It has not. Evolution is not a process that can happen to individual organisms; it's change that happens to a species over many generations.
Http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072434/
There is a website with some info. Hope it helps! :)
The reasons why 241am smoke detectors are perfectly safe is because;
(i) The amount of americium is very little.
(ii) The aluminium core is where the detector is hosted.
(iii) The detector has a plastic cover.
(iv) Radiation is limited in penetrating power.
(v) There is a low number which is leaving the case.
(iv) ions get trapped by electrodes.
