AW: [ RadSafe ] Annual dose from Nature/Background/Man-made sources

[Rainer.Facius at dlr.de]

Wes,

 

thank you for your reminder of your paper which I already had in my 'archive'.  

 

Among other 'off the cuff' attempts to 'explain' the negative associations revealed by Cohen's data, your proposal differs in being based on a valid factual negative association between altitude and lung cancer risk. You argue correctly that increased intracellular oxidative stress is a causative agent for molecular and cellular processes which are part of the pathways leading to transformed cells. The depleted absolute oxygen concentration at higher altitudes is a fact. You refer to experimental studies the results of which "... are consistent with the hypothesis that hyperoxia-induced DNA fragmentation is associated with the expression of GADD genes that may participate in DNA repair and/or apoptosis.", i.e., that hyperoxia may advance neoplastic transformations in cells 

 

Nevertheless, I think that you characterize the nature of your argument appropriately: "We conjecture that absolute oxygen concentration correlates directly and causally with lung cancer rates." It is a conjecture which needs more experimental support before I would consider it suggestive - not to speak of compelling. 

 

One of the minor loose ends which I perceive in your argument concerns the question to what degree the decreased extra cellular oxygen concentration at the higher altitudes where people still live actually converts into reduced intracellular oxygen concentration. You yourself address this question in stating: "Persons who live at higher elevations adapt to the lower atmospheric oxygen concentration by physiological changes such as increased breathing rate, increased tidal volume, ... ". 

 

Finally, I wonder if even in 2003 it was still appropriate to ignore what you ignored when you stated in your abstract: "Cohen's strong inverse association between radon and lung cancer is surprising since there is no plausible biological reason for an inverse causal relationship between the two."

 

What was known then about the adaptive capacity of living systems to counteract cyto- and genotoxic stress from a host of stressors in my view offered very plausible reasons for the observed inverse (causal) relationship observed. 

 

By the way, did you consider the possibility that the correct interpretation of the negative association between altitude and lung cancer risk may be confounded by the positive association which you presented between radon levels and elevation - if indeed the negative association between radon levels and lung cancer risk reflected a causal relation?

All in all I think - while belonging to the more plausible alternatives - your conjecture needs more experimental support before it can be considered a compelling explanation for "Cohen's strong inverse association between radon and lung cancer".

 

Best regards, Rainer

 

________________________________

Von: Wes Van Pelt [mailto:WesVanPelt at verizon.net]
Gesendet: Fr 03.08.2007 18:45
An: Facius, Rainer; radsafe at radlab.nl
Betreff: RE: [ RadSafe ] Annual dose from Nature/Background/Man-made sources



Rainer,

In my paper, EPIDEMIOLOGICAL ASSOCIATIONS AMONG LUNG CANCER,RADON EXPOSURE
AND ELEVATION ABOVE SEA LEVEL-A REASSESSMENT OF COHEN'S COUNTY LEVEL RADON
STUDY, Health Physics, October 2003, Volume 85, Number 4, I conjecture that
decreased atmospheric oxygen concentrations at higher altitude protects
against radiation damage (lung cancer).

I stratify Dr. Cohen's data and remove much, but not all, of his negative
association between lung cancer and radon. I believe Dr. Cohen accepts my
analysis but argues that EITHER less oxygen or more radon (or a combination
of both) is associated with decreased lung cancer. My argument in this case
also rests on biological plausibility. That is, lower oxygen concentration
at the sensitive cells in the lung is more likely to decrease lung cancer
than is high LET alpha radiation likely to decrease lung cancer.

Best regards,  Wes
Wesley R. Van Pelt, PhD, CIH, CHP
Wesley R. Van Pelt Associates, Inc. 
 


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Rainer.Facius at dlr.de
Sent: Wednesday, August 01, 2007 3:22 AM
To: Peter.Vernig at va.gov; idias at interchange.ubc.ca;
jdaitken at sugar-land.oilfield.slb.com; Mike.Brennan at DOH.WA.GOV;
radsafe at radlab.nl
Subject: AW: [ RadSafe ] Annual dose from Nature/Background/Man-made sources

"... a few of us, unfortunately have a very high [radon] exposure if we live
in a problem house ..."

Peter:

Why do you call the 'few of us' unfortunate if indeed the fact of being
exposed to higher levels of domestic radon has incontrovertibly been shown
to be associated with significantly reduced lung cancer mortality - in line
with most other studies, which have investigated the association of low dose
and dose rate exposure to ionizing radiation with lung cancer? Proposed
explanations of the radon findings by means of confounders abound but I have
seen none published which was amenable to a quantitative analysis and which
could be upheld in the light of a subsequent quantitative re-analysis by
Bernard Cohen.

Regards, Rainer