Low Levels of Ionizing Radiation May Cause Harm

[ballscratcher]

Ten REM lifetime dose seems to be the value at which all of the research entities agree: adverse health effects (cancer incidence) become measurable.

The excerpt below (don't trust me, I could have edited the text; click the link) is the most straightforward proclamation from among the many findings.  All of the reports agree on the value, it's usually more indirectly stated.


http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=11340

If that one doesn't work:

http://national-academies.org/        In the "search" field, type: Low Levels of Ionizing Radiation May Cause Harm

(excerpt from the publication)
Assessing Health Risks

The committee's risk models for exposure to low-level ionizing radiation were based on a sex and age distribution similar to that of the entire U.S. population, and refer to the risk that an individual would face over his or her life span. These models predict that about one out of 100 people would likely develop solid cancer or leukemia from an exposure of 0.1 Sv (100 mSv) (10 Rem). About 42 additional people in the same group would be expected to develop solid cancer or leukemia from other causes. Roughly half of these cancers would result in death. These particular estimates are uncertain, however, because of limitations in the data used to develop risk models.


Bill Nichols
billnich@hpnc.com

[ballscratcher]

An excerpt from BEIR VII, phase II; The excerpt continues on page 201


http://www.nap.edu/openbook.php?record_id=11340&page=200


The three-country and the NRRW studies (Cardis and others 1995; Muirhead and others 1999) of nuclear industry workers currently provide the most comprehensive and precise direct estimates of the effects of protracted exposures to low levels of low-LET radiation. Although the estimates are lower than the linear estimates obtained from studies of atomic bomb survivors, as seen in Table 8-7, they are compatible with a range of possibilities, from a reduction of risk at low doses, to risks twice those on which current radiation protection recommendations are based. Overall, they do not suggest that current radiation risk estimates for cancer at low levels of exposure are appreciably in error. Uncertainty concerning the exact size of this risk, remains, however, as indicated by the width of the confidence intervals presented.

Bill Nichols
billnich@hpnc.com

[Marlin]

I don't read it that way. It states a rate of cancer for that exposure but the text seems to imply that there is no threshold, which seems to be the gist of the study. It did also state that they relied to a large extent on data from Hiroshima!! Don't we have enough radiation workers to make a meaningful study? There must be be many more radiation workers over the last fifty some years than the survivors from Hiroshima who had other environmental factors to influence outcome such as poverty and lack of basic services at the end of the war.


I'm just saying.

I could be wrong, that's just my opinion. D.M.

[ballscratcher]

The American Nuclear Society's position statement on low level exposure; specifically, this position statement discounts the linear, no threshold theory.  The ANS is an outlier in its dismissal of the LNT theory but it's interesting to note that it (the ANS) regards 10 REM as a demonstrable threshold.

http://www.ans.org/pi/ps/docs/ps41.pdf

excerpt from link:

“In accordance with the current knowledge of radiation health risks, the Health Physics
Society recommends against quantitative estimation of health risks below an individual
dose of 5 rem1 in one year or a lifetime dose of 10 rem in addition to background
radiation......."

Bill Nichols
billnich@hpnc.com


Few (actually, I can't find any) of the academic entities agree with the ANS position and yet even the ANS supports the 10 REM lifetime threshold.

[ballscratcher]

Marlin,
I'm posting this stuff as fast as I can.  The LNT topic is, despite my last post of the ANS position, dead; everybody agrees on LNT (well, not everybody but among those who count, only the ANS has a contrary position).

The specific issue that I'm determined to establish is the 10 REM threshold.  Many of us exceed or dramatically exceed that value.
Yes, there are studies of Rad Workers.  Dr. Steven Wing (UNC) is an epidemiologist who has worked in three such studies.  As each non Hiroshima / non Nagasaki study emerges, estimates for cancer incidence (as a function of exposure to ionizing radiation) go up and the dose at which they begin to be seen goes down.
I'll continue posting what I've got.  Some of the links have ceased to work (I've been compiling them since '02) and some of the best nuggets have disappeared from my records.

Ten REM is only one issue that I wish to address at this time.  It (10 REM) is the most consistent and, therefore, most non-contentious issue.  The other close-to-home issue (I'm self-serving) is exposure to individuals over 50.  I haven't posted anything on that subject yet, but I will.

Bill Nichols
billnich@hpnc.com

[ballscratcher]

I haven't tried this link in a while; hopefully it still works.

Subsequent to this study, Dr. Wing amended his threshold age to 50.  Following his research at ORNL, he further amended it to age 45.  Don't believe it, though, until I provide the links.


