Re: background vs man-made emmissions

["Zack Clayton" <zack.clayton@epa.state.oh.us>]

Something just hit me as I read Sandy's response to Norm on the issue of nuclide concentration in organs.  Sandy danced around the issue of the biological response to isotopes.  With the possible exception of the light element isotopes such as Hydrogen, Deuterium, and Tritium; most of the biologic process don't much care what isotopes are used at levels that are going to make a difference in the lifetime of the organism.  (Yes, I know about paleotemperature analysis using differential uptake and secretion of O16 and O18, but that's mostly due to the preferential evaporation of one isotope over the other - a physical process.)  

So what I am saying is the body doesn't differentiate between I-131 and I-127 (stable).  If the thyroid needs an iodine, it grabs whatever is there.  The same would be true of alkali earths.  The bone/tooth  building process wants to use calcium, most of which are stable,  but will use strontium if it is above a certain Sr/Ca equilibrium in the body.  The body doesn't care if the Sr is Sr90, of the stable forms Sr84, Sr86, Sr87, or Sr88.  

What I would suspect with elevated levels of  Sr 90 in teeth is that  all Sr is elevated and this might point to a calcium deficiency during the stage of tooth formation.  I don't remember if the Tooth Fairy questionnaire captured this information or not, but if so it was indicated as one of the optional bits.  I don't think this info is optional at all.  It would impact directly on the results.  For the same reason, just a Sr90 data point is useless unless compared to the other Sr concentration.  



Zack Clayton
Ohio EPA - DERR
email:  zack.clayton@epa.state.oh.us
voice:  614-644-3066
fax:        614-460-8249

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