Lead shot has greater mass per volume than sand and mass is what is desired when filling stands. Sure lead is toxic if handled all the time, but inside your stands poses no danger to you, your kids or pets. Some folks like to mix sand in with the lead to fill the gaps, but lead is soft and doesn't vibrate, so sand isn't really needed.
Sand and shot?
This question is really for what most bookshelf speakers sit on--the stand. I'm planning on filling a set of stands(24") but just have the sand presently. Do I really need lead shot as well or will the sand be enough. Most reviews I read on speakers mention stands with both. Any help would be most appreciated.