There are two points of view for the answer of this question:
- The biological view, the only one that I faced during my research, states that since it can trigger perilous conditions like metabolic acidosis, cause a neurologic sequelae, etc. methanol is toxic.
- The chemical point of view in an answer, which is the one I seek, is the reactions that occur in the body with methanol as a reactant.
Why should it be a reaction? Because I assume something will be toxic for humans when it reacts and disables some of their bodies' vital compounds; e.g.: Hydrogen cyanide reacts with enzymes, renders their active sites useless, and finally causes heavy reduction in bio-chemical reactions that results in quick death.
So, the question is: What reactions use methanol in the body that makes it toxic for us?