It's a fascinating story of new technology, corporate irresponsibility (or what would now be considered felonious behavior), power run amuck, and the rise of workers' rights.
Undark and the Radium Girls
In 1902, twenty years prior to Grace's mysterious ailment, inventor William J. Hammer left Paris with a curious souvenir. The famous scientists Pierre and Marie Curie had provided him with some samples of their radium salt crystals. Radioactivity was somewhat new to science, so its properties and dangers were not well understood; but the radium's slight blue-green glow and natural warmth indicated that it was clearly a fascinating material. Hammer went on to combine his radium salt with glue and a compound called zinc sulfide which glowed in the presence of radiation. The result was glow-in-the-dark paint.