If you have a nuclear medical facility in the hospital/clinic where you live, the isotope carriers that the vials of isotopes are transported in are generally pure lead. The last ones I got were shaped like a backgammon die, and they fell all over themselves giving them to me for free so they didn't have to bother recycling them.
However, that was 20+ years ago, and I still haven't worked my way through the 1000+ pounds of lead I got. With the price of lead these days, hysterical haz-mat policies... maybe they won't even talk to you. But (especially if you know somebody that works there), it's worth a try. If they are recycling them, perhaps they'll tell you who comes and takes them away.