Re: Chromosome abnormalities in populations... Nevermind.

[John Goldsmith <gjohn@bgumail.bgu.ac.il>]

Dear Jim:
     The last paragraph in the BEIR V report deals with studies of
populations living in high background areas, and specifically cites
Guarapari, Brazil, Kerala, India, and Yanjiang County, PRC.  It says:
"In areas of high natural background radiation, an increased frequency of 
chromosome aberrations has been noted repeatedly.  The increases are
consistent with those seen in radiation workers and in persons exposed at
high dose levels, although the magnitudes of the increases are somewhat
larger than predicted.  No increase in cancer has been documented in
populations residing in areas of high natural background radiation."
     Some obvious questions occur to me.  What is the prognosis (
relative health status over time) of the persons with the chromosome 
aberrations ?  Are there any other unusual attributes of those who show
such aberrations as compared to those who do not?  What of the
reproductive experience of the populations and of the individuals with
chomosome changes?  Is there any difference in the types of chromosome
changes, and any associations with other exposures such as smoking and
alcohol use?  Some such associations were shown by Lazutka in a population
of Chernobyl clean-up workers ? (Lazutka et al. "Cytogenetic Study in
Peripheral Blood Lymphocytes of Chernobyl Clean-up Workers" Acta medica
Lituanica No. 2. pp62-67, 1997.  If you want a copy the address is
Department of Botany and Genetics, Vilnius University, M.K. Ciurlionio 21,
Vilnius 2009, Lithuania)
            John Goldsmith, M.D., M.P.H., Professor of Epidemiology
            gjohn@BGUMAIL.bgu.ac.il
 On
Tue, 18 Nov 1997, James S Jr Dukelow wrote:

> 
> 
> The 25 April 1997 issue of Nature had a striking paper (Baker et al., 
> High Levels of Genetic Changes in Rodents of Chernobyl, Nature, v. 380, 
> pp. 707-708) on unusually high mutation rates in the mitochondrial DNA 
> of voles captured near the Chernobyl plant vs. more normal rates in 
> voles captured 28 km from the plant.  With another paper on high 
> mutation rates at minisatellite loci in human germline cells from 
> Belarus populations highly exposed to Chernobyl fallout in the same 
> issue (Dubrova et al., op. cit., pp. 683-686), the cover of the issue 
> had a picture of Chernobyl 4 and the sarcophagus and the news and 
> editorial sections of the issue had additional comment on the two papers 
> and other questions raised by the accident. 
> 
> The current issue (6 November 1997) of Nature has on the last text page 
> a retraction of the main conclusion of the Baker et al. paper.  No 
> fanfare accompanies the retraction.  Baker et al. were unable to 
> replicate their work when the DNA sequencing was done using an automated 
> sequencing machine instead of the manual methods used in preparing their 
> 1996 paper.  The recalculated mutation rates are still elevated, but, 
> because of the small sample sizes, no longer statistically significant. 
> 
> An interesting issue raised by the original papers and by some earlier 
> work (specifically, the study of Chinese populations from regions of 
> high background radiation) is the relevance of cytogenetic damage in 
> conjunction with absent or unexpectedly low observable health impacts.  
> Both the Baker et al. paper and the accompanying News and Views 
> commentary by Hillis note that in spite of the high mutation rates the 
> vole populations at the Chernobyl site are thriving and reproducing.  
> Hillis offers some hypotheses regarding this apparent paradox.  Since I 
> am not familiar with the methodology or the literature on the use of 
> minisatellite loci and other biomarkers, I would appreciate comments by 
> others who are. 
> 
> Best regards.
> 
> Jim Dukelow
> Pacific Northwest National Laboratory
> Richland, WA 
> 
> js_dukelow@pnl.gov
> 
> These thoughts are mine and have not been reviewed and/or approved by my 
> management or by the U.S. Department of Energy 
> 
>