A really interesting post from Deborah Blum on the "radium girls" who painted wristwatches in the 1920s - to fatal effect:
At the factory, the dial painters were taught to shape their brushes to a fine point with their lips, producing the sharp tip needed to paint the tiny numbers and lines of watch dials, the lacy designs of fashionable clocks. Each worker was expected to paint 250 dials a day, five and a half days a week. They earned about $20 a week for that work, at a rate of one and a half cents per completed dial.
The painters were teen-aged girls and young women who became friendly during the hours together and entertained themselves during by breaks by playing with the paint. They sprinkled the luminous liquid in their hair to make their curls twinkle in the dark. They brightened their fingernails with it. One girl covered her teeth to give herself a Cheshire cat smile when she went home at night.
Read the rest at PLOS - she's posting it in installments.