An interesting article appeared in the Journal of the National Cancer Institute in October 2010, in which authors Igor Shuryak, Rainer K. Sachs, and David J. Brenner discuss whether the age at which Japanese victims of the atom bomb were exposed to radiation influenced their likelihood of developing radiation-induced cancer later in life. The study, entitled “Cancer Risks After Radiation Exposure in Middle Age,” is particularly relevant now, given the uncertainty and risk surrounding exposure to radiation from the Fukushima nuclear power plant.
Epidemiological data show that radiation exposure during childhood is associated with larger cancer risks compared with exposure at older ages. For exposures in adulthood, however, the relative risks of radiation-induced cancer in Japanese atomic bomb survivors generally do not decrease with increasing age of adult exposure. These observations are inconsistent with most standard models of radiation-induced cancer, which predict that relative risks decrease with increasing age at exposure, at all ages.
The authors study this apparent paradox using Monte Carlo simulation, and come up with some interesting results.