Evaluation of the Linear-Nonthreshold Dose-Response Model for Ionizing Radiation-D1C7435B

Report No. 136 (2001) presents an evaluation of the existing data on the dose-response relationships and current understanding of the health effects of low doses of ionizing radiation. This reevaluation was carried out by Scientific Committee 1-6, which was charged to reassess the weight of scientific evidence for and against the linearnonthreshold dose-response model, without reference to associated policy implications. The evaluation was prompted by the need to reassess the common use, for radiation protection purposes, of the linear-nonthreshold dose-response hypothesis in the light of new experimental and epidemiological findings, including growing evidence of adaptive responses to small doses of radiation which may enhance the capacity of cells to withstand the effects of further radiation exposure, and new evidence concerning the possible nature of neoplastic initiation. The evaluation focuses on the mutagenic, clastogenic (chromosome-damaging), and carcinogenic effects of radiation, since these effects are generally postulated to be stochastic and to increase in frequency as linear-nonthreshold functions of radiation dose. For each type of effect, the relevant theoretical, experimental and epidemiological data are considered. Furthermore, in an effort to avoid overlooking pertinent data in the evaluation, input was obtained from authorities in the field and from the scientific community at large.