NCRP Dr. Brenner

["Field, R. William" <bill-field@UIOWA.EDU>]

Jim,



The abstract Dr. Brenner has listed http://www.ncrp.com/2002-Program.PDF 

for presentation at the next NCRP meetings appear to present a slightly 

different view than the abstract below.  It would be worthwhile to ask Dr. 

Brenner whether or not his findings are in agreement with those of Drs. 

Little and Wakeford.



Regards, Bill Field





At 05:40 PM 03/24/2002 -0500, muckerheide wrote:

>Friends,

>

>Note the following "LNT establishment" abstract. It partially recognizes

>that the presumption that the bystander effect can reflect increased risk at

>low doses can not be valid,  though this is short of recognizing that the

>bystander effect is intrinsic to the intercellular signaling that enables

>adaptive response and hormetic effects.

>

>Regards, Jim

>============

>

>Radiat Res 2001 Dec;156(6):695-699

>

>The Bystander Effect in C3H 10T Cells and Radon-Induced Lung Cancer.

>

>Little MP, Wakeford R.

>

>Department of Epidemiology and Public Health, Imperial College of Science,

>Technology and Medicine, St. Mary's Campus, Norfolk Place, London W2 1PG,

>United Kingdom; Author to whom correspondence should be addressed at

>Department of Epidemiology and Public Health, Imperial College of Science,

>Technology and Medicine, St. Mary's Campus, Norfolk Place, London W2 1PG,

>UK: e-mail mark.little@ic.ac.uk.

>

>Bystander effects, whereby cells that are not directly exposed to radiation

>exhibit adverse biological effects, have been observed in a number of

>experimental systems, including C3H 10T(1/2) cells exposed to alpha-particle

>radiation. The bystander effect implies that risks from exposure to low

>doses of radiation obtained by linear extrapolation from data for high-dose

>exposures might be substantial underestimates. The best estimate of the

>ratio of the lung cancer risk among persons exposed to low (residential)

>doses of radon daughters to that among persons (underground miners) exposed

>to high doses of radon daughters is in the range of 2.4-4.0, with an upper

>95% confidence limit of about 14. Assuming that the bystander effect

>observed in the in vitro C3H 10T(1/2) cell system applies to human lung

>cells in vivo, these epidemiological data imply that the central estimate of

>the number of neighboring cells that can contribute to the bystander effect

>is between 0 and 1, with an upper 95% confidence limit of about 7. As a

>consequence, the bystander effect observed in the experimental C3H 10T(1/2)

>cell system probably does not play a large part in the process of

>radon-induced lung carcinogenesis in humans.



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