Talk:Linear no-threshold model

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[edit] This

This statement: "(i.e. the cancer a study focuses on does not exist in humans, a clear threshold could not be established in humans, the assumptions are seriously flawed)." Makes absolutely NO sense.... someone who knows what they were trying to say should fix it, or it should be removed. Not just the bad grammar, but the entire point here makes no sense. A study advocating the linear model is ignoring evidence that the non-linear thresholded model is incorrect??? Think about it... it doesn't make sense.--Jlc46 20:52, 3 August 2006 (UTC)

[edit] Rewrite requested

Article should define the LNT is and say who developed it. Also it should explain policy implications of the model.

Has LNT been applied to hazards other than radiation, such as cyanide in drinking water?

I'd especially like to see any studies which treat LNT as a hypothesis and have made predictions from it. Have any scientists made or tested such predictions? --Uncle Ed 18:42, 27 October 2006 (UTC)

Yeah, i think the article mentions that EPA uses this for all carcinogens. Pdbailey 03:45, 28 October 2006 (UTC)
That wasn't what I asked. You answered the question, "Does anyone rely on LNT as a guiding principle?" (no longer wondering whether it's true or not). My question was whether anyone is testing the model. (actively trying to determine whether it's true or not).
I guess you mean that the EPA bypassed the stage of determining whether it's true and went right ahead into using it as a guiding principle.--Uncle Ed 16:03, 15 November 2006 (UTC)

I think we still need some more explanation about LNT.
In its very pure form LNT means, that you basically integrate the radiation rate over your lifetime. The result is the complete life-long radiation dose to which you were exposed (in Sieverts). In its pure form LNT says that this number is proportional to the risk of getting radiation induced cancer.
Now already it is clear that this is an oversimplification which is wrong. Basically getting 4 Sv spread out over your whole lifetime (>50 years) is dangerous, but your chances of survival are good; especially when you are not irridated in your first few years. WP says if you get this dose in a short time-frame your chance of surviving the next month is < 50%.
So it is already widely accepted that long-term low rate radiation is far less dangerous then short-term high-rate radiation. This is already a departure from pure LNT.
Now for "middle" dose radiation LNT seems to hold (even if I really have no clue about what kind of time-frame we are talking about. 10 years 20 years life-long ?). So basically you add up the doses per year. The result seems to give a pretty good estimate about radiation induced cancer.
For "low" rate radiation, statistical data is so difficult to obtain, that it simply is not known if LNT is completely appropriate.
—Preceding unsigned comment added by 84.154.23.40 (talk) 23:50, 9 September 2007 (UTC)

[edit] Cuts

  • In this application the question of a threshold does not arise, so this is not strictly the LNTM.

This sentence does not make sense with respect to radiation. If a threshold "does not arise" this is an example of the LNT assumption.

The controversy over LNT is whether the assumption holds true, all the way down to trace doses. This has hugely expensive implications for public policy.

The question is:

  • Is there a level of exposure below which it doesn't make sense (moral or even economic) to keep "scrubbing" the environment? Or,
  • Is there no level of safe exposure and this does it make moral and economic sense to "keep scrubbing"?

Help me write about the controversy. It relates to the "precautionary principle". --Uncle Ed 16:00, 15 November 2006 (UTC)

[edit] NPOV

I just rewrote the introduction to this in order to improve the NPOV. Before, the article seemed to state that the LNT model was wrong without even defining what it was, and stated that there was "some evidence" that there was a threshold without even mentioning what it was.

I have included a link to a recent review article in the Proceedings of the National Academies of Sciences.

Frankly, I don't think that we should be citing the Wade Allison talk - if he wants to make this argument he should get it published somewhere. At the very least I removed the clearly NPOV words "closely reasoned".

Mgolden 04:08, 30 July 2007 (UTC)

