Effect of prolonged radiation exposure on the thyroid gland of residents living in ⁶⁰Co-contaminated rebar buildings

Purpose: To evaluate prolonged low dose-rate γ-exposure effects on the thyroid glands of residents living in ⁶⁰Co-contaminated steel buildings. Materials and methods: Physical examination and ultrasonography of the thyroid, determination of thyroid function and anti-thyroid microsomal antibodies were performed for 1346 residents. Ultrasound-guided aspiration cytology was done for thyroid nodules. The study subjects were stratified by age at examination (≤ 15 and > 15 years), sex and exposure dose to the body. Dose-response data on the prevalence of various thyroid diseases were analysed by the multiple logistic regression analysis. Results and conclusions: The prevalence of simple goitre was related to the exposure with a dose-response relationship for males of all ages, and for females of ≤15 years. There was a biological gradient of thyroid cyst prevalence with the increase in exposure dose for females of all ages. The prevalence of elevated serum tri-iodothyronine level showed a dose-response relationship for males of ≤15 years. A significant increase in thyroid abnormalities with dose was observed for males of all ages, and for females of ≤ 15 years.