Thyroid cancer risk to children calculated

The Chernobyl reactor accident was followed by a sharp increase in the incidence of thyroid cancer among children and adolescents in Belarus (Belorussia) and Ukraine1,2. Exposure to iodine-131 (131I) was responsible for most of the doses that affected the thyroids of these children; however, among evacuees, up to 40% of each dose could derive from other incorporated radionuclides and external exposures3. From the data set compiled after this incident, we estimated the increased risk of developing thyroid cancer after exposure to radioactive iodine. The figure we obtained for most of the affected regions fell within the 95% confidence interval of a previous follow-up of thyroid cancer after external exposures.