I was curious about this question.
So, I used my library's Science Direct data base to find the answer.
Here is what i found.
1. Ionizing radiation is a protoypical DNA-damaging agent. (Wilson et al, 2010)
2. Cancer risks increases with iodizing radiation exposure even at low doses
3. Ionizing radiation damages DNA repair mechanisms. Thus, bodies lose the capability to repair DNA damaged by the radiation or by other mutagens
4. Cancer, birth defects, and immunological problems can thus result from the effects of exposure to low-level ionization
5. There appears to exist individual differences in the susceptibility to the damage causes to DNA repair mechanisms with the possibility being that some subset of the population is particularly vulnerable
6. IMPLICATIONS: EXPOSURE TO LOW LEVELS OF IONIZING RADIATION FROM FUKUSHIMA IS NOT SAFE, PARTICULARLY FOR SUB-SETS OF THE POPULATION THAT MAY BE PARTICULARLY SUSCEPTIBLE TO THE DNA-REPAIR DISRUPTIONS CAUSED BY EVEN LOW LEVELS OF IONIZING RADIATION
Wilson et al in 2010 essay "Inter-Individual Variatin in DNA Double-Strand Break Repair in Human Fibroplasts..." Mutation Research/Fundamental Mechanisms of Mutagenesis, vol 683, pp. 91-97
A.M. Kellerer, Risk estimates for radiation-induced cancer–the epidemiological
evidence, Radiat. Environ. Biophys. 39 (2000) 17–24.
D.J. Brenner, R. Doll, D.T. Goodhead, E.J. Hall, C.E. Land, J.B. Little, J.H. Lubin, D.L.Preston, R.J. Preston, J.S. Puskin, E. Ron, R.K. Sachs, J.M. Samet, R.B. Setlow, M.Zaider, Cancer risks attributable to low doses of ionizing radiation: assessing
what we really know, Proc. Natl. Acad. Sci. U.S.A. 100 (2003) 13761–13766.
R. Wakeford, The cancer epidemiology of radiation, Oncogene 23 (2004)
P. Bhatti, J.P. Struewing, B.H. Alexander, M. Hauptmann, L. Bowen, L.H. Mateus-
Pereira, M.A. Pineda, S.L. Simon, R.M. Weinstock, M. Rosenstein, M. Stovall, D.L.
Preston, M.S. Linet, M.M. Doody, A.J. Sigurdson, Polymorphisms in DNA repair
genes, ionizing radiation exposure and risk of breast cancer in U.S. radiologic technologists, Int. J. Cancer 122 (2008) 177–182.