The important question is how much of a sample was lost. Ultimately, AIUI, the health risk depends upon the exposure in a ~ linear fashion. At least, in radiolo

The important question is how much of a sample was lost. Ultimately, AIUI, the health risk depends upon the exposure in a ~ linear fashion. At least, in radiological protection that's used. The LNT model errs on the side of caution; assume that any exposure is harmful, linearly extrapolating from the high dosages seen in Hiroshima, etc, where we have data of the impact of exposure on the body. In reality, we expect a threshold effect as the body is able to repair some damage. The dose of radiation has different meanings; absorbed, equivalent, effective. These are just different calculations, starting from how much energy the body received (absorbed), to taking into account the different kinds of radiation whose effects differ (equivalent), to where in the body the dose as received (different organs at different risk, effective). The half-life of 210Po is 138 days, so it's ~10x less active than 223Ra. That's meaningless with respect to the health risk, though; the activity of the sample is ultimately selected by its intended use. Most samples are sized according to the dose requirements. At least, that's my understanding (physics, not medical). In general we don't want to over-size a source as there are greater regulations. Similarly, we don't want sources to become useless too quickly. In any case, this is definitely bad — 5000x less activity is not good if it's greater than the lethal dose. Because radioactive sources are so small, the risk is not likely to be distributed; you get the whole dose, or nothing.* * Unless it gets dispersed somehow. Dose: https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI_Radiation_dose_units.png https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI... LNT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/