Comparative evaluation of thyroid operational intervention levels depending on age and biokinetic model in nuclear accidents

In order to minimize the risk of stochastic effects resulting from thyroid exposure by radioiodine during a nuclear accident, it is essential to implement prompt and timely protective actions. These actions should be based on accurate assessments of thyroid dose utilizing precise biokinetic parameters. However, the age of the representative person was not accurately considered when applying these parameters to evaluate the current default thyroid Operational Intervention Level (OIL8_γ). This study evaluates the impact of various age groups and iodine biokinetic models on OIL8_γ functions through comparative analyses among OIL8_γ functions based on subject-specific parameters. The results indicate that the OIL8_γ functions in the 1-year age group, characterized by faster iodine clearance rates, and in the Korean model, which accounts for higher dietary iodine consumption, demonstrates a significantly more rapid decrease compared to other age groups and models. These results suggest the need for conservative adjustments to the OIL8_γ criterion, better reflecting the biological characteristics of infant age groups and the Korean biokinetic model. Correct application of the biokinetic parameters relevant to specific groups is crucial when deriving the OIL8_γ criterion, ultimately supporting targeted monitoring strategies for populations with unique iodine biokinetics, ensuring timely and effective protective actions during a nuclear accident.