Nuclear plant accidents can be a risk for thyroid cancer due to iodine radioisotopes. Near the Fukushima Daiichi nuclear power plant, cattle were exposed to radiation after the accident occurred in May 2011. Here we estimated the total radiation exposure to cattle thyroid and its effects on thyroid function. Until October 2016, the estimated external exposure dose in Farm A was 1416 mGy, while internal exposure dose of ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs were 85, 8.8, and 9.7 mGy in Farm A and 34, 0.2, and 0.3 mGy in Farm B, respectively. The exposed cattle had thyroid with relatively lower weight and lower level of stable iodine, which did not exhibit any pathological findings. Compared with the control, the plasma level of thyroid-stimulating hormone (TSH) was higher in Farm A cattle born before the accident, while the plasma thyroxine (T4) was higher in Farm A cattle born after the accident, suggesting that exposed cattle showed slight hyperactivation of the thyroid gland. In addition, Farm A cattle have higher level of cortisol, one of the anterior pituitary gland-derived hormones. However, we did not observe a causal relationship between the radiation exposure and cattle thyroid.

由于碘放射性同位素，核电站事故可能是患甲状腺癌的风险。在福岛第一核电站附近，2011 年 5 月事故发生后，牛受到了辐射。这里我们估算了牛甲状腺的总辐射暴露及其对甲状腺功能的影响。截至 2016 年 10 月，农场 A 的估计外照射剂量为 1416 mGy，而内照射剂量为¹³¹ I、¹³⁴ Cs 和¹³⁷Cs 在农场 A 中分别为 85、8.8 和 9.7 mGy，在农场 B 中分别为 34、0.2 和 0.3 mGy。暴露的牛的甲状腺重量相对较低，稳定碘水平较低，没有任何病理发现。与对照组相比，A 场事故前出生的牛血浆促甲状腺激素（TSH）水平较高，而事故后出生的 A 场牛血浆甲状腺素（T4）水平较高，表明暴露牛表现出甲状腺轻微过度激活。此外，A 农场牛的皮质醇水平较高，皮质醇是垂体前叶腺衍生的一种激素。然而，我们没有观察到辐射暴露与牛甲状腺之间的因果关系。