The piece now has a much better balance. Added academic citation for Wade Allison, as suggested. --Old Moonraker 05:24, 30 July 2007 (UTC)
Still need peer reviewed paper to be something. Stronger claims (i.e. that the NAS is wrong) require strong sources. They are not yet there, and I'd suggest removing that paper and it's claims. Pdbailey 01:22, 31 July 2007 (UTC)
The paper User:Pdbailey wants to delete is published by the physics department of Oxford University, England. The author, originally a particle physicist who now teaches medical and environmental physics, has incorporated the material into a book from the Oxford University Press and I have now added this citation. The benefit of having the online sources referenced is that users may read them for themselves, without the expense of a GBP50 bill from Amazon! Old Moonraker 05:47, 31 July 2007 (UTC)
Moonraker, these articles are often called "Grey" literature and are not held up as excellent sources. In addition, books are less throughly edited (in the peer review sense) than journal articles. It would be one think if we were debating the quality of these sources, but in this case the author contradicts a NAS study, this is the pinnacle of peer review. You may care to read the start of the hormesis page (linked at the top of the LNT article) to see the other science organizations that have commented similarly on hormesis/LNT. Pdbailey 13:31, 31 July 2007 (UTC)
The description of the NAS study as the "pinnacle" is obviously right. However it would be wrong to leave the article without some idea of the well-qualified dissent. This doesn't have to be from Allison: however I've had a look at the WP guidelines and it specifically recommends ...university-level textbooks...published in university presses as a preferred source. This exactly describes Allison's book which was ...developed from a course given to third year students at Oxford [University]—publisher's blurb. His paper is less useful for our purpose but as it was written by an established expert (quoting from WP:V again) it does seem to be acceptable, with the added advantage of being available in full for download. His lecture notes from 24 November 2006 (now moved to "External links") are included only because they seem more accessible to the lay reader. --Old Moonraker 14:18, 31 July 2007 (UTC)
I agree with you that the multiple references is better than either one alone in the sense that it increases accessibility and depth. I would argue that there are many, many better articles (in peer reviewed journals) that make similar arguments. But non are in line with the NAS or other authoritative bodies. I think the article should state that before the work of any dissenters should be viewed in this light, then I think the NPOV tag should be removed Pdbailey 02:07, 1 August 2007 (UTC)

[unindent] So, to sum up, the article needs to emphasise more that the NAS study has very broadly based acceptance and use a citation from a better, peer-reviewed work that indicates that there is a threshold. I would be very happy with that. --Old Moonraker 05:17, 1 August 2007 (UTC)

This is hands-down the most controversial topic in radiation protection. The National Research Council of the National Academy of Sciences convenes the Biological Effects of Ionizing Radiation (BEIR) Committee periodically to assess the state of knowledge and provide guidance for future research. They review hundreds of published articles and review and respond to comments and suggestions from the public. Seven reports have been published since 1956. Reports I, III, IV, V, and VII focused on risk of exposure to low levels of radiation. The bottom line in each report was the same – insufficient evidence to support any theory other than LNT. This conclusion is certainly not the definitive or final word on the subject. However, it does represent a consensus among some of the leading minds in the field.

I see the single biggest problem with these reports as the lack of clear and convincing data, for any theory, beyond that provided by Atomic Bomb Life Span Study (LSS). The problem remains that radiation is a relatively poor carcinogen. The risk of cancer from any one exposure is relatively insignificant (1 in 1000 or less). We all live with a 17% lifetime risk of developing fatal cancer. This makes finding a statistically significant increase in radiation-induced cancer a daunting task. Th'wing 20:07, 29 August 2007 (UTC)

Just my 2 cents: I think Th'wing summed it up perfectly. I myself I am not an expert on radiation but I have a good understanding of statistics. The main problem really is, that if you assume LNT, then in the low dosage regions the expected effects are so extremely small, that they can't be really detected by a statistical method.

I find it somewhat irritating that the NAS review uses the phrasing "the most reasonable assumption" . This is a little bit like saying "given our current state of knowledge (around 1850) the most reasonable assumption is the existence of an Äther" (which proved to be the wrong assumption...). I would find this review far more convincing if they stated that there simply seems to be no conclusive evidence in any direction (which is the reality as far as I can tell). It seems only philosophers like to admit that they don't know something :-). 84.154.32.72 23:09, 6 September 2007 (UTC)

Äther = Æther for readers of advancing years using Br En.
Seriously, though, how do the respected proponents of the theory come to their conclusions? I wish someone with proper knowledge could add this. For example, Allison's work seems to be applying the results of controlled medical studies to the gaps in the statistical method. This is cited in the article but not explained. --Old Moonraker 06:33, 7 September 2007 (UTC)
One of the biggest experiments is the "megamouse" project (google for it). Unfortunately this experiment doesn't deal with the risk of cancer, but with the risk of genetic mutations. I only read summaries about this experiment. As far as I can tell for genetic mutations the data seems to point in the LNT direction; on the other hand it is also stated that it there is a strong "dose-rate" effect (so if the dose is given over a short period of time, or over a long period of time), which I (as far as I understand LNT) interpret as an argument against LNT. My meaning: It is a big difference if you get a high dose in a short timeframe or a low dose in a long timeframe; I think it is not totally impossible that if the dose per year is low enough than there isn't any effect anymore, even if the overall dose over once lifetime is not that low. It also seems that there are several studies about populations which are exposed to a higher background radiation (for example, because you have radon in your house, or you are living in an area with an increased amount of uranium in the soil). I will try to find out where to get the original studies. —Preceding unsigned comment added by 84.154.61.90 (talk) 00:25, 8 September 2007 (UTC)

