To be fair, something can be highly radioactive for a short time, moderately radioactive for a long time, AND slightly radioactive for a very long time, assumin

To be fair, something can be highly radioactive for a short time, moderately radioactive for a long time, AND slightly radioactive for a very long time, assuming there are at least three different radioisotopes involved. Also, it's a exponential decay curve, so something that's slightly radioactive a very long time from now is probably still fairly dangerous right now.