Re: LNT - a semantic comment

[Bernard Cohen <blc+@PITT.EDU>]

There is nothing about the Taylor series that says the coefficient of 

the linear term cannot be zero or negative. The dominance of the linear 

term occurs only very close to zero dose.

    In general, any possible dose-response curve ican be valid and the 

Taylor series can always accommodate to it.



Bjorn Cedervall wrote:



> The email below was sent to me directly (thank you!). I agree - the 

> linear term will remain in the limit - some people in favor of 

> thresholds may not like this aspect but it should be noticed - I don't 

> see a possibility to circumvent the linear term (as the dose ->zero) 

> of a Taylor series.

>

> If anything, the Taylor series is general theory for functions. The 

> mechanistic problem is about what the corresponding function actually 

> looks like and it was in this sense I looked at the use of the word 

> "theory". Bill's comment is indeed very important - what may look like 

> thresholds in observations could conceal what is going on in the limit 

> (I favor this idea of a linear component in the limit - it must not 

> necessarily make people hysterically afraid of radiation).

>

> To summarize, if we refer to the general Taylor aspect - LNT is a 

> theory but most often I think that the context is more about "we don't 

> know what is going on there (low doses)". One could say that the 

> Taylor approach is the first step of a theory - then it is "just" to 

> expand the theory with all the other elements of the mathematical 

> series... :-)

>

> Thanks again Bill.

>

> My personal initiative only,

>

> Bjorn Cedervall   bcradsafers@hotmail.com

> --------------------------------------------------------------------

>

> Dear Bjorn,

>    One point that bothers me is this-Taylor's theorem shows that for 

> small

> enough changes in the independent variable, any function approximately 

> behaves

> linearly. So I have always thought that linearity was a first order

> approximation to the unknown function in the low dose region and hence 

> shouldn't

> be a fundamental issue-the really important aspect is the assumption 

> about the

> value of the intercept-ie that it is zero.

> Cheers,

> Bill

>

>

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