors. At the species level, epidemiology is considered the most relevant source of radiological information, and limitations have been recognized in extrapolating animal data to human risks. A recent study demonstrated a fundamental relationship between cancer risk and somatic mutation rate in humans and mice. This relationship could lead to a new extrapolation method, which could be used to protect a wider range of species, including humans and other mammals. Thus, considering diversity in radiation cancer risk provides insight into the underlying aspects of radiobiology of radiological protection.