Re: RE: Field's comments on Cohen's Observation

["Gary Howard" <radiation@webmail.co.za>]

Mark,



I think I understand this from what Dr. Fields tried to explain to us

before, I think he means that while lung cancer incidence and radon

exposure are linear in the relative risk according to the LNT, they

are not linearly related in the scale of absolute risk.



This is what Doctor Jay Lubin at the NCI pointed out so eloquently in

his his last paper concerning Dr. Cohen's work.



Dr. Jay Lubin

Biostatistics Branch, Division of Cancer Epidemiology and Genetics,

National Cancer Institute, Rockville, MD 20892-7244, USA.



If you do not agree, why not write a letter to Dr. Lubin or email him

lubinj@mail.nih.gov rather than yelling at Dr. Field?



Journal of Radiolological Protection

June 22(2):141-8, 2002

The potential for bias in Cohen's ecological analysis of lung cancer

and residential radon.



Cohen's ecological analysis of US lung cancer mortality rates and mean

county radon concentration shows decreasing mortality rates with

increasing radon concentration (Cohen 1995 Health Phys. 68 157-74).

The results prompted his rejection of the linear-no-threshold (LNT)

model for radon and lung cancer. Although several authors have

demonstrated that risk patterns in ecological analyses provide no

inferential value for assessment of risk to individuals, Cohen

advances two arguments in a recent response to Darby and Doll (2000 J.

Radiol. Prot. 20 221-2) who suggest Cohen's results are and will

always be burdened by the ecological fallacy. Cohen asserts that the

ecological fallacy does not apply when testing the LNT model, for

which average exposure determines average risk, and that the influence

of confounding factors is obviated by the use of large numbers of

stratification variables. These assertions are erroneous. Average dose

determines average risk only for models which are linear in all

covariates, in which case ecological analyses are valid. However, lung

cancer risk and radon exposure, while linear in the relative risk, are

not linearly related to the scale of absolute risk, and thus Cohen's

rejection of the LNT model is based on a false premise of linearity.

In addition, it is demonstrated that the deleterious association for

radon and lung cancer observed in residential and miner studies is

consistent with negative trends from ecological studies, of the type

described by Cohen.



Gary Howard





On Mon, 23 Jun 2003 10:42:05 +1000 Sonter Mark

(sonterm@epa.nsw.gov.au) wrote:



Yuo say that "radiologically induced lung cancer is not linearly

related to

dose in person-rems" ---  BUT THAT IS PRECISELY WHAT THE LNT

HYPOTHESIS

DECLARES, without qualification.



If it's not so, fine, but then the LNT is not true!!!!



Mark Sonter





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