The U.S. Nuclear Regulatory Commission is in the process of rescinding or revising guidance and policies posted on this webpage in accordance with Executive Order 14151 Ending Radical and Wasteful Government DEI Programs and Preferencing, and Executive Order 14168 Defending Women From Gender Ideology Extremism and Restoring Biological Truth to the Federal Government. In the interim, any previously issued diversity, equity, inclusion, or gender-related guidance on this webpage should be considered rescinded that is inconsistent with these Executive Orders.

Half-life, effective

The time required for the activity of a particular radioisotope deposited in a living organism, such as a human or an animal, to be reduced by 50 percent as a result of the combined action of radioactive decay and biological elimination. Effective half-life is related to, but different from, the radiological half-life and the biological half-life.

Page Last Reviewed/Updated Tuesday, March 09, 2021