The hormesis theory is that within limits the radiation, by stressing the cells, makes the bodies defences work (ie the damage response). This obviously only applies up to the level where the radiation is more than the body can easily repair. There is no particular reason why hormesisi should not work as well in humans as animals & plants (where it has been proven experimentally for up to a century & is not disputed). Whatever creationists & LNT supporters say we are very similar at the cellular level.
It seems likely from the history of Kerala & similar natural radioactive sites that the optimum radiation level is considerably higher than we, or indeed the people of Chernobyl, experience.
Perhaps an analogy might be a place like fictional Mayberry which gets no real crime at all, vs. someplace that gets just enough managable crime to have an experienced police force. Mayberry will not deal with a biker meth gang coming to town as well as someplace more practiced at dealing with real trouble.
For example, a 2004 study claimed more than 10,000 Taiwanese accidentally exposed for a decade or more to radioactive recycled steel used in building construction showed much lower than expected rates of cancer and congenital heart defects. The cancer rate, for example, was 3.5 cases per 100,000, compared to a normal 116
If 10,000 Taiwanese were the sample population, how was the cancer rate 3.5 per 100,000? That would mean 1/3 of one person got cancer, right? Am I math impaired or is this a totally bogus statistic?
Well I’m not sure who you are quoting but the actual case lasted for more than 20 years before it was discovered so at 3.5 per 100,000 annually that would be above 7 cases, as against above 2,320.
I was quoting Cecil’s column, which didn’t say anything about the 3.5 figure being per annum. Assuming it was, though, that would be 3.5 * 10 years in the study = total of 35 cases per 100,000. Since the actual population cited was 10,000, divide that by 10 and we have 3.5 cases of cancer. Still got partial people there unless Cecil was really rounding his figures pretty wildly, no? Your figure of 7 assumes a population of 20,000 which is double what he cited.
And I think the scientists are right to be skeptical
And basic evolutionary theory says this is unlikely – Not impossible, but unlikely, meaning it’s rational to require a bit more positive evidence to be convincing.
The argument, in short words, is that if a more active ‘damage response’ is more healthy for an organism, why haven’t organisms evolved to have a higher response even before they’re zapped with excess radiation?
Different articles in my neighbourhood so thanks - I will keep them to hand. However it is clear from all 3 that though they find hormesis politically inconvenient & thus wish to temporise they are aware of clear & repeated evidence.
1 - “Frequently documented” by scientific experiment & “difficult to reproduce” are clearly mutually incompatible.
2 - Quite clearly accepts the data exists eg “The High Background
Radiation Research Group has investigated thyroid
nodularity and cancer rates in the Guangdong Province
in China, an area with a natural radiation level ‘@‘3
times normal (54). For the years 1975—1978t,he high
background area had a cancer mortality rate of 36.53
per 10(5) person-years, compared to 52.85 per iO@
person-years for the control area (4). In the U.S., the
states with the three highest mean radon levels (Cob
rado, North Dakota, and Iowa) show a lung cancer
death rate of 41 per i0@,as compared to a rate of 66
per i0@in the 3 lowest radon level states (Delaware,
Louisiana, and California)” (I wasn’t previously aware of the Guandong stuff)
3 - “Usually small being under 10%” is certainly an acknowledgement that it has been proven to exist. In any other field a 10% reduction in mortality would not be considered small. Lung cancer kills 1.3 million annually so clearly smoking has a much less than 10% effect on mortality which is not generally taken to mean that there is reasonable doubt of the connection.
All your links prove is the extreme disincentive among scientists to discuss a subject politicians have already decreed on when the scientists clearly know the politicians are not telling the truth.
However your last question is an interesting one - though irrelevent to the fact that radiation hormesis has been repeatedly experimentally observed it is relevent to the mechanism. If asked to guess & it is clearly only that, I would suggest that an evolutionary path that lowered the barrier to stimulation would have more than matching side effects - possibly making the immune system less effective in other areas, or likely to turn on itself or possibly making the body less able to detect other mutations. It is certainly a field in which far more research should have been done long ago. Indeed researching the not fuully understood is what scintists are supposed to do. 10% across the board for an unprocessed medicine is a lot.
