Radioactive decay
Radioactive decay can lead to the emission of particulate radiation or electromagnetic radiation. Ingesting even small quantities of some particulate emitting radionuclides may be fatal. For example, the median lethal dose (LD-50) for ingested polonium-210 is 240 μCi; about 53.5 nanograms. Although, millicurie quantities of electromagnetic emitting radionuclides are routinely used in Nuclear Medicine.