RE: comparing individual and collective doses

["Richard Orthen" <rorthen@EARTHSCIENCES.NET>]

Mike--Your note is unclear on what your comparison endpoint is, but the two

quantities you refer to are not meant to be directly comparable.  It has

been almost universal NEPA practice to use individual and population dose

estimates as surrogates for health impacts.  Health impacts to an individual

are expressed in terms of the risk (likelihood) of latent fatal cancer

induction using an EDE integrated for the individual (your first example).

For populations, the health impact of interest is the occurrence of latent

cancer fatalities (LCF) based on the collective EDE delivered (your second

example).  For both the risk and occurrence estimates, the same risk factors

are applied [0.0004/person-rem for voluntary (worker) exposures and

0.0005/person-rem for public exposures].  While the derivation of these risk

factors continues to be debated, they are nonetheless often used without

much controversy by regulators and scientists.  The result that is

customarily demonstrated is that the RAM handling event/operation has been

optimized and/or mitigated such that the individual LCF risk is below 10-6

(or whatever the acceptable benchmark happens to be) and the population LCF

occurrence is well below 1.0.  The overall intent is to reduce individual

cancer risk to "acceptable" levels and prevent an LCF occurrence in the

population.



Rick Orthen

Earth Sciences Consultants, Inc.

Export, PA



-----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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