Death by lethal metabolizing products
Methanol (= “wood alcohol”) is broken down in the human body in the same way as ethanol (= “drinking alcohol”), by an enzyme called alcohol dehydrogenase.
In this particular case this biological process is most unfortunate, because while the metabolization of ethanol produces harmful but tolerable chemicals, the metabolization of methanol produces disasterously toxic substances, among them:
formaldehyde -
A nasty substance, in earlier days used as a murderous “kill-everything”-disinfectant. Anatomical specimens used to be kept in formalin, a solution of formaldehyde. Formaldehyde attacks the mitochondria of nerve cells, especially the optic nerve, and does damage to the liver and kidneys.
formic acid -
The liquid that ants spray into ant-bites, to make bites really hurt. Formic acid attacks the kidneys and the liver. Most people who have drunk methanol die of severe and sudden kidney and liver failure.
lactic acid -
Due to lactic acid/lactate production, a metabolic acidosis (= increased acidity) develops in the body, in addition to the accumulation of formic acid/formate. Lactic acid also attacks the kidneys and the liver.
Fatal hangover
The onset of symptoms occurs 8-36 hrs post ingestion, when the action of alcohol dehydrogenase has produced sufficient amounts of toxic products. So it’s not the methanol drink per se that gets you. It’s the methanol hangover.
Chemical ignorance, leading to death
Methanol poisoning, while reportedly rare in the United States, is a relatively serious problem elsewhere, e.g. in the Nordic countries. Here the preferred strategy in the “war against alcoholism” has been to try to tax the guilty chemical, ethanol, into oblivion. The resulting exhorbitant prices of alcoholic beverages have made people look for less expensive solutions, e.g. moonshining and industrial ethyl alcohol. But from there it is just a small step to fatally confusing industrial ethyl alcohol and industrial methyl alcohol. To a person with insufficient knowledge of chemistry, the label “Methyl alcohol” on an industrial drum may look as a heaven-sent supply of cheap “alcohol”.
Methanol poisoning disasters
This confusion regularly leads to a small number of scattered deaths, 1-3 at the time, sprinkled with a few cases of blindness. But sometimes the methanol accidents take on catastrophic proportions. In Estonia in 2001, a group of people found a drum of industrial methyl alcohol. Sensing the business opportunity, they diluted the concentrated methanol with water, filled the mixture into vodka bottles and sold it as vodka. In a few days 67 people were dead.
In San Salvador a similar incident occurred in 2000, killing over 100.
Remedies, if any
It is often too late to save the victim when the symptoms have already appeared. In the early stages, however, the key to saving victims of methanol poisoning is trying to inhibit the action of alcohol dehydrogenase. One method is to give the patient large doses of ethanol, in the hope that the alcohol dehydrogenase will be busy metabolizing ethanol, while the methanol levels will slowly decrease by themselves. (This mechanism seems to save drinkers of industrial ethanol, which is often contaminated by 2-5% methanol.) Sodium bicarbonate is used for trying to control the acidosis.
Lately intravenous administration of fomepizole, an alcohol dehydrogenase inhibitor, has been used with some success.
Reference:
Jeffrey Brent, M.D., et al: Fomepizole for the Treatment of Methanol Poisoning, New England Journal of Medicine, Volume 344:424-429, February 8, 2001