It's both. DU is never completely "depleted" because radiation falloff is asymptotic. DU is primarily an alpha emitter and alpha particles cannot penetrate skin, but they can cause damage if you breathe, eat, or inject DU dust.

That's why our use of big lumps of DU as door stops was considered "safe" (at that time several years ago) but in labs where people machined the stuff they were a lot more careful.