Most discussions about radiation safety seem to concentrate on being exposed to emissive radiation sources. In small doses and in exceptional situations where y

Most discussions about radiation safety seem to concentrate on being exposed to emissive radiation sources. In small doses and in exceptional situations where you walk away from the source, it does indeed seem low risk. I'm no expert, but I've seen much less discussion and safety study about radiation exposure via intake and biological binding. The pathway of concern there would where dust or other particles of a radioactive substance are spread in an environment, then concentrated via natural means: erosion or biological (e.g. predators taking in prey); then exposed to humans. In that context, even a small amount of bound material may be continuously emitting where one is always getting a dose. We actually take advantage of this pathway for short-lived isotopes for medical procedures, but obviously longer lived isotopes are more dangerous. Most safety in radiation discussions seem to measure the emissive strength, and declare things safe while ignoring the accumulation side of things. I think it's actually a much more difficult risk to characterize and to perform experiment with for obvious reasons..