A correction for Bob Boese - he states: "The smaller the size of the weight, the better. But atomic weight of lead is 207.2 while tungsten is 183.85 and tin is 118.71. That means that your tin weight must be almost twice as large as your lead weight. Tungsten is only 12% larger but many times more expensive ? if you can find them."

Actually, the characteristic of interest is density, not atomic weight. Lead is 11340 kg/m3 vs. tungsten at 19250 kg/m3. Tin is 7310 kg/m3. (webelements.com) So, price aside, tungsten is a much better alternative as the same weight is only ~60% the volume of lead. Hence, the high weight of relatively small tungsten beads. Tin would be quite a bit larger.

He may be right about lead not having much of an effect in waterways, but probably still better to avoid it if possible. I use a temp sensitive putty that seems to stay on the leader about as well as lead shot ever did. Not hard to find in the shops.