Re[2]: Tritium in exit signs and on watch dials

[LIPTONW@dteenergy.com]

You're right.   This limit is circa 1986.  NCRP 95 states (page 9):  "Data 
reported by industry sources indicate that tritium gas tube light sources 
(GTLS) were produced for only a few years.  Such sources were used to 
backlight liquid crystal display (LCD) watches.  Problems with the leakage
of 
small amounts of tritium from GTLS, which typically contained about 7.4 GBq 
(200 mCi) [These SI units are a pain!] of this radionuclide, apparently made 
these sources unable to compete on an economic basis with battery operated 
units..."  This sounds like what you had. 
 
The opinions expressed are strictly mine. 
It's not about dose, it'a about trust. 
 
Bill Lipton 
liptonw@dteenergy.com 
 
You wrote: 
 
     >I'm not sure if the NRC limit listed by Bill is relatively new, since  
     >this isn't my area of expertise, but I have an older Timex watch from  
     >the early 80's, that clearly states on the back that it contains "200  
     >mCi 3H". It also has the trefoil symbol on the back. I quit wearing it
 
     >after a radiochemistry lab manager "borrowed" it for a few days and  
     >found detectable tritium leaching out of it. It does glow nicely in  
     >the dark... :-) 
      
     >Steven D. Rima, CHP, CSP 
     >Manager, Health Physics and Industrial Hygiene 
     >MACTEC-ERS, LLC 
     >srima@doegjpo.com 

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html