Radiation risks of thyroid cancer incidence resulting from exposure of emergency workers to iodine radioisotopes

The paper discusses the results of analysis of radiation risks of thyroid cancers among the Chernobyl emergency workers (living in Russia) resulting from exposure to iodine radioisotopes. Due to the lack of documented doses from this source, the characteristics of the curve of this radionuclide decay were used for analysis. The analysis was performed by two independent methods: the exposed versus unexposed (the exposed are the emergency workers who worked in the 30-km zone during the first 65 days after the accident and the unexposed are those working there later) and the regression analysis based on the maximum likelihood method using the surrogate dose (period and time of stay in the 30-km zone during 131I decay). By both methods statistically significant estimates were derived for the relative radiation risk - 1.8 (1.2; 2.8 95 % CI) and for the excess radiation risk per unit surrogate dose - 2.5 (0.2; 6.5 95 % CI). The obtained results indicate that the follow-up of the emergency workers in relation to this issue should be continued.