Re: Plutonium toxicity

["Ron L. Kathren" <rkathren@beta.tricity.wsu.edu>]

Search a little harder -- try the US Transuranium and Uranium Registries 
Home page at www.beta.tricity.WSU.edu.   

On Tue, 17 Oct 1995 cooperc@teleport.com wrote:

> gopher://nisc2.upenn.edu:70/00/cancer_news/plutonium_1
> 
> 
> Results of a little netsearch.......
> 
> > 
> >               PLUTONIUM'S RISK TO HUMAN HEALTH DEPEND ON ITS FORM
> > 
> >    In a nuclear explosium, plutonium-239 fissions and releases a huge
> >    amount of energy and radiation. But plutonium itself is a highly toxic
> >    element that requires a great deal of care in handling.
> > 
> >    Experts agree that the silvery, unstable metal plutonium-239, with a
> >    half-life of 24,000 years, is hazardous and sould be isolated from the
> >    biosphere. However, the risks posed to workers and communities by
> >    stored plutonium depend on the route of exposure as well as the
> >    particle size, isotope, and chemical form.
> > 
> >    Weapons-grade plutonium outside the body presents little risk unless
> >    exposures are frequent and extensive. It emits primarily alpha
> >    particles, which cannot penetrate skin, clothing, or even paper.
> >    Nearly all the energy from plutonium is deposited on the outer,
> >    nonliving layer of the skin, where it causes no damage. The neutrons
> >    and the relatively weak gamma photons it emits can penetrate the body,
> >    but large amounts of weapons-grade plutonium would be needed to yield
> >    substantial doses.
> > 
> >    Workers wearing only lead aprons can handle steel drums containing
> >    solid plutonium metal with no immediate untoward effects. However, as
> >    weapons-grade plutonium ages, it becomes more dangerous because some
> >    of the contaminating plutonium-241 is converted via beta decay to
> >    americium-241, which emits far stronger gamma radiation.
> > 
> >    On the other hand, plutonium inside the body is highly toxi. Solid
> >    plutonium metal is neither easily dispersed nor easily inhaled or
> >    absorbed into the body. But if plutonium metal is exposed to air to
> >    any degree, it slowly oxidizes to plutonium oxide (PuO2), which is a
> >    powdery, much more dispersable substance. Depending on the particle
> >    size, plutonium-239 oxide may lodge deep in the alveoli of the lung
> >    where it has a biological half-life of 500 days, and alpha particles
> >    from the opxide can cause cancer. Also, fractions of the inhaled
> >    plutonium oxide can slowly dissolve, enter the bloodstream, and end up
> >    primarily in bone or liver.
> > 
> >    Plutonium oxide is weakly soluble in water. If it is ingested in food
> >    or water, only a small fraction (4 parts per 10,000) is absorbed into
> >    the gastrointestinal tract. However, it may take just a few millionths
> >    of a gram to cause cancer over time. In animals, small doses induce
> >    cancer, especially in lung and bone.
> > 
> >    In published studies of plutonium's effects on humans, most subjects
> >    were exposed to multiple sources of radiation. Some researchers say
> >    the available health data on plutonium workers have not yet been used
> >    to do careful epidemiological studies, because researchers have been
> >    denied access to much of the data on workers and military personnel
> >    exposed to plutonium. In the studies done so far, plutonium workers do
> >    not show major excesses of any type of cancer.
> > 
> >    Becuase of the relative lack of human data, the risks of chronic
> >    exposure to plutonium are uncertain. Exposure standards in the U.S.
> >    are based partly on studies of survivors of Hiroshima and Nagasaki and
> >    partly on animal experiments. A 1991 White House Office of Science &
> >    Technology Policy studye says that "sufficient human data are not
> >    available to provide accurate risk assessment of exposure."
> 
> 
> And from the Radsafe archives:
>