Re: The most hazardous substance

["Otto G. Raabe" <ograabe@ucdavis.edu>]

At 02:18 PM 5/8/00 -0500, Jerry Cohen wrote:
>
>For those who insist that plutonium is the most hazardous substance, and =
>want to technically justify that belief, I estimate that it would take =
>only about 10 grams of plutonium to kill everyone on earth assuming: all =
>of the pu is converted to nitrate form, dissolved in water, and ingested =
>by an individual. Death due to heavy metal poisoning will occur in a =
>relatively short time. ETC..............

********************************
May 8, 2000
Davis, CA

I don't follow this scenario at all. Firstly, the solubility product
constant for Pu(4+) is about 10^-52. Hence, there are no ions at
physiological pH, and you can't swallow the nitrate in water unless it is
laced with concentrated nitric acid in which case the risk would be from
acid burns no Pu. It is not poisonous and the uptake of plutonium via the
gastrointestinal tract is 10^-5 or less, and even if some gets into the
blood it does not cause heavy metal poisoning since there are no ions to
enter into biological processes. So Pu travels in the blood as a complex
with citrate and transferin, and deposits on bone surfaces and in liver
nodules and does not readily enter the mineral bone or liver metabolism
since it is insoluble in the body. Hence, we are dealing with a
biologically inert material that happens to be radioactive. Radiation
damage will always be more important that chemical toxicity for Pu.
Inhalation of finely divided small particles in the respirable size range
is the most potentially dangerous route of exposure.

Otto
	*****************************************************
	Prof. Otto G. Raabe, Ph.D., CHP
	Institute of Toxicology & Environmental Health (ITEH)
	(Street Address: Bldg. 3792, Old Davis Road)
	University of California, Davis, CA 95616
	E-Mail: ograabe@ucdavis.edu
	Phone:(530) 752-7754, FAX:(530) 758-6140
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