Re: Occupational exposure to radon?- REPLY

[RADPROJECT@aol.com]

Bill Field wrote:
<<I am writing a chapter for an occupational medicine book on the occurrence
and health risks of radon.  I would like to include information on non-mining
occupations that may receive higher than "normal" radon exposure. .....Is
anyone
else familiar with other occupations that work in high radon environments?>>

Some years ago, I visited a large welding supply house to buy some liquid
nitrogen to top up an already chilled portable Ge(Li) detector I was using at
the time in the field.  I happened to observe that right behind the counter
where the clerks were standing were tall racks of 50 lb. boxes of  Tig(?)
welding rods, about 8 feet tall and more than about 15 feet in length. Tig
welding rods are 2% thoria by weight (I purchased one for a demo source at the
time). Of note, I asked the clerk if he would mind if I hooked up a portable
MCA to the detector and acquire a spectra.

It took only a few seconds of counting to acquire a gamma spectra for the
thorium decay series from a location in front of the service counter. A worker
at the rear of the counter would have seen higher gamma flux than I counted on
the customer side of the counter.  It is clear that this situation presents a
very unusual situation where non-radiation workers can be exposed to very
elevated levels of lung dose due to  thoron, as well as substantial direct
radiation from the gamma component of the inventory,  by working in the
vicinity of thousands of pounds of welding rods that are 2% thoria by weight.

Stewart Farber
Public Health Sciences
401 727-4947

radproject@usa.net



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