[ RadSafe ] LNT Dogma? - Future of Radiation Safety Regulations

Fri Aug 21 09:57:41 CDT 2015

The irony is that if not for the concern for potential effects at low
levels, and the ALARA requirement, many of us would not be employed in
Radiation Safety.

Mike Borisky
ARL Health Physics

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of KARAM, PHILIP
Sent: Friday, August 21, 2015 8:39 AM
To: The International Radiation Protection (Health Physics) Mailing List
<radsafe at health.phys.iit.edu>
Subject: Re: [ RadSafe ] LNT Dogma? - Future of Radiation Safety Regulations

There are a few ways that an incorrect model might still be useful.

First - real life might have hundreds of variables, the majority of which
have only second- or third-order effects. A completely accurate calculation
might have to consider all of these, but ignoring them might put you in
error by only a few percent. In this case, the simplified model is easier to
use and, perhaps, the chance of keystroke error in a more involved
calculation might be larger than the errors from using a simplified model.
Or, also, the combined measurement error in multiple parameters might exceed
the error from using the "best" solution. 

Second, the practical ("on the ground") results might turn out the same
anyhow. Consider, for example, a world in which everybody agrees that
there's a threshold of 10 rem (100 mSv), below which there are no adverse
effects from radiation exposure. If we assume that people can be exposed to
radiation for 70 years, this means that someone could receive about 1.5 mSv
(150 mrem) annually while remaining below the threshold dose by the end of
their lives. It would make sense to round this down to 1 mSv (100 mrem) for
the sake of safety and to allow for a longer life - and we'd end up exactly
where we are for public radiation exposure under a regulatory system based
on LNT. 

Of course there's more to it than that. For example, a really precise
regulatory structure based solely on risk should also take into account the
latency period of cancer, radiation sensitivity of various tissues at
various ages, maybe diet and lifestyle, travel habits, genetic propensity
for cancer, and so forth. But this would mean generating an annual
radiogenic risk profile for every person every year - something that's
currently beyond our abilities, not to mention a huge time-suck, and hard to
regulate. So even though LNT is very likely wrong, it does make the
book-keeping easy, and it's a lot easier to administer than the most precise
(and most accurate) model we can imagine.

One last thing is that we cannot look at radiological risks in isolation
because there are all sorts of risks out there. If I think I might have
cancer, I'll gladly accept the radiation from a CT or x-rays because the
risk of not having diagnostic information is substantially higher. And as a
society, the number of lives that can be saved with universal vaccination
programs (or smoking cessation programs) is far higher than the number of
lives that can be saved by reducing dose limits slightly (or by cleaning up
a mildly contaminated site). I am familiar with at least a few remediation
projects in which the risks from traffic accidents and construction
accidents was far higher than the risk from a little extra radiation
exposure. But LNT alone will not help with this issue since LNT simply tells
us to get dose as low as we can. Similarly, more people died during
evacuation from the area around Fukushima than would have been affected by
elevated radiation exposure - again, loo  king solely at radiation dose
reduction would not suggest that the safer course of action would be to
simply hunker down in a contaminated area for a few days (or weeks). The
bottom line is that dose reductions only help with reducing radiological
risk (and maybe not even there if dose is being reduced below a threshold) -
they cannot impact any of the non-radiological risks that society faces.
And, in some cases, pursuing greater radiological "safety" can increase
overall societal risk.

Andy

P. Andrew Karam, PhD, CHP
NYPD Counterterrorism
One Police Plaza, Room 1109
New York, NY 10038
(718) 615-7055 (desk)
(646) 879-5268 (mobile)

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