The offending substance in the liquor tragedies leading to blindness, etc. is

1. Liquor tragedies involving illicit or improperly distilled alcohol often result in severe health consequences like blindness and death. 2. The primary psychoactive component in alcoholic beverages intended for consumption is ethyl alcohol (ethanol). 3. However, during improper distillation or intentional adulteration, methyl alcohol (methanol) can be produced or added. 4. Methyl alcohol is highly toxic. The human body metabolizes it into formic acid and formaldehyde, which are extremely poisonous. 5. Formic acid accumulation causes metabolic acidosis and specifically damages the optic nerve, leading to blindness, and can also cause kidney failure, coma, and death. 6. Amyl alcohol and benzyl alcohol have industrial uses but are not typically the main toxic component in these tragedies.