AFIP "announced" no such thing. They mentioned their mistaken assumptions in a self-serving newsletter intended to show people how important they are and what good work they do.
Why don't you ever ask why they failed to "announce" or even mention the presence of polymerized glass? Is it because it would show that AFIP didn't really know what form the silicon and oxygen was in?
AFIP ANNOUNCED that silica was the key aerosol enabling component of the Daschle anthrax.
The facts indicate that AFIP was never again trusted with any aspect of the Amerithrax investigation.
The were evidently "out of the loop" and didn't have a clue as to what other labs had determined.