Question

How taking pure ethanol can be fatal while only its refined form is used in daily life?

Answer 1

Pure or lab grade or denatured ethanol that is 98-99% pure contains impurities such as methanol, pyridine, benzene, acetone, etc. Methanol is highly toxic and if ingested is extremely harmful for humans. Initial symptoms include nausea, vomiting and mild nervous damage including impaired vision. Consumption of about 10 ml of methanol can cause damage to the optic nerve and may cause permanent blindness. About 25 ml of methanol can prove fatal. Also, pure ethanol is lipid soluble, it affects the normal working of membrane proteins by interfering with cell membranes.
Pyridine and benzene are carcinogenic.

Therefore, it is refined to make fit for drinking purposes.