11 replies to this topic

[olaf.larsson]

I wonder mutations are generally associated with cancer and not aging.
Suppose you irradiate mice frequently during their entire lifetime with high but sublethal radiation does.
Will the animals show sympoms similar sto premature aging?

[Cyberbrain]

Maybe ...

[spaceistheplace]

i live about 10 miles away from where they did some nuclear testing. according to those in charge it is safe but i have noticed high cancer rates in the area.

[olaf.larsson]

...but i have noticed high cancer rates in the area.

Radiation without doubt couses cancer but why is there no strong association between radiation and aging?

Edited by olarsson, 26 June 2007 - 06:32 PM.

[Live Forever]

RAdiation without doubt couses cancer but why is there no strong association between radiation and aging?

If radiation causes cancer, then it certainly is associated with aging since cancer (or, more specifically mutations within cells) is one of the components of aging.

Of course, just saying "radiation" does not explain a lot. There are different types of radiation, some of which are harmless.

[niner]

Radiation does cause mutations. High energy photons like X-rays or gamma rays are probably the most important from a health standpoint, because they penetrate deep into the body.

However...

Starvation is bad for you, but Caloric Restriction causes sirtuin activation which leads to improved health outcomes and longer lifespans. This phenomenon could be called starvation hormesis. "hormesis" occurs when something bad for you produces a good outcome in the right dose.

What does this have to do with radiation, you ask? A lot. Radiation induces your DNA repair systems (among other things) to become more active. This effect is not only enough to counteract the effect of the radiation, but also deals with other damage not caused by radiation. Humans exposed to the right dose of radiation have less cancer, and live longer than humans exposed to no radiation. This is known as radiation hormesis. There is a fairly extensive literature on radiation hormesis, although it is little known by the lay public. Google it. You'll be amazed.

[JohnDoe1234]

Yeah, niner, I've never heard of "radiation hormesis" but I have heard that living things need a certain amount of radiation to function (e.g. killing bacteria infections, providing energy)... I guess that is similar.

But anyway, I think it is definitely involved in aging, since a large component of aging is the accumulation of cell damage (which sounds good to me), I think that enough of the wrong radiation would be triggering the exact same sort of deterioration in your cells that would normally occur over a longer period of time due to "aging" I don't see how it couldn't bring about premature aging.

Aging isn't just memory loss and "scribbily skin" as 5yr olds call it now days. Aging is anything that causes your cells to function incorrectly with a net effect of killing you in my opinion, and radiation definitely has that potential.

EDIT: I need to ask my dad about this, but he mentioned some researchers found a genetically isolated group of fish which live in water pools in caves with no sunlight, and they have almost completely translucent bodies... now the interesting thing about this is that they also found their genetic cousins which still resided in the sun, and the ones who lived in the caves lived several times longer. Again, my facts might be skewed but I will ask my dad about this again and hopefully find an article or two

[bgwowk]

But anyway, I think it is definitely involved in aging, since a large component of aging is the accumulation of cell damage (which sounds good to me), I think that enough of the wrong radiation would be triggering the exact same sort of deterioration in your cells that would normally occur over a longer period of time due to "aging" I don't see how it couldn't bring about premature aging.

I'm afraid this is completely wrong. Mutations are a practically negligible part of aging, and there is no evidence that radiation affects normal human aging. People have been accidentally exposed to 100 times typical background radiation levels at a low dose rate for years with no obvious effects on health. As a medical physicist, I must point out that unnecessarily exposing people to such high doses is not ALARA (as low as reasonably achievable) and therefore not recommended. But that people have been exposed to high doses of radiation for decades without experiencing accelerated aging refutes the notion that typical human radiation exposures contribute to aging.

If you wonder why mutations have such little importance in aging, Aubrey deGrey explains it as follows: There are certain mutations in single cells that rapidly kill the entire organism. They are known as cancer. To survive any length of time, mulicellular organisms need powerful repair systems that protect against cancer-causing mutations. The side effect of this cancer protection is powerful repair systems against mutations generally. Any mutations that overwhelm our amazing repair systems are going to first manifest as cancer, not aging. And indeed the primary effect of large sub-lethal doses of radiation is cancer, not aging.

[olaf.larsson]

But that people have been exposed to high doses of radiation for decades without experiencing accelerated aging refutes the notion that typical human radiation exposures contribute to aging.

bgwowk do you have a source for this claim? There must be papers were mice are exposed to chronic high, but sublethal radiation.
Yesterday I saw claims in one text that mice aged more rapidly due to sublethal radiation exposure. Unfortunatly I dont remember were the text was.

Edited by olarsson, 26 June 2007 - 07:59 PM.

[bgwowk]

bgwowk do you have a source for this claim?

One of the problems of assessing radiation risks in humans is that at cummulative doses less than 100 years worth of background (3 mSv per year), biological effects barely climb out of the noise. There are only a few historical instances of large groups of people getting more radiation than this to their whole body. One is A-bomb survivors, which is the most widely used dataset for extrapolating human radiation risk. Another is this amazing incident in Taiwan where hundreds of people where exposed to large sublethal doses of radiation for years because of radioactive isotope contamination of the rebar used to build their apartment buildings.

http://www.jpands.org/vol9no1/chen.pdf

Nobody experienced accelerated aging, nor would they be expected to for reasons I've already explained. Sublethal radiation doses increase the risk of specific pathologies like cancer and cataracts (though the opposite effect was observed in the Taiwan incident), but not generalized aging.

There must be papers were mice are exposed to chronic high, but sublethal radiation.

There have been lots of animal radiation radiation experiments. Generalized aging is not on the menu of known bioeffects of radiation. Look, people get acute doses of *thousands* of times annual background radiation to specific parts of their body (or even the whole body for bone marrow transplants) during the course of cancer therapy, and they don't turn into old men and women. This is because mutations are not a big part of aging.

[advancedatheist]

The science fiction author H. Beam Piper, writing a few years after the invention of the atomic bomb, postulated that advanced human civilizations would use nuclear power so extensively, including in warfare, that natural selection would favor people with a tolerance to much higher background radioactivity levels. Everything on Earth would become radioactive at much higher levels than today, including human bodies. What would happen if someone with a highly radioactive body travelled backwards in time to the era before this adaptation had occurred?

Piper wrote a story about it, titled "Flight From Tomorrow," which orignally appeared in some pulp science fiction magazine. The link also features a couple of really cheesy illustrations, apparently from its original venue.

[caston]

You guys may want to check out the Chernobyl tissue bank:


http://www.chernobyl...m/research.html

At the moment I'm reading oxygen: the molecule that changed the world by Nick Lane.

Interesting that we need oxygen so that our mitochondria can produce energy but at the same time oxygen is actually a deadly toxin and most of it got here as a by-product of photosynthesis. In the book it describes it as stripping electrons like a paint stripper strips paint. Certain oxygen hating bacteria when placed in water containing oxygen will move to the side of the tank with the least amount of oxygen. When the amount of oxygen is even throughout they will clump together. Perhaps this explains in very simple terms why we have multicellular life forms.

I'm willing to bet that exposure to oxygen causes far more mutations and cell death than (in most situations) radiation does yet we reply on it as it is vital for our respiration.

I do think it might be possible that exposure to certain amounts of radiation may up regulate DNA repair. You may notice that some people that spend a lot of time with computers look very young for their age.

I'm fascinated by the idea that it might somehow be possible to adapt our bodies to survive without oxygen.

"Anaerobic humans" anyone?

Even if it could be done would you leave the oxygen breathing world behind so that you could avoid ageing?