[ RadSafe ] Cohen's radon results and LNT

[Chris Hofmeyr]

Prof Cohen, Radsafers,
In the condensed notes on Cohen's radon studies (attached to posting on Radsafe
21 Sept), I attempt to show unequivocally, although slightly unconventionally,
that Cohen's lung cancer (LC) mortality rates are basically independent of the
average domestic radon concentrations as determined by Cohen on a per county
basis. This independence clearly means that LNT is REJECTED, since lung cancer
is not perceptibly correlated with domestic radon up to the maximum average
levels found by Cohen, while it is accepted as a carcinogen at higher levels
found in some mines. It effectively means that in the domestic situation lung
cancer cannot meaningfully be ascribed to radon levels. What is more, this
independence can be inferred without the necessity for a smoking correction to
the lung cancer data. 

In his publications on this subject, Cohen tacitly assumed and accepted
dependence, but did not objectively test for it. In his approach, he had to
correct the LC data for smoking, particularly because there was an
anti-correlation between county average radon and smoking prevalence. I suspect
his smoking correction may be incomplete, not verifiable and a smoking residual
component may be instrumental in the apparent (inverse) correlation between LC
and average radon concentration.

I backed up my treatment of Cohen's radon data by an exact equivalent in which
county radon concentration was replaced by altitude above sea level (thanks to
Van Pelt). See my notes posted on 18 Sept. Fortuitously the parallel worked out
100%.  The indication that LC is not primarily dependent on altitude is at least
as strong as in the radon case without smoking correction in the region 1259 to
10000 feet. As in the case of radon, Cohen's smoking correction fails to change
the negative gradient of LC against altitude in the region 0 - 1259 ft, which
can, primarily, with reasonable confidence, be ascribed to smoking. Any
reasonable proposal for another responsible factor would be welcomed. I pointed
out to Van Pelt that his oxygen concentration thesis was less plausible because
of an almost 30% average decrease in LC over 3.5% decrease in oxygen and
nothing further.

A thought for the hormesis enthusiasts, in case you want to base it on Cohen's
radon results: you could possibly do much more against LC by inducing the
residents of coastal US cities/towns to move to a higher location, but more
than about 1250 ft is not worth extra effort. The proviso: you believe Cohen's
smoking correction to LC data. Another caveat: data spread.