Re: 20 mSv/a - 17 Sv/min - Chernobyl

[Harald Weiss <weiss@ki.comcity.de>]

Dolf Brits schrieb:
> 
> 1. 20 mSv/a
> 
> It has been stated in the paper that "low doses of radiation caused a much
> larger risk of cancer than expected from the linear model". The (only)
> researcher on this topic mentioned by name is Wolfgang Kohnlein who "argued
> that the actual risks of radiation exposure may be 20 times higher than
> predicted by the linear model".
> 
> Should we now plan for a future lowering of dose limits ?

This is a main thesis supported by the "Gesellschaft fuer
Strahlenschutz" in Germany, namely Prof. Koehnlein and Dr. Kuny. It is
opposed to the findings of numberous other knowledged researchers
throughout the world, that indicate that low level radiation is less
harmful than predicted by the linear model. The majority of the
professionals in this field (in Germany represented by the "Fachverband
fuer Strahlenschutz") doesn't follow Koehnlein et al. I expect ICRP will
sooner or later recommend a dose/effect model that assumes no risk by
radiation doses up to 3 or 5 mSv/a (uniform or fractioned). I guess you
should wait for further evidence before taking actions.

> 
> 2. 17 Sv/min
> 
> Now how do you explain spending money on a 20 mSv/a dose limit to a miner
> who faces extremely though (and lethal) working conditions. ?
> The person that received 1000 times the dose (in about a minute), against
> which the miner is protected over a year, is not killed instantly.

I think you ought not mix this up. 250 mGy as a one-time whole body dose
temporarily cause symptoms of acute illness, 10 Gy are expected to be
lethal. Smaller doses will not lead to acute illness but may cause
statistical effects: cancer and damage to the germ cells. Thumb values
range in the order of magnitude of a 1 % risk for a fatal carcinom per
person-Sievert applied dose, compared to a 30 % risk of spontaneous or
other not radiation induced fatal cancer. The limit of 20 mSv/a is fixed
so as to ensure that this risk is not greater than normal risks in life,
even in working places with a high safety standard. You might consider
raising this limit according to other risks in hazardous jobs, but I
would consider such an approach not only questionable but objectable.
Radiation safety should not be a luxury but a standard.

> 
> 3. Chernobyl deaths
> 
> a). ... "Chernobyl....caused an estimated 25 000 deaths from cancer".
> 
> b). The Chernobyl report of the NEA Committee of the OECD (Nov 1995) refers
> to 31 dead (p.12), a significant increase in carcinomas (no deaths ?) among
> children (p.13) and not even "any increase in cancers" (p13) in the
> population. This population however received significant doses - 120 people
> received more than 200 mSv during 1986-89 (p. 51).
> 
> c). According to the Ukraine's ambassador, the "Chernobyl disaster killed 4
> 229 people" as reported on
> http://www.chernobyl.com/health.htm.
> 
> How many Chernobyl deaths ?
> 

You can count the victims of acute illness only. The victims of
statistical effects can only be estimated, with a huge uncertainty. Try
your own estimate, perhaps based on the figures I gave above. I'm afraid
we will never know better.

These all are my personal opinions which not necessarily coincide with
those of my employer or his customers. 

Harald

--
Harald Weiss     weiss@ki.comcity.de
Preetzer Strasse 263, D-24147 Kiel, Germany
..

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