Do You Know Where Your Americium 241 Is?

We changed the batteries in two of our three smoke alarms today and while Bob was balancing on a chair snapping one back into the ceiling, I read the back of the other one and was disturbed to find a familiar symbol along with a warning: I'm no smoke-detector expert, and maybe all the smoke detectors in places I've lived have carried the same matter-of-fact statement of radioactivity, but it's still somewhat disconcerting to see the words "contains radioactive material" on a household device. It's supposedly just fine, with a radiation dose to house occupants of "essentially" (don't like that word) zero, and the detectors themselves can be put in regular landfill when they're no longer useful, but I still feel a bit strange about this discovery. The websites say that you could even eat the radioactive component and be completely fine, but I won't be doing that anytime soon!