system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how does tabacco contain radioactive polonium? Where does it come from? Does the plant make it radioactive, does it collect it? Do other plants do this too?
gpt
Tobacco absorbs radium from the soil it's grown in. You can find radium all over (particularly where there are granite deposits), but it's especially rich in soils treated with phosphate fertilizers (because it's common in the rock that they mine the phosphate from). It radioactively decays into polonium.

It does make the plant radioactive (and toxic as a heavy metal), more than other plants, but not strongly so. It's enough to be a concern if you are, say, smoking it, but if you stood next to a tobacco plant you'd be at no risk.

All plants absorb some radioisotopes that decay. Some are absorbed from the soil, and some from the air. The absorption of carbon-14 from the air is the basis for radio-carbon dating, for example. Everything (including you) has some level of radioactivity.