Radiation induced Thyroid Cancer in mic

[JMUCKERHEIDE@delphi.com]

Dear Michael,

Can you provide a reference to the fact that it is "clear that
131iodine-induced thyroid cancer in children is the most pronounced excess
malignancy with a latency period of only a few years." Is there something more 
recent than the 1996 10-year report conferences with WHO, IAEA, and others
reporting on the late health effects? 

Certainly the thyroid cancer is clear, but my understanding of the conclusions 
presented by WHO and others is still uncertain about the cause. It seemed to
me that the estimates of I-131 doses are not necessarily consistent with the
cancers, for example, the Brest area with the lowest thyroid dose estimates
has the highest thyroid cancers in the 5 regions of Belarus. Equivalent doses
from I-131 therapies in children do not result in excess thyroid cancers,
while external x-ray doses do (usually after about 9 years). There is
uncertainty about the fact that the thyroid cancers appeared primarily in
children 1-2 years old at the time of the accident, and almost entirely in
children between several months before birth to about 5 years old, and that
this period of thyroid development is more active, and that most I-131 therapy 
tends to occur at older ages. 

Other shorter-lived radionuclides from this fast-excursion/explosion of the
reactor to the atmosphere might have played a radiological impact role that
would have decayed much faster than I-131 and not been estimated the way the
I-131 doses were monitored for (with weeks before they decay away) and
associations between estimates and Cs-137 as the indicator of fallout
distribution. The thyroid blocking agents may also be of possible
significance. Dr. Jaworowski in Poland notes that the greatest influence may
be the screening procedure itself, with strong evidence that other populations 
that have been screened for any reason have found much higher thyroid cancers
than appear through recognition in normal medical practices. Thyroid cancer
rates of a few per 100,000 become thousands per 100,000 (5,000 to 35,000) when 
occult cancers without clinical manifestation are found at autopsy. Dr.
Jaworowski also reports (in press) that these occult cancers are of the same
papillary type as those found in Belarus with the same growth patterns, noting 
that the potential to find increases through aggressive screening "is
enormous", vs the 11.3/100,000 found in the Gomel region in Belarus. 

I would also be very interested in any mice experiments that have attempted to 
assess the effects. 

Thank you.

Regards, Jim Muckerheide
======================

> After the Chernobyl accident it became clear, that 131Iodine induced
> Thyroid cancer in children is the most pronounced excess malignancy with
> a latency period of only a few years.
> 
> I'm wondering whether anybody knows of animal experiments,
> preferentially in mice, which support this and would permit
> the search for genetic predisposition. Searching Medline, I did not
> found anything on this subject, but may be someone among the 
> Radiobiology community is better informed than Medline.
> 
> I would be grateful for every hint.
> 
> 
>    Greetings    Michael    (rosemann@gsf.de)