In the 1920s, many Americans and Europeans were regularly consuming radium. Marketed as a cure-all, radium was an ingredient in a variety of over-the-counter nostrums, from face creams to tonic waters. It was used to treat “almost everything from impotence to insanity” (1). One company advertised it as “liquid sunshine” (2). Famously, radium was used for its luminous properties to make watch dials glow in the dark. A New Jersey dentist noticed that several of the factory girls who painted watch dials had developed “diseased jawbones that failed to heal after dental work” (1). The dentist learned that the girls would lick their radium-laced paintbrush bristles to make the tips finer. The girls would even paint their nails and teeth with the radium paint to make themselves glow in the dark. Five “Radium Girls” died as a result of their ingestion of the radioactive element and the resulting scandal branded radium a killer (2). Though it fell out of favor within 30 years of its discovery, radium was vitally important to the discovery and characterization of radioactivity.

Radium will always be tied to its discoverer, the remarkable Marie Curie. Pierre and Marie Curie won the Nobel Prize for Physics in 1903 “in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel” (3). In 1911, five years after Pierre’s death, Marie won the Nobel Prize for Chemistry “in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element” (4). Marie remains the only woman in history to have won two Nobel Prizes (5). Through her work with radium and other radioactive elements, Marie won international fame and recognition. However, as a result of her groundbreaking experiments, excessive exposure to radioactivity destroyed her body and hastened her death.

At the end of the 19th century, the Curies were intrigued by the newly-discovered X-rays and Becquerel rays, which had been characterized by William Roentgen and Henri Becquerel, respectively. Roentgen, in sending a high-voltage electric current through a cathode ray vacuum tube, found that unknown rays were escaping the tube and causing a nearby piece of paper to glow. He learned that the rays could pass through glass as well as “paper, ebony, rubber, and thin layers of metal” (6). The ability of X-rays and Becquerel rays to penetrate materials that block visible light and cathode rays was intriguing. Foreshadowing the use of the X-ray as a medical diagnostic tool, Roentgen found that the rays could also pass through flesh. Further experimentation revealed that X-rays were produced by the collisions of high-energy electrons with a material (6). Shortly afterward, Becquerel, experimenting with the origin of phosphorescence, made an accidental discovery. He found that if uranium salts were placed on a photographic plate, the developed plate would show a black negative image of the uranium salts. The radiation from the uranium salts was similar to the X-rays, but was produced spontaneously, whereas the X- rays were produced by electron collision. These new rays were termed Becquerel rays. When the Curies learned of these developments, they decided to further characterize these phenomena and to find, if possible, other sources of Becquerel rays (6).

The Curies experimented with the ability of uranium to ionize the air and enable it to conduct electricity. Marie monitored the strength of the electric current in the air surrounding a sample of uranium as a measure of the sample’s activity. She learned that uranium metal is responsible for the ray emissions, “independent of the chemical or physical state” of the metal (6). Furthermore, she found that as she increased the amount of uranium in the sample, the amount of radiation produced by the sample increased. Marie invented the term radioactivity to define these spontaneously-emitted rays. Marie and Pierre then sought to find other sources of radioactivity (6). They focused on a dense, black mineral called pitchblende, one of the primary uranium ores (7). The radioactivity of pitchblende was higher than the Curies expected, based on its uranium content. They suspected that the ore contained another radioactive element and began to separate pitchblende into its constitutive parts. The purification was a difficult and painstaking process and took several weeks to complete. A new radioactive substance was purified from the mixture in June of 1898 and was found to be about 400 times more radioactive than uranium. They submitted their results and named the new element Polonium, after Marie’s homeland of Poland. In September, the Curies isolated another radioactive material from the pitchblende, and christened it Radium, from the Latin for ‘ray.’ The new element was one million times more radioactive than uranium (8). The properties of radium astounded scientists. Its ability to glow in the dark and perpetually radiate heat appeared to violate the First Law of Thermodynamics – the conservation of energy. Also, the discovery of radium’s ability to produce helium gas “was the first evidence of the transmutation of elements” (9). Investigation of these unusual qualities led to important discoveries about the nature of radioactivity. Scientists learned that the large size of radioactive atoms causes them to be unstable. They emit heat, light, and subatomic particles in the process of converting into smaller, more stable atoms, such as lead. The speed of radioactive decay varies among different radioactive elements. Radioactive elements emit alpha or beta particles, or both. Alpha particles are equivalent to helium nuclei, while beta particles are essentially electrons emitted from a nucleus. Gamma radiation may also be produced (9); gamma rays have no mass and no charge (10).

