Some people think I'm trying to be funny, but seriously:

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

Under "Causes": Excessive drinking of fluids.

> When sodium levels in the blood become very low, water enters the brain cells and causes them to swell. This results in increased pressure in the skull and causes hyponatremic encephalopathy.

My point being the fact that something is "neurotoxic" says little about its practical safety.