RE: comparing individual and collective doses

["George J. Vargo" <vargo@physicist.net>]

Ted,



No analogy is perfect.  My point is that from a purely collective dose

viewpoint 1 mrem given to 1E6 individuals would be equivalent to 1E6 mrem

given to a single individual.  While the collective dose is the same in both

cases, the consequences are vastly different!  The use of the collective

dose concept has to be bounded by trivial individual doses (i.e., ~

background levels) on the low end and something well below the threshold of

deterministic effects to any single individual.





George J. Vargo, Ph.D., CHP

Senior Scientist

MJW Corporation

http://www.mjwcorp.com

610-925-3377

610-925-5545 (fax)

vargo@physicist.net





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

From: Ted de Castro [mailto:tdc@xrayted.com]

Sent: Thursday, December 04, 2003 9:16 AM

To: George J. Vargo

Subject: Re: comparing individual and collective doses





I believe that film reciprocity (or lack thereof) ONLY applies to light

exposure - not ionizing radiation.



"George J. Vargo" wrote:

>

> Mike,

>

> Take a look at "Principles of Collective Dose in Radiation

> Protection," NCRP Report 121, dated November 30, 1995.  In particular,

> look at Section 4 on Limitations.  This section lays the groundwork

> for a later admonition by the ICRP in its Publication 77, which

> cautions against excessive aggregation of collective dose over time

> and space (Sect 5.3)

>

> The analogy that I like to use with respect to collective dose is that

> of the optical density response of film to radiation exposure.  There

> are practical, physical limits to reciprocity (i.e., 4 x 0.25 rem = 2

> x 0.5 rem being a reasonable extrapolation, while 1E+6 x 1E-6 rem does

> equal to 1 x 1 rem is a completely unreasonably extrapolation.  It is

> also inappropriate to integrate collective dose between generations.

>

> Anybody else care to weight-in on this one?

>

> George J. Vargo, Ph.D., CHP

> Senior Scientist

> MJW Corporation

> http://www.mjwcorp.com

> 610-925-3377

> 610-925-5545 (fax)

> vargo@physicist.net

>

> -----Original Message-----

> From: owner-radsafe@list.vanderbilt.edu

> [mailto:owner-radsafe@list.vanderbilt.edu] On Behalf Of Michael

> McNaughton

> Sent: Wednesday, December 03, 2003 2:31 PM

> To: radsafe@list.vanderbilt.edu

> Subject: comparing individual and collective doses

>

> Dear RadSafers

>

> I have often read that when applying the ALARA principle, it is

> important to consider both individual and collective dose equivalents.

> Is there any guidance on how to compare these two? For example, how

> would one compare n mrem to the most exposed individual member of the

> public with a collective dose of n rem distributed evenly among a

> million people?

>

> mike

> Mike McNaughton

> Los Alamos National Lab.

> email: mcnaught@LANL.gov or mcnaughton@LANL.gov

> phone: 505-667-6130

>

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