Risk of Thyroid Nodules in Residents of Belarus Exposed to Chernobyl Fallout as Children and Adolescents

Abstract Context: Although radiation exposure is an important predictor of thyroid cancer on diagnosis of a thyroid nodule, the relationship between childhood radiation exposure and thyroid nodules has not been comprehensively evaluated. Objective: To examine the association between internal I-131 thyroid dose and thyroid nodules in young adults exposed during childhood. Design, setting, and participants: In this cross-sectional study, we screened residents of Belarus aged ≤18 years at the time of the Chernobyl nuclear accident for thyroid disease (median age, 21 years) with thyroid palpation, ultrasonography, blood/urine analysis, and medical follow-up when appropriate. Eligible participants (N = 11,421) had intact thyroid glands and doses based on direct individual thyroid activity measurements. Main outcome measures: Excess odds ratios per Gray (EOR/Gy, scaled at age 5 years at exposure) for any thyroid nodule and for nodules grouped by cytology/histology, diameter size, and singularity. Results: Risk of any thyroid nodule increased significantly with I-131 dose and, for a given dose, with younger age at exposure. The EOR/Gy (95% confidence intervals) for neoplastic nodules (3.82; 0.87 to 15.52) was significantly higher than for nonneoplastic nodules (0.32;