2010 Marie Curie prize lecture: low-dose induced protection invalidates the linear-no-threshold model in mammalian bodies â a system-biology approach

Low-dose irradiation of mammalian tissues causes damage and protection, the ratio of which increasingly advances damage as doses increase. Below about 100 mSv, there is no observation of increased cancer incidence in exposed human populations. These data contradict the linear-no-threshold (LNT) dose-risk model. A biological system approach formalises the body to be organised in hierarchical levels. Depending on dose, primary damage to molecules, especially DNA, induces damage and protection that both can propagate through ascending levels and eventually affects the whole body. Even if crude in the face of stochastic patterns of energy depositions in exposed tissues and the enormous complexity of biological systems, the present approach again principally leads to contradict the LNT model in favour of a dose threshold for risk and hormesis in terms of mitigation of both radiogenic and spontaneous oncogenesis, both after acute and protracted low-level exposures, in agreement with experimental and epidemiological data.