Ionizing radiation interacts with material meanwhile secondary electrons and radiation are produced. The secondary electrons and the radiation with certain energy can travel within the organization and have secondary ability producing ionizing or excitation when interacted with materials. In addition, the radiation toxins (glycoproteins with high enzymatic activity including high proteolytic, lipidolytic and carbohydratelytic properties) produced by primary radiation effect can be transferred through blood and fluid circulation to the place far away from the primary site of radiation interaction and induce effect similar to the primary radiation. It is visible that the effect induced by radiation can occur in both sites of the rays primarily hitting and the sites far away from the original. Both primary and secondary effects can be induced in different places. Radiation hazard evaluation of low dose exposure should not only see the early radiation effects but also consider the late effects induced by radiation and should not only pay attention to results from somatic cells and whole animal experiments and more should pay attention to the results from epidemiological survey of population.Cited