And it is not like the hexavalent chromium suddenly vanishes after you use it either -- it spreads out into the environment at large, and propogates a trail of death.
In terms of really toxic, nasty things to put into the environment, I would rank:
1) Plutonium
2) Dioxin
3) Hexavalent Chromium
4) DDT
....lots of other stuff.
This is why I've avoided using Alodine also.