An analysis of Ukrainians exposed to Chernobyl's radioactive fallout as children shows they have a greater risk of developing benign thyroid tumors known as follicular adenoma.
The research, published recently by the American Journal of Epidemiology, estimated risk of follicular adenoma in relation to radiation dose after Chernobyl. The Fogarty-supported study team analyzed baseline data from those exposed as children or adolescents. A stratified random sample was selected from all individuals who were younger than 18, had thyroid radioactivity measurements taken within two months after the accident, and resided in the three heavily contaminated areas in Ukraine.
Of the 12,504 subjects screened, 23 cases of follicular adenoma were discovered. All subjects referred for surgery complied and pathologists confirmed the diagnosis.
The risk of tumors was significantly higher in women compared with men but age-at-exposure effects were unclear with no consistent pattern. The risk of follicular adenoma is lower than the risk of thyroid cancer, according to the study.
A large increase in the incidence of thyroid cancer occurred among people who were young children and adolescents at the time of the Chernobyl accident and lived in the most contaminated areas of Belarus, the Russian Federation and the Ukraine. This was due to the high levels of radioactive iodine released from the reactor in the early days after the accident. Radioactive iodine deposited in pastures was eaten by cows--whose milk was subsequently drunk by children. This was further exacerbated by a general iodine deficiency in the local diet causing more of the radioactive iodine to be accumulated in the thyroid, according to the WHO.
A cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: dose-response analysis of thyroid follicular adenomas detected during first screening in Ukraine (1998-2000). Zablotska LB, Bogdanova TI, Ron E, Epstein OV, Robbins J, Likhtarev IA, Hatch M, Markov V, Bouville AC, Olijnyk VA, McConnell RJ, Shpak VM, Brenner A, Terekhova GN, Greenebaum E, Tereshchenko VP, Fink DJ, Brill AB, Zamotayeva GA, Masnyk IJ, Howe GR, Tronko MD. AM J Epidemiol. 2008 Feb 1;167(3):305-12.