Have you ever heard that moonshine can make you blind? How does that happen? Can it happen and what's the science behind distillation that can allow blindness and death.
The magic sauce behind alcohol blindness is the foreshots, the first stage of distillation which can lead to acetone and methyl alcohol. Once the foreshots (poison) have been condensed out of your mix, you've got to get rid of the heads then you'll get to the precious heart of the distillation cut. That's the good stuff. The head's, if consumed too much, will give you a raging headache, so you don't want too much of those in your distillate.
Then you get to the tails, another thing you want to avoid getting into your distillate. The blindness happens when the distillate is made incorrectly and the foreshots have been left in the mix as 10ml of Methyl Alcohol can damage your optic nerve and that's a NO THANK YOU helping of bad distilled beverage.
But, it doesn't have to be moonshine, it can be gin, vodka, bourbon, whatever. Bad is just bad.