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Re: FW: ICRP Discussion paper
Dear Nick, Radsafers,
Warm seasonal greetings returned from the Southern hemisphere. Thanks for
forwarding the ICRP discussion document. I tend to support your comments.
Paragraph 12 (also 11) on page 4 has a slight evangelising ring to it, for
the simple reason that the enormity of numbers in the molecular world is
carefully avoided. One milli-Gray (100 mR, ~ the annual dose limit to the
public) actually equates, according to a quick calculation, to 1.8e14
ionisations per kilogram of tissue. That means damage to a large number of
cells, even considering say 0.1% pertains to material in cellular nuclei.
The statement in this form about radiation damage to one cell as an
initiating event seems unbalanced and not quite in context. Of course,
this also neatly sidesteps the "natural" processes which cause and repair
150 000 DNA breaks per day in every cell. Cheers.
Own musings
Chris Hofmeyr
chofmeyr@nnr.co.za
You wrote:
"Tsurikov, Nick"
<nick.tsurikov@ilu To: Multiple recipients of list
ka.com> <radsafe@romulus.ehs.uiuc.edu>
Sent by: cc: (bcc: Christoph Hofmeyr/CNS1)
radsafe@romulus.eh Subject: FW: ICRP Discussion paper
s.uiuc.edu
2000/12/21 06:08
Please respond to
radsafe
Merry Christmas and Happy New Year from Eneabba (+38 C today...)!
For your information, the latest discussion paper from Prof Roger Clarke,
Chairman of ICRP, on the possible revision of the ICRP Recommendations is
posted on Australasian Radiation Protection Society (ARPS) Web site, the
link is http://www.arps.org.au/ICRP_Dev.htm
<http://www.arps.org.au/ICRP_Dev.htm> Please do have a look.
I posted some questions/comments to ARPS list, but did not get any comments
back yet. Maybe someone can enlighten me?
>>>>>>>>>>>>>>
There are some interesting points in the paper:
1. Paragraph (12) on page 4 says: "Because the sequence of events leading
to
cancer can start in the DNA of a single cell, and because the effectiveness
of the repair mechanisms is unlikely to vary with small doses above those
from natural radiation sources, it is likely that there is no threshold of
dose below which there is no probability of stochastic effects."
2. Paragraph (16) on page 5 says: "The first consideration in the proposed
system of protection is to limit the dose to each individual from each
controllable source. The need for protective action is influenced by the
individual dose, but not by the number of exposed individuals. The second
consideration stems from the recognition that there is likely to be some
risk to health, even at small doses."
OK, so there is no safe dose of radiation... We know that...
Now, let's have a look on Table 2 on page 17. What it's saying to me that
if the dose for a worker in a 'practice' is 9.95 mSv/year - I do not need
to
do anything at all - "no further action"... And if the dose in a practice
is about 95 mSv/year I will need to either "plan to reduce the dose" or
"consider reducing the dose"...
IS THIS WHAT I THINK IT IS? DOES ICRP PLANNING TO INTRODUCE A KIND OF AN
EFFECTIVE "THERSHOLD"...?
Somehow it does not work together with statements in paras (12) and (16),
or
may be I am misunderstanding something?
Does this mean that we do not need to have any radiation protection
programs
and if there will be any questions from a regulatory authority, we all just
answer - "please see ICRP recommendations, they say that we don't need to
bother for anything below 10 mSv"?
How we can possibly justify any reduction of the dose if ICRP says it's
OK...?
If I am an RSO for a practice (mine, processing plant, hospital,
laboratory,
nuclear power plant, whatever) I know that we have to reduce dose as low as
reasonably practicable. But with the ICRP document like this one... I
should forget about all the funding for radiation protection and the
position of an RSO will be redundant in about a month (it's not that I mind
- I am also noise, ventilation and occupational hygiene specialist, so - no
worries for me personally). That's the problem - that radiation hazard
will
become something like "illumination" or "vibration" one (usually low
priority).
And HOW do we suppose to explain to our employees and "save the earth,
dude"
activists that dose 9.5 mSv/year is OK if "there is no safe dose", may I
ask???
I will definitely appreciate some enlightenment on this, please.
<<<<<<<<<<<<<<<
Kind regards
Nick Tsurikov
Eneabba, Western Australia
http://eneabba.net/ <http://eneabba.net/>
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