Linear No-Threshold model for radiation safety

• The U.S. Nuclear Regulatory Commission (NRC) upheld the Linear No-Threshold model to prescribe radiation safety standards.

• Petitioners’ proposed substantial increase in dose limits to workers; raise the public dose limits to be the same as the worker doses; end differential doses to pregnant women, embryos and fetuses, and children less than 18 years of age.

• Convincing evidence has not yet demonstrated the existence of a threshold below which there would be no stochastic effects from exposure to low radiation doses. As such, the NRC’s view is that the LNT model continues to provide a sound basis for a conservative radiation protection regulatory framework that protects both the public and occupational workers.


• The Linear no-threshold model (LNT) is the most commonly used model to estimate the biological risks from ionizing radiation.

• 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.

• The linear no-threshold model is based on biological responses at high radiation doses and dose rates.

• The higher the dose and dose rate, the higher the biological response; the lower the dose and dose rate, the lower the response.

• This model assumes the simplest possible relationship, a straight line (hence linear no-threshold model).

Uses of LNT Model:

• The LNT model helps agencies to regulate radiation exposures to diverse categories of licensees, from commercial nuclear power plants to individual industrial radiographers and nuclear medical practices.

Ionizing radiation:

• Ionizing radiation is a type of energy released by atoms in the form of electromagnetic waves or particles.

• People are exposed to natural sources of ionizing radiation, such as in soil, water, and vegetation, as
well as in human-made sources, such as x-rays and medical devices.

• Ionizing radiation has many beneficial applications, including uses in medicine, industry, agriculture and research.

• As the use of ionizing radiation increases, so does the potential for health hazards if not properly used or contained.

• Acute health effects such as skin burns or acute radiation syndrome can occur when doses of radiation exceed certain levels.

• Low doses of ionizing radiation can increase the risk of longer term effects such as cancer.


Mains Paper 3: Science and Tech

Prelims level: Linear No-Threshold model for radiation safety

Mains level: Read the newsfeed

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