Dr Steven Wing is an epidemiologist at the University of North Carolina. His name is routinely referenced during studies of the effects of exposure to low-level ionizing radiation.
This paper was published at the conclusion of one such study and its finding was (quote from the paper) ".....additionally, radiation doses received at younger ages were not associated with cancer deaths. However, readings on radiation badges worn by workers when they were ages 55 and above were associated with death rates for cancer, and particularly for lung cancer."

The link : (hurry! the link that I first pasted here was dead)

http://www.unc.edu/news/archives/jun05/wing8061605.htm

Bill Nichols
billnich@hpnc.com

[ballscratcher]

Here is an abstract that proposes forty-five years of age as the age threshold for measurable effects from exposure.  I'll look for the published, final product and post it at that time.
This is Dr. Wing's amended age threshold.

http://ije.oxfordjournals.org/cgi/content/abstract/28/3/428

excerpt:

METHODS: Vital status and cause of death were ascertained through 1990 for 8307 white males hired at ORNL from 1943 through 1972. Associations between whole body ionizing radiation dose and all-cancer mortality were quantified using life table regression methods for time dependent exposures. Analyses focused of differences in radiation- cancer associations with age at exposure. Length of follow-up, period of hire, and age at risk were considered as alternative explanations for effects of age at exposure. RESULTS: Cumulative radiation dose was associated with a 1.8% (SE = 0.9) increase in all-cancer mortality per 10 mSv, assuming a 10-year lag between exposure and mortality. However, radiation doses received at older ages exhibited larger associations with cancer mortality than doses received at younger ages. Doses received after age 45 were associated with a 5.9% (SE = 1.7) increase in cancer mortality per 10 mSv, adjusted for doses received before age 45. Dose-response associations between cancer mortality and doses received after age 45 appeared consistent across periods of follow-up, periods of hire, and ages at risk.

Bill Nichols
billnich@hpnc.com


Here's the promised link to the complete publication:
http://www.bvsde.paho.org/bvsacd/cd59/exposure.pdf   bn

[HydroDave63]

It did also state that they relied to a large extent on data from Hiroshima!! Don't we have enough radiation workers to make a meaningful study?

Because it's always easier to rehash other older stats from Hiroshima ( since it has a lot of unknowns from exposure pathways after the blast, and using Hiroshima data gives that sub-conscious 'anything nuclear ultimately results in miserable cancer death' flavor to the study ) rather than look at thousands of S/G workers with comparatively high doses and tens of thousands of us 'baseliners' in the rest of the industry, who still (within the typical American lifestyle issues) live to the actuarial tables...

[ballscratcher]

Where's a math guy?  Is an exposure of fifteen REM (three doubling doses): 2 X 3  or two raised to the third power?


BEIR VII, phase II reports that five Rem is the doubling dose for the incidence of cancer. Does 10 Rem result in a "quadrupling" risk? Would 15 Rem only result in a six-fold increase in cancer risk or would it be an eight-fold increased risk? What are the increased risks associated with lifetime exposures of ten Rem, fifteen, twenty, etc?


Bill Nichols
billnich@hpnc.com

[ballscratcher]

Here's a publication that focused on Canadian Rad Workers.  The study involved only occupationally exposed personnel dating back to 1951.

The link:

http://aje.oxfordjournals.org/cgi/content/full/153/4/309#T1

"In conclusion, in this first analysis of cancer incidence using data from the National Dose Registry of Canada, a number of associations with occupational exposure to ionizing radiation were noted. In the light of results from previous studies, our findings for the cancers of the thyroid and testis are of particular note."

The full report states that its results can't be fully appreciated until the subjects have reached "extinction".

Bill

[ballscratcher]

Just another link..............
This is NRC's response to BEIR VIII, phase II (2002).  The report spends some time refuting BEIR's use of dosimetric model DS02 (instead of DS86) but is otherwise in agreement with its (BEIR's) conclusions.
What's interesting is that the discussion centers on "low" doses; those < 10 REM.  There's no discussion regarding doses above 10 REM (why is that?).

the link:

http://www.nrc.gov/reading-rm/doc-collections/commission/secys/2005/secy2005-0202/2005-0202scy.html

excerpt:

"For the purpose of this review, low dose was defined as exposures between 0 and 100 mSv (10 rem) or 100 mGy (10 rads). The BEIR VII Committee also was asked to limit its review to data related to low linear energy transfer (LET) radiation (e.g., x-rays and γ-rays) and low doses of neutron radiation. "


Bill Nichols
billnich@hpnc.com

[ballscratcher]

(based on the disclaimer on a particular site, I'm afraid to even post a link to it.  The disclaimer states that the page exists only for search engines)

If you enter the following into your Google search, you'll find lots of information:

Health Risks from Exposure to Low Levels of Ionizing Radiation: Beir VII Phase 2 studies for all cancers.

