The dose-response relationship between low-dose ionizing radiation and thyroid hormone of medical workers

Abstract

Objectives To explore the dose-response relationship between low-dose ionizing radiation and thyroid hormone levels of radiation medical workers and provide theoretical basis for occupational health protection to this population. Methods Using a prospective cohort study design, we collected health examination reports on employees that worked on jobs with occupational exposure to radiation at hospital with individually dose monitoring data for 1 237 workers. The effective cumulative radiation dose was divided into three groups: 0~2.586 mSv, 2.586~3.757 mSv, 3.758~31.272 mSv by the interquartile range. The low-dose group was used as a reference to compare the changes in thyroid hormones of medical workers in different cumulative radiation dose groups. The generalized linear models and restricted cubic spline model were used to examine the association and dose-response relationship between the cumulative effective dose and changing thyroid hormones. Results There were statistically significant differences in changing thyroxine (T4) and Free triiodothyronine (FT3) levels among three different dose groups of 1 237 subjects ( P < 0.05). The results of generalized linear models analysis revealed that 2.586~3.757 mSv was a significant risk factors of changing T4, with β of 3.514 (95% confidence interval [95% CI]: 0.900~6.128) after adjusting for gender, age, working duration, occupation, medical level and smoking, while the association with changing FT3 was not observed ( P > 0.05). The restrictive cubic spline (RCS) model analysis indicated a non-linear dose-response correlation between cumulative radiation dose with changing T4 ( P = 0.023). Conclusion Longterm exposure to low-dose ionizing radiation could induce the thyroid damage among medical occupational population. And there is a dose-response relationship between cumulative radiation dose and changing thyroxine. 摘要： 目的 探宄低剂量辐射与甲状腺激素水平的剂量-反应关系, 为放射工作人员防护工作重点提供理论依据。 方法 采用前瞻性队列研宄设计, 收集 1 237 名放射工作人员健康体检报告及个人剂量监测数据。以辐射累积有效剂 量作为观察指标并按照四分位间距分 0~2.586 mSv、2.586~3.757 mSv、3.758~31.272 mSv 3 组, 低剂量组为参照, 比 较不同累积辐射剂量组放射工作人员甲状腺激素变化情况。采用广义线性模型和限制性立方样条模型分别估计累积 有效剂量与甲状腺激素变化的关联及剂量反应关系。 结果 1 237 名放射工作人员的甲状腺素 T4、FT3 水平变化在不 同剂量组间的差异有统计学意义( P < 0.05)。调整性别、年龄、工龄、职业、医疗等级和吸烟后, 广义线性模型分析显 示, 2.586~3.757 mSv ( β = 3.514, 95% CI: 0.900~6.128) 与放射工作人员 T4 水平变化显著相关, 而累积有效剂量与 FT3 水平变化无关 ( P > 0.05)。限制性立方样条分析结果显示, 累积有效剂量连续变化与 T4 水平变化呈非线性剂量反 应关系 ( P = 0.023)。 结论 长期低剂量电离辐射对放射工作人员甲状腺功能造成一定的损伤, 辐射累积有效剂量与 T4 水平变化存在剂量-反应关系。