My favourite essay in ‘The Faber Book of Science’ (edited by John Carey) is ‘Shedding Life’ by Miroslav Holub, who is a poet and immunologist. In this essay he recollects mopping up the blood of a recently shot muskrat, and he ponders on the exact nature of death. The death of an organism as a whole is generally taken to be defined as brain death or heart failure. But what about all the constituents of that organism? Holub points out that many of these; blood cells, hormones, enzymes etc., are all capable of living on for some time after the apparent death.
When Marie Curie died (in 1934) her belongings, such as her note books, were discovered to be so radioactive that they had to be deposited in lead-lined boxes. Even now, anyone who wants to look at them has to wear protective clothing.
She died of cancer, most likely caused by a lifetime of working with radioactive substances without being properly protected from the resulting radiation. Her most famous achievements were to discover new chemical elements, by virtue of the fact that they were radioactive. In making these discoveries she helped to shed light on the nature of radioactivity, and show that there are three different types; alpha, beta and gamma radiation. When an element emits or absorbs alpha or beta particles it changes into another element. This is why the study of radioactivity has been considered to be a sort of alchemy. (You can get gold from radioactive mercury, but it is very difficult).
Marie Curie worked with a uranium ore called pitchblende, exposing herself to alpha particles, and to radon gas. Both of these would have been absorbed by her body, causing damage to the cells. At an atomic level some of the alpha particles may have been absorbed by the atoms in the cells (Humans are carbon-based and so most of these atoms are carbon atoms. The process of carbon atoms absorbing alpha particles and transmuting into oxygen atoms is what happens in dying stars.)
Radon gas has a long half life but eventually decays into polonium, one of the elements Marie Curie is famous for discovering and which she named after the land of her birth; Poland. Polonium is called a ‘daughter product’ of radon as a result of this process.
Her body is interred in the Pantheon in Paris. It is still radioactive; alongside the more usual organic decay processes taking place there are also the atomic ones. She is being transmuted herself.