FE-55 and low energy photons

[ballscratcher]

(RP/HP stuff)

The Centers for Disease Control first cited low energy (<30 keV) X-rays as carcinogens in its 2005 list of KNOWN carcinogens.  Since that time, they've expanded the list to include neutron, alpha and, later, gamma.  The photon energy threshold has now been removed from their definition.

The question (observation, wonderment, puzzle) is this: if the original value (<30 keV X-rays) emerged as the first known carcinogen associated with ionizing radiation, does it not stand to reason that it's the most limiting?
We don't actually measure Fe-55; its presence is inferred.  Our ability to measure low energy photons is almost non-existent given the fact that these photons are swallowed-up and obscured in the background / noise / Compton-scatter continuum at the low end of the photon spectrum.  Is it appropriate to disregard Fe-55 and other low energy photons when they were the first to be declared as carcinogenic by the CDC?
If we don't measure it and don't account for it and can't detect it does that mean it's not a concern?  Pretending that Fe-55 isn't there doesn't mean that it's not.  Whole body counters don't see it.  MCAs don't see it.  Ion chambers and GMs definitely don't see it.  Urinalysis is the only manner for its in-vivo presence and who does routine urinalyses?  Who, when they perform non-routine urinalysis, looks for Fe-55?
Have you noticed that, recently, Fe-55 has become the limiting isotope in waste streams (unless, of course, you have transuranics)?

For more light reading on the subject of the effects of exposure to low levels of ionizing radiation, go here:

http://cpnpp220.proboards.com/index.cgi?board=exposure

Bill Nichols
billnich@hpnc.com

[ballscratcher]

This isn't about Fe-55, although it (Fe-55) plays a role in the concern.

The point that I'm trying to make is that we ignore (which is, perhaps, a poor term for use, here, but that's precisely what we do) their presence (Fe-55 and other low energy photons).  To my knowledge (that disclaimer is for you, Marssim), we don't scale Fe-55 into dose algorithms after processing the TLD.  Its dose contribution isn't reflected yet its energy makes it a prime carcinogen.
I read a few posts about EC (contamination) areas and found them intriguing.  If we can't detect it, we haven't "found" it yet we're willing to take conservative action against its (possible?) presence.  If it's not a problem, it's not a problem, right?

As they offered their infinite wisdom, INPO made us look at our Fe-55 "problem".  For awhile, we were forced to SAM all of our clean area Masslinns; guess what happened?  The SAMs were able to "see" activity that would have, otherwise, remained undetected.
Okay, Fe-55 has been determined to be an administrative nuisance so we no longer SAM our clean area Masslinns; problem solved.  Of course that isn't the case, we simply relegated it to the "don't worry about it" pile.
If because of its low energy photon Fe-55 isn't a health concern, why did the CDC add them (low energy photons) to  their list of KNOWN carcinogens?

Fe-55 is scaled into our effluents.  It's scaled into our radioactive shipments.  Rad Man accounts for all of our DTMs and scales them accordingly.  The only area where its presence isn't accounted for is in personnel dose.

If "disregard" is an offensive term, I apologize; perhaps it was hastily used.  "Invisible" could have been used in its place but it's not a particularly good term, either.  "Ignored" seems to have the same capacity to offend as does "disregard".  "Appropriate accounting for" would be an excellent substitute but it would be inaccurate.
Finally, if there's no reason to be concerned with low energy photons as dose contributors, let's not.  If there's no reason to concern ourselves with <30 keV photons, let's advise the CDC that it's our professional opinion that they are mistaken.  Until then, I stand by my original premise: we don't factor-in Fe-55 or other low energy photons as dose contributors and we go to great lengths to avoid their detection / identification.
As long as you're already pissed-off at my suggestion, let's add another: what's all that junk in the lower-end of the gamma spectrum that we call " noise" and "background"?  Why does its magnitude grow as a function of sample activity?   Dare I say it?  Bremsstralung X-rays and unaccounted for Compton interactions.
We analyze the sample and identify the isotopes present.  We assess the activity of each of the contributors to the whole and are satisfied with the results.  What about the continuum of unidentified photons in the "noise" region?  Because there aren't any specific channels into which they regularly fall (as would be expected from beta induced X-rays), they're just "noise", right?  Wrong.
Now let's take that example into the plant.  What's the isotopic mix of the gammas in a room?  Well, we've already determined our waste streams so we know the answer, right?  Wrong again.  There aren't any radionuclides that decay by gamma, most decay by beta emission with resultant gammas.  What does the beta-induced photon spectrum look like?  Oh, that's just "noise".

