"Geiger counters go off and people go nuts. Is a great terror weapon."
And, if I recall correctly, a single isotope can kill within months. I don't know a thing about radiation, but someone was talking with Boortz about dirty nukes a few weeks ago. Isotopes floating in the atmosphere, getting into drinking water, into food, etc. It's a real mess.
Your smoke detector has radioactive isotopes in it. Of course there is always the possibility that they can get ahlod of some really nasty stuff.
The real danger is the conventional explosion.