Radium

Marie and Pierre Curie processed several tonnes of pitchblende residue by hand between 1898 and 1902 to isolate a tenth of a gram of radium chloride, work that won two Nobel Prizes and left notebooks still too contaminated to handle without protection. Radium's faint blue glow made it a marketing miracle — radium water, radium toothpaste, radium suppositories — and its most infamous use was luminous watch dials, painted by young women who shaped their brushes with their lips and later died of jaw necrosis and bone cancer. The Radium Girls' lawsuits in the 1920s established the legal right of workers to sue for occupational disease and shaped modern industrial safety law. Chemically radium is simply a very heavy alkaline earth; biologically it is dangerous because the body files it as calcium and stores it in bone.