Ignorance is probably the appropriate heading under which I fall.  I'm ignorant of the goings-on in the noise region of the photon spectrum.  What I am not and will never be is a subject of the status quo.  If it doesn't make sense, I'm going to challenge it.  Your response, Marssim, while technically accurate, doesn't address or explain the phenomenon; it echos the mantra of the industry.  For just one moment, pretend that I'm right.  Clear your head of all of the this-is-the-way-we've-always-done-it-so-it-must-be-right thoughts and wonder about the low-end of the spectrum.  All noise?  And that, my friend, is the point.

[ballscratcher]

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?)

[HydroDave63]

I ask for a truce. 


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. 

10 yard penalty for lack of sincerity

P.S. I actually liked the post til the last paragraph

[ballscratcher]

Marssim,

I was an a$$hole for proposing a truce then reneging on it.  My bad and sincere apologies (no, really; I sometimes know when I've been an a$$hole).

Bill

[RDTroja]

Marssim,

I was an a$$hole for proposing a truce then reneging on it.  My bad and sincere apologies (no, really; I sometimes know when I've been an a$$hole).

Bill

See there? You are not as ignorant as you profess.

[RDTroja]

Everything is safe until someone looks closely enough. Life is fatal in exactly 100% of cases. There are even things that were safe, found unsafe, and are now safe again (saccharine comes to mind, but there are many others.)

The bottom line on radiation-induced cancer is that we will never likely know the exact level of risk because we cannot conduct anything resembling a real scientific study. There is no control group since everyone gets 'some.' I know far more people that have developed cancer that work outside the nuclear industry than in it. Is that any proof of the relative safety of the industry? Of course not. One of the BIER reports finally came out and said that hormesis is not real... but there is no other conclusion they could come to no matter what any evidence said. It would be scientific suicide to say radiation at any level is good for you. Again, there is no way to reliably tell since there are no controls.

One major reason we keep cranking down the exposure limits is that we have proven that each time we do, the industry survives. We don't know where the safe level is, so lets be conservative and crank it down again... and they will. The industry will adapt, better ALARA practices will be put in place, new resins will come along to clean up systems better, shielding will be installed, etc. Time will pass, someone will hit the 'scare' button again and limits will be lowered again. Where is the right place to stop? Nobody knows... and that is exactly the point. So, they will lower the limits again. At one time we could not imagine working with a limit of 5 REM/Yr. Crank it down to 2 and there will be more wondering how we will do it, but we will. Crank it down to 1 and we will adapt again. Eventually there is a breaking point, but we are not there yet.

If a utility does an outage with 100 RPs and the next year can only get 90, they make do with that. So that is the new standard because it worked. The following year they can only get 80, and they survive that outage, too, so there now is an new, new standard. Works the same way. Crank it down until you achieve failure. Same for exposure limits.

I am sure there is evidence that more people are developing cancer because of low-level radiation exposure, but I submit that there is nothing sound that can be declared with any confidence because of the lack of good controls. There are just too many other causes, no group that has an exposure level of 0 dose, etc. More likely is that there is a general feeling that lower is better so we should be lower... and that is fine. It gets expensive after a while, but that is OK because we are saving lives, right? Maybe not, but it sounds good and feels good to the people making the decisions. And likely justifying their job, too. It is easy to draw conclusions you are looking for when there is not a lot of hard and fast proof.

[ballscratcher]

RD Troja,

Well stated.

In another thread (health effects of exposure to ionizing radiation or something like that), there are links to research studies.  Based on those studies, there's a consensus opinion (proof?, that's impossible, of course) that 10 REM is the threshold for demonstrable cancer incidence.  The measurable increase addresses the likelihood of cancer death from 42% to 43%; a relatively small increase; but a scientifically demonstrated reality (that's a strong word and I wish that I could provide a less powerful synonym; probability?).

Don't accept anything that I write here without a challenge; checkout the links to arrive at your conclusion.  I'm just a technician with some questions.

Bill Nichols