Which group is at risk of increased radiosensitivity?

Younger infants are at risk of increased radiosensitivity due to several biological and developmental factors. In the early stages of life, a child's cells are rapidly dividing and differentiating, making them more susceptible to the damaging effects of radiation. The developing tissues and organs are particularly vulnerable as they are still undergoing critical development processes.

Moreover, infants have a longer remaining lifespan in which radiation-induced effects can manifest, such as the potential for developing cancers later in life. Their immune systems and repair mechanisms are also not yet fully mature, which contributes to their heightened sensitivity.

In contrast, middle-aged adults and senior citizens generally have a lower radiosensitivity because their cells are not dividing as rapidly and they may have already been exposed to and survived various environmental risks. Occupational workers with past exposures may have developed a certain level of resilience or adaptation to radiation risk over time, but it does not help them in a direct comparison to the inherent sensitivities seen in younger infants. Thus, the combination of rapid cell division, developmental vulnerability, and lifetime cancer risk makes younger infants the group most at risk for increased radiosensitivity.