Methanol is the simplest alcohol, being only a methyl group linked to a hydroxyl group. It is a light, volatile, colourless, flammable liquid with a distinctive odour very similar to that of ethanol (drinking alcohol). Methanol when drunk is metabolized first to formaldehyde and then to formic acid or formate salts. These are poisonous to the central nervous system and may result in blindness, coma and death. Because of these toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses.