This is a sad tale. The Radium Girls, five employees of the
United States Radium Corporation, were women who worked with radium
paints and sued the company because they became ill. Grace Fryer,
Edna Hussman, Katherine Schaub, and sisters Quinta McDonald and
Albina Larice were the plaintiffs in this famous lawsuit. All of
them ended up dying within a few years of the litigation, and all
their deaths were a direct result of radiation poisoning due to
radium. These women (and many others) applied the radium-containing
coatings to the dials of clocks and aircraft instruments so they
would "glow in the dark" and could be seen without light (owing to
the radioluminescent property of the paints). Radioluminescent
paint contains a radioactive isotope (in this case radium-226)
combined with a radioluminescent substance (copper-doped zinc
sulfide paint). To paint on the radium compounds, these women would
put the tips of the brushes (that had the radium paint on them) on
their lips to give the bristles an optimum shape. This quite
naturally left a bit of the highly radioactive material on their
lips. Over a period of time, these women got a large dose of
radiation, and they (and a large number of others who worked with
them as well as others who worked to refine the radium and make the
paints) developed serious (and sometimes fatal) medical maladies.
They had been told the paint was harmless. A link to the Wikipedia
article on the Radium Girls is provided. A link is also provided to
the imdb post on the 1987 documentary film "Radium City" which
covers the particulars. This film is worth watching. It's accurate,
gritty.