Each type of radiation causes a different type of destruction in living tissue. Joseph Selman summarizes the different effects: “Alpha and beta particles ionize matter directly, whereas gamma rays do so indirectly, like x rays” (11). Alpha particles have a difficult time breaching tissue because of their large size, but cause much destruction once they have done so. Beta particles, which are smaller, enter tissue more easily and cause less destruction; however, their negative charge causes damage because it interferes with the charges on atoms of the tissue. Gamma radiation is essentially a high energy X- ray, but arises from radioactive atoms rather than electron collision. Gamma rays easily penetrate into living tissue, but do less damage than alpha or beta particles, whose mass and charge affect tissue. Different elements in the radium decay scheme produce different combinations of alpha particles, beta particles, and gamma radiation. The radium decay scheme proceeds as follows: Radium → Radon → Radium A (Polonium) → Radium B (Lead Isotope) → Radium C (Bismuth) → Lead. Radium has an atomic number of 88, a mass number of 226, and a half life of 1622 years (11).

It was soon discovered that radium shared properties with X-rays. Both were capable of burning skin and became popular for use in burning off lesions, warts, or cancers as early as 1903. Soon afterward, radium began to be marketed as a panacea for internal complaints. According to Claudia Clark, “early experimenters believed that radium did not just burn away tissue; they suggested that it selectively destroyed morbid cells and even more amazingly promoted the growth of healthy cells” (12). Clark asserts that even Marie Curie has been credited with this belief (12). Radium was marketed as a bactericide and a germicide, and used to treat many diseases including diphtheria, typhoid, malaria, diabetes, and kidney and liver diseases. People bathed in radium water and inhaled radon fumes. In 1906, scientists published a correlation between inhalation of radon and decreased rates of arthritis and rheumatism. These diseases were also reputedly alleviated by radium water treatments (12). American usage of radium as a medical supplement did not truly begin until 1910, but within three or four years, it had been accepted as a cure-all (12). The publishing of research articles that promoted the use of radium injections to treat high blood pressure, anemia, leukemia, diabetes, and gout served to bring radium into the limelight (12). However, the high costs ($89,000 – $125,000 per gram between 1914 and 1921) kept radium relatively inaccessible.

Indications that radium was not the panacea it seemed emerged in 1913 with studies that showed radium deposition in bone. Ten years earlier, X-ray overexposure was discovered as a cause of a number of maladies, including carcinoma, leukemia, and sterility (13). Radium is chemically similar to calcium (11), and when ingested, the radioactive material is incorporated into bone mass. Blood diseases such as anemia and lowered white and red blood cell counts began to plague people who exposed themselves to radium. The deposition into bone was wreaking havoc on the bone marrow, home to hematopoietic stem cells and blood cell production (13). In 1917, an article appeared in the Reference Handbook of the Medical Sciences that asserted that experimental success in the use of radium to treat diseases had been “greatly exaggerated” (13). In the same year, the watch dialpainters of Orange, New Jersey began their work.

The deaths of the dialpainters set off a toxicological campaign to understand if and how the radium was to blame. Harvard researchers learned that even the dust on the factory floor was radioactive. Not only were the women ingesting radium by licking the paintbrushes, but they were breathing it in. Their clothes and skin were covered with radioactive dust. A subsequent study conducted with cats showed that breathing in radium dust resulted in radium deposition in bone. Researchers concluded that radium was to blame for the deaths of the dialpainters (14). The study was published in the Journal of Industrial Hygiene in August of 1925 (14). Another article written by Frederick Hoffman, a researcher for the U.S. Department of Labor, was published in September of 1925, and detailed the health problems suffered by the dialpainters, including necrosis of the teeth and jaw, anemia, back and joint pain, and tumors (14). Analyses of the body of the fifth dialpainter who died showed radioactivity in her spleen, liver, and bones. The woman’s sister, who also worked as a dialpainter, was suffering grotesque symptoms: “most of her teeth were missing, her lower jaw was fractured, and her palate had eroded so that it opened into her nasal passages. She was also anemic. Tests showed her to be radioactive” (15). The researchers were discovering that no matter how radium entered the body, it would deposit into bone and cause anemia (15).

Corporations such as U.S. Radium resisted the calls for investigation of radium’s dangerous properties. According to Clark, “the industry stood to lose money to liability suits if workers’ claims proved true. It stood to lose business in the radium internal medicine market if radium treatments proved dangerous” (16). Clark asserts that personal reasons also led the radium industries to ignore the dangers of radium. The corporations’ workers had suffered massive exposure to radium and denial of the hazardous effects would help to allay fears of impending disease and death. Indeed, huge numbers of radium workers, from those who investigated the element’s properties to those who labored to harvest it from ore, developed the symptoms of radium poisoning and died early deaths. However, Clark states that “existing medical literature justified the industry’s stand” (16). Radium was poorly characterized at the time and had been used widely before it could be properly studied. Clark also identifies many of the authors of pro-radium research articles of the time as having a financial interest in the radium corporations (16).

As for Marie Curie, her groundbreaking work with radium had taken its toll on her body. She experienced an incessant ringing in her ears and her hands bore radium scars (1). She died in 1934 at the age of 67 from “a form of pernicious anemia, which was hastened by what her physicians termed ‘a long accumulation of radiation which affected her bones and prevented her from reacting normally to the disease,’” according to the New York Times (17). In 1995, Nature discussed evidence that X-rays, rather than radium, were responsible for Marie Curie’s death (17), but it remains unclear whether radium or X-rays contributed more to her ill health. Several “Radium Girls” sought reparations from the U.S. Radium Corporation for their radium poisoning, and some received payment after many months in court. Radium products fell out of favor after the discovery of the health risks. Some consumers who bought into the radium craze were fortunate enough to have purchased their medicines from fraudulent companies that claimed to use radium but did not. Others who ingested or bathed in radium in hopes of improving their health were actually depositing radioactivity in their bones. At great human cost, radium was critical to the discovery of the power and danger of radioactivity.

1. D. Brian, The Curies: A Biography of the Most Controversial Family in Science, John Wiley & Sons, Inc., Hoboken, 2005, pp. 204-205.
2. B. Kovarik, The Radium Girls (2002). Available at http://www. (25 July 2006).
3. The Nobel Prize in Physics 1903. Available at http://nobelprize. org/nobel_prizes/physics/laureates/1903/index.html (27 July 2006).
4. The Nobel Prize in Chemistry 1911. Available at http://nobelprize. org/nobel_prizes/chemistry/laureates/1911/index.html (27 July 2006).
5. D. Brian, The Curies: A Biography of the Most Controversial Family in Science, John Wiley & Sons, Inc., Hoboken, 2005, p. 80.
6. D. Brian, The Curies: A Biography of the Most Controversial Family in Science, John Wiley & Sons, Inc., Hoboken, 2005, pp. 53-57.
7. Pitchblende (2007), Encyclopædia Britannica. Britannica Concise Encyclopedia. Available at 9375345 (14 January 2007)
8. D. Brian, The Curies: A Biography of the Most Controversial Family in Science, John Wiley & Sons, Inc., Hoboken, 2005, pp. 58-61.
9. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, pp. 41-43
10. Gamma Radiation, Available at radinf/gamma.htm (14 December 2006)
11. J. Selman, The Fundamentals of X-Ray and Radium Physics (8th ed.), C.C Thomas, Illinois, 1994, pp. 450-453.
12. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, pp. 43-47.
13. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, p. 57-60.
14. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, pp. 89-97.
15. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, p. 103.
16. C. Clark, Radium Girls: Women and Industrial Health Reform 1910-1935, University of North Carolina Press, North Carolina, 1997, pp. 202-203
17. D. Brian, The Curies: A Biography of the Most Controversial Family in Science, John Wiley & Sons, Inc., Hoboken, 2005, pgs. 252-253.