Risk of thyroid cancer after exposure to 131 I in childhood

Background: After the Chernobyl nuclear power plant acci-dent in April 1986, a large increase in the incidence of child-hood thyroid cancer was reported in contaminated areas. Most of the radiation exposure to the thyroid was from io-dine isotopes, especially 131 I. We carried out a population-based case – control study of thyroid cancer in Belarus and the Russian Federation to evaluate the risk of thyroid cancer after exposure to radioactive iodine in childhood and to in-vestigate environmental and host factors that may modify this risk. Methods: We studied 276 case patients with thyroid cancer through 1998 and 1300 matched control subjects, all aged younger than 15 years at the time of the accident. Indi-vidual doses were estimated for each subject based on their whereabouts and dietary habits at the time of the accident and in following days, weeks, and years; their likely stabl