system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does radiation poisoning kill you, and why does it sometimes take weeks?
gpt
Radiation is dangerous when it’s “ionizing,” which means a single particle has enough energy to “ionize” the atoms it collides with. That means knock an electron loose, which in turn means the bonds holding together the molecules it is part of break apart, which means it is causing chemical changes in what it hits.

DNA is the chemical in the cells in your body that tell it how to do everything, including reproduce new cells. It is also able to repair itself, but not without limit. If a cell’s DNA is damaged enough by radiation, it can’t function properly any more and it dies. Or, it fails to reproduce, save dies later. Or, it malfunctions AND reproduces, so you have new malfunctioning cells taking over - that’s cancer. Any and all of these can be caused by radiation and all can kill you in different time frames.