LNT implies that any dose, no matter how low, can pose
risks for genetic (hereditary) defects or cause cancer. Cancer
risk is assumed to increase linearly with increasing radiation
dose, with no threshold. LNT was derived using statistically
significant doseeresponse (DR) relationship between radiation
dose received by the survivors of the atomic bomb explosions
in Hiroshima and Nagasaki and the observed health
effects, mainly hereditary disorders and cancer (Decades
later, non-cancer risks are also derived from the same population).
The DR was based on the observable significant clinical/
deterministic effects that were seen on population
exposed at high doses, from 0.2 Gy upwards. Below this dose,
there were no observable effects seen on the population.
Nevertheless, DR is assumed to be linear down to zero dose.
The extrapolation to zero of the DR has not been supported by
sufficient evidence/data in man to show its linearity at low
doses. However, this assumption has been accepted to be the
conservative and most careful approach to address the
delayed effects of ionizing radiation, and to estimate health
risks at low doses (