6. Radium

In the early 20th century, radium was heralded as a miraculous element, finding its way into glow-in-the-dark watches, toothpaste, and even beauty products. Many believed it offered health benefits, but the dark reality soon emerged. Workers known as the "Radium Girls," who painted radium onto watch dials, experienced severe radiation poisoning, resulting in devastating illnesses and deaths.
Despite assurances from Radium Corp. that their work was safe, the company was well aware of the dangers. A report commissioned by the U.S. Radium Corporation in the early 1920s highlighted the complete lack of safety measures. This put the dial painters at grave risk. HowStuffWorks states that by 1927, over 50 women had lost their lives due to radium paint poisoning.