![]() It is, in no way, addressing the physicists, chemists or nuclear scientists and will not go far beyond the necessary for a basic understanding, although a few more scientific issues could not be avoided. The intention of this book is to give a general overview of radium- and tritium issues for the vintage watch collector interested in this subject. True, the glow is gone - but not the radium (or many other radioactive substance used as an activator, as well as other substances following down the decay chain. Many ask themselves why those watches should still pose a threat to human health, whilst the 'glow' is long gone. Opinions differ from what concerns eventual health risks, not only amongst watch collectors, but also between professionals. Radium and Tritium contained as activators in luminous paint on watch dials and hands, besides other radioactive materials, are subject to never ending discussions amongst vintage watch collectors, especially those, who own lumed timepieces from earlier periods or are even working on them. All rights reserved.Radium, Tritium and other radioactive activators on watch dials and hands. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced.Ĭopyright © 2012 Elsevier Ltd. The risk from old watches containing radium appears to have been largely forgotten today. ![]() Estimates of the activity of (226)Ra in the watches ranged from 0.063 to 1.063 μCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 μCi (0.46 to 32.38 kBq) for wrist watches. Over 6 weeks highs of the order of 2000 Bq m(-3) were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m(-3) on several occasions. Radon concentration average was 259☙ Bq m(-3) over 16 h, compared to background average over 24h of 1.02 Bq m(-3). All watches were placed in a room with a RAD7 real-time radon detector. ![]() Radium ((226)Ra) decays to the radioactive gas radon ((222)Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 B qm(-3). The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. This assumes exposure from the back of the watch which is generally around 60-67% of that from the front. For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 μCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 μSv h(-1)). Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 μSv h(-1)), although the highest ambient dose equivalent rate noted was 20 μSv h(-1). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 μSv h(-1), to the pocket watches, with its cover open. ![]() Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 μSv h(-1) at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 μSv h(-1)). This study re-examines the risk to health from radium ((226)Ra) dial watches.
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