Bill

[Marlin]

   Even after all of that, the paper describes 10 rem above background as a qualitative number below which the effect is negligible not necessarily non existant. No carcinogen has had more money spent on it than ionizing radiation and there are still debates on minutia. I doubt the debates are over. The fact that a consensus that there is an acceptable risk that we can live with is at least a step forward.  I still think stupidity should have a higher ranking in the risk tables. 

[kp88]

What's interesting is that the discussion centers on "low" doses; those < 10 REM.  There's no discussion regarding doses above 10 REM (why is that?).

Perhaps because the typical station employee receives much less than ONE Rem TEDE in their life?

[Marlin]

It is interesting to note that the total number of cancers for exposed workers is below the expected number of cancers in the Oxford paper even though some individual cancers are in excess. Hormesis? Yes I know, too simplified.

[Motown homey]

Here is an abstract that proposes forty-five years of age as the age threshold for measurable effects from exposure.  I'll look for the published, final product and post it at that time.
This is Dr. Wing's amended age threshold.

http://ije.oxfordjournals.org/cgi/content/abstract/28/3/428

Based on the SEER data from the National Cancer Institute, the longer you live, the more likely it is that you will exhibit one or more cancer.  How does this increased probability in persons only receiving background amounts of radiation (e.g., general public) compare to the increased cancer in radiation workers?  After answering that question, what were the other carcinogens that could have caused their cancer?  What about regional, ethnic or genetic factors?

Only having read this one report by Dr Wing, it appears that to me that correlating cancer directly to radiation exposure in an aging population is not as easy as the report would make it.  I cannot dismiss this out of hand, but I can't accept without reservation.

[UncaBuffalo]

Perhaps because the typical station employee receives much less than ONE Rem TEDE in their life?

?

http://www.nrc.gov/reading-rm/doc-collections/news/2008/08-156.html

"To determine a plant's collective dose, hundreds of workers’ individual doses are added up and the result is expressed in person-rem. The average American receives a dose of about 360 millirem every year from all radiation sources; the average nuclear plant worker in recent years received about an additional 160 millirem each year on the job. NRC regulations allow workers at nuclear power plants to safely receive a job-related dose of up to 5,000 millirem each year."

[kp88]

the average nuclear plant worker in recent years received about an additional 160 millirem each year on the job

If you request your NRC Form 5 from a licensee, does it list 160 mR TEDE?

[UncaBuffalo]

If you request your NRC Form 5 from a licensee, does it list 160 mR TEDE?

The way I read the link, the average nuke plant worker's dose records would say they got 160mRem last year...your mileage may vary...

[ballscratcher]

Perhaps because the typical station employee receives much less than ONE Rem TEDE in their life?

kp-88,

You said (or words to the effect) that it's because most Rad Workers receive less than 10 REM lifetime (addressing the 10 REM threshold).

I agree with your statement; most Rad Workers DO receive less than 10 REM.
Most (many? some?) of us old timers, however, have received far in excess of 10 REM.

I believe that the 10 REM threshold is the value below which cancer incidence is only theorized, cancer incidence is projected but its rate is relatively small; cancer incidence above 10 REM has been clearly established.
To avoid appearing to be like chicken little, this needs to be put into perspective.
42% of all people, regardless of lifestyle, socioeconomic position, occupation...will die of cancer; period.  Exposure to 10 REM lifetime has a statistical probability of adding one cancer death to that total.  One who has received 10 REM will bring the percentage to 43%; not exactly a huge increase.

The other point is that there will be one excess cancer DEATH from said exposure; cancer incidence (treated and cured) does not find its way into the final tally (death).

Bill

[ballscratcher]

motown homey,

you said:

Based on the SEER data from the National Cancer Institute, the longer you live, the more likely it is that you will exhibit one or more cancer.  How does this increased probability in persons only receiving background amounts of radiation (e.g., general public) compare to the increased cancer in radiation workers?  After answering that question, what were the other carcinogens that could have caused their cancer?  What about regional, ethnic or genetic factors?

Only having read this one report by Dr Wing, it appears that to me that correlating cancer directly to radiation exposure in an aging population is not as easy as the report would make it.  I cannot dismiss this out of hand, but I can't accept without reservation.


Nor should you.........Please take everything that I post here with a grain of salt.  Please do your own research.  I provide the links because I'm subject to fits of Alzheimer's and sometimes confuse facts.
I've written in another forum that the doubling dose for cancer incidence is 3 REM.  I swear that I remember reading it but can't, for the life of me, find it again.  The only reasonable conclusion is that it isn't true; the doubling dose  (from BEIR VII) remains at 5 REM (until I can find the referenced publication).

Please just regard me as a gomer with an axe to grind until / unless you see REAL stuff that changes your mind.  Hopefully, the links contain the REAL stuff.

Bill Nichols
billnich@hpnc.com

[RDTroja]

All of this points out a lot of the problems with epidemiological data... averages can't be construed to mean anything to anyone individually. They often can't be used to indicate anything at all.

