[ RadSafe ] Fwd: LNT and the WHO guidance on red meat

[Chris Alston]

Wiser Heads than I

This does not answer Joe's question.  But, don't we have a further
complication in that, as best I recall, the EPA (perhaps at the behest of
the U.S. Congress) uses risk coefficients of the order of 10E-6?  Can they
do that for radiation *without* effectively applying the LNT?  Am I way
off-target?

TIA.
ca
---------- Forwarded message ----------
From: <jjshonka at shonka.com>
Date: Wed, Oct 28, 2015 at 9:14 PM
Subject: Re: [ RadSafe ] LNT and the WHO guidance on red meat
To: "The International Radiation Protection (Health Physics) Mailing List" <
radsafe at health.phys.iit.edu>
I appreciate the humor, but my question was serious.
The EPA sets guidelines for all federal agencies, including the NRC.  EPA
published Guidelines for Carcinogen Risk Assessment in 2005 (
http://www2.epa.gov/risk/guidelines-carcinogen-risk-assessment ).  I am
trying to understand when regulators should use linear extrapolation from
POD (point of departure, where you have data and uncertainty bounds) and
when non-linear can be used.  I think EPA makes a conservative assumption
that carcinogens that directly affect DNA can cause cancer regardless of
the dose.  The non-linear approach (to extrapolation from known data to
lower levels) is only used when the agent is non-mutagenic ( my reading of
Section 3.3.1 of that report).  For EPA, linearity is considered health
protective.
As an aside, if one limits the consumption of farm raised fish for PCB
concerns, and consumers substitute red meat as a protein source,
cardiovascular disease (instead of cancer) from the red meat may cause more
deaths than are saved by avoiding fish with PCBs.  Thus, linearity might,
at times, be non-protective.  Hormesis aside, radiation does not seem to
fall into that category since there would be no substitution if a source of
radiation exposure is avoided.  (use of surgery instead of x-ray imaging is
not a realistic option).
Joe Shonka