Skupina B - velmi toxické:
Ca45, Fe59, Sr89, Y91, Ru106 + Rh106, Ag110m, I126, I129, I131, Cs134,
Ba140 + La140, Ce144 + Pr144, Sm151, Eu152, Eu154, Tu170, Bi207, Ra223,
Ra224, Ac228, Th227, Th228, Th230, Th232, Th234, Pa230,
Pa231, Pa234, uran 230 až uran 237.