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Cohen derived LNT formula
Dr. Cohen,
I do agree this is going nowhere, and agree it is not worth further effort
to further communicate on this issue.
------------------------------------
Field previously wrote: I addressed a very specific problem below with your
study. You
state that a basic theory takes into account, "the most important things."
I consider
smoking intensity and duration two of the most important parameters to
consider in validating your derived LNT formula.
Dr. Cohen previously wrote: I am testing the BEIR formulas, and they do not
include
these things
-----------------------------------------
I was merely looking for a clarification about your previous assertion that
the BEIR formula does not provide the opportunity to control for factors
such as pack-year rate and duration of smoking in addition to even non
linear effects of smoking? I was just looking for a yes or no answer?
Obviously, I feel the BEIR formula is general enough to allow for control of
smoking using pack-year rate and duration of smoking.
Also, you previously have criticized my assertion that one method you used
to treat smoking was the use of cigarette taxes. Sales tax and
socioeconomic factors were the only methods you could hope to get some
information about pack-year rate. In fact, in the HPJ, 75(1), p24 you state
you derived S values from cigarette sales tax collection for 1960, 1970, and
1975 to crudely introduce the pack year concept in addition to the use of
socioeconomic factors. I agree that these indeed are very crude measures of
pack-year rate and no consideration was ever given to duration of smoking.
As we pointed out before, (HPJ 75(1),p12) in the BEIR formula that in
addition to age, Mo(A) may depend on other covariates such as smoking
history, sex, and calendar time. In your derived LNT formula, smoking is
treated as a dichotomous variable that is independent of age in its effect
on the risk of lung cancer, the BEIR formula does not necessitate such a
procedure.
As we pointed out before, the poor predictive power of your S is due in part
because of the failure of your formula to allow for the effects of smoking
duration and intensity (HPJ 75(1), p14.) Further, we pointed out before
(HPJ 75(1), p16), the contradictory results you find do not imply a failure
of the linear no threshold theory for carcinogenesis from inhaled radon
decay products, but that the assumptions implied in your risk model are not
valid. Even after repeated requests, you have never provided referenced
support for your assumptions as we detailed in the HPJ 75(1), 1998.
But, reasonable people do not always have to agree and we can end it there
and let others decide the validity of testing the LNT with ecologic data. I
am sure there will be upcoming papers published on this topic.
Bill
--------------------------
Field wrote: I addressed a very specific problem below with your study. You
state that a basic theory takes into account, "the most important things."
I consider
smoking intensity and duration two of the most important parameters to
consider in validating your derived LNT formula.
Dr. Cohen wrote: I am testing the BEIR formulas, and they do not include
these things
Field response:
Dr. Cohen, the BEIR formulas DO indeed include "these things". As we
explained many years ago, HPJ 75(1), July 1998, page 13. The BEIR model
is quite general and allows for any degree of control for smoking. You can
include factors such as pack-year rate and duration of smoking in addition
to even non linear effects of smoking. As was pointed out in BEIR IV, "The
choice of an appropriate age specific background rate for this calculation
involves proper treatment of smoking, sex, and calendar time."
Your previous response was that you "crudely" treat pack-year rate. But
your crude treatment is after the cross-level bias already occurred. My
point which you have ignored for years is that you have not derived an
equivalent BEIR model. You can not assume smoking intensity and duration,
are not important factors to include in your LNT derived formula. Then
latter try to treat the problem of smoking intensity and duration by using
aggregate data. You are not really testing the LNT using your formula.
Your findings do not convince me the LNT fails, I am only convinced that
your formula is not robust enough to test the LNT. It is not surprising, as
Dr. Gilbert pointed out, that that your results are confounded by smoking,
because other smoking related cancers are also negatively associated with
your county radon data.
Bill Field
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