The remaining question for me is does the section look like two sides wrote it. There is a lot being swept under the rug on the Addison piece (i.e. that nobody assumes that the dose response is the same at japan bomb survivor radiation levels, that tobacco and radon are well known to interact and there's no issue for LNT with that) Pdbailey 18:02, 8 September 2007 (UTC)

I think the balance is not too bad. After now reading the NAS article, I think even NAS doesn't seem to think that a threshold model is unrealistic. They simply argue that there is not enough evidence, and that the LNT model is very plausible. Besides the LNT model is very vell suited to formulate principles of radiation protection. So of course as long as there is not extremely conclusive evidence for a threshold model, there is simply no good reason to switch models.
I think the most interesting studies concerning low-dose radiation are the once about areas with a natural high background radiation. Unfortunately the problem seems to be, that you usually simply do not have the statistical infrastructure in place to really get a good comparison with other areas. Studies would be only useful, if you compared the statistics of a high-background-radiation area to a nearby area with low-background-radiation. That would require to monitor the cancer incidences as closely as possible. Unfortunately that kind of exact data usually seems not to be availabe...
By the way I found another paper, which seems to be in favor of hormesis, but I really can't judge its credibility. 84.154.23.40 23:22, 9 September 2007 (UTC)

At this time, I would propose removal of the NPOV tag form the "controversy" section. I believe it does a great job of capturing the controversy in this area without going overboard. Truth be told I think the last paragraph is out of place -- i.e. why include a few individual authors when we have collective opinions form NAS, NCRP, UNSCEAR, HPS, and ANS? But I think that the current version is close enough so as not to warrant the tag. Pdbailey 01:37, 10 October 2007 (UTC)

Agree with removal of the tag. As the guilty party regarding the inclusion of individual scientists' views (albeit in the Chernobyl disaster effects#Other studies and claims piece), I also accept that, now more collective opinions are included, the para carries less weight than it did. I can only return to the previous discussion (above): some of the references that support the inclusions are a useful further resource for readers. --Old Moonraker 06:43, 10 October 2007 (UTC)
Old Moonraker, my sense is that including aggregated opinions on both sides is useful and follows NPOV, I would argue that including particular papers on only one side goes against that. I would also argue that the transition to that section is now awkward and in serious need of fixing. I would, but i don't see a great way of doing it without drastically changing the intention. Undoubtedly, someone would rv my edit.
In any case, if we do want to keep individual opinions and articles from one side, I would argue we need them from both. Parity is in order. Pdbailey 15:19, 10 October 2007 (UTC)
Again, I am not in disagreement: the individual scientists quoted are all on one side of the argument. They were originally copied over from Chernobyl disaster effects#Other studies and claims by User:Ed Poor when LNTM was a lot shorter than it is now. There, they are lost in the generality of the topic: here is the only page where someone with a particular interest can get easy access to the external references, which I believe are of value. Are you suggesting adding quotes from individual scientists presenting the conventional viewpoint for better balance?
I certainly don't want to contaminate the NPOV equilibrium on Radiation hormesis by putting them there. --Old Moonraker 15:48, 10 October 2007 (UTC)
I'm proposing one of two options. (a) have individual papers that are pro-LNT and anti-LNT, or (b) have no individual papers. I would go for (b) because I think accumulated opinions are more informative to an encyclopedia reader and that including individual papers can bog down a topic that has perhaps hundreds or thousands of papers written on it. Pdbailey 16:01, 10 October 2007 (UTC)

Note that the United States National Research Council and the French Academy of Sciences (two comparable institutions) released reports around the same time; however, one accepted LNT but other rejected it, even though they read the same literature. The differing opinions of these two institutions neatly illustrates the controversy. --Diamonddavej (talk) 04:09, 27 March 2008 (UTC)

Diamonddavej, the reference here is [1]. It is difficult for me to judge the status of the French Academy of Sciences which looks like it might be closer related to the American Philosophical Society, I can't tell. Pdbailey (talk) 21:21, 27 March 2008 (UTC)
This is the French Academy of Sciences-National Academy of Medicine report in English, which I reference on wiki [2]. The French National Academy of Medicine is especially instituted to respond to requests from the French government for advice. They are thus a reputable institution and are more akin the US National Academy of Science, who are also instituted to respond respond to government requests for expert opinion. Here is the French National Academy of Medicine website: [3] --Diamonddavej (talk) 03:34, 30 March 2008 (UTC)

[edit] propose deletion from "Several scientists also disagree with the Linear No Threshold Hypothesis" on down

The reason I don't think this belongs is that there are literally hundreds of papers on the topic, but we have something much better above---the opinions of the UN, US government, and a few societies. Lets keep it short and sweet and not make this a link farm down at the bottom. Pdbailey (talk) 03:17, 10 March 2008 (UTC)

I agree with removing the "Several scientists also disagree with X", one can always find a contrarian to fit any view point. The best way forward is to illustrate the controversy by quoting consensus studies/position statements from respected sources that are for/against LNT. That section needs some tidying up. --Diamonddavej (talk) 03:31, 27 March 2008 (UTC)

[edit] a pity

It's a pity that this article ends its introduction by quoting a reference supporting the LNT model. Surely, this is controversial, and the introduction should give both sides equal space? As it stands, all three references in the introduction are supportive, and this one is given particular prominence by placing it in the concluding paragraph.

