Methanol

Methanol (methyl alcohol, wood alcohol) is the simplest alcohol and one of the most hazardous common solvents. In automotive products it is used primarily in windshield washer fluids (30–60% concentration) and some fuel treatments. **Critical hazards:** Methanol is acutely toxic via all routes — ingestion (H301, fatal oral dose ~1 mL/kg), skin absorption (H311), and inhalation (H331, GHS Acute Tox 3). Its extreme danger comes from metabolic conversion: the body oxidizes methanol to formaldehyde, then formic acid. Formic acid causes metabolic acidosis and selectively destroys the optic nerve. Even a tablespoon of methanol can cause permanent blindness; a few ounces can be fatal. H370 (STOT SE 1) reflects the optic nerve targeting. **Consumer context:** In windshield washer fluid, the primary risk is accidental ingestion — methanol smells and looks like water or other beverages. Never store washer fluid in beverage containers. During normal reservoir fill operations, inhalation risk is low outdoors but real in enclosed garages. Brief skin contact during spills poses lower acute risk, but wash off promptly.