[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Re: Risks of low level radiation - New Scientist Article
On Thu, 13 Dec 2001, John Williams wrote:
>
> It remains unclear to me how Cohen’s ecological data can be used to
> test LNT
> (or any other predictive theory). Cohen states that “…case-control
> studies
> investigate the causal relationship between radon exposure and lung
> cancer,
> whereas our work has the much more limited objective of testing the
> linear
> no-threshold theory” (Health Physics, Volume 72(4), page 625, April
> 1997).
> It is absurd to suggest that testing the LNT theory is not a test of a
> causal relationship. The LNT theory, in this context, only has
> meaning if
> radiation causes cancer. If Cohen’s work does not test for a causal
> relationship, how can his data be a test for LNT (or any other
> predictive
> theory)?
--LNT is a particular type of a causal relationship. My work
tests that particular type. A case-control study can determine any type
of causal relationship.
> Cohen goes on to say “We have…never claimed that low level exposure
> to radon
> is protective against lung cancer” (Health Physics, Volume 72(4),
> page 625,
> April 1997). If the data refute LNT then what do the data support if
> not
> hormesis (as suggested by the strong negative correlation for radon
> concentrations <150 Bqm-3)? Cohen cannot have it both ways.
--I miss your logic here. A test can show that some particular
theory fails without determining what the correct theory is. For example,
one can test Newton's theory F = ma by measuring distance travelled vs.
time. But if there is friction so that the theory does not check out, one
could not determine the correct relationship (unless he did other
experiments in which there is no friction)
> Cohen quotes Richard Feynman in support of his test of LNT. According
> to
> Feynman “we look for a new law by the following process: first we
> guess at
> it. Then we compute the consequences of the guess to see what would be
> implied if this law we guessed is right. Then we compare the result
> of the
> computation with …observation, to see if it works. If it disagrees
> with
> experiment [the law] is wrong. In that simple statement is the key to
> science. It does not make any difference how beautiful your guess is.
> It
> does not make any difference how smart you are, who made the guess,
> or what
> his name is-if it disagrees with experiment it is wrong. That is all
> there
> is to it.” (Health Physics, Volume 72(4), page 624, April 1997).
> Implied in
> Feynman’s statement is that the data provide a bona fide test of the
> theory.
> If the data are erroneous (e.g., use of faulty data analysis, use of
> inappropriate statistical tests, use of inappropriate experimental
> methods)
> then the data do not provide a test of the theory even though the
> data, on
> its face, might suggest the theory is wrong.
--If my data were not valid, that would explain everything; in
fact for some years, I thought that was the explanation. But I kept
getting more data, and the results did not change. Then I got the EPA data
which was completely independent of mine, and the results were the same.
Before that, I got data for various individual states, including excellent
studies by Florida and New Jersey, and they agreed with my results for
those states. With all of this, it is hard to understand how the data
could be wrong. I am very open to suggestions on this.
--I offered to do a new study with any ground rules or oversight
that anyone wanted to impose, for a modest cost, but no one was
interested.
--Note that my results are the same if we consider only one
section of the country, or if we select counties on any other basis.
************************************************************************
You are currently subscribed to the Radsafe mailing list. To unsubscribe,
send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
radsafe" (no quote marks) in the body of the e-mail, with no subject line.