It used to be that the statistics were used to say that if you gave 10,000 people a dose of 1 REM, 3 people would develop cancer because of that exposure. The data was averaged from Hiroshima data and extrapolated down using the linear non-threshold model, which is losing credit. That was also taken to mean that if you gave one person 10 REM he had a 0.003% chance of developing cancer due to that exposure... statistically speaking. But is that kind of statistical extrapolation valid in calculating radiation exposure risk? We just don't know. None of the statistics are proof of anything and there is a good chance that the inferences taken from large doses don't mean a thing in small doses. Unfortunately it is the only valid data we have at this point that makes a lot of sense. The rest of the data conflicts itself.

As Marlin stated, we should be seeing far more cancers among nuclear workers than we are... we are actually seeing fewer than expected in a normal population. Either the numbers are screwed up, the statistics are being misapplied, the theories are wrong, hormesis is a fact, we don't have enough information yet, or we just don't understand the workings of the human body and its reaction to radiation exposure well enough. Take your pick, there is probably some truth in all of them... or maybe none at all and something else is at work. From a scientific study standpoint, we have a poor environment in which to conduct experiments, no 'blind' group to work with and a contaminated laboratory. Therefore all of the data is suspect.

The bottom line is we don't yet know what really causes cancer and what doesn't, why some people get it and some don't given similar circumstances. There is a theory that we develop and get rid of cancer several times a day, and only a failure of the mechanism designed to get rid of it produces what we consider to be the disease.

[ballscratcher]

Healthy Worker Effect

Researchers have been confounded by the low rate of cancer deaths among exposed people in the face of research that indicated that there should be an INCREASE in cancer deaths.

The healthy worker effect states this: Most of us are educated.  Most of us receive a relatively handsome income.  Most of us have health care insurance and make regular trips to the doctor.  We exercise preventive health care and the result is better overall health: the healthy worker effect.
The inverse of the healthy worker effect is that poor people, those without an education, those who have less-than-stellar incomes, cannot afford and do not have health care insurance; consequently, they don't enjoy preventive health care.  The final insult to their injury is that they are OVER-REPRESENTED in any epidemiological study; not just with respect to exposure to ionizing radiation.
That segment of society isn't present where we work but their statistical probability of poor health is incorporated into most epidemiological studies.  For that reason, we seem to have a lower-than-expected rate of cancer.

Without medical attention, (most, some, a few, many, a couple, one; please circle your answer) cancers will become fatal.

Health Physics research has, historically devoted itself to the measure of cancer deaths.  Measurement of cancer incidence is a new research objective and we're starting with a clean sheet of paper. 

Bill

[Marlin]

As Marlin stated, we should be seeing far more cancers among nuclear workers than we are... we are actually seeing fewer than expected in a normal population. Either the numbers are screwed up, the statistics are being misapplied, the theories are wrong, hormesis is a fact, we don't have enough information yet, or we just don't understand the workings of the human body and its reaction to radiation exposure well enough. Take your pick, there is probably some truth in all of them... or maybe none at all and something else is at work. From a scientific study standpoint, we have a poor environment in which to conduct experiments, no 'blind' group to work with and a contaminated laboratory. Therefore all of the data is suspect.

Very true, look around the room (without busting out laughing). The coworkers you are looking at are above average intelligence, above average health, and above average income. All of the aforementioned facts are fog for studies of nuclear workers as compared to general populace. A good example is an old one, the shipyard workers at Portsmouth. The initial study showed a higher than normal cancer rate for the shipyard workers. After closer scrutiny it was noted that they were compared to the national average and in fact their rates of cancer were lower than that of the local populace. Statistics, politics, and used car salesmen all require close scrutiny.

[ballscratcher]

Based on the SEER data from the National Cancer Institute, the longer you live, the more likely it is that you will exhibit one or more cancer.  How does this increased probability in persons only receiving background amounts of radiation (e.g., general public) compare to the increased cancer in radiation workers?  After answering that question, what were the other carcinogens that could have caused their cancer?  What about regional, ethnic or genetic factors?

Only having read this one report by Dr Wing, it appears that to me that correlating cancer directly to radiation exposure in an aging population is not as easy as the report would make it.  I cannot dismiss this out of hand, but I can't accept without reservation.

I've long-since lost the link to this paper, but Dr's Rudy Nussbaum and Wolfgang Kohnlein contend that a significant number of cancers are directly linked to background radiation.  In one's lifetime, one receives an average of 5 REM from background radiation (there are noteworthy exceptions; Kerala India, for example).
Background radiation is inescapable so we simply must deal with it but its contribution to cancer, in their opinion, is equally inescapable.

I have no link to provide so you must disregard this post as having any value.

Bill