On Tue, 16 Jul 2013 16:18:17 -0700 (PDT),
wrote:

They call it "tracking powder" because the stuff sticks to the rodent (hence "tracks" it, I guess), then the rodent later licks it off.

My gut feeling is the amounts present aren't that dangerous to humans, because we're so much larger than a mouse, but in principle the stuff is pretty nasty.

It may not even be active now, after a few years.

The suggestion to wet mop and clean it is a good idea.

Let us know how it turns out.