File:Schematic representation of the three main dose–response models linking cancer risk to dose of IR exposure.png

English: Figure 1. Schematic representation of the three main dose–response models linking cancer risk to dose of IR exposure. The Linear Non-Threshold (LNT) model states that cancer risk increases with dose in a linear fashion from a dose of zero units onwards. It is supported by human epidemiological data at intermediate to high doses, whereas supporting evidence in the low dose region (<100 mGy) is weak. The LNT is a foundation of the regulatory policies put forth by the International Commission on Radiological Protection. The Threshold model implies the existence of a threshold dose, below which no measurable increase in cancer risk is observed. The radiation hormesis model assumes a negative cancer risk at low-dose exposures, resulting in protection from cancer. The radiation hormesis model is supported by a large body of radiobiological literature showing beneficial responses to LDR, including in vivo animal cancer and mortality studies.