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RE: Medical radiation workers see reduction in cancer risk
That is 30 Gy per year. Less deadly.
--- Sandy Perle <sandyfl@earthlink.net> wrote:
> Isn't 1 Gy equal to 100 rads. 30 Gy would be ...
> Deadly!
>
> --
> Sent from my PalmOne Treo
>
> -----Original Message-----
> From: Stabin, Michael
> Date: 9/22/04 8:18 am
> To: John Jacobus, radsafe,
> know_nukes@yahoogroups.com
> Subj: RE: Medical radiation workers see reduction
> in cancer risk
>
>
> I have to agree that a level of 30 Gy per year
> should not be recommended
> for radiation workers.
>
> Mike
>
> Michael G. Stabin, PhD, CHP
> Assistant Professor of Radiology and Radiological
> Sciences
> Department of Radiology and Radiological Sciences
> Vanderbilt University
> 1161 21st Avenue South
> Nashville, TN 37232-2675
> Phone (615) 343-0068
> Fax (615) 322-3764
> Pager (615) 835-5153
> e-mail michael.g.stabin@vanderbilt.edu
> internet www.doseinfo-radar.com
>
>
>
> -----Original Message-----
> From: owner-radsafe@list.vanderbilt.edu
> [mailto:owner-radsafe@list.vanderbilt.edu] On Behalf
> Of John Jacobus
> Sent: Wednesday, September 22, 2004 7:35 AM
> To: radsafe; know_nukes@yahoogroups.com
> Subject: Medical radiation workers see reduction in
> cancer risk
>
>
> I saw this through another list server and thought
> it
> would be of interest.
> -----------------------
> Medical radiation workers see reduction in cancer
> risk
> 9/21/04
> By: Shalmali Pal
>
> Thanks to stringent radiation protection policies,
> the
> cancer risk for modern imaging professionals has
> been significantly
> reduced. Unfortunately, the same cannot be said for
> their predecessors,
> who showed markedly higher rates of disease,
> according to a
> meta-analysis in the journal Radiology. Shinji
> Yoshinaga, Ph.D., and
> colleagues from Japan and the U.S. reviewed
> previously published
> epidemiologic data on cancer risks in more than
> 270,000 international
> radiologists and technologists.
>
> While close attention should be paid to the risk
> posed
> to patients from localized, high radiation doses,
> the detrimental
> effects of worker exposure to low doses over the
> whole body should not
> be neglected, said Yoshinaga, who is from the
> National Cancer Institute
> (NCI) in Bethesda, MD, and the National Institute
> for Radiological
> Sciences in Chiba, Japan. Yoshinaga's co-authors are
> also from the NCI.
>
> The authors compiled data from eight studies
> conducted
> in the U.S., the U.K., Denmark, China, Japan, and
> Canada between 1920 and 1998.
>
> "These cohorts represent a valuable source of
> information obtained from a large number of people
> who
> worked over several decades during which modern
> radiology and radiologic protection evolved," they
> wrote (Radiology, September 16, 2004).
>
> The authors parsed the earlier studies for the
> standardized mortality ratio (SMR), or the ratio of
> the number of deaths, and the standardized incidence
> ratio (SIR), which is the ratio of the number of
> incident cases. The specific disease processes they
> examined included leukemia, melanoma, and breast
> cancer.
>
> Their two main findings were as follows: Increased
> mortality due to leukemia was found among radiology
> professionals who
> worked before 1950, when recommended radiation doses
> started at a high
> of 30 Gy per year, before dropping to 0.3 Sv per
> year, and then down to
> 0.1 Sv per year.
>
> The SMR/SIR was 1.75-2.29 for leukemia found in U.S.
> radiologists,
> Japanese technologists, and male Chinese x-ray
> workers. From 1920-1939,
> the SMR was 1.38 for all cancers in U.S.
> radiologists versus other
> physician specialties.
>
> For women workers employed between 1940 and 1949,
> the
> relative risk for breast cancer was elevated (2.17),
> especially if they'd been exposed to radiation for
> one
> to four years. The authors noted a particular trend
> among pre-1950 Canadian radiation workers: Melanoma
> was limited to dental workers, who may have held
> bitewing film in patients' mouths during x-ray,
> resulting in high exposure to their hands.
>
> Second, lower exposure levels were recorded after
> 1957, when the International Commission on
> Radiological Protection (ICRP) reduced the suggested
> dose limit to 0.05 Sv per year. In 1990, the
> commission revamped that policy to an occupational
> dose limit of an average of 0.02 Sv per year, over
> five years, and not to exceed an annual dose of 0.05
> Sv in a single year.
>
> After 1950, the SMR for all types of cancer was less
> than 1. In addition to better dose parameters, a
> trend
> known as the "healthy-worker effect" may have
> contributed to the reduction as these professionals
> tend to lead healthier lifestyles and have better
> access to medical care, the authors stated.
>
> "We found no clear evidence of cancer risk in any of
> the latest subcohorts of radiologists or
> technologists," the group concluded. "While safe
> radiation practices currently are an assumed part of
> medical radiation work ... it is important to
> continue follow-up."
>
> Future research should include data on individual
> doses to radiation workers, which would allow for a
> direct comparison of risk between high-dose and
> low-dose settings. In addition, the authors
> cautioned
> that workers from 1960-1982 have yet to enter the
> time
> period when background cancer risk is increased.
> Radiation protection practices will require updates
> based on exposure levels of new radiologic
> procedures.
>
> By Shalmali Pal
> AuntMinnie.com staff writer
> September 21, 2004
>
>
> =====
> +++++++++++++++++++
> "A devotee of Truth may not do anything in deference
> to convention. He
> must always hold himself open to correction, and
> whenever he discovers
> himself to be wrong he must confess it at all costs
> and atone for it."
> Monhandas K. Gandhi, in "Autobiography"
>
> -- John
> John Jacobus, MS
> Certified Health Physicist
> e-mail: crispy_bird@yahoo.com
>
>
>
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=== message truncated ===
=====
+++++++++++++++++++
"A devotee of Truth may not do anything in deference to convention. He must always hold himself open to correction, and whenever he discovers himself to be wrong he must confess it at all costs and atone for it."
Monhandas K. Gandhi, in "Autobiography"
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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