When do the greatest percentage of long-term effects of radiation typically occur?

The greatest percentage of long-term effects of radiation exposure commonly manifest between 10 and 15 years after the exposure. This timeframe aligns with the latency period that is well-documented in radiobiology, during which the biological effects of radiation can develop and become noticeable.

Long-term effects, such as cancer and genetic mutations, often do not appear immediately after exposure. Instead, they have a delayed onset, and various studies, including those following survivors of atomic bomb attacks, have indicated that significant increases in cancer rates often become apparent within this specific period.

This 10 to 15-year window is critical because it encompasses the time required for radiation-induced cellular damage to evolve into observable health issues, particularly cancers, which typically have a long development time. Outside of this window, while long-term effects can still occur, the likelihood decreases as time progresses beyond 15 years for initial presentations of these specific types of radiation-induced effects.