I ask for a truce. I have no desire to debate the intricacies of low energy photons and their accounting. The subject bears on a larger issue but it (low energy photons) isn't where I choose to focus.
Here's where I'd like to have started the thread, "Exposure to low levels of ionizing radiation is more harmful than we've been lead to believe". That's a pretty dramatic statement and it's explanation is lengthy, very lengthy.
I chose to begin with what I hoped would become a dialog. I began with one of the nuggets of current science; science that has improved dramatically since each of us attended our respective HP High Schools. I could just as easily have begun with a post titled, "Five Rem is the doubling dose (for risk of cancer incidence)" but I didn't. I might have begun with, "Occupationally received dose should end at age 50", but I didn't. Each of these is a conclusion that has been reached by the folks who provide us with Health Physics research, principles and recommendations.
Those of us who are old timers (I started TSTI in 1976) got into the business in a 5(N-18) not-to-exceed-3-REM/quarter-world. When the revision to 10CFR20 went into effect in 1994, we adopted a more conservative 5 REM per year limit - the rest of the world went to a 2 REM per year limit at that time.
The NRC has (or is about to) opened public comment on adopting a 2 REM per year limit. (NRC docket #No. 09-078 April 27, 2009)
(You're now going to have to be patient as I attempt to flesh this out, make my point, pose my query, state my case)
The erythema dose was abandoned as the original radiation protection standard because it proved to have been non-conservative (there's probably a better way to characterize it but I'll leave it alone). True?
Radium dial watch painters ceased to "point" their brushes using their tongues because jaw cancer incidence was linked to the practice. Again, we established what could be argued to have been a non-conservative radiation protection standard. True?
We embarked on an era of 5(N-18) with the assumption that it was a safe standard. True? I decline to make any observations as to its abandonment and will leave its reason up to you.
Five REM per year became the next radiation protection standard but is currently on its way out (in favor of the 2 REM per year standard). True? (NRC docket #No. 09-078 April 27, 2009)
TLDs are being abandoned in favor of OSLs. (NCRP report # 158)
To each of these points I ask only, "Why?"
Possible answers can be gleaned from ICRP publications 39, 60 and 103. More possible answers can be found in BEIR V but more importantly, in BEIR VII phase II. Other contributors to the answer (why?) can be read in reports from UNSCEAR, NCRP, IAEA, NAS, etc, etc, etc.
Following is a potential grenade lobbing observation:
The asbestos industry was safe until it wasn't.
The way it went down was probably something like this (conjecture on my part): 1) The entire world knew that asbestos was safe. 2) Almost everybody assumed asbestos was safe. 3) One guy worried that asbestos wasn't safe. 4) Some researcher determined that asbestos wasn't safe. 5) Several independent researchers determined that asbestos wasn't safe. 6) Individuals within the asbestos industry were approached with the results of scientific studies but the results were rejected. 7) Somebody within the asbestos industry began to worry that asbestos wasn't so safe after all.

This individual approached others within the company and was dismissed (figuratively or literally).

Science proved conclusively that asbestos was a health hazard. 9) The asbestos industry could no longer ignore the results.
Does the sequence of events, despite being overly-simplified, seem reasonable? (Please think to yourself, "Yes".)
Health Physics researchers said, in effect, that the erythema dose was a poor radiation protection standard. Health Physics researchers determined that 5(N-18) not to exceed 3 REM per quarter was ______________(fill in the blank). Health Physics researchers determined that 5 REM per year was ______________ (fill in the blank).
Health Physics researchers now propose 2 REM per year (not UNSCEAR, they propose 1 REM per year).
I don't want to ruffle any feathers by proposing a reason but I MUST repeat the earlier question: Why?
Is the original question about low energy photons now in perspective? I don't know why the academicians are recommending lower dose limits. I don't know how Fe-55 plays-out in the world of Health Physics / Radiation Protection. I can fill volumes with stuff that I don't know and my ignorance can be extended to include why dose limits are being reduced.
If you suspect that I have proposed reason, you're right. No matter how far off the mark my proposed reason might be, it has nothing to do with the actions being taken by the folks who do the research and make the recommendations.
Are low energy photons worthy of note from a whole body dose perspective? I don't know. Are beta-induced, low energy photons worthy of an in-depth look? I don't know. Is lifetime dose a concern? I don't know. At what value? I don't know. Over what period of time? I don't know. Is the effect of a given amount of dose given to a thirty year old different than the same amount of dose given to a forty year old or a fifty year old? I don't know.
What I DO know from having read the reports is that these are recurring themes and that there are a significant number of studies that SUGGEST that our former dose limits have been non-conservative and that's the motivation for a reduction in annual limits to 2 REM per year.
Was the asbestos industry safe? Yes...............until it wasn't.
In my original post, I provided a link which, in turn, provides links to the various reports. I didn't fund the studies nor am I in any way responsible for any of their content (we know that I'm not a contributor because I'm ignorant and the reports were generated by learned folks). I have, however, read them and have drawn my own conclusions. My contention is only this: we embarked on this career with the assumption that there were certain, associated risks. The research shows (to me, not necessarily to you) that the risk is greater than we were told. Nobody told us any lies, they simply gave us the best available information they had AT THAT TIME. There's not a great deal of consolation to be taken in knowing that we weren't lied to but, instead, the old research was quite lacking.
Is the occupational exposure (nuclear) industry safe? Yes.............until________
__.
Bill Nichols
billnich@hpnc.com
P.S. Are you HP / RP management, Marsimm? You exhibit the same sort of condescending, brow-beating, humiliating tone as is typical of one who is in the managerial ranks. Of course I could be wrong (that makes it okay, right?)