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

Sun Aug 5 14:25:51 CDT 2007

Radsafers,
Please correct my prior post as it relates to the range of alphas in tissue.
The range is about 50 micrometers, not 5 micrometers. 
Thanks to one Radsafer who sent me this correction privately. Feel free to
post your email to Radsafe. 

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 Wes Van Pelt
Sent: Sunday, August 05, 2007 12:17 PM
To: Rainer.Facius at dlr.de; radsafe at radlab.nl
Cc: 'Wes Van Pelt'
Subject: RE: [ RadSafe ] Annual dose from Nature/Background/Man-made sources

Rainer,

Thanks very much for the kind and accurate critique of my paper. I find
myself agreeing with almost all of you comments. However, I make a few
points below. My comments are indented to distinguish them from yours.

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: Saturday, August 04, 2007 9:55 AM
To: WesVanPelt at verizon.net; radsafe at radlab.nl
Subject: AW: [ RadSafe ] Annual dose from Nature/Background/Man-made sources

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, ... ". 

		None of the physiological adaptations change the actual
oxygen concentration at the interface between the air in the lungs and the
surface of the cells in the lung.

		Since radon decay product alpha radiation affects cells
within the range of an alpha (about 5 micrometers in tissue), one should
consider the effect of oxygen concentration within 5 micrometers from the
air in the lungs. This represents only one or two cell thicknesses. So for
my conjecture to remain plausible in the face of the "physiological
adaptation to altitude" argument, I need show only that the changes in
oxygen concentration and the associated oxidative stress are effective for
only 1 or 2 cell thicknesses from the air interface in the lungs. It seems
to me that this would be the case.

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."

		A good point. I should have been clear in that I was
considering that high LET radiation is not likely to have the hormetic
effect seen with low LET radiation.  My thought was that high LET alpha
radiation, with its multiple simultaneous hits within a cell, would be more
likely to damage the DNA than stimulate its repair.

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?

		Yes. And I believe so did Dr. Cohen in his published replies
to my paper. Therefore, the drop in lung cancer as radon goes up and oxygen
goes down may be due to either, both or neither. My conclusion would be to
advise future researchers to take oxygen concentration into consideration
when evaluating lung cancer epidemiology that includes people from
substantially different altitudes.

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

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