[Terr_]

> All else being equal you're generally safer being exposed to stable things that don't break down than unstable things that happily react with all sorts of things

There's a similar paradox in nuclear radiation. (Sometimes expressed with a puzzle about differently radioactive cookies and what to do with each.)

Gamma rays are scary because it takes a lot of lead shielding to even slow them down... but that also means that they aren't stopping to interact with things--like yourself--as they travel.

Alpha particles seem relatively safe because they don't travel far and are blocked by your skin... But that means they're doing something to that skin, and luckily for you any damage is being dealt to already-dead cells on the outside.

But if you had to put one of them inside your body, it's quite possible the gamma ray emitter would be the safer option, simply because more of its energy would escape harmlessly.

[nordsieck]

> But if you had to put one of them inside your body, it's quite possible the gamma ray emitter would be the safer option, simply because more of its energy would escape harmlessly.

That's definitely the case with Polonium-210. Even though it emits alpha particles, it's very dangerous to ingest.