Answer to Question #8678 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I've read all your answers on smoke detectors and couldn't find the following. One of the americium-type smoke detectors fell off my ceiling and onto a tile floor. Many tiny little metallic/glass-looking shards were there, which I cleaned up using many wet paper towels. The plastic unit itself was still intact so I don't know where the shards were coming from. I'm worried about radiation. Did I clean up americium? Was I exposed to enough radiation to be dangerous?
I doubt you were exposed to any americium (americium-241), which I believe is still in the unit itself. I do not know what the shards are, but simply falling from the ceiling to the floor is not enough to compromise the integrity of the sealed radiation source. The amount of radioactivity in a smoke detector is so small that it does not pose a safety concern. Smoke detectors are safe. They were tested for extreme environments, including fire, water from fire departments, leachability, and tampering. The radioactivity is simply not easily removed.
Now some detailed information. Smoke detectors were tested extensively prior to even being authorized by the U.S. Nuclear Regulatory Commission (NRC), the agency responsible for licensing exempt sources of radioactive materials. NRC takes very seriously the concerns that the radioactive isotope americium-241 is in smoke detectors. However, before any amount of radioactivity was authorized in smoke detectors, NRC performed several technical analyses in the 1970s, 1981, and most recently in 2001 to determine if NRC's earlier calculations regarding any potential health effects from use of such consumer products containing very small amounts of radioactivity would be detrimental before authorizing its use.
NUREG-1717, which is available on NRC's Web site, discusses the radiological assessment that NRC performed for smoke detectors and other types of consumer products. Radiation doses were estimated for the normal life cycle of the smoke detector, covering routine uses as well as inadvertent uses of the device (such as many thousands of smoke detectors burning in a warehouse fire). Americium-241 used in smoke detectors is embedded (fused) onto a layer of foil; it does not pose any danger to you or your family. This is one of the reasons NRC originally authorized its use in the 1970s. The americium-241 cannot be scraped off or inhaled.
For additional information, I refer you back to the Health Physics Society Web site—search on "smoke detectors."
I hope this helps.
Orhan Suleiman, MS, PhD