The Development of Bio-assays Based on Non-targeted Effects of Radiation; a Potential Worm-Hole into Ecosystem Level Biomarkers

The role of non-targeted effects (NTE) in radiation biology and radiation protection is problematic and controversial. These effects include bystander signaling between irradiated and non-irradiated cells and also describe effects in progeny of irradiated progenitors which have recovered - a form of non-clonal genomic instability. They dominate the low dose response but saturate after very low doses yielding flat dose response curves meaning that low doses can have disproportionately large effects. In vivo many of the impacts of NTE are adaptive or protective. There are many well developed assays for NTE but because they are not based on measurement of primary DNA damage, they are not usually used to monitor radiation effects in humans or the environment. In this paper, we will review the use of NTE assays in human and environmental radiobiology and will propose that far from being irrelevant, these assays may provide the much needed system level bio-markers which could predict perturbations at the ecosystem level.