Not the kind of exposure you would get through 3rd stage decay products from the pitchblende walls of their fortress.
Uranium decays into radon gas.
Radon gas decays into polonium, which then oxidizes in the atmosphere to become polonium oxide powder. (after just a few days living as radon.)
Consequences for a fortress:
Dwarves breathing the air will be breathing in radon gas in pretty large quantities. (see the linked article I made for the details needed to make an estimate. It's quite a lot with that much surface area.) That gas will convert into polonium while inside their lungs. This causes the polonium oxide to stick to their lung lining, causing prolonged, systemic exposure to a very fragile tissue.
The polonium produced elsewhere in the fortress accumulates as dust. When dwarves wet a floor to make "mud", guess where that polonium ends up? Yup-- in their food. Being a higher trophic level organism, the dwarves will sequester that polonium in their bodies.
Nopey nope. Dwarves living in a chiseled out pitchblend deposit are gonna develop a wide raft of radiation related illnesses, including systemic lung and GI cancers.
Since they dont, it's clear evidence that Toady has not implemented such fun. I personally think he should.