Re: Pu Toxicity

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

Uranium is indeed a 'bone seeker', although only a small fraction of the
uranium taken into the body deposits in the skeleton. A recent publication
of the USTUR reports results of measurement of uranium in two whole body
donors; the results clearly show that the skeleton is the primary depot of
systemic deposition of uranium.  

These data are presented in the USTUR Annual Report for 1996, which is
accessible via our Web page at:  WWW.tricity.WSU.edu/~ustur/.  Note that the
'critical organ' concept which was put forth in ICRP 2 about 40 years ago,
has long since been replaced, and may not even be properly applicable to
natural or low enriched uranium because the chemical toxicity exceeds the
radiotoxicity.  Certainly the GI tract cannot be considered a 'critical
organ' in the case of intake via a wound or inhalation.  In a relatively
recent article in Health Physics, Rich Leggett has provided an excellent
discussion of uranium nephrotoxicity. 

ALI's are based on activity, and for low specific activity materials such as
Th-232, it may be important to consider the mass as well.

Ron Kathren
Director, US Transuranium and Uranium Registries


 At 04:32 PM 10/2/97 -0500, Harold Reynolds wrote:
>I didn't include natural uranium because I don't think it is generally
>considered a bone seeker. While U does go to the bones in some degree, I think
>the primary critical organs for U Nat are the GI and the kidney.
>
>I should have included the fact that the ALI in 10 CFR 835 for Th-232 is much
>lower than that of Pu-239 indicating that it is more toxic.
>
>