What dose is generally considered lethal in humans for CNS death from radiation exposure?

The discernment of a lethal dose of radiation for central nervous system (CNS) death stems from studies on human and animal responses to radiation exposure. Generally, a dose in the range of 200-300 rad (which corresponds to 2-3 Grey) is established as the threshold for severe, often fatal damage to the CNS.

This dose range is supported by historical data and research that link radiation exposure to neurological impairments, including the shutdown of vital brain functions, leading to death. In cases of high radiation exposure, particularly doses exceeding this range, the risk of irreversible damage increases significantly, resulting in loss of vital bodily functions governed by the CNS.

While lower doses, such as those below 200 rad, may lead to acute radiation syndrome and other severe health issues, they are less likely to result directly in CNS death. The high range of 300-400 rad tends to be associated with even more acute and widespread destruction of biological systems, well beyond what is typically defined for CNS-specific lethality. Thus, the choice of 200-300 rad reflects the critical threshold where CNS failure becomes a likely consequence of radiation exposure.