Re: Hormesis and LNT

["Joan Stovall" <joans@PCEZ.COM>]

Thank you for your questions about my comments.  I will outline my

reasoning.



What I was talking about was the necessary sample size to test for

statistical significance.  Considering that cancer has a stochastic

incidence, with a probability p.



The expected incidenc is  np   where n is the sample size and p is the

probability of cancer occurring.



The expected variance is npq   where q is the probability of cancer not

occurring.



Then, the standard deviation should be the square root of npq.



Then, the standard deviation of the incidence rate should be equal to pq

divided by the square root of n.



Hence, if we want a resolution of 0.1 times the minimum detectable with a

given sample size, we would have to use a sample equal to 10 squared (or

100) times the original sample size.



I do sometimes have a problem with being sarcastic about the Linear No

Threshold risk model.  Partly, because of misuse by the anti-nuclear

faction.

----- Original Message -----

From: "Fritz A. Seiler" <faseiler@nmia.com>

To: "Joan Stovall" <joans@PCEZ.COM>

Cc: <radsafe@list.vanderbilt.edu>

Sent: Sunday, April 29, 2001 9:31 PM

Subject: Re: Hormesis and LNT





> Hi All,

>

> Well, Joan, I agree with the tenor (or should I say soprano? Alto,

> perhaps?) of your mail.  However, I disagree with your last statement,

> if it is not meant as a parody.  These days you never know for sure!

> :-)

>         Anyway, your statement is the logical LNT trap that Joe Alvarez

> and I also fell down into, oh so many years ago!  Fortunately, we

> realized relatively soon that this is a fallacious argument cooked up by

> the Linear Mafia.  It is easy to show this argument to be wrong: Let us

> assume that the excess risk function goes steadily down toward zero as

> the dose approaches small values but then assumes a J-shape, so that you

> are dealing with a hormetic cause-effect function.  Now decrease the

> dose below the point called Zero-Effects-Point (ZEP), where the excess

> risk is indeed  zero.  Below that dose the excess risk goes negative as

> in the Shipyard Worker study to a value of - 0.24 +- 0.03 (Relative risk

> 0.76 +- 0.03). Now that is not at all hard to measure, is it?  Also look

> at Bernie Cohen's radon/lung cancer data which are hormetic and well

> measured below the ZEP.

>         As you can see, the LNT Mafia's argument only works if the

> effect goes monotonically to zero as the dose goes monotonically to

> zero.

>

> Best regards, Fritz

>

> Joan Stovall wrote:

>

> > Of course, they cannot very well test the risk model at low doses and

> > low exposure levels.  Why?  The necessary sample size increases with

> > the inverse of the square of the resolution they desire.  Soon, the

> > sample size will become larger than the entire population they are

> > studying.  Of course, they cost of performing such a study would

> > spiral out of control.

>

> --

>

>  " The American Republic will endure until the day Congress

>  discovers that it can bribe the Public with the Public's money."

>                                        Alexis de Tocqueville

>                                        Democracy in America

>

> ***************************

>

> Fritz A. Seiler, Ph.D.

> Sigma Five Consulting

> P.O. Box 1709

> Los Lunas, NM 87031, USA

> Tel.    505-866-5193

> Fax.    505-866-5197

> e-mail: faseiler@nmia.com

>

> ***************************

>

>

>



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