BACKGROUND Michigan residents were directly exposed to endocrine-disrupting compounds, polybrominated biphenyl (PBB) and polychlorinated biphenyl (PCB). A growing body of evidence suggests that exposure to certain endocrine-disrupting compounds may affect thyroid function, especially in people exposed as children, but there are conflicting observations. In this study, we extend previous work by examining age of exposure's effect on the relationship between PBB exposure and thyroid function in a large group of individuals exposed to PBB. METHODS Linear regression models were used to test the association between serum measures of thyroid function (total thyroxine (T4), total triiodothyronine (T3), free T4, free T3, thyroid stimulating hormone (TSH), and free T3: free T4 ratio) and serum PBB and PCB levels in a cross-sectional analysis of 715 participants in the Michigan PBB Registry. RESULTS Higher PBB levels were associated with many thyroid hormones measures, including higher free T3 (p = 0.002), lower free T4 (p = 0.01), and higher free T3: free T4 ratio (p = 0.0001). Higher PCB levels were associated with higher free T4 (p = 0.0002), and higher free T3: free T4 ratio (p = 0.002). Importantly, the association between PBB and thyroid hormones was dependent on age at exposure. Among people exposed before age 16 (N = 446), higher PBB exposure was associated with higher total T3 (p = 0.01) and free T3 (p = 0.0003), lower free T4 (p = 0.04), and higher free T3: free T4 ratio (p = 0.0001). No significant associations were found among participants who were exposed after age 16. No significant associations were found between TSH and PBB or PCB in any of the analyses conducted. CONCLUSIONS This suggests that both PBB and PCB are associated with thyroid function, particularly among those who were exposed as children or prenatally.

中文翻译：

---

甲状腺激素水平与成人儿童时期接触多氯联苯和多溴联苯有关。

背景密歇根州居民直接接触内分泌干扰化合物、多溴联苯（PBB）和多氯联苯（PCB）。越来越多的证据表明，接触某些内分泌干扰化合物可能会影响甲状腺功能，尤其是儿童时期接触过的人，但存在相互矛盾的观察结果。在这项研究中，我们通过在一大群暴露于多溴联苯的个体中检查暴露年龄对多溴联苯暴露与甲状腺功能之间关系的影响来扩展之前的工作。方法 使用线性回归模型来测试甲状腺功能血清测量值（总甲状腺素（T4）、总三碘甲状腺原氨酸（T3）、游离 T4、游离 T3、促甲状腺激素（TSH）和游离 T3：游离 T4 比率）之间的关联。密歇根州 PBB 登记处 715 名参与者的横断面分析中的血清 PBB 和 PCB 水平。结果 较高的 PBB 水平与许多甲状腺激素指标相关，包括较高的游离 T3 (p = 0.002)、较低的游离 T4 (p = 0.01) 和较高的游离 T3:游离 T4 比率 (p = 0.0001)。较高的 PCB 水平与较高的游离 T4 (p = 0.0002) 和较高的游离 T3:游离 T4 比率 (p = 0.002) 相关。重要的是，多溴联苯和甲状腺激素之间的关联取决于接触时的年龄。在 16 岁之前接触 PBB 的人群中 (N = 446)，较高的 PBB 接触与较高的总 T3 (p = 0.01) 和游离 T3 (p = 0.0003)、较低的游离 T4 (p = 0.04) 和较高的游离 T3 相关： T4 比率（p = 0.0001）。在 16 岁之后暴露的参与者中，没有发现显着的关联。在进行的任何分析中，都没有发现 TSH 与 PBB 或 PCB 之间存在显着的关联。结论 这表明多溴联苯和多氯联苯均与甲状腺功能相关，特别是在儿童期或产前接触过的人群中。