Re: More on DU

[col_eric_daxon@MEDCOM2.SMTPLINK.AMEDD.ARMY.MIL]

     Keith Bradshaw wrote:
     
     >>I calculated an Annual Limit of Intake (inhalation) of 32Bq, which 
     corresponds to 2100microgram of DU for members of the public (1mSv/yr 
     limit). At 2000 hr per year and a breathing rate of 1.2m3/hr, you 
     obtain a Derived Air Concentration (DAC) of 0.013 Bq/m3 which 
     corresponds to 0.88microgram/m3. This is a factor of 227 times more 
     restrictive than the ACGIH limit.<<
     
     There are several points I would like to make.  First the ACGIH limit 
     quoted in the RAND report is an occupational limit and not a limit for 
     the general public.  It is based primarily on chemical considerations. 
     The DAC (occupational) for insoluble depleted uranium with the mix 
     quoted is approximately 0.7 Bq/m3 which is approximately 0.05 
     milligrams/m3 for an ALI of approx 100 milligrams.
     
     Second point and perhaps more germane to the discussion is the 
     difference between the risk associated with a calculated dose and the 
     actual risk of the exposure.  The RAND report also made the point and 
     I will quote from the report, "Although any increase in radiation to 
     the human body can be calculated to be harmful from extrapolation from 
     higher levels, there are no peer reviewed published reports of 
     detectable increases of cancer or other negative health effects from 
     radiation exposure to inhaled or ingested natural uranium at levels 
     far exceeding those in the Gulf."
     
     Third the statement Keith Bradshaw made:
     
     >>>"The consensus of sensible replies seems to be that the limit of 
     200microgramU/m3 set by the American Conf. of Gov. Induustrial 
     Hygenists is based on chemical toxicity. The Rand report says this 
     limit applies to both soluble and insoluble forms."  << 
     
     Is incorrect.  The RAND report on page 11 makes a clear distinction 
     between soluble (0.05 ug/m3) and insoluble (0.2 ug/m3) uranium 
     standards.
     
     Finally, perhaps my eyes are getting old, but I cannot find where the 
     RAND report stated that protection from the chemical risks would 
     automatically protect from radiation exposures.
     
     
     
     Eric G. Daxon, PhD, CHP
     Daxfam@aol.com
     (210) 221-6612



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