Study on abnormalities of thyroid and its risk factors in radiation workers of some tertiary hospitals in Guangzhou city

Objective To investigate the status of thyroid abnormalities in radiation workers of some hospitals and to explore the effects of long-term low-dose ionizing radiation on thyroid morphology or function on them,and to provide a scientific basis for managing the thyroid abnormalities aggregation incidents in medical staff.Methods According to convenience sampling method,there were 144 radiation workers with length of service longer than 5 years from 7 tertiary hospitals in Guangzhou were selected as the exposure group,and 200 staffs with length of service longer than 5 years who were not exposed to occupational ionizing radiation,were selected as the control group.Individual exposure dose monitoring and thyroid B-type ultrasonic examination were conducted.Cubital vein blood was collected to detect three triiodothyronine(T3),thyroxine(T4),thyroid stimulating hormone(TSH) levels.Moreover,urine samples were collected to detect urinary iodine levels.Results The annual total effective dose in exposed group was 0.12-2.44 m Sv/a,with a median of0.30 m Sv/a.The prevalence of thyroid nodules in exposed group and control group were 32.64%(47 /144) and 31.00%(62 /200),respectively,showing no significant difference(P 0.05).The T3 level in the exposed group was higher than that of the control group [(1.63 ± 0.34) vs(1.55 ± 0.32) nmol/L,P 0.05]; THS level was lower than that of the control group [1.39(0.96,2.12) vs 1.98(1.29,2.67) m IU/L,P 0.01]; T4 level showed no significant difference between the two groups [(107.69 ± 23.30) vs(110.93 ± 18.96) nmol/L,P 0.05].All the indexes including the prevalence of thyroid nodules,T3,T4,TSH levels and their abnormality rates showed no significant difference in different types of work subgroups and exposure dose subgroups(P 0.05).The prevalence of thyroid nodules in the exposure group and control group with different urinary iodine levels showed no significant difference respectively(P 0.05).The results of multiple Logistic regression showed that the irradiation exposure,length of service and the work type had no correlation with the prevalence of thyroid nodule(P 0.05),but the female,increase of age and smoking were the independent risk factors for the thyroid nodules(P 0.05).Conclusion Long-term low-dose ionizing radiation exposure could have some impacts on T3 and TSH levels of radiation workers in hospital,but it did not increase the risk of thyroid nodules.Female,increase of age and smoking can increase the risk of thyroid nodules.Ionizing radiation in the hospital may not be the reason of thyroid abnormalities aggregation incidents.