LNT and Bystander Effect

["Tom English" <englishtoma@HOTMAIL.COM>]

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Regarding the LNT, has anyone had a chance to read this article?



Radiat Res 2001 Mar;155(3):402-8 Related Articles, Books



The bystander effect in radiation oncogenesis: II. A quantitative model.



Brenner DJ, Little JB, Sachs RK



Center for Radiological Research, Columbia University, New York, New York 

10032, USA.



There is strong evidence that biological response to ionizing radiation has 

a contribution from unirradiated "bystander" cells that respond to signals 

emitted by irradiated cells. We discuss here an approach incorporating a 

radiobiological bystander response, superimposed on a direct response due to 

direct energy deposition in cell nuclei. A quantitative model based on this 

approach is described for alpha-particle-induced in vitro oncogenic 

transformation. The model postulates that the oncogenic bystander response 

is a binary "all or nothing" phenomenon in a small sensitive subpopulation 

of cells, and that cells from this sensitive subpopulation are also very 

sensitive to direct hits from alpha particles, generally resulting in a 

directly hit sensitive cell being inactivated. The model is applied to 

recent data on in vitro oncogenic transformation produced by broad-beam or 

microbeam alpha-particle irradiation. Two parameters are used in analyzing 

the data for transformation frequency. The analysis suggests that, at least 

for alpha-particle-induced oncogenic transformation, bystander effects are 

important only at small doses-here below about 0.2 Gy. At still lower doses, 

bystander effects may dominate the overall response, possibly leading to an 

underestimation of low-dose risks extrapolated from intermediate doses, 

where direct effects dominate.



Tom English

englishtoma@hotmail.com







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