Study suggests that at low dose-rate, radiation poses little risk to DNA

[Tank]

New look at prolonged radiation exposure: Study suggests that at low dose-rate, radiation poses little risk to DNA

A new study from MIT scientists suggests that the guidelines governments use to determine when to evacuate people following a nuclear accident may be too conservative.

The study, led by Bevin Engelward and Jacquelyn Yanch and published in the journal Environmental Health Perspectives, found that when mice were exposed to radiation doses about 400 times greater than background levels for five weeks, no DNA damage could be detected.

Current U.S. regulations require that residents of any area that reaches radiation levels eight times higher than background should be evacuated. However, the financial and emotional cost of such relocation may not be worthwhile, the researchers say.

"There are no data that say that's a dangerous level," says Yanch, a senior lecturer in MIT's Department of Nuclear Science and Engineering. "This paper shows that you could go 400 times higher than average background levels and you're still not detecting genetic damage. It could potentially have a big impact on tens if not hundreds of thousands of people in the vicinity of a nuclear powerplant accident or a nuclear bomb detonation, if we figure out just when we should evacuate and when it's OK to stay where we are."

Until now, very few studies have measured the effects of low doses of radiation delivered over a long period of time. This study is the first to measure the genetic damage seen at a level as low as 400 times background (0.0002 centigray per minute, or 105 cGy in a year).

"Almost all radiation studies are done with one quick hit of radiation. That would cause a totally different biological outcome compared to long-term conditions," says Engelward, an associate professor of biological engineering at MIT...

This is an interesting finding that has cropped up in different guises for many years. I first saw a BBC Horizon programme on this. There are areas on Earth with far higher level of background radiation than would be considered safe. One is in Turkey where the background radiation is 200 times the average yet the incidence of radiation induced cancers was not raised. It would appear that as all organisms have evolved in a radiation saturated environments, all be it at a low level, there are mechanisms to repair low level damage to DNA.

[Sweetdeath]

Well, dont we already get low dose radiation from our phones and computers?

[Tank]

Well, dont we already get low dose radiation from our phones and computers?

Sort of. When one considers radiation there are two uses of the word. There is the radio energy 'radiating' from your phone or PC which is a lot less dangerous than the ionising 'radiation' coming from radioactive elements such as uranium and plutonium. When one considers the 'background radiation' dealt with in this article it's the second type or ionising radiation from radioactive elements and cosmic rays. Air crew are subjected to a much higher radiation dose from cosmic rays than people living at sea level. The atmosphere is quite a good protective barrier.

[xSilverPhinx]

I just watched a PBS documentary on 'Radioactive Wolves' (as it's called) living in abandoned Chernobyl. It seems life is actually thriving really well there, even though it's been stipulated that the radiation levels are still too high for humans to live there.

Though there it would be the other way round, animals which live in the soil have a higher exposure rate than those who don't.  

[Tank]

I just watched a PBS documentary on 'Radioactive Wolves' (as it's called) living in abandoned Chernobyl. It seems life is actually thriving really well there, even though it's been stipulated that the radiation levels are still too high for humans to live there.

Though there it would be the other way round, animals which live in the soil have a higher exposure rate than those who don't.  

Definitely seeing contradictory reports about Chernobyl wildlife. There appears to be a lot of it, there is quite a bit of mutation and of course we don't see the spontaneously aborted or unsustainable mutations that are stillborn or die shortly afterwards. So we are seeing the non fatal mutations which could well be biasing conclusions.

[xSilverPhinx]

I just watched a PBS documentary on 'Radioactive Wolves' (as it's called) living in abandoned Chernobyl. It seems life is actually thriving really well there, even though it's been stipulated that the radiation levels are still too high for humans to live there.

Though there it would be the other way round, animals which live in the soil have a higher exposure rate than those who don't. 

Definitely seeing contradictory reports about Chernobyl wildlife. There appears to be a lot of it, there is quite a bit of mutation and of course we don't see the spontaneously aborted or unsustainable mutations that are stillborn or die shortly afterwards. So we are seeing the non fatal mutations which could well be biasing conclusions.

Could be, and I guess we'll see if those mutations are deleterous in the future. Don't know if something with some sort of hyper DNA correction mechanism could evolve out of that environment, but I'm just speculating.

[Tank]

I just watched a PBS documentary on 'Radioactive Wolves' (as it's called) living in abandoned Chernobyl. It seems life is actually thriving really well there, even though it's been stipulated that the radiation levels are still too high for humans to live there.

Though there it would be the other way round, animals which live in the soil have a higher exposure rate than those who don't. 

Definitely seeing contradictory reports about Chernobyl wildlife. There appears to be a lot of it, there is quite a bit of mutation and of course we don't see the spontaneously aborted or unsustainable mutations that are stillborn or die shortly afterwards. So we are seeing the non fatal mutations which could well be biasing conclusions.

Could be, and I guess we'll see if those mutations are deleterous in the future. Don't know if something with some sort of hyper DNA correction mechanism could evolve out of that environment, but I'm just speculating.

Based on our understanding of natural selection I think there is every reason to believe that extended radiation immunity will develop in organisms in the Chernobyl radiation area. With so much mutation across so many species across such an extended area over such a long period of time the probability of advantageous mutations occurring and then being fixed in the population must be higher that in normal environments. How much higher I couldn't say but I would guess significant.