At factories like the Radium Luminous Materials Corporation on Third Street in Newark, young women like 14-year-old Katherine Schaub passed their days with tiny paintbrushes in their mouths. Beside each girl sat a small dish of radium powder, which she mixed with a few drops of water and adhesive. The combination made a luminescent green paste called Undark, which they used to painstakingly paint the numbers on the faces of watches. The girls were called dial painters, and they were told to hold the brushes in the mouths for increased precision.

What they didn’t know is that the work they were doing was killing them.

Radioactivity is now known to be practically synonymous with death. But in the early 20th century, the newly discovered chemical element radium seemed to hold the promise of modernity, and America went wild for it. In her new book, The Radium Girls: The Dark Story of America’s Shining Women, Kate Moore tells the story of young women who were drawn to glamorous work with radium in the 1910s and 20s, only to have their lives taken — painfully, horrendously, and very early — by the lethal substance.

Radium was discovered by the Polish-French chemist and physicist Marie Curie and her husband Pierre Curie in 1898. Along with another scientist, André-Louis Debierne, Marie isolated it as a pure metal in 1910. The substance, the progenitor of all things “glow in the dark,” literally gleamed with possibility. It was seen as lifesaving, thought to be able to restore vitality to the elderly and cure all manner of health problems, including, ironically, cancer. It was soon being used in everything from toothpaste to eyeshadow, chocolate and toys. It was even used in jock straps, lingerie, suppositories, and in the treatment of impotence. “The element was dubbed ‘liquid sunshine,’” writes Moore in The Radium Girls, “and it lit up not just the hospitals and drawing rooms of America, but its theaters, music halls, grocery stores, and bookshelves. It was breathlessly featured in cartoons and novels.”

Polish physicist and chemist Madame Marie Curie, left, in a laboratory, with her daughter Irene, in Paris France, April 20, 1927. (AP Photo)

It’s no wonder that radium seemed like magic. When she arrived at the factory in February of 1917, “Katherine could see that the powder got everywhere,” writes Moore. “There was dust all over the studio. Even as she watched, little puffs of it seemed to hover in the air before settling on the shoulders or hair of a dial-painter at work. To her astonishment, it made the girls themselves gleam.” Before leaving the factory at night, some even painted their nails or teeth with Undark to wow dates or as a party trick.

For the dial painters, proximity to radium seemed like a dream, even though the work itself was taxing and the girls were pressured to be exacting in their application of the paint. After all, radium cost $120,000 a gram ($2.2 million today). Still, according to Moore, they felt incredibly lucky. Though they were paid piecework, the girls could make a lot of money — “some even earned more than their fathers.” For working class young women in Newark like Katherine Schaub, it was exciting. When demand skyrocketed after America’s entry into WWI, radium factories hired many more women, expanding into a larger studio and becoming the United States Radium Corporation in Orange, New Jersey.

Hotel postcard advertising radium baths, c.1940s. (Wikimedia)

When Schaub suddenly broke out with a face full of pimples, she saw a doctor who asked whether she’d been working with phosphorous, a known toxic agent. He’d noticed strange changes in her blood as well. But Schaub was confident she’d had no exposure to phosphorous and continued working. By 1919, demand was high, and Schaub was exhausted, complaining of a “cracking and stiffness” in her legs.

Eventually, the United States Radium company realized it would be more cost effective to sell its paint directly to manufacturers, who could apply it themselves in house. Though demand was still through the roof, the company dismissed a number of dial painters. Others, like Katherine Schaub and some of her friends, left in search of more stable employment. She took a job in the office of a roller-bearing company. Then in 1920, she was headhunted to train dial painters, and returned to radium. “Katherine taught scores of girls the method she herself had learned,” Moore writes. “‘I instructed them,’ [Schaub] said, ‘to put the brush in their mouth.’”

In the early 1920s, when dentists began to see young female patients with major dental problems — many needing multiple teeth removed — some became suspicious of their work with radium. The problems looked a lot like “Phossy jaw,” the grim result of phosphorous exposure, but, as Moore writes, “radium was such an established medical boon that it was almost beyond reproach; people didn’t question it.” Sadly, it took many deaths for that questioning to begin, to become coordinated, and finally, to yield results.

One of the young women who precipitously fell ill with what came to be known as radium necrosis, was Schaub’s cousin, Irene, who she’d gotten a job dial painting. She grew anemic and listless, developed a toothache which ultimately deteriorated her entire jaw, and she died a painful death at the age of 20.

Knowing nothing of the few local doctors pursuing the links between jaw necrosis and radium, Schaub filed a complaint with the United States Radium Corporation, but nothing was done.

Soon, it was Katherine’s mouth that was aching. She went to a dentist, who removed two crumbling teeth. She immediately thought of her cousin. “A severe nervousness developed which affected her mental health, a situation that did not improve when…another former co-worker passed away.” Many others were falling ill. One, Marguerite Carlough, was told by her dentist she needed a tooth extraction. When he pulled it, a decayed piece of her jawbone came out with it.