system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I recently got an electric toothbrush that has a UV chamber to kill germs. How can such a little blue light actually do anything?
gpt
The blue light is just what your eyes actually see. Ultraviolet light is beyond the range of human eyesight.

DNA, when exposed to UV light, will take damage. This will kill living cells. Shining bacteria in the stuff will kill them fairly quickly with minimal effort.