HeH, I don't think that polonium 210 is found on tobacco leaves as it is a radio active. Here is an excerpt from wikipedia

"A rare and highly radioactive metalloid,[1] polonium is chemically similar to tellurium and bismuth, and it occurs in uranium ores."

It occurs in uranium ores, not tobacco leaves. LoL not to mention that if you read the whole wiki on polonium you would also realize that polonium is highly expensive and would not be something the tobacco companies would be adding to their cigarettes...