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Re: Newspaper article on Plutonium



August 25, 1997
Davis, CA

The article that was cited about the Cassini mission to Saturn is just one
of many that we will be seeing during the next two months. The CBS
television program "60 Minutes" is doing a special feature on the risk from
Pu-238 in this space vehicle. The "radiation experts" that they will
utilize will probably be physicians associated with the Helen Caldicott
organization called "Physicians for Social Responsibility" who dabble in
radiation risk without any real training in health physics or risk assessment.

After the launch the Cassini vehicle is scheduled to swing back around the
earth to get an extra boost for its trip to Saturn. If the whole vehicle
vaporizes in the atmosphere during the fly-by, I calculate that people on
earth will inhale trace amounts of Pu-238 that will lead to a maximum
average yearly effective dose equivalent from alpha particles of a few
mrem. The key organs for Pu-238 irradiation are lung and bone surfaces
because of its inherent dispersibility (solubility). If the rocket blows up
at the Cape on blastoff, the contamination will be quite localized, and the
respirable fraction will be small. A complete risk analysis has been done
by the Interagency Committee on Nuclear Risks, which I believe is chaired
by Marvin Goldman.

The quotes from the works of Helen Caldicott about plutonium toxicity are
all wrong. Of course, she is referring to Pu-239 rather than Pu-238. The
specific activity of Pu-238 is about 270 times that of Pu-239. Seventy-two
pounds is about 560,000 Ci. The only model that will lead to the suggested
large risk is assuming that in which all of the Pu-238 is converted to
respirable small particles and they will all miraculously end up inside the
lungs of people on the earth. 560,000 Ci / 5,000,000,000 people on earth =
110 microcuries per person. That would be bad, but it is obviously
impossible. The problem with this model is "delivery". This is equivalent
to saying that there is enough water in the great lakes to drown everyone
who lives in Chicago.

Check out the web site CANCEL CASSINI at
www.op.org/DomCentral/justice/8alrtcas.htm

I hope we can mount a fierce rebuttal. The media will love this one.
Usually, the press does not want to hear from people who really know how to
calculate the true risks, so we have to start contacting science writers
now to give them a realistic appraisal.

Otto
		*****************************************************
		Prof. Otto G. Raabe, Ph.D., CHP
                [President, Health Physics Society, 1997-1998]
		Institute of Toxicology & Environmental Health (ITEH)
		     (Street address: Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 916-752-7754     FAX: 916-758-6140
		E-Mail: ograabe@ucdavis.edu
		******************************************************