Re: Kosov DU - New Scientist Report

[keith bradshaw <Keith.G.Bradshaw@soc.soton.ac.uk>]

Hi again Radsafers

Sorry, but here's another DU question.

According to the Rand report vol 7
(http://www.gulflink.osd.mil/library/randrep/du/mr1018.7.chap1.html), the
American Conference of Government Industrial Hygenists set the MPC for
insol or soluble U at 200 microgram/ m3 air in 1993.

Now if you take nat-U as 0.0254 Bq/microgram, a breathing rate of 1.2 m3/hr
(ICRP reference man), an average dose coefficient of 3.3E-05Sv/Bq (English
NRPB) and a 2000 hr working year, you obtain
 
200 x 0.0254 x 3.3E-05 x 1.2 x 2000 =0.4 Sv/yr, ie. 400mSv per year.

The dose limits are 1mSv/yr for members of the public and 20 mSv / yr for
occupational dose. So there's clearly a discrepancy here.

In fact, the 1mSv/yr limit corresponds to about 0.5 microgram/m3, and the
20mSv/yr limit to 10 microgram/m3. If you do a similar calc. for DU it
comes out a bit higher, 0.7 microgram/m3 for 1mSv/yr.

Can anyone explain why the ACGIH set a figure of 200 microgram/m3? Have I
made an error somewhere? Is there a misprint somewhere along the line?

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