In the 1920s and 30s, the industrial workers who painted the numbers and hands on clock faces, which would glow in the dark, were mostly immigrant women and girls. Unwittingly they were being poisoned by the luminescent chemical in the paint, Radium, which was radioactive. Many of these workers fell ill and died from radiation poisoning and this instance is the first known legal case where an employer was sued for damages around occupational health.