[ RadSafe ] RadSafe Digest, Vol 749, Issue 1, message 3

[Harrison, Tony]

Good questions all.  You don't need me to remind you that the Sv is a unit intended to quantify stochastic/probabilistic effects.  Presumably the absorbed dose (Gy) would be more meaningful.

But since Busby has yet to enumerate any heart attack data from Japan or anywhere else, I have trouble worrying about it too much.


Tony Harrison, MSPH
Colorado Department of Public Health and Environment
Laboratory Services Division
303-692-3046



From: "Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV>
Subject: Re: [ RadSafe ] Sr-90 in Maple Syrup, Ra-226 in mineral
	waters,	Cs-137 in woodash,	etc.  was: Re:  Re. Tritium found near VT
	Yankee 		 (panic time!)
To: "The International Radiation Protection (Health Physics)
	MailingList"	<radsafe at health.phys.iit.edu>
Message-ID:
	<37C41083D3480E4BBB478317773B845D075059F3 at dohmxtum31.doh.wa.lcl>
Content-Type: text/plain;	charset="us-ascii"

Interesting (I only have access to the abstracts).  I assume the
researchers collected some mouse ejaculate (Oh, the life of a grad
student!) for analysis, to demonstrate that Sr90 actually transferred
between the male and female.

It is a shame that the control group was injected with a salt solution,
rather than the same solution as the experimental group, but with stable
strontium.  This would have controlled for the possibility that the
effects were due to chemical rather than radiological factors.  It also
would have been interesting if the males had been given different body
burdens, so it could be determined if there was a relationship between
dose and outcome (if any of these were done in the experiment, great!
But as it was not mentioned in the abstract, I assume it was not).  

It also would be interesting for someone to calculate how many atoms of
Sr90 were on average attached to each chromosome, what the likelihood of
a decay.  

The more I think about it, the more important it is to determine how
many atoms of Sr90 adhere to the genetic material in a sperm, as each
developing mouse only has the load from one sperm (unless someone
contends that the other sperm somehow also contribute their Sr90, which
is something that would require some proof).  If one knows how many
atoms of Sr90 are present at fertilization, and the rate of decay (a
given and constant for the length of time of interest) and the rate of
cell division (exponential for some period of time, rapid thereafter),
one could calculate the number of decays per fetus per period of time,
and see if that is reasonable when compared to the observed results.  

It all depends on demonstrating that Sr90 actually adheres to the sperm,
and quantifying the amount.  It is a shame the cited studies didn't
appear to do that.  

It also would be interesting to know the mechanism by which the Sr90
cause damage that caused "... develoipement defects mainly heart".  I
would have expected the Sr90 delivered by sperm to become randomly
distributed throughout the body (with only a small percentage of the
cells having even one atom of Sr90 in them.  

" effects here at 1mSv or less."  To what?  I don't know that dose is a
meaningful concept when talking about something like this.  It might be,
but it doesn't feel like it is.  At the very least, it isn't comparable
to dose to something like a fully developed organism.  I agree that the
effects of radiation exposure would be greater to a developing organism,
I am just not sure that dose is a useful way of quantifying it.