I might be more concerned about the glass than the metal BB's. I had a thermometer break in one of my brews and the majority of the wax dissolved into the beer, the BB's fell out and there was surely some glass in there. The BB's were steel (tested with a magnet, if they are lead they will not be attracted to a magnet, steel will). When I racked for bottling, I doubled over a fine mesh nylon back over the racking cane and I didn't have any issues. I'm still alive to tell the tale even! But if you have any doubts, remember: better to be safe than sorry.