I want state again that I’m skeptical of radiation hormesis myself, but there are pretty strong indications that the Linear No Threshold (LNT) hypothesis for radiation exposure is invalid.
I wonder if we have situation similar to the failure of the medical profession to recognize that most ulcers were caused by bacteria and could be cured by antibiotics. It is common for people to fail to recognize facts when there is a financial incentive not to recognize them. There was a industry that revolved around treating ulcers rather than curing them.
There is currently an industry that revolves around protecting people for low level radiation and disposing of low level radioactive waste. If those risks are in fact non-existent, then some people’s Ox is going to be gored big time.
Can’t argue with that Joel. Anybody respecting science must be sceptical. I think the case for hormesis to be much stronger than many things that are treated as fact though that (eg passsive smoking) is not a high standard. We absolutely should be doing, indeed should for decades have been doing, more research on it.
The LNT theory appears to have no evidential basis whatsoever, except for being another “scientific consensus”, but has deprived the human race of decades of cheap power & probably of a spacegoing civilisation by now, on top of the medical costs.
The heavily official LNT theory depends on there being no repair mechanism & thus the number of cancers is directly proportional to the number of interactions of radiation & cells. This theory predicts that large multicellular creatures with big ears & trunks will be particularly susceptible to radiation & will drop like flies. Flies won’t.
That brings up comic I read years ago. “It’s a proven fact that people will eat hot dogs, no matter what you put in them. This suggests an excellent method for disposing of nuclear waste.”
Not quite. Hormesis actually fits quite well with evolutionary theory. First you must realize that evolution does not select for long lifespan, but reproductive success. There’s only a slight fitness advantage to living longer in order to reproduce more often. The basic argument (supported by quantitative genetic modeling) is that genes that allow an individual to age a bit slower and reproduce successfully for an extra season or two don’t confer much of an advantage since that individual is likely to be killed off through a multitude of other causes (disease, predation, competition, etc). Furthermore, there’s a strong link between reproductive timing and longevity. Experiments have shown that if you take a population and select for earlier reproduction, you also get shorter lifespans. The converse is also true – select for delayed reproduction, and you get animals with longer lifespans.
How does this connect with hormesis? Well, that hits another fundamental evolutionary trade off: should I spend the resources to reproduce now, or grow and maintain my body so I can better reproduce later? In times of plenty, with good conditions and availability of food, a successful individual will reproduce as much as possible. But in harder times, that individual will have greater success by conserving resources to survive until better conditions arrive again. Hormesis is thought to be part of the mechanisms involved in sensing conditions, and allocating resources in the body accordingly.
Dietary restriction is probably the most obvious sort of example – it’s not exactly the same as hormesis, but it has a lot of shared underlying genetics. When there isn’t much food around, reproduction is clearly a foolish choice, since neither the parent nor the offspring are likely to survive. So under those conditions, animals activate genetic pathways that allocate resources away from reproduction and instead to maintenance and longevity. Similar results occur from other types of stress that are known to cause hormesis.
(FWIW, I study the genetics of longevity and hormesis, using aforementioned worms.)
There are actually plenty of reasons. While all plants and animals obviously do share many cellular mechanisms, they are not the same. Even though radiation hormesis clearly extends the lifespan of worms, flies, and possibly mice, there are still plenty of reasons why this may not apply to humans. The most obvious is that worms and flies do not get cancer of any sort! Mice do get cancers, but they’re not the same kinds that humans get. The underlying genetics is different enough that mice are susceptible to different sorts of cancer, and they will never live long enough to develop many of the slow growing cancers that are a major health concern for humans.
