During the American Prohibition, moonshine was responsible for over 750 deaths and more than a hundred thousand cases of blindness or paralysis in New York City alone. Over eighty years later, in early 2019, several outbreaks of toxic alcohol poisoning lead to hundreds of deaths and injuries in northeast India. The culprit in both of these cases was methanol contamination. Chemically, the only real difference between methanol and ethanol is the number of carbons (two in ethanol and one in methanol). Methanol and ethanol taste about the same and produce about the same initial intoxicating effect. The only difference is that methanol, once ingested, is metabolized by the liver into formaldehyde and formic acid—chemicals that can damage the optic nerve, leading to blindness and eventually resulting in death.
Methanol is a common contaminant of moonshine, which is typically made from fermenting a “mash” of corn, sugar, and yeast for a few days and then distilling the mixture. During the fermentation process, the enzymes in the yeast convert the sugar into energy. A byproduct of this reaction is ethanol, the main ingredient of alcohol. Methanol is not a direct byproduct of fermentation, but instead it forms from the breakdown of pectin in corn. After fermentation, the slurry is distilled by boiling it and running the gas through a still. The first element of the still is a long upward shaft through which the gas rises. The length of this shaft prevents anything that is not gas from escaping to the next stage. Next, the gas travels downwards through another shaft that’s kept ice cold. On the other side of this shaft, the gas is cool enough to condense into liquid again. This process allows for all of the elements of the fermented slurry to separate, based on their boiling points. Methanol, having the relatively low boiling point of 148.5°F (64.7°C), boils off first, followed by acetone, and then ethanol. Experienced distillers throw out the first few fractions of the distillation, which contain high levels of methanol and acetone.
Methanol is easily removed in regulated alcohol production, and extensive testing is required by the U.S. government to ensure that very little methanol makes it into the final batch. In fact, the FDA recently started requiring that manufacturers test the alcohol they use in hand sanitizers for methanol content. In the case of alcohol that is used for industrial purposes, methanol is often added back into the batch after distillation to make it toxic and bad tasting. The foul taste of this type of alcohol, typically called “denatured alcohol,” is meant to dissuade people from drinking it. Because it is undrinkable, denatured alcohol is also exempt from alcoholic beverage taxes. Bootleggers can use this cheaper methanol-tainted alcohol to turn a considerable profit.
During the Prohibition, the government doubled the amount of methanol in industrial alcohol to make it more toxic and to discourage bootleggers from stealing and redistributing it. Bootleggers put significant effort into overcoming these measures, hiring chemists to distill the toxic chemicals out of their alcohol. But the government only doubled down their efforts, adding up to 10% methanol and a whole slew of other poