Although the use of radium for cancer treatment offered hope to previously hopeless patients, radium also had a dark side. Exposure to radium--or any other form of ionizing radiation--carried significant health risks. Almost as soon as doctors began working with x-rays, radium, and other sources of radiation, they noticed that radiation could cause a skin reaction similar to a sunburn. The burns could be severe enough to leave permanent scars. The instructions on the safety card handed out by Frank Hartman to his doctor and hospital clients, shown at right, mostly related to this type of exposure hazard.

The most significant danger of radium, however, came from accidental consumption. Radium comes from the second column of the periodic table--the same column as calcium. When a person ingests radium, it, like calcium, gets deposited in bone tissue, where it causes a variety of health problems. In large quantities, radium can destroy the surrounding tissue, causing bones to weaken and fail, or lead to painful and deadly bone cancers. Between 1915 and 1920, a steady trickle of warnings about the dangers of working with radium appeared in various medical journals, mostly as anecdotal accounts from researchers at radium labs. Eventually, the danger of radium ingestion was confirmed and made very public by the terrible case of the so-called "Radium Girls": women hired to paint watch faces with glow-in-the-dark radium paint. The women continuously licked their brushes to give them a precise tip, and ingested radium paint in the process. Beginning in 1920, women from the U.S. Radium factory in Orange, New Jersey, began to report jaw pain and problems with their teeth. Doctors and dentists found that the bones in the women's faces were literally rotting from within; all would eventually die of complications from radium poisoning.

The body eventually does rid itself of radium, so lower, more occasional exposures do not produce the same immediate, obvious harm suffered by the Radium Girls. But since ionizing radiation disproportionately affects rapidly dividing cells, like those in the bone marrow, long-term exposure to radium can lead to anemia, as the tissues responsible for blood-cell production accumulate permanent damage over time. Both Robert Abbe and Marie Curie suffered this fate.

Abbe died in 1928, at the age of 76. As the autopsy report noted, Abbe's bones showed no signs of lingering radioactivity, but they were weakened and misshapen, leading the coroner to record the primary diagnosis as Paget's disease. The autopsy report also noted that samples taken from the right femur contained "a large amount of amorphous brownish material not at all resembling normal red marrow," and blamed bone marrow atrophy for the "blood destruction" and chronic anemia that had necessitated numerous blood transfusions towards the end of Abbe's life. Marie Curie suffered with similar health problems, dying in 1934, at the age of 66, of what is usually described as aplastic anemia (although it may have been a form of leukemia).