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

PURPOSE: To evaluate prolonged low dose-rate gamma-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 (< or = 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 < or = 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 < or = 15 years. A significant increase in thyroid abnormalities with dose was observed for males of all ages, and for females of < or = 15 years.