Long term, I completely agree with you. That crap getting into the groundwater is a nightmare.
But, it is also a very localized issue.
on this topic I only know what I read.
there are claims that the very fine particles can travel quite a ways in air, be inhaled (or end up ingested on plants), and bind (I think in place of calcium but could be another mineral) in our bodies.
ignoring the radioactivity angle, just the idea of having fine lead or cadmium dust sprayed all over would be equally bad.
there are a number of allegations about this in serbia and the middle east, and some quite horrific birth defects. not that anyone is admitting it in the west, so as I said, I only know what I read.
but there is a pretty straight forward proposed mechanism for this type of injury/defect.
who knows what was destroyed in this huge explosion. (we may never know).