AW: [ RadSafe ] Contribution from natural back ground radiation andmedical radiation procedures

Wed Feb 15 03:15:04 CST 2006

Dear Dr Rainer  Facius,
  Thank you very much for the information.Values of medical radiation doses to population in different countries are available in UNSCEAR publications.Also it seems that most of it, in developed countries is contributed by computed tomography examinations. What is notable is that in many countries a substantial part of radiation exposure to population comes from medical radiation procedures.The absolute values may differ from individual to individual. This is likely to be a major confounding factor in epidemiological studies of radiation workers.
  For a radiation worker with an occupational history of 20 to 25 years, the occupational radiation dose may be higher during the early part of his career; dose from medical radiation sources may be less. During the end of his career, medical radiation dose may be a significant part of the total dose.Occupational doses indicate decreasing trends whereas medical exposures show increasing trends.
  But human tissue is "secular"; it will not distinguish between medical radiation and occupational radiation!
  With best regards
  K.S.Parthasarathy

Rainer.Facius at dlr.de wrote:
  Dr. Parthasarathy:

In Germany the average annual exposure from medical sources - nearly 100% from diagnostic X-rays as you say - amounts to 2 mSv rather than 1 mSv per caput.

Regards, Rainer

Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX: +49 2203 61970

________________________________

Von: radsafe-bounces at radlab.nl im Auftrag von parthasarathy k s
Gesendet: Mi 15.02.2006 05:36
An: mister radiation; goldinem at songs.sce.com; radsafe at radlab.nl
Betreff: [ RadSafe ] Contribution from natural back ground radiation andmedical radiation procedures

Art Vandaly,
Yet another important variable is the contribution from medical radiation procedures.The average effective dose to population from medical radiation procedures (mostly from diagnostic x-ray procedures) could be as high as one mSv annually in advanced countries. The absolute dose will be different for different workers. The integrated dose to these workers over the years will be of the order of or more than their occupational dose.
I recollect when the erstwhile National Radiological Protection Board UK (J.A.Reissland, NRPB-R-79) reviewed the work of Mancuso et al on Hanford workers, the variability of the background radiation dose and medical radiation dose was highlighted. Mancuso et al in their analysis reported doubling doses for cancer of the bone marrow as 0.8 rad;pancreas 7.4 rad; lung 6.1; all cancer 12.2 rads. Mancuso's paper was published in Health Physics (1977). Mancuso's paper drew extensive criticism.
Regards

K.S.Parthasarathy Ph.D
(formerly, Secretary, Atomic Energy Regulatory Board)
Raja Ramanna Fellow
Department of Atomic Energy
Room No 18
Ground Floor, North Wing
Vikram Sarabhai Bhavan
Mumbai 400094
E-mail ksparth at yahoo.co.uk
91+22 25555327 (O)
91+22 25486081 (O)
91+22 27706048 (R)
9869016206 (mobile)

mister radiation wrote:
Eric,

You have hit the nail squarely on the head. BAM!!! The background and it's variability is ignored in such epidemiological studies. For that reason they are not as useful as we like to tell people. The variation in dosimeter readings is also never considered. (This keeps employers from being sued and fined into oblivion when that dose comes in just under the limit.) Not to knock the radiationepidemiologists, it is difficult to find the right piece of hay in giant haystack.

The good news in all of this is that we will be able to continue debate Hormesis vs. LNT models for all eternity.

Have a nice day,

Art Vandaly

goldinem at songs.sce.com wrote:

Somehow I've been roped into helping some high school students on a
radiation biology project. I suggested that they look into some major
epidemiological questions - one them being the risk from occupational
exposure. I have the BMJ Cardis paper on the 15 countries and had a
quick question. The cumulative exposure for the workers under
consideration averaged about 20 mSv. But for the sake of argument, most
of the workers are about 40 years old so they'd have an additional 100
or more mSv from natural background alone. I am far from an
epidemiologist but I assume that the basis for the risk coefficient
development was the determination of risks as a function of dose for the
dose distributions. But wouldn't the variability in natural background
be a huge confounder? I didn't see anywhere in the paper where natural
radiation exposure was even addressed.

Anyone have any clue whether that was considered or am I just missing
it? Thanks, Eric

Eric M. Goldin, CHP

_______________________________________________
You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html

For information on how to subscribe or unsubscribe and other settings visit: http://radlab.nl/radsafe/

---------------------------------
Brings words and photos together (easily) with
PhotoMail - it's free and works with Yahoo! Mail.
_______________________________________________
You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html

For information on how to subscribe or unsubscribe and other settings visit: http://radlab.nl/radsafe/

---------------------------------
To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre.
_______________________________________________
You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html

For information on how to subscribe or unsubscribe and other settings visit: http://radlab.nl/radsafe/

---------------------------------
How much free photo storage do you get? Store your holiday snaps for FREE with Yahoo! Photos. Get Yahoo! Photos