[ RadSafe ] DU Proven Deadly To Human Bronchial Cells

[Otto G. Raabe]

At 02:37 AM 5/10/2007, Roger Helbig wrote:

>Subject:  DU Proven Deadly To Human Bronchial Cells
>Particulate Depleted Uranium Is Cytotoxic and Clastogenic to Human Lung Cells
>Sandra S. Wise, W. Douglas Thompson, AbouEl-Makarim Aboueissa, 
>Michael D. Mason, and John Pierce Wise, Sr.*
>Depleted uranium (DU) is commonly used in military armor and 
>munitions, and thus, exposure of soldiers and non-combatants is 
>potentially frequent and widespread. DU is considered a suspected 
>human carcinogen, affecting the bronchial cells of the lung. 
>However, few investigations have studied DU in human bronchial 
>cells. Accordingly, we determined the cytotoxicity and 
>clastogenicity of both particulate (water-insoluble)
>and soluble DU in human bronchial fibroblasts (WTHBF-6 cells). We 
>used uranium trioxide (UO3) and uranyl acetate (UA) as prototypical 
>particulate and soluble DU salts, respectively. After a 24 h 
>exposure, both UO3 and UA induced concentration-dependent 
>cytotoxicity in WTHBF-6 cells. Specifically, 0.1, 0.5, 1, and 5 
>g/cm2 UO3 induced 99, 57, 32, and 1% relative survival, respectively.
>Similarly, 100, 200, 400, and 800 M UA induced 98, 92, 70, and 56% 
>relative survival, respectively. When treated with chronic exposure, 
>up to 72 h, of either UO3 or UA, there was an increased degree of 
>cytotoxicity. We assessed the clastogenicity of these compounds and 
>found that at concentrations of 0, 0.5, 1, and 5 g/cm2 UO3, 5, 6, 
>10, and 15% of metaphase cells exhibit some form of chromosome 
>damage. UA did not induce chromosome damage above background levels. 
>There were slight increases in chromosome damage induced when we 
>extended the UO3 treatment time to 48 or 72 h, but no meaningful 
>increase in chromosome damage was observed with chronic exposure to UA.
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May 10, 2007

This article is really bothersome since the authors used giant doses 
of toxic chemical forms of uranium to show that the uranyl ion is 
toxic at high doses. That is already well known. Exposures to 
chemically unstable uranyl oxide and soluble uranyl acetate are not 
representative of any realistic exposures to insoluble uranium metal 
or the stable oxides such as uranium dioxide. Even biologically 
essential trace metals such and selenium and copper are toxic at high 
doses of soluble forms.

The authors repeatedly write that they studied "DU" and even that DU 
was "Proven Deadly To Human Bronchial Cells", but what they used in 
their studies were probably natural uranium compounds rather than DU 
compounds.  I believe that  chemical companies normally sell reagents 
utilizing natural uranium rather than DU.  Reporting that they 
studied natural uranium compounds would not have been as exciting.

An exposure to an aqueous solution of 100 micromoles per liter (uM or 
micromolar solution) has 0.0001 moles per liter of solution. The 
molecular weight of depleted uranium is very close to 238 grams. 
Therefore, a 100 microM solution has 0.0238 grams per liter or 0.0238 
mg/mL or 23.8 micrograms/mL. According the ICRP 23 ( page 281) there 
are 42,000 g of water in the human body of Reference Man.  That's 
42,000 mL. For the human body cells to be exposed to 23.8 
micrograms/ml (100 uM) there would have to be 42,000 mL x 23.8 
micrograms/mL= 1,000,000 ug = one gram or 0.4 microcuries of depleted 
uranium in the total body fluids. According to ICRP 23 (page 318) 
there is normally only 90 micrograms of uranium in the whole body of 
Reference Man. These studies of uranyl oxide and uranyl acetate are 
unrealistic to extreme.

I have no idea what they mean when the authors claim that they 
studied "concentrations of 0, 0.5, 1, and 5 g/cm2 UO3". Grams per 
square centimeter? Wow!

My conclusion is that these studies were done with gigantic 
concentrations of uranium in the most reactive and soluble form 
possible and the results have no bearing on possible realistic human 
exposures to metallic depleted uranium or its common oxides.

There were extensive inhalation of inhaled uranium oxides done at the 
University of Rochester beginning over 50 years ago that show that 
the cells of the lung are relatively insensitive to the common forms 
of uranium particles.

References: "Handbook of the Toxicology of Metals", Friberg et 
al.(1990), "Uranium, Plutonium, Transplutonium Elements", Hodge et 
al. (1973), "A five year inhalation study with natural uranium 
dioxide", HEALTH PHYS 25, 230258 (1973), "Depleted Uranium In The 
Gulf": http://www.gulflink.osd.mil/du_ii

Otto


**********************************************
Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140
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