[pkhagah]

Breathing pure oxygen is also harmful.

[jcoffland]

Or drinking too much water.

[BurningFrog]

Everything is toxic in too large amount.

https://en.wikipedia.org/wiki/The_dose_makes_the_poison

[agumonkey]

I was recently reading about the blood / kidney salt balance too. Same for pH. Interesting how our body spends time in a balancing act.

[snuxoll]

The Adam Ruins Everything segment on this was great, it takes a large deal of water to poison yourself but somehow people manage to do it because of myths about hydration.