Most hospitals gladly accept "donations" to their sharps boxes. That's the point of a sharps box - hazardous materials go directly into the box and are permanently sealed in so no-one ever touches them. They would much rather you dropped your needles/blades/whatever there than tossed them in the trash.
+1 on this, and sometimes they will give you an empty sharps container in return to fill with used blades. Real easy to store under the counter and it will take years to refill.
Clayton