Of concern in the current situation is ionizing radiation, which is produced by spontaneously decaying heavy isotopes, such as iodine 131 and cesium 137.
目前情况下值得忧虑的是电离辐射，它由重同位素——如碘131和铯137——自发衰变而生成。
2
Most of the samples that have passed across Hasegawa's desk have proved to be within the legal consumption limit of the radioactive isotopes cesium 134 and 137 and iodine 131.