In case it's a lesson you're not familiar with, the Radium Girls of the 1920s changed history: after radium dial companies knowingly exposed the young factory workers to radium poisoning, the women's cases led to landmark labor laws and standards, and can even be said to have led to the creation of the Occupational Safety and Health Administration (OSHA). Featured this week in a Library of Congress exhibit focusing on Labor Day and released today, Rachel Sumner's “Radium Girls (Curie Eleison)" tells the story of these brave women, often absent from most history books.