[ RadSafe ] Low, chronic doses of gamma radiation had beneficial effects on meadow voles

[goldinem at songs.sce.com]

From the University of Toronto news, not intended to create LNT/anti-LNT
flames.  Just the facts from an ANS news list:

Radiation may have positive effects on health: study
http://c.moreover.com/click/here.pl?t373940281&f=242834
(University of Toronto, Aug 19)


                   Radiation may have positive effects on health: study
                   Low, chronic doses of gamma radiation had beneficial
                   effects on meadow voles
                   January 28, 2005
                   by Karen Kelly


                   A new study from the University of Toronto at
                   Scarborough has found that low doses of radiation could
                   have beneficial effects on health.


                   The findings, published in the latest issue of
                   Environmental Toxicology and Chemistry, found that low,
                   chronic doses of gamma radiation at 50 to 200 times
                   background levels had beneficial effects on the stress
                   axis and the immune axis of natural populations of
                   meadow voles. The paper provides evidence of hormesis
                   from the only large-scale, long-term experimental field
                   test ever conducted on the chronic effects of gamma
                   radiation on mammals.


                   Hormesis is defined as a phenomenon in which low doses
                   of an otherwise harmful agent can result in stimulatory
                   or beneficial effects. This phenomenon has been observed
                   in a broad range of chemicals including alcohol and its
                   metabolites, antibiotics, hydrocarbons, herbicides,
                   insecticides and fungicides, as well as physical
                   processes such as radiation exposure. The effects of
                   hormesis have been observed in a wide range of
                   organisms, from microbes and fungi to plants and
                   animals. Hormetic responses are varied in form and
                   include increased longevity; growth, reproductive and
                   physiological responses; and metabolic effects.


                   "Exactly how low-level radiation causes a hormetic
                   response remains uncertain because few laboratories have
                   studied the pathology or physiology of mammals exposed
                   throughout life to dose rates below those causing
                   detrimental effects," said Professor Rudy Boonstra of
                   the Centre for the Neurobiology of Stress and Department
                   of Zoology. “This study provides a potential mechanism
                   to explain the benefical effects.”

                   In the study, Boonstra, along with researchers Richard
                   Manzon, Steve Mihok and Julie Helson, studied the meadow
                   vole populations at the Whiteshell Nuclear Research
                   Establishment at Pinawa, Manitoba, Canada. The
                   experiment, entitled ZEUS (Zoological Environment Under
                   Stress), was set up by Atomic Energy of Canada to test
                   the effects of chronic gamma radiation on natural
                   populations. In isolated populations, voles received one
                   of three radiation treatments over a four-year period.


                   "Our findings suggest that a moderate increase in
                   glucocorticoid levels, associated with low-level
                   radiation, could be an important factor underlying the
                   increase in longevity that has been observed in other
                   shorter studies on small mammals exposed to low-level
                   radiation," said Boonstra.


                   The ZEUS experiment was funded by Atomic Energy of
                   Canada and the hormonal analysis was funded by the
                   Natural Sciences and Engineering Research Council of
                   Canada (NSERC).


                   Contact:


                   Rudy Boonstra, Centre for the Neurobiology of Stress,
                   UTSC, (416) 287-7419;
                   e-mail: boonstra at utsc.utoronto.ca

Eric M. Goldin
<goldinem at songs.sce.com>