[ RadSafe ] Excess relative risk

[Jerry Cohen]

Where has it been ruled that the dose/response relationship must be linear in nature? 
Why, for example can it not be a conic section curve. I think an inverted parabola
 (U - shaped) would accommodate the observed data nicely.
Jerry




 
----- Original Message ----- 
From: "Otto G. Raabe" <ograabe at ucdavis.edu>
To: "howard long" <hflong at pacbell.net>; <radsafe at radlab.nl>
Sent: Wednesday, January 16, 2008 8:49 AM
Subject: Re: [ RadSafe ] Excess relative risk


> 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.
> 
> Otto
> 
> 
>>
>>----- 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
> *********************************************** 
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
> 
> Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html
> 
> For information on how to subscribe or unsubscribe and other settings visit: http://radlab.nl/radsafe/
>