I see this has been the subject of much discussion above. Just adding my observation! Andrewa (talk) 19:01, 12 March 2008 (UTC)

Andrewa, there really is no equal space claim in the Wikipedia charter, it is about well referenced claims and scientific consensus. It is really rare to have the authority level that this article as in entire books written by bodies like NCRP, the UN, and the NAS that all agree. It is true that most health physicists disagree with these conclusions, as noted by the HPS societies position; and this appears in the text because it is a high quality source. I don't really see the pity, but maybe I misunderstood your point. Pdbailey (talk) 20:24, 12 March 2008 (UTC)
Wrong on most counts. For the policy on equal space see Wikipedia:Neutral point of view#Balance and Wikipedia:Neutral point of view#Undue weight. And there's nothing particularly scientific about Wikipedia's policy of consensus.
My point is that this reads as an endorsement of the LNT. IMO Wikipedia should avoid any such endorsement. Andrewa (talk) 01:40, 13 March 2008 (UTC)
You miss the point when you like to Wikipedia's sense of consensus. That is not a general definition of the word, it is a definition of consensus at wikipedia. If you want a definition of scientific consensus, the closest thing to meeting the definition would probably be a NAS study. Also, I think this page clearly meets those policy statements of wikipedia, except that I think there should be less anti-LNT articles since it is so far out of the mainstream. Pdbailey (talk) 20:03, 13 March 2008 (UTC)
Don't really know what that first sentence means. What point am I missing?
Do you really think:
(a) That the article as it stands avoids endorsing the LNT as a model of radiation exposure? OR
(b) That there's scientific consensus on this model? OR
(c) That it's appropriate for Wikipedia to endorse one side of this controversy?
My point remains: The article currently supports use of the LNT as a model of radiation esposure. This is not generally accepted, but promoted by a those of a particular political view. Wikipedia is committed to avoiding such bias. Andrewa (talk) 16:17, 14 March 2008 (UTC)
Yes, I think (a) is true. I think the article is encyclopedic and reports about what sources say on the topic and reports their stance on the topic. I can't say I really understand what you mean when you write, "This is not generally accepted, but promoted by a those of a particular political view." What would you say about the sentence from the NAS, "In summary, given our current state of knowledge, the most reasonable assumption is that the cancer risks from low doses of x- or gamma-rays decrease linearly with decreasing dose." Pdbailey (talk) 02:21, 27 March 2008 (UTC)
A poll of scientists at the international Ultra-Low-Level Radiation Effects Summit in January 2006,[4] found that over 80% of the attendees think that below a certain threshold, radiation is harmless due to innate defense mechanisms (page 29 [5]). --Diamonddavej (talk) 04:19, 28 March 2008 (UTC)

[edit] What the LNT is good for

The LNT is useful as a model for setting an upper limit on the amount of damage done by low doses of radiation, in order to set standards for acceptable radiation doses to personel.

This is a completely different thing to making an estimate of the damage done by low doses. It's a deliberately conservative approach, used in the absence of better data.

In some cases, there is now data that indicates that the LNT is overly conservative, see radiation hormesis. In others, there's still no data, so the LNT remains the appropriate model. Even in cases where the LNT is now known to be overly conservative, there's a general reluctance to relax standards.

It may be that some day we will find cases where the LNT is insufficiently conservative, but these have yet to be discovered.

Those are the facts as I believe them to be. But there are also some authoritative government reports, and many, many political papers, that do use the LNT to estimate damage done by low doses of radiation, most famously the estimates of large numbers of casualties of the Three Mile Island and Chernobyl nuclear accidents.

I notice that the article on radiation hormesis now reads scientific consensus has now developed against the theory, and references disproving this controversial claim have been removed from that article. Oh well. We can only try. Andrewa (talk) 16:17, 14 March 2008 (UTC)

Andrewa, almost zero radioactive material was released from TMI, and TLDs placed around the community found zero additional exposure due to TMI, LNT would predict almost zero additional cancer deaths from this. Is there a source for your claim to the contrary? Pdbailey (talk) 02:24, 27 March 2008 (UTC)
Also, if you want to see super-linearity, see this working paper. Pdbailey (talk) 02:36, 27 March 2008 (UTC)