Internal exposures and alpha strong toxicity
The curve illustrates the dangers of alpha and beta emitters fixed l in the body where the radiation can cause the most damage. In tissue whose density is similar to water, alpha emitters such as radium and plutonium deposit their 5 MeV of energy over a short path of a few hundredths microns. These alpha particles may reach sensitive bone cells and eventually cause osteosarcomas. In the case of beta emitters such as strontium 90, beta rays are less energetic but travel a longer path. They can reach as far as the bone marrow and eventually cause leukaemia.