RE: uranium in histologic procedures/soluble, depleted, natural U

From:Jim at ProSciTech <>

A few years ago the J Microscopy (V 106, 85-86, January 1976) published my 
paper "Potential hazards of uranium and its compounds in electron microscopy: a 
brief review. Uranyl nitrate in terms of toxicity and radioactivity is 
virtually identical to U acetate.
The radioactivity of 1% uranium nitrate is minimal and a small volume would 
emit less harmful radiation than a smoke detector or the back of a computer 
screen - and I 'm not suggesting that smoke detectors or screens in normal use 
are dangerous.
What danger there is relates to the chemical toxicity of SOLUBLE uranium 
compounds. These are powerful kidney poisons and they are more toxic than 
Don't eat or drink or touch soluble uranium compounds! In histo labs the 
quantities used are small and with basic precautions there should be no 
trouble. I have never heard of a case of kidney poisoning due to U compounds in 
histo or EM labs.
The good news is that these compounds are not accumulated, in fact they are 
rapidly excreted.
The issue of "depleted U" is totally irrelevant to chemical toxicity.

Uranium metal is not soluble in body fluids and its danger is from radiation 
and this relates to quantity of the metal, the isotopes present, distance and 
other factors.
The most damaging to human health, may be small U particles. These are inhaled 
and can sit in the lung "forever". They are not detectable by blood tests and 
irradiate the lung with a large range of radiation, some of which are quite 
powerful. Particles in the lung would be very small, but they are at very close 
range to unprotected tissues.

A daughter product of several U isotopes in natural and depleted U is the very 
heavy (in fact the heaviest known gas) radon. Both radon and radiation are 
known to cause cancers, radon infamously so. (Early underground U miners died 
by the thousands in poorly ventilated shafts. This is peripheral to this 
server, but when 3000 tons of U is vaporized, as it was in Bosnia, it stands to 
reason that some of this was inhaled by anybody within miles, particularly 
downwind. So some histologist just may come across U particles in a lung.

"Depleted U"? Yes, the most powerful radiation is that of the isotope U235, 
which in natural U amounts to 99.3% of the total. Depletion of that isotope is 
not done to make the U safer, but to enrich some U for use in reactors and to 
make bombs. Depleted U is the cheap by-product and so it is used as a counter 
weight in the tail fin of jumbo jets (300kg!).
It appears that depletion rarely is to less than 0.3% of U235. In any case, the 
word depleted  just means that this material would be most expensive to use for 
the production of enriched uranium. It is acknowledged that there is a 
difference in radiation between depleted and natural U, but its minimal. It 
appears that a lot of people have been fooled by the "depleted" label; it seems 
that we have been led to think that natural uranium was much safer, which is 
not the case.
Depleted is not the most important issue with U and its compounds. Is it 
soluble, is it in small particle form and how much is there? These are the more 
important health considerations.
Jim Darley
ProSciTech                 Microscopy PLUS
PO Box 111, Thuringowa  QLD  4817  Australia
Ph +61 7 4774 0370  Fax:+61 7 4789 2313
Great microscopy catalogue, 500 Links, MSDS, User Notes
ABN: 99 724 136 560            

On Saturday, February 10, 2001 4:27 AM, Weems, Joyce [] 
> We purchase the 1% from PolyScientific. It's warnings would scare the pants
> off ya! Nothing about being depleted.
> Joyce Weems
> Pathology Manager
> Saint Joseph's Hospital of Atlanta
> 	-----Original Message-----
> 	From: []
> 	Sent:	Friday, February 09, 2001 12:20 PM
> 	To:;;
> 	Subject:	uranium in histologic procedures
> 	Uranium nitrate (uranyl nitrate) is used in a few histologic stains,
> in
> 	particular silver impregnation stains, including a recently
> discussed stain
> 	for Helicobacter. Questions are often raised about its radiotoxicity
> and
> 	chemical toxicity. A recent editorial in The Lancet is informative.
> 	Toxicity of depleted uranium - by N.D. Priest (School of Health,
> Biological
> 	and Environmental Sciences, Middlesex University, London N11 2NQ, UK
> -
> The Lancet 27 Jan 2001; 357: 244-6. (I suppose
> it's on
> 	the Web, but I've got a paper copy.)
> 	Priest describes depleted uranium as uranium from which 70-80% of
> the highly
> 	radioactive U-235 and U-234 have been removed. Depleted uranium has
> come into
> 	commercial use in several settings, including X-ray shielding in
> hospitals,
> 	but it has recently gained notoriety because of its use in
> armor-piercing
> 	munitions in the former Yugoslavia (and in fact earlier, in the Gulf
> War).
> 	Of histologic interest is the statement that "Depleted uranium has
> replaced
> 	uranium of
> 	natural isotopic composition as a less radioactive substitute for
> some uses -
> 	e.g., laboratory chemicals." Is this substitution stated on labels?
> I don't
> 	have a recent label to check. - The substitution is not sufficient
> to affect
> 	computations at the level of precision needed in histologic work.
> 	Priest's review suggests that the need for chemical or radiologic
> precautions
> 	with handling uranyl salts is not very great from a practical
> viewpoint -
> 	though what keeps the Herrn Inschpektors happy is another question.
> 	(Parenthetically, some bottles of lithium carbonate note that the
> lithium has
> 	been depleted of lithium 6 - used in making tritium for hydrogen
> bombs - and
> 	this substitution might actually be of soposition.)
> 	I've cross posted this note to the pathologists' PATHO-L list and to
> the
> 	histologists' Histonet.
> 	Bob Richmond
> 	Samurai Pathologist
> 	Knoxville TN

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