In the years during and after the First World War, hundreds of young women went to work in factories in New Jersey, Illinois, and Connecticut painting the numbers on watch and clock dials with a luminous paint called Undark. The glow came from radium, an element discovered by Marie Curie two decades earlier and still surrounded by an aura of wonder rather than dread. The work was delicate. To keep a fine point on their brushes, the women were taught a technique called lip-pointing: they would draw the bristles between their lips to shape them, dip into the radium paint, apply it to a dial, and then bring the brush back to their mouths to point it again. A single painter might do this hundreds of times a day. With every pass, she swallowed a small amount of radium.
Nobody told them this was dangerous, and at the time the companies may not have fully understood how dangerous it was, though they learned faster than they admitted. The women were young, many of them teenagers, and the job paid well and carried a certain glamour. The paint made their work clothes glow in the dark. Some of the women painted their nails, their teeth, and their faces with it for fun before going out at night, delighting in the way they shimmered. They were called the ghost girls. The substance that made them glow was, cell by cell, taking their bones apart.
Radium behaves inside the body almost exactly like calcium, which means the body mistakes it for a building block and deposits it into bone. Once lodged there, it does not leave. It sits in the jaw, the spine, the legs, emitting radiation into the surrounding tissue continuously, for years. The first signs appeared in the mouth. Painters developed aching teeth, then loose teeth, then sores that would not heal. Dentists pulling a bad tooth found that pieces of jawbone came away with it, or that the socket simply would not close. In the most severe cases, a woman's lower jaw would deteriorate so badly that it could be removed by hand. Doctors gave the condition a name: radium jaw. Beyond the mouth, the women suffered spontaneous fractures, collapsing spines, anemia, and tumors. Many died young, in their twenties and thirties, after years of misdiagnosis.
The companies, most notably the United States Radium Corporation, resisted responsibility with a strategy that has since become grimly familiar. They commissioned studies and then buried the unfavorable ones. They suggested the women were suffering from syphilis, a diagnosis calculated to shame them into silence and discredit them publicly. They relied on the fact that medicine did not yet have a clear framework for occupational disease, and on the legal reality that workers had almost no standing to sue an employer for harm that appeared years after the exposure. When a group of dying women in New Jersey, later known as the Radium Girls, finally found a lawyer willing to take their case in the late 1920s, several of them were already too weak to raise their arms to be sworn in.
The legal fight mattered far beyond the individual women involved, which is what makes the case a turning point rather than simply a tragedy. At the time, the dominant assumption in American industry was that the risks of a job were the worker's own to bear. If labor was dangerous, that danger was priced into the wage, and what happened to a body on the factory floor was largely the body's own problem. The Radium Girls cases, along with a parallel suit brought by the painter Catherine Donohue in Illinois, helped dismantle that assumption. The litigation established that an employer could be held liable for illnesses that developed slowly, long after exposure, and that companies had a duty to protect workers from hazards the workers themselves could not see or understand. This principle, obvious as it sounds now, did not exist in any settled form before these women forced the question into court.
The consequences rippled outward for decades. The cases contributed directly to the development of occupational safety standards, to the eventual creation of federal workplace protections, and to the scientific study of how ingested radioactive material behaves in the human body, research that later informed the safety limits used in the nuclear age. Some of the surviving Radium Girls agreed to have their bones studied for the rest of their lives, and even after death, so that scientists could learn how radium moved through and destroyed the body. Their skeletons became a data set. There is something bleak and fitting in that final detail: women who were poisoned because no one bothered to warn them ended up teaching the world how the poison worked. The knowledge that might have saved them was, in the end, extracted from what was left of them.