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Chernobyl's legacy
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biffvernon



Joined: 24 Nov 2005
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PostPosted: Wed Apr 27, 2011 5:45 pm    Post subject: Reply with quote

Squabbling over deaths from radiation is a bit silly. The fact is that we just don't know how good biology is at repairing damage from ionising radiation. A single gamma photon, beta particle or alpha particle has the potential to knock out a critical atom from a DNA molecule and trigger a cancer. It doesn't happen often and when it does happen repair is usually possible. Repair is less likely if two critical atoms of a pair are knocked out in close succession with insufficient time for repair. That's more likely if the rate of radiation arriving is higher.

A critical unanswered question is whether there is a low threshold below which ALL damage is repaired. If so, then deaths from events like the Chernobyl accident will be on the low side of estimates. If there is no threshold, but damage and subsequent cancer rates, decreases linearly all the way to zero with declining radiation exposure, then the big numbers of hundreds of thousands of excess Chernobyl deaths will be the true picture. However, even hundreds of thousands of excess cancer deaths would be lost in the general population and only careful epidemiology over time will indicate the truth.

Anyone who says with certainty how many deaths have or have not been, will or will not be, caused by our nuclear experiment does not understand the science, or is being wilfully disingenuous.

Me, I prefer the precautionary principle, and think the linear no-threshold model (LNT) should be accepted until it is proved wrong.

http://en.wikipedia.org/wiki/Linear_no-threshold_model
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RenewableCandy



Joined: 12 Sep 2007
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PostPosted: Wed Apr 27, 2011 5:58 pm    Post subject: Reply with quote

Quote:
A critical unanswered question is whether there is a low threshold below which ALL damage is repaired.
I've a feeling there is, but that it's very-little higher than the levels a typical person is exposed to. People live in Cornwall, and Aberdeen, and at high altitudes, after all.

But the nuclear industry should no more seize on that as an excuse to be lax, than the baccy industry should (for example) seize on RenewableGranny, who was a 40-a-day lady from the age of 14 'til...90!
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kenneal - lagger
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PostPosted: Wed Apr 27, 2011 6:15 pm    Post subject: Reply with quote

The position is further complicated by the question of whether the radiation source has been ingested in some way or not.
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Aurora



Joined: 24 Jan 2007
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PostPosted: Wed Apr 27, 2011 6:18 pm    Post subject: Reply with quote

Interestingly, a Prof Geraldine Thomas (Molecular Pathology Dept. Imperial College) was featured in an MSN article today.

Quote:
<snip>So what have we learnt from Chernobyl? Cancer risk is determined by the age at exposure and concentration of radioisotopes in particular tissues. Low dose exposure to caesium-137, even over a long period of time, is perhaps not as damaging to health as we would have predicted.

The one thing we appear not to have learnt is how to deliver information about radiation risk to an exposed population. There have been considerable psychological consequences, unrelated to the actual radiation risks for human health, from the Chernobyl accident, which have been poorly researched.

Radiation risk must be put into context. The consequences for the most exposed group of atomic bomb survivors was an average loss of life expectancy significantly lower than that caused by severe obesity or smoking. A rational debate about nuclear power means putting the risks and benefits into perspective. Unfortunately it seems that when radiation knocks at the door, science and rational thinking go out of the window.

Original Article

I'm with Biff. What's wrong with the LNT model? Smile
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biffvernon



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PostPosted: Wed Apr 27, 2011 6:20 pm    Post subject: Reply with quote

RenewableCandy wrote:
I've a feeling there is, but that it's very-little higher than the levels a typical person is exposed to. People live in Cornwall, and Aberdeen, and at high altitudes, after all.
And people in Aberdeen Cornwall and at high altitudes die of cancer. Sorting the radiation related deaths from the noise of all the others is the tricky part. With all due respect for your feelings, RC, they ain't very scientific.
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RenewableCandy



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PostPosted: Wed Apr 27, 2011 6:59 pm    Post subject: Reply with quote

biffvernon wrote:
RenewableCandy wrote:
I've a feeling there is, but that it's very-little higher than the levels a typical person is exposed to. People live in Cornwall, and Aberdeen, and at high altitudes, after all.
And people in Aberdeen Cornwall and at high altitudes die of cancer. Sorting the radiation related deaths from the noise
can never be done precisely but one can for example try and put together "matched" populations (i.e. all other things equal) and compare.

The fact that very low-level (external) radiation exists in nature, and that we are all still here, would imply that we have somehow evolved some extent of a protection mechanism against it.
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biffvernon



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PostPosted: Wed Apr 27, 2011 9:00 pm    Post subject: Reply with quote

Yes indeed. I'm not a biologist but I gather DNA has kinda pairs of sticky out bits and if one half of a pair gets damaged then its easy to repair it because the other half acts as a template. If both halves get zapped at the same time there's trouble. With a low rate of radiation it is very unlikely that this should happen, hence we tend to stay alive. But it's only a tendency.
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biffvernon



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PostPosted: Wed Apr 27, 2011 9:10 pm    Post subject: Reply with quote

kenneal wrote:
The position is further complicated by the question of whether the radiation source has been ingested in some way or not.


Oh yes, that makes all the difference. A tiny speck of radioactive dust in the body sits there zapping the same spot for ever. Iodine concentrates in the thyroid gland and has most certainly caused a great many thyroid cancers in the Chernobyl area, though with treatment this is usually not fatal. Alpha emitters such as plutonium can be handled safely but inside the body are deadly.

In the video I posted recently of the survey in Fukushima City, the measurements of average radiation in the air are not so worriesome but accumulations of dust deposited at the outflows of roof gutters and downpipes suggest that a child playing in the dirt and then liking its fingers could easily get a deadly dose.
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An Inspector Calls
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PostPosted: Thu Apr 28, 2011 8:47 am    Post subject: Reply with quote

I've said before: as a first pass or for day to day safety of operations, use LNT.

But it clearly hassn't worked in the case of Chernobyl - simply contrast the initial high projections with out-turn.

And I certainly do not accept Busby's homeopathic view of radiation damage.
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DominicJ



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PostPosted: Thu Apr 28, 2011 9:25 am    Post subject: Reply with quote

Quote:
Me, I prefer the precautionary principle,

Unsurprising, you do know its inherantly flawed dont you?

Since we have no way of knowing which way is "precautionary", without crystal balls.

For example
Burning fossil fuels in tractors, may cause global warming, and kill billions of people, so as a precaution we should not burn fossil fuels.

Not burning fossile fuels in tractors, may cause global foodshortages, and kill billions of people, so as a precaution, we should burn fossile fuels.

See?
The precautiobnary principle only works if you discount the arguements you dont like.

Whatever we do, people die.
The precautionary principle ignores that fact that not doing something *IS* doing something.
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2 As and a B



Joined: 28 Nov 2008
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PostPosted: Fri Apr 29, 2011 7:29 am    Post subject: Reply with quote

No silly! It's about damaging the environment we depend upon.

The second case in your example is not precautionary, it is exploitative. It is what we, as a species, have done and continue to do. In the end there will be many more billions die off than if we had burned fossil fuels so as to maintain a steady state - and of course to have put fossil fuel investment into developing and implementing sources of renewable energy.
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DominicJ



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PostPosted: Fri Apr 29, 2011 8:34 am    Post subject: Reply with quote

Foodimista
It sounds like your argueing for a cost benefit analysis.
Which Is what I would advise.

Remember Avian Flu?
Was going to kill us all?
As a precaution, the government spent billions on drugs for Avian Flu?
Then there was no outbreak?

What if it had spent those billions on windfarms instead?
Precaution against avian flu prevented precaution against global climate disruption change

The Precautionary Principle ignores the fact that we have scarce resources, it exists in the government world, where other peoples wallets are an unlimited resource.
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2 As and a B



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PostPosted: Fri Apr 29, 2011 9:05 am    Post subject: Reply with quote

I think you mean swine flu.

I am not arguing for a cost benefit analysis. I am saying that we should introduce technology only when we know for sure that it will not damage the environment that we all, man and all other life, depend upon.

Of course politics comes into the decisions that are made about the use of technology. And of course the natural tendency is to exploit energy sources. And of course I wonder whether it could ever have been otherwise or whether we can avoid what would be the inevitable collapse - whether we can turn it around in the last seconds before midnight. But then if no one cared and everyone was just busy enjoying the party, the collapse would be inevitable and very, very painful.
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