Finally, I’m not sure I understand the hostility you show towards the LNT model. We know that at some moderate radiation level, people have an elevated risk of cancer and increased mortality. Higher levels than that only increase the risk – this is well supported by all sorts of evidence. And with background radiation, there’s a certain “background” level of all sorts of health problems. It’s a fairly natural assumption to interpolate between those points and say that low levels of radiation probably cause a small risk increase.
Definitive human experiments would be grossly unethical, so all we can do for now is try to look for epidemiological evidence. Which is coming along (and you’ve cited many good studies!), but IMO there’s not evidence to state that low doses of radiation would provide a clear health benefit.
Inmteligently argued Lazybratsche. Firstly in my defence my objection is not to LNT being accepted post Hiroshima. Little information was available & it was an instance where the precautionary principle was valid. The problem is that that is 65 years ago & it has become a very official “consensus” despite a vast amount of evidence to the contrary. I came to this not through medicine but because I support nuclear power & the entire anti-nuclear scare depends on miniscule amounts of radiation being a real problem. Without this false scare we would have an enormously more developed nuclear industry. The “to cheap to meter” line is widely ridiculed by those who do not know its origin but it would not be impossible. Beyond that there is no doubt that if we had had nuclear space launches 45 years ago, as was possible, we would have a spacegoing civilisation now. It may just be my presbyterian heritage but such wasted opportunities offend me.
I am intrigued by the suggestion that the hormesis effect particularly extends life. That fits with the example of 75 cattle which were exposed to 150 rads during the Trinity A-bomb test in 1964 & kept for study. In 1964 they, or as many as remained, were put to sleep to avoid embarrassment. That would make them between 18 & 25 years old - the maximum recorded age of cattle is about 22. I regard destroying such evidence as a crime against science & humanity.
I didn’t realise flies never get cancer. I guess that makes elephants somewhat more susceptible.
Thinking over Lazybratsche’s words it strikes me that his definition of a moderate amount, above which radiation is dangerous is, from his experience, going to be something significantly above a normal X-Ray whereas the sort of moderate exposure I think of, in terms of nuclear, is something above 1.5 mSv a year, common natural background radiation & orders of magnitude less. Thus we have a broad agreement concealed by a common language.
Against my case it strikes me that there is evolutionary evidence that humans live much longer than would be expected of mammals like us (being able to engage in complex learning. longevity would be much more useful than for ordinary animals). If the mechanisms of longevity are already stretched by evolution it could be that humans will not benefit so much from radiation as animals do. This could perhaps be checked experimentally by comparing hormesis with lifespan in plants & animals, particularly related species with different lifespans.
Nonetheless a reduced benefit from hormesis is still a benefit & there is considerable evidence of hormesis in humans as I have linked previously.
So you’re arguing that
a) the U.S. Government – which had just invested millions in developing nuclear weapons and then millions more in researching and promoting nuclear power – was by 1964 so set on demonizing nuclear power that it would destroy evidence of nuclear power’s safety and cover it up; and
b) the U.S. Government – the largest and most unwieldy organization on Earth – was able to come to a single attitude about nuclear power, create a cover-up plan, and pull off the nefarious destruction of evidence (Presumably without audibly cackling, twirling its mustache on national TV, and bragging about it)?
But then, maybe you should consider whether you’re letting yourself perhaps a little bit see what you want to see. It’s easy to do, and very difficult to avoid – most of the hard work of science is figuring out how to make sure we’re not finding what we’re expecting and/or wanting. lazybratsche – thanks for your insight from someone actually in the field.
A) Government likes scare stories it keeps them in charge & remeber that the US government had all these scary nukes under their control
B) If you need moustachjes to make the scenario look silly then perhaps it isn’t. Occasionally governments, even the US one, don’t tell the truth.
Of course there is the risk of bias. That is why I have repeatedly said there should be research & criticised the failure to do so over the last 65 years. Thatr argument cuts both ways & where is your call for the LNT theory not being enforced until there is some evidence.
