system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does using a tootbrush how we do not make us sick? It is never sanitised and sit in your bathroom all day.

Sorry about the terrible title I posted right before I went to sleep after I brushed my teeth.
gpt
Soap, your faucet, your tooth brush, the glass you drink water out of, all has bacteria on it. We don't live in a sterile environment and we ourselves are not sterile. You have more bacteria in your mouth, and fungal spores, than on your tooth brush. 

Having bacteria isn't the problem, it's having a place for bacteria to multiply and grow into a colony unopposed and for that you need food, water, shelter, and no competition. Your tooth brush has only one of those things. 

The job of a tooth brush is not to sterilize your mouth, it's to wash away the metabolic junk and plaque that eats away at your teeth. It denies the colonies in your mouth food and a medium to safely grow in (plaque).