Fear Dealer said:

I work in radiation. I am looking for a new job because most of what I do is BS.
Pretending LNT is valid is only in the best interest of people who work in radiation protection (and those who derive political leverage from it). Fear mongering = job security.
At seminars I often hear that LNT at low doses is not observable… but that doesn’t mean it’s not there.

Try this – You can’t see my car payment… but that doesn’t mean it’s not there.

LOL, your comment about what you do is BS was a good one. Though I would say that in everything there’s a positive and negative whatever work your in. Look at it in the way of the least evil and the one with the greatest benefit.

Try this – You can’t see my car payment… but that doesn’t mean it’s not there.

All because it has been politically useful.

Any theory for which proponents attempt to produvce no evidence is, by definition, not testable & therefore not part of science. When the testing has been done & repeatedly proven the opposite theory, hormesis, to be true & LNT [proponents simply refuse to acknowl;edge the evidence that is much worse than simply not being science.

Those US states with high levels of background radiation generally have lower cancer rates; the negative relation between radon in homes & lung cancer has been repeatedly demonstrated, most thoroughly by Professor Cohen http://www.world-nuclear.org/sym/1998/cohen.htm ; the hormesis effect on plants, microbes & lab animals (which unlike human experiment is ethical) have, repeatedly, for over a century shown the hormesis effect & are not now disputed; health records of nuclear reactor workers, nuclear naval dockyard workers & UK radiologists have all shown improved health; a Taiwanese apartment complex, built with steel contaminated by Co60 & which is as close to a controlled human experiment as possible, showed a cancer reduction of 96.4% compared to the population at large http://www.jpands.org/vol9no1/chen.pdf ; there are parts of the world like Kerala in India where natural background radiation is anything up to 200 mSv a year, 13 times the official safe limit yet no adverse effects have been noticed over thousands of year; in the disgraceful & quite unscientific decision in 1964 to quietly euthanase a herd of cows exposed to a bomb test in 1946 having achieved extreme longevity; in the failure of Chernobyl to produce any statistical increase in long term cancers let alone the up to 250,000 predicted.

See also http://a-place-to-stand.blogspot.com/search/label/Hormesis

        Franck said:

Bruce, I would totally agree with you if you were considering the effects of radiation on an inorganic target, but people are living things, that have protection (primarily outer skin, already dead tissues) and repair devices.
The LNT is assuming these protections are useless.

Also, if you want to stay on purely mechanical ground, it would mean that I will surely break someone’s arm by shaking it every day for enough years, after all, I will deliver quite a lot of energy (and it’s not only because the person is living, even inorganic materials have to some extend an elesticity range in which they can dissipate absorbed mecanical energy without damage).

Laws of energy are linear, but try to find something else that momentum for which there is no theshold to permanent effect, that would be a very interesting exercise.

It’s a facinating subject, and I agree that it’s not simply linear. One of the issues that I remember reading has to do with single strand versus double strand DNA damage. Since DNA has an internal repair mechanism, where each half of the DNA is capable of regenerating the other, it’s believed that a double strand break is worse than twice as bad as a single strand break. Single strand damage is almost always reparable but double strand damage may not be.

This is important, because the probability of a double strand damaging event is not linear. It increases as ionization increases, such that if a cell is hit by multiple photons in a short period of time, there’s a much greater likelihood of double strand damage.

Maybe a good example as an analogy is error correction in other areas. I admit I’m not an expert on this one, but I’ll give it a shot. When you watch satellite TV or something like that, where you’re dealing with long distance signaling, some of the bits are lost in the transmission. Every frame has a small portion missing. This is okay, however, because there’s error correction in the signal. The signal contains some extra data that lets the receiver do some basic mathematics to detect which parts are probably an error and to correct them. It works perfectly up to a point. If you are missing, lets say, 1% of the data, it can all be recovered through the error correction process. Maybe it could be if you’re missing 2%, but it depends on how the error correction is encoded and how much of it there is. At some point too much of the data is missing for the error correction to fill in the gaps and when that happens, you get problems in the picture.

We know our DNA has error correction. Actually, software developers have even looked at DNA research as a guide for developing new error-resistant means of storing data efficiently.

Another point: Based on the simplistic interpretation of the theory behind damage from radiation and the LNT hypothysis, the more opportunity there is for a particle or photon to cause damage and the more cells there are to be damaged, the greater the probability of cancer. More cells mean more places for something to go wrong.

Therefore, in theory, if we expose a mouse, a rat, a cat, a human and an elephant to the same radiative flux, the mouse will have the least probability of cancer, the elephant the most and the rat, cat and human are in between, in order of size. Most of the radiation passes through the mouse without ever causing ionization, but the elephant has many cells and is big, so absorbs more radiation.

The problem: experimental results don’t indicate any greater increase in risk with the size of the organism. The implication from this is that viewing each cell event in isolation is not an accurate way of representing the total damage.

        DocForesight said:

Dr. Buzzo — Am wondering what your thoughts are about thermography (using infrared camera and software) to identify areas of increased heat as an adjunct to mammograms. If cancerous tumors require increased blood flow to feed it and that increased blood flow would be indicated by an increased “heat print” compared to surrounding tissue, would it not follow that a change in physiology would precede a change in structure (tissue)? If that is true, then a thermogram could alert a health professional to biopsy a tissue before a tumor formed (which is only what a mammogram is capable of doing – finding it after the fact).

Not to mention, the thermogram is non-iradiative and causes no discomfort to the patient.

Here is one site for your review: http://www.thermology.com/

I’m not a doctor, but I do recall Orac (Respectful Insolence) commenting a little on thermography. He’s a surgical oncologist specializing in breast cancer. If I recall correctly, he was conservative on the subject, so I think it’s probably premature to tout thermography as superior to mammogram or MRI, but the jury is still out on that one. He’s had some words on the subject of MRI, too, which is becoming more popular as an alternative to mammogram. One of his big concerns is the rate of false positives. Biopsies are not benign processes; they can be painful for quite a while after, and can result in nasty complications. So false positives are a serious problem with respect to medical imaging and breast cancer.

Also, I don’t think it would make any sense whatsoever to biopsy before a tumor formed; if there’s no tumor, then there is nothing for a pathologist to find in the biopsy sample.

        Bruce said:

Shouldn’t it follow: The linear non-threshold is a reasonable inference? So, those who doubt it are the ones who have the burden of proof, not those who are its proponent. For example, according to classic physics, the momentum is the square of the velocity. It’s not necessary to prove that this property is true at 5 to 10 mph, we can assume it is true because we know it is true at 20, 30 and 100 mph. If I came along and said, “well, we don’t know, maybe momentum is not the square of speed above 100 mph or below 5 mph”, I would be laughed off.

But somehow, people make exactly this assertion with radiation!

Complex systems do not follow the same linear principles as fundamentally basic ones.

You can analyse two objects colliding based on speed and mass and be confident of the outcome in terms of momentum based on a dozen or so rules (mainly involving infinite stiffness, zero friction etc). Apply this to Buzz0’s analogy of a person jumping off a building and you will find that a linear relationship of collision momentum and fatality rate is clearly a pile of trash. People have survived jumps from planes without parachutes (very rarely, I accept) and no-one dies from stepping off their doorstep (unless they trip over, but based on CoG that’d be a fall of more than a foot and thy’d have to have a pre-existing medical problem).

Oh, and SBuzz0: given you cited the wonderful bastion of British media brilliance that is The Daily Mail, I feel you might appreciate the following website, which provides a summary of their superb analysis of the various factors affecting your risk of contracting a cancer:

http://kill-or-cure.heroku.com/

Next time you’re wondering what to eat for dinner, maybe you should check which meal causes cancer and which cures…

Also, if you want to stay on purely mechanical ground, it would mean that I will surely break someone’s arm by shaking it every day for enough years, after all, I will deliver quite a lot of energy (and it’s not only because the person is living, even inorganic materials have to some extend an elesticity range in which they can dissipate absorbed mecanical energy without damage).

Laws of energy are linear, but try to find something else that momentum for which there is no theshold to permanent effect, that would be a very interesting exercise.

        Bruce said:

By the way, green energy continues progress…

http://greeninc.blogs.nytimes.com/2010/03/15/nevada-wind-turbine-factory-to-create-1000-jobs-backers-say/

While I am tempted to point out some flaws in this statement and refute the infrence that this represents a net positive impact, I’ve decided not to dignify such comments with a response when they are placed on a post that is entirely off topic when there are plenty of perfectly on-topic posts that it could be made on.

Actually, a while back there was this guy who proposed that the laws of motion that work well at 5 and 10 mph and even 100 mph don’t work so well around 186,000 miles per second – or for that matter, even half of that speed.

He also proposed that the effect he described also existed at 5 mph and 100 mph but was too small to be measured by instruments of the time and was generally insignificant.

Maybe you’ve heard of him? His name was Albert Einstein.

Oh, there were some other dudes who said that the classical laws don’t work at really really small scales. Maybe you’ve heard of them? Max Planck, Werner Heisenberg, Erwin Schrödinger, Niels Bohr

Oh, also, they weren’t laughed off. They generally were seen as being brilliant.

        Bruce said:

Shouldn’t it follow: The linear non-threshold is a reasonable inference?

The carcinogenic risks of radiation that are observed at high doses be extrapolated to low doses, is what is being asserted with the LNT model. Unlike the laws of motion from classical physics, it has never been proven so your analogy falls apart right there.

What we do know is that there is not a linear dose response for other types of radiation, the best example being sunlight. The human body evolved being exposed to sunlight, and while too much exposure can and does cause tissue trauma, and death can occur in extreme exposures, low doses are not only provably harmless, but are in fact needed to maintaine good health.

We also know that humans evolved being exposed to a certain level of background ionizing radiation, and while it may be premature to say that we need some to stay healthy, claiming that there is a quantifiable risk to DNA down to zero is demonstrably absurd.

Plus there is a vast amount of data accumulating that even moderate exposures are not as harmful as originally thought, thus as consequence the LNT hypothesis is demonstrably wrong.

But somehow, people make exactly this assertion with radiation!

By the way, green energy continues progress…

http://greeninc.blogs.nytimes.com/2010/03/15/nevada-wind-turbine-factory-to-create-1000-jobs-backers-say/