The study of the absorbed dose and the biological effects caused by radiation from environmental radon

1. 为评价环境辐射的生物学效应，采用31 keV的x射线照射两组大鼠。第一组用主x射线照射，第二组用低剂量x射线初步照射，然后再用主x射线照射。主x射线照射吸收剂量为0.5 Gy/大鼠，初x射线照射吸收剂量为0.09 Gy/大鼠。主x线照射后，用亚硝酸盐法测定两组大鼠肝脏和脾脏SOD活性，在x线照射后6h， SOD活性比正常水平升高27%，随后又降至正常水平。值得注意的是，x射线照射后，第一组SOD活性暂时下降到比正常水平低15%，尽管如上所述，SOD活性再次升高。必须强调的是，第二组在主x射线照射后，SOD活性没有降低。这似乎说明了初步进行低水平x射线照射的重要意义。Rn环境^ < 222 >。建立了快速制备已知量的^<222>Rn的方法，并将小鼠暴露于^<222>Rn中48小时。用Ge谱仪对小鼠肺进行了测量，测定了^<222>Rn的γ发射子，即^<214>Bi在肺中的作用。在3.5h内，^<222>Rn及其子元素达到瞬态平衡，所有这些核素都具有相同的放射性。因此，估计了^<222>Rn引起的吸收剂量。由于对低水平辐射暴露的详细调查可能会导致对辐射激效机制的更好理解，因此作者开发了确定环境^<222>Rn的方法。在此基础上，开展了环境辐射对生物效应的评价实验。

1. X-ray irradiation To evaluate the biological effects of environmental radiation, two groups of rats were irradiated with X-ray (31 keV). The first group was irradiated with the main X-ray and the second group was preliminarily irradiated with low-level X-ray, then, irradiated with the main X-ray again. The absorbed dose for the main X-ray irradiation was 0.5 Gy / rat, and for the preliminarily X-ray irradiation was 0.09 Gy/rat.After the main X-ray irradiation, the SOD activity of rat's liver and spleen was measured by the nitrite method for both groups, which increased to 27% higher than its normal level at 6h after X-ray irradiation, and reduced to its normal level.It is noted that, after X-ray irradiation, the SOD activity of the first group temporarily reduced to 15% lower than its normal level, although it increased again as described above. It must be emphasized that there was no reduction of the SOD activity of the second group after the main X-ray irradiation. It seems to show the important significance of the preliminary low-level X-ray irradiation.2. Environmental ^<222>Rn. The rapid method for preparing known amounts of ^<222>Rn was developed and the mouse was exposed to ^<222>Rn for 48h. The lung of the mouse was measured with a Ge spectrometer, and the gamma-emitting daughter of ^<222>Rn, that is, ^<214>Bi on the lung was determined. During 3.5h, ^<222>Rn and its daughters came to transient equilibrium and all of these nuclides have the same radioactivity. Thus, absorbed dose due to ^<222>Rn was estimated. Since a detailed investigation of low-level radiation exposure might lead to a better understanding of the mechanisms of the radiation hormesis, the authors developed the method for determining the environmental ^<222>Rn. Based on the results, the experiment to evaluate the biological effects due to the environmental ^<222>Rn is underway.