Radiation effects are not confined to directly irradiated tissues. The contribution of systemic “outof-target” effects to the risks of a long-term health detriment following exposure to radiation is largely unknown. Indeed, both protective and damaging effects have been described, and no information on a dose response relationship exists. From the radiation protection standpoint this level of uncertainty of the risk is problematic, as workplace, environmental and medical exposures frequently involve partial body exposures to low dose irradiation. The aim of this project is to look at molecular and cellular damage in non-irradiated organ portions (brain, heart and liver) evaluating the transcriptome, non-coding RNAs, protein and metabolic levels. By combining this cellular, molecular and bioinformatic data we will be able to identify the response pathways in the different tissues, and by inference, suggest the candidate signalling molecules involved. A second major outcome of this project will be the discovery of candidate biomarker molecules of both whole body and partial body irradiation responses. We will also investigate exosomes from exposed tissues, and their specific bioactive cargo - particularly RNA content – for their role in mediating out-of-target effects in vitro and in vivo.