Consistency of The Mortality of Chronically-irradiated Beagles with the Linear No-Threshold Model

This note explores whether the lowest dose-rate mortality data from the beagle tissue archive might be consistent with the Linear No-Threshold (LNT) Model and might give evidence in favour of that model. I suggest that the answer may be ‘yes’; further statistical analysis will be required to establish how strongly the data favour LNT over alternative non-linear models. 1 The mortality data A paper by Fliedner et al. (2012) presents interesting data adapted from Fritz (2002) showing the mortality curves of dogs after whole-body chronic gamma-irradiation at various dose-rates. These curves have been obtained from the beagle tissue archive1, which preserves the results of experiments in which hundreds of dogs were chronically exposed to gamma radiation for their entire lives Carnes and Fritz (1993). The dose-rates to the whole body were 3mGy/day, 7.5mGy/day, 18.8mGy/day, 37.5 mGy/day, 75 mGy/day and 127.5 mGy/day, 262.5 mGy/day, 375 mGy/day and 640 mGy/day. A control group received no gamma radiation. In the high dose-rate groups (540 mGy/day, 375 mGy/day and 262.5 mGy/day), all observed deaths were caused by hemopoietic failure. In the middle dose-rate groups (127.5 mGy/day, 75 mGy/day and 37.5 mGy/day), deaths are caused by hemopoietic insufficiency with septicemia and aplasia or myeloproliferative disorders and fatal tumours. At dose rates below 1http://janus.northwestern.edu/dog_tissues/