Radium is scary. Period.

Element number 88, like all radioactive elements, poses some health risk in that… well… it’s radioactive. Radium, however, has a unique and insidious trick up its sleeve. Looking at a periodic table, one would see that radium is in the second column of the table. Generally speaking, elements in the same column on the periodic table are chemically similar to each other and behave similarly in chemical reactions. The second column contains a family of elements known as the alkaline earth metals. This family includes radium, beryllium, magnesium, strontium, barium, and (most importantly) calcium, the element which plays a vital role in the human skeleton. Being so chemically similar to calcium, radium, if allowed to enter the body, has the potential to replace the calcium in the skeleton, where it will slowly, constantly irradiate the bone marrow and surrounding tissue. This trait of radium caused a revolution in worker’s rights in the 1920s when it was found to be slowly killing the “radium girls”.

In the early part of the 20th century, watches and clocks were widely produced with radium-painted dials. The numbers and hands of a timepiece were painted with a substance consisting of an adhesive, powered zinc sulfide, and powdered radium. When the radium underwent radioactive decay, it emitted alpha particles. When the alpha particles struck the special activated ZnS in the paint, it produced a blue-green glow similar to the phosphorescent glow-in-the-dark items we are all accustomed to today  (which, thankfully, don’t contain radium, and don’t function based on radiation). My radium sample of one of these watches.

An example of a watch using radium paint on the dials and hands. Because the ZnS in the paint degraded decades ago, the watch is no longer luminescent. The radium, however, is still there, as evidenced by the energetic response it garners from my Geiger counter.

In the factories where these watches were produced, the dials were hand-painted by young women who would eventually become known as “radium girls”. While working, the dial painters would often sharpen the points on their brushes by using their lips, ingesting a small amount of the radium-laced paint each time they did so. Not knowing the dangers of radioactivity and radium, the workers would also paint their fingernails, faces, and even teeth with the luminescent paint for amusement.

Eventually, one by one at first, and then in droves, the radium girls became sick. Their employers, who knew full well the dangers posed by radium, tried to cover up their illnesses, even though the girls were showing all the classic symptoms of radiation sickness, as well as the anemia, brittle bones, and necrosis of the lower mandible (known as “radium jaw”) that were tell-tale signs of radium poisoning.

The truth, however, was finally realized, and the case of the radium girls spurred on a crusade in establishing employee’s rights to a safe workplace. After the case was settled in 1928, radium paint continued to be used on timepieces, but the workers painting the dials were better educated about the dangers of radium and were given protective equipment.

Though I can’t confirm whether or not my radium watch is from this period, it is an interesting piece none the less.