Answer to Question #7667 Submitted to "Ask the Experts"

Category: Consumer Products — Watches, Clocks, and other Glow-in-the-Dark

The following question was answered by an expert in the appropriate field:

Q

I recently did some work at a retired watchmaker's house and noticed a box that said "watch hands." The box looked old, maybe from the 50s or 60s. I worked about three to four feet away for about 15 minutes. He later told me they were luminous watch hands, but said they were not the radioactive kind. He was a very old man and was sort of forgetful. Can being near or even touching the box be harmful if they were the radium type?

A

No, touching or being near would pose little or no risk, even if they were coated with radium. Today many watches using luminous displays are not radioactive. However, older watches may very well have been coated with a radioactive substance, such as radium or tritium. The hazard from tritium is almost nonexistent, but the radium dials were particularly hazardous to the workers who actually ingested the radium back in the 20s and 30s, as they sharpened the brushes with their mouths. The radium-dial workers is a tragic epidemiological story which actually led to the development of radiation protection standards. Even then, the primary hazard was from the ingestion of the radium, not the external exposure.

The easiest thing to do would be to survey the watch parts with a radiation survey meter. Most health physicists, your state radiation control agency, your hospital nuclear medicine department, or the radiation safety officer at any site that possesses radioactive material would have access to such instrumentation. I am sure they would be more than willing to check out the watches!

An interesting website that discusses luminous dials and cites other interesting websites, including how to identify some of the watches from the manufacturers' markings, is the Elgin website.

Orhan H. Suleiman, MS, PhD
 

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 8 July 2008. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.