What factor is critical in determining the lethality of radiation exposure?

The dose and duration of exposure to radiation are pivotal in determining its lethality because radiation effects are dose-dependent. Higher doses of radiation generally lead to more severe biological damage, while prolonged exposure can also increase the risk of detrimental health effects, including acute radiation syndrome and long-term risks such as cancer. The body can often repair minor damage from low levels of exposure, but when doses exceed certain thresholds, the ability to recover diminishes significantly, leading to increased mortality risk.

Thus, understanding how much radiation is absorbed and over what time frame is fundamental for assessing the potential health impacts on an individual exposed to radiation. Other factors like the type of tissue affected, age, and genetic background play roles in individual susceptibility and outcomes but are secondary to the primary influence of dose and exposure duration.