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

Purpose : To evaluate prolonged low dose-rate gamma -exposure effects on th e thyroid glands of residents living in Co-60-contaminated steel buildings. Materials and methods : Physical examination and ultrasonography of the thy roid, determination of thyroid function and anti-thyroid microsomal antibod ies were performed for 1346 residents. Ultrasound-guided aspiration cytolog y was done for thyroid nodules. The study subjects were stratified by age a t examination (less than or equal to 15 and >15 years), sex and exposure do se to the body. Dose-response data on the prevalence of various thyroid dis eases were analysed by the multiple logistic regression analysis. Results and conclusions : The prevalence of simple goitre was related to th e exposure with a dose-response relationship for males of all ages, and for females of less than or equal to 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 showe d a dose-response relationship for males of less than or equal to 15 years. A significant increase in thyroid abnormalities with dose was observed for males of all ages, and for females of less than or equal to 15 years.