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Re: Access to letter





The complete text is available on-line at



http://www.iop.org/EJ/S/3/362/yoE3aewPM8E7wusW.hYaTw/abstract/0952-4746/22/1/104



It is copied here:



Whilst I appreciate the concerns that Barrie Skelcher may have with regard

to the healthy worker effect (HWE), may I assure him

that it is not fundamental to understanding the risks from radiation

exposure. Not only is the HWE much quoted, it is a much studied

and multifaceted phenomenon in occupational epidemiology. It is a bias

induced by comparing the worker population with the national

population, often resulting in lower than expected SMRs and/or SRRs, and

is not peculiar to occupational studies of nuclear workers.

As these comparisons are known to be subject to bias, the SMRs and/or SRRs

must be interpreted with caution. The evidence for a

statistical association between health outcome and exposure arises,

however, out of the trend tests. These tests are `internal', i.e. they

are not dependent on any external population and hence are unaffected by

the HWE.



If Barrie accepts the Popperian philosophy that hypotheses cannot be

proved right but can only be discredited, then, to cast doubts on

the utility of the linear non-threshold (LNT) hypothesis it is necessary

to show that either the dose response is non-linear at low doses

and/or that there is a threshold below which there is no dose response.

Because radiation-induced diseases do not leave a `marker' to

distinguish them from non-radiation induced diseases, epidemiological

studies are unlikely to invalidate the LNT hypothesis in the

foreseeable future. Barrie may note that this argument does not depend on

the existence of the HWE. If a study does not find any

detrimental effects on health resulting from radiation exposure, the HWE

cannot therefore be `wheeled out' to explain this so called

anomaly with the LNT hypothesis. The reasons that some studies are unable

to demonstrate a dose response is more to do with the

power of the study. The power of the study is dependent on such factors as

the number of participants in the study, the number of

years that they have been followed up for and, of course, the exposures

that the participants have encountered.



Yours faithfully,



Dave McGeoghegan







Bernard L. Cohen

Physics Dept.

University of Pittsburgh

Pittsburgh, PA 15260

Tel: (412)624-9245

Fax: (412)624-9163

e-mail: blc@pitt.edu





On Mon, 8 Apr 2002, muckerheide wrote:



> Friends,

>

> Do you have the following ref?

>

> J Radiol Prot 2002 Mar;22(1):94

> Healthy worker effect.

> McGeoghegan D.

> Publication Types:

> *    Letter

>

> Thanks.

> Jim Muckerheide

>

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