Proton spin-lattice relaxation time (T-1) of water in aqueous solutions of ferrous and ferric ions and in the corresponding agarose,eel systems have been studied in the light of NMR relaxation theory. The theoretical analysis of 1/T-1’s has revealed that, at the microscopic level, changes in the solvation states of paramagnetic ions in aqueous or gel environment are greater than difference in the paramagnetism between ferric and ferrous ions. The former change is the primary factor for the exhibition of radiation effect. At the phenomenological level, we have confirmed and demonstrated that : (1) Radiation effect is almost exclusively exhibited through changes in 1/T-1 caused by the interactions between water proton and ferrous or ferric ions; and (2) fraction of conversion of ferrous to ferric ions induced by radiation is the "true" representation of the spatial distribution of radiation dose.