RE: Question on low-dose rad effects

["Carroll,Raymond" <carrollrg@pgdp.usec.com>]

As I sit and muse regarding the question it also dawns on me that the dose
come from the dose rate which is normally assumed to be uniform over the
whole bode (or most of it).  The dose rate over a certain surface area such
as 1 cm^2 would be the same for the mouse and the elephant.  The elephant
would intercept many more photons (or whatever radiation is emitted) but the
dose to the 1 cm^2 would be the same, at the surface, for the mouse or the
elephant.  Organ dose would be different due to distance and shielding
within the beasties.

That observation, from our "for what it's worth dept", is worth what you
paid for it.   :-)

Ray Carroll

-----Original Message-----
From: Bernard L Cohen [mailto:blc+@pitt.edu]
Sent: Friday, October 22, 1999 9:47 AM
To: Multiple recipients of list
Subject: Re: Question on low-dose rad effects


	An extension of the question asked here is why does a 25 gram
mouse have the same risk as a 100,000 gram person for a given energy
deposit per gram? I would bet that elephants also have similar risk.

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 Thu, 21 Oct 1999, Jerry Cohen wrote:

> Dear Radsafers,
>      Perhaps someone could enlighten me on something that has puzzled me
for
> a long time. Why is the degree of harm, detriment, etc. from low-level
> radiation  expressed in terms of rad, rem, sieverts, etc. which are
> functions of absorbed energy per unit mass (i.e. ergs/gm)?
>  Isn't the probability of a mutation, or other adverse effect a direct
> function of the total number of ionizing events occuring in the vicinity
of
> suseptible DNA molecules and isn't that ,in turn, a function only of total
> absorbed energy?
>      For example, consider two individuals of the same age, sex, and
general
> state of health with the only difference between the two being that one
> weighs twice as much as the other.  Given that both recieve a radiation
dose
> of say 1.0 rem, have they both experienced an equal degree of harm? Due to
> his/her larger mass, the heavier individual gets twice as many ionizing
> events occuring near twice as many DNA molecules any one of which might
> result in an adverse mutation.  Why doesn't the individual with twice the
> mass, get twice the risk???     Jerry Cohen
> jjcohen@prodigy.net
> 
> 
> 
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