Marie Curie and her husband Pierre discovered polonium and radium, and she is generally credited with being one of the most important pioneers in the study of radioactivity.
Radioactivity was so poorly understood that she and Pierre kept samples of these substances in their pockets and handled them freely. They wore standard lab clothing.
What killed Marie Curie ?
She died of aplastic anaemia, which was a consequence of her being exposed to so much radiation, but not before she won two Nobel Prizes, in both physics and chemistry.
After she died, the Curie’s house kept on being used by the Institute of Nuclear Physics, before being abandoned in 1978.
But her notebooks were transferred to the Bibliotheque Nationale, where they still are.
Why is Maria Curie’s notebook the most dangerous book in the world ?
The reason Maria Curie notebooks are considered the most dangerous book(s) in the world, is not so much because of the knowledge contained in them.
It’s because they’re still radioactive.
They are stored in a lead-lined box. If you want to consult them, you have to sign a waiver. You can only inspect them in a special reading room away from the other reading rooms, you have to wear protective clothing, and you have to use contamination monitoring during and after handling.