Re: Sr-90 question (Tooth Fairy Project)

[Franz Schoenhofer <schoenho@via.at>]

At 13:15 28.04.2000 -0500, you wrote:
>This is probably a very dumb question, but I am going to ask it 
>anyway.

Sandy,

It is not dumb, it is most probably not possible to answer it correctly by
providing data. I try to find some analogies.




>The Tooth Fairy Project is attempting to determine if nuclear power 
>plants have caused an increase in children's teeth due to living near 
>a nuclear power plant.
>
>My question is, besides uptake due to fallout in ground deposition, 
>milk from grazing cattle and water supplies, etc., can Sr-90 be 
>passed on to the fetus from a mother who had been exposed to fallout 
>from exposure decades ago? 

Sr-90 would to some extent have been incorporated into bone tissue. The
turnover of bone tissue is to my knowledge very low. This means, that
liberation of Sr-90 would even in the case of a very high contamination of
the mother (and fallout was very low!) be at the most "modest" or rather
"extremely low".

Another "common sense" thought: The contamination of the environment with
Sr-90 and Cs-137 and C-14 and Tritium from fallout was at its height in
1963 and 1964, after which a dramatic decrease was observed. A female
person, born during that height would nowadays be at least 36 years old.
The bone mass corresponding to the adult bone mass and the possibility to
incorporate Sr-90 would have been achieved at about 1980, when Sr-90
contamination of the environment had decrease to very low level. 

Sr-90 is only found in bone tissue. I do not know whether there exist any
quantitative data on the liberation of calcium from the skeleton of the
mother during gravidity - we know that it happens. Therefore again a very
small amount of Sr-90 could theoretically be incorporated into the skeleton
of the child, which would very soon be diluted by the uptake of almost
Sr-90 free calcium from the diet after birth. 

I think that I can say with very good reasons that any contribution of
fallout to the Sr-90 concentration in children can be totally excluded. I
cannot think of any method to rule out that the Sr-90 came from the mother
which does not exclude that more knowledgable people will be able to do it.
Sr-89 seems not to be applicable in this case....

Regards,

Franz


Franz Schoenhofer
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A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at


Office:
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Federal Ministry of Agriculture, Forestry, Environment and Water Management
Radiation Protection Department (BMLFUW I/8 U)
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