|Fig. 1: "Radium dials" referred to illuminated clock hands garnering their brightness from zinc sulfide's tendency to luminesce when struck with radioactive elements. (Source: Wikimedia Commons)|
The advent of "radium dials" was not only a supremely bad idea at the time, it is one of the more tragic legacies that stems from nuclear technology in the civilian sector. The term refers to wristwatches, pocket watches, and other clock faces coated with luminous paints that garner their brightness from zinc sulfide's tendency to luminesce when struck with radioactive elements. The true harm befell those involved in the manufacturing of these dials.
Radium's ability to cause certain materials to fluoresce was well known by the time the idea to illuminate clocks and watches came about. This property was standard procedure to measure the strength of an alpha-emitting source: observations were made through a microscope on the number of light flashes given off in a time interval.  Following this principle, Dr. Sabin Arnold Von Sochocky introduced his commercial paint, dubbed Undark. The paint was a concoction of crystalline phosphorescent zinc sulphide (ZnS) with the addition of radium (Ra-226, half-life of 1600 years), mesothorium (Ra-228, half-life of 5.8 years) and radiothorium (Th-228, half- life of 1.9 years) in the form of insoluble sulphates. 
Von Sochocky was an enthusiastic proponent of the technology. He envisioned piano keys and conductors batons coated with the paint and for it to even be used as an artistic medium well suited for winter or moonlit scenes. He once propounded:
"The time will doubtless come when you will have in your own house a room lighted entirely by radium. The light thrown off by radium paint on walls and ceiling would be in color and tone be like soft moonlight."
Many products were in fact produced. By the end of WWI, the US was producing over 4 million watches a year with radium-luminous dials, but productions of military materials quickly gave way to civilian 'novelties'. Over a 7 year period, there were several spin-offs including crucifixes, light-pulls, fishing lures, and revolver sights. For $3 one could buy a DIY Radium Illuminating Set. By the 1970's there were estimated to be over 10 million watches and clocks in the USA with luminous Ra-226 dials, like the one depicted in Fig. 1. 
"When they began contracting deadly bone cancer the Chicago newspapers named them 'The Legion of the Doomed.' Most died in their youth. Others suffered for years. Today if you take a Geiger Counter to the Catholic cemetery just out of town, and place it over the graves of those dial painters, you'll hear it ticking over those poor girls still." 
Of course all these products had to be manufactured, which is where the real harm befell workers. The Radium Dial company produced their watches in Ottawa Illinois. The work of painting the luminous material employed many young women attracted by the relatively high pay. Dial painters were paid $20-25 a week, when they may have earned $15 in an office.
Part of the delicate work entailed pointing the tip of the brush between the lips in order to lay down paint more precisely. It's estimated that if a worker pointed the brush an average of 14 times per dial, painting 250 dials daily (which was the minimum expectation), a worker could ingest 125mg to 1.75g paint daily. This would contains from 3 to 43 micrograms of radioactive substance. Dial workers were unaware of the radioactive poisoning that they were slowly being exposed to. Women would use up their leftover paint by painting their faces, teeth, hair, and lurking about in the dark. There is report of one worker wondering why her handkerchief glowed after she blew her nose. 
With time, women began suffering from anemia, necrosis of the jaw, and bone fractures. Eventually women from the plant brought a lawsuit against the company, and settled the case for $10,000 in the autumn of 1928. Radium Dial Company closed down but Luminous Processes opened up blocks away, six weeks later. There claimed to be no danger of radium poisoning, despite being held by the same owner Joseph Kelly. The plant continued to produce products for the US military throughout World War II. 
The town of Ottawa saw prolonged efforts to clean up the city and grasp the impact radiation poisoning had upon the workers. By 1948, Argonne National Laboratories was set up on a 68 million dollar research project, 75 miles outside Ottawa. Part of this entailed contacting former dial workers. Within 20 years, 205 volunteers were tested for body burden radioactivity. Though no worker was ever compensated financially, it became the most expensive medical study of a group of workers ever done in America. 80% had radium caused cancers. 50% died by the time the study ended. Much of this work set nuclear exposure standards.
Furthermore, the buildings themselves were contaminated. The Radium Dial building was torn down in 1968 with no regards to potential radioactive danger, resulting in radioactive debris left all over the town. By 1984 Illinois approved 2.5 million dollars to tear down the Luminous Processes building, by which time forty women formerly employed by the plant had been linked to radium poisoning deaths. Within 2 years, over 6.5 million had been spent decontaminating the site. There are still "hot spots" that can be spotted by the absence of snow settling on them during winter. 
© Matt Estrada. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 R. E. Rowland, "Radium in Humans: A Review of US Studies," Argonne National Laboratory, ANL/ER-3, September 1994.
 H. S, Martland and R. E Humphries, "Osteogenic Sarcoma in Dial Painters Using Luminous Paint," CA - Cancer J. Clin., 23, 368 (1973).
 D. A. Harvie, Deadly Sunshine: The History and Fatal Legacy of Radium (Tempus, 2005).
 J. Maslin, "Radium City (1987): Film Festival; A View of the Radium Dial Horror," New York Times, 29 Sep 87.