[ RadSafe ] Excess relative risk

Otto G. Raabe ograabe at ucdavis.edu
Wed Jan 16 10:49:05 CST 2008

At 09:13 AM 1/12/2008, howard long wrote:
>What would make clear in that formula that kD is
>a NEGATIVE excess relative risk when radiation exposure is under 
>~20cGy (rad), rapid rate,
>i.e. hormesis?  +-kD?

January 16, 2008

The linear model formula forces you to accept the structural 
hypothesis that risk is a linear function of dose with a fixed 
coefficient that is independent of dose (in this case k) from zero 
dose to some upper dose limit. So you cannot use this formula if the 
risk is negative over some lower dose range and positive over some 
higher dose range.


>----- Original Message ----
>From: Otto G. Raabe <ograabe at ucdavis.edu>
>To: radsafe at radlab.nl
>Sent: Friday, January 11, 2008 12:11:10 PM
>Subject: [ RadSafe ] Excess relative risk
>January 11, 2008
>If R=R(0)[1+kD] then the excess relative risk is kD.
>Excess relative risk is {R-R(0)}/R(0) = {R(0)[1+kD]-R(0)}/R(0) =kD

Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140

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