The U.S. Nuclear Regulatory Commission (NRC) decisively upheld the Linear No-Threshold model to prescribe radiation safety standards, ending the protracted controversy on the topic.
Linear No-Threshold model
The LNT model states that biological effects such as cancer and hereditary effects due to exposure to ionising radiation increase as a linear function of dose, without threshold.
Significance of LNT model
The LNT model helps the agencies to regulate radiation exposures to diverse categories of licensees, from commercial nuclear power plants to individual industrial radiographers and nuclear medical practices.
In 2015 three petitions requested the NRC, “to amend its regulations based on what they assert is new science and evidence that contradicts the linear no-threshold (LNT) dose-effect model that serves as the basis for the NRC’s radiation protection regulations.”
The petitioners support “radiation hormesis,” a concept that posits that low doses of ionising radiation protect against the deleterious effects of high doses of radiation and result in beneficial effects to humans.
The NRC denied the three petitions because they failed to present an adequate basis supporting the request to discontinue use of the LNT model. Therefore, the NRC will maintain the current dose limit requirements.
The NRC noted that although there are studies and other scholarly papers that support the petitioners’ assertions, there are also studies and findings that support the continued use of the LNT model, including those by national and international authoritative scientific advisory bodies.