High Doses Produce Lower Aberrations

["Otto G. Raabe" <ograabe@ucdavis.edu>]

December 15, 2000
Davis, CA

Dear Radsafers:

I found the following on the Radiobiology list, and I am taking the libery
of reposting it here. Please send copies of your responses to the author as
well as RADSAFE.

Otto
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Dear Colleagues

   Pohl-Ruling (1990) reported that upon reaching a certain level of cell
damage the production of repair enzymes is triggered which decrease the
frequency of chromosome aberrations. In this regard it can be claimed that
low doses of ionizing radiation are unable to reach the "damage threshold"
so they may produce more chromosome aberrations than the relatively higher
doses which reach the damage threshold and activate the production of
repair enzymes. Increased levels of chromosome aberrations in lymphocytes
can be used to predict cancer risk in humans (Hagmar 1994). By the way, the
hypothesis can be used for cancer risk estimation too. I'd like to know
whether there is any other report on this topic (the existence of a damage
threshold).

Regards,
Javad Mortazavi
---
S. M.Javad Mortazavi, Ph.D
Assistant Professor of Medical Physics
Secretary, National Committee on High
Background Radiation Areas (NCHBRA)
Present address:
National Radiation Protection Department
Iranian Nuclear Regulatory Authority
P.O. Box 14155-4494
Tehran
Iran
Tel (98 21) 8026280 ext. 4154, 4155
Fax (98 21) 8009502
Email mortazavi_smj@asia.com
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Prof. Otto G. Raabe, Ph.D., CHP
Institute of Toxicology & Environmental Health
(Street Address: Bldg. 3792, Old Davis Road) 
University of California, Davis, CA 95616
E-Mail: ograabe@ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140
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