Methanol is produced naturally in the
anaerobicmetabolism of many varieties of bacteria, and is commonly present in small amounts in the environment. As a result, the atmosphere contains a small amount of methanol vapor. But in only a few days, atmospheric methanol is
oxidized by sunlight to produce carbon dioxide and water.
Methanol is also found in abundant quantities in star forming regions of space, and is used in astronomy as a marker for such regions. It is detected through its spectral emission lines.
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. This addition of methanol exempts industrial ethanol (commonly known as "
denatured alcohol" or "methylated spirit") from liquor
excise taxation in the US and some other countries.
Methanol is poisonous to the central nervous system and may cause blindness, coma, and death. However, in small amounts, methanol is a natural endogenous compound found in normal, healthy human individuals, concluded by one study which found a mean of 4.5
ppm in the exhaled breath of subjects. The mean endogenous methanol in humans of 0.45 g/d may be metabolized from pectin found in fruit; one
kilogram of apple produces up to 1.4 g methanol.