Water might seem like the least harmful substance on the planet, but drinking too much of it can kill.
So can too much or too little of a number of other things most of us take for granted, from caffeine to the stuff you use to clean your bathroom.
To calculate how much of each of these items would be dangerous enough to kill, we've used a $4, the individual dose it would take to kill half the animals it was tested on.
This amount can vary pretty significantly depending on someone's health, gender, and medical history. The potentially deadly dosages in the slides that follow were calculated for $4.