輻射物
Radiation is an effect of radioactive items in Slimefun.
More specifically, it is a deadly combination of status effects you receive when carrying such items: Wither III, Blindness IV, Confusion IV, Weakness III, Slowness II, and Mining Fatigue II, for a duration of 20 seconds.
For this reason, it is highly recommended you only carry them for a short amount of time. Better yet, wear a full hazmat suit: this will make you completely immune to the effects of radiation.
Radioactive items
The following items will induce radiation while in your inventory:
Not listed here is the Nether Star Reactor, which makes nearby entities wither, but does not actually cause radiation.