The radiation is not the part I'd be worried about, but uranium is about as toxic as lead. And a chemistry set that contains brittle lead ores/alloys that "ten

The radiation is not the part I'd be worried about, but uranium is about as toxic as lead. And a chemistry set that contains brittle lead ores/alloys that "tend to flake and crumble" is not something I'd want a 12 year old using unsupervised. Nor would I trust the vast majority of adults for that matter...