It is generally conceded by most reasonable (and hell, probably some unreasonable) individuals, that radiation in excess, like anything else, can do more harm than good. Now, we all know that radium dials are a feature of vintage watch and clock collecting. We all also know the cautionary tale of the Radium Girls, who received fatal doses of radiation from the practice of licking the tips of radium paint brushes, in the early 1920s. We jested light-heartedly about the subject on the late lamented Friday Live. And we all know that such dials should pose little in the way of actual hazards as long as you don’t make the mistake of opening up the watch, and accidentally inhale a fragment of radium paint (radium, let’s recall, has a half life of about 1600 years, so radium dial watches and clocks from the early part of the 20th century are still enthusiastically emitting radiation).
At least, that’s what we thought we knew. Unfortunately, it turns out that most if not all of us who looked at the evidence and said, “eh, it’s probably fine, just don’t lick the damned things,” may have been wrong. Very, very wrong.
A new study from the good folks at the University of Northampton has shown that we all forgot one essential fact: radium decays to radioactive radon gas, which is readily inhaled and will in sufficient doses significantly increase the risk of lung cancer. Radon is the second leading cause of lung cancer in the USA after cigarette smoking; the EPA estimates that radon is responsible for about 21,000 cancer deaths annually.
The study found that 30 radium dial watches, when kept in a poorly ventilated space the size of “a typical boxroom” (UK-speak for a small bedroom or storage room) produced radon levels a whopping 134 times the recommended maximum safe level. In addition the study says, ” … three of the watches in poor condition gave rise individually to radon concentrations – when kept in the same poorly ventilated room – well in excess of the threshold where Public Health England would recommend remediation.” Occasionally folks have pointed out on various watch forums that radium’s decay products (such as radon) pose a potential hazard, but this is the first study I’m aware of that shows that radon from radium dials can accumulate to such previously unsuspected high levels.
You can read the statement from the University right here – the data seems to indicate that radon outgassing represents a previously un-considered potential hazard for those owning and storing radium dial vintage watches. It’s certainly useful information to consider if you’re a collector. We’re obviously not in the medical advice or radiation remediation biz, but it seems that logical steps to take might include considering ventilation issues, and investing in a radon detector for the room in which you keep your collection (radon monitors are inexpensive and recommended for most homeowners anyway).