-"harry" wrote in message
...
-On 8 Aug, 14:57, Tim Streater wrote:
In article
,





harry wrote:
On 8 Aug, 10:15, Tim Streater wrote:
In article
,

harry wrote:
That is complete ********. Radiation exposure is cumulative. The NS
is a political magazine representing entrenched interests in the
USA.
(Mainly medical)
No level of radiation exposure is safe.

Better get your lead underwear on, then. You're exposed to radiation
all
the time. Hmmm. cosmic-ray levels are quite high at 30k ft, so all
flying is out, better not go anywhere where there's granite (lots of
radium) or near any coal fired power station (1 part per million of
uranium in coal, lots of Radon emitted).

No place to hide, really, for you :-)
Quite right. Why do you suppose there has always been people died of
cancer?
The more you get, the greater chance of getting cancer.

The greatest cause of cancer is the oxygen you breathe.It is carefully
transported around the body and delivered to your cells where combustion
takes place, and energy is produced. Some of the by product of this is
oxygen radicals that are *highly* reactive chemically and attack your
DNA. This causes damage. Fortunately all cells have repair mechanisms
that fix this damage up, continually. Above a certain level of damage,
however, these mechanisms can't cope. And for reasons I won't go into,
this gets worse as you get older.

Radiation splits up water molecules and produces the same sort of oxygen
radicals, which is why the damage is similar. Below a certain radiation
level, the body copes. Above it, it can't. That's why Linear no
Threshold is cobblers.

--
Tim

"That excessive bail ought not to be required, nor excessive fines
imposed,
nor cruel and unusual punishments inflicted" -- Bill of Rights 1689- Hide
quoted text -

- Show quoted text -

-Another hypothesis here says the exact opposite.
-http://cancerres.aacrjournals.org/content/55/8/1617.short

It would hardly be surprising that free radical formation can kill cancerous
cells although if you read later papers that cite the one above you will see
that the methodology used above does not prevent tumour growth in a whole
body system although there do seem to be some interesting effects when the
oxygen radical is combined with poly ethylene glycol. Of course a man, like
yourself, with such a vast scientific background will know that modeling an
effect in mice (*) does not actually mean there will be as much of an effect
when used clinicaly.

The low end of all dose response curves has always been difficult to draw as
there are legitimate differences in the way that models are drawn in order
to compensate for a lack of definite knowledge of the effects of low doses
(of compund or radiation) - there is a general acceptance that there is no
threshold for carcinogenic or mutagenic effects this does not mean that
there is a straight line relationship between dose and response - but there
is a lack of evidence for extremely low dose response curves due to the
difficulty in identifying the actual causes of harm in the large population
sizes needed to gather such data.

Cheers

Mark

(*)I may be unusual here in actually having conducted animal studies into
carcinogenicity - although I don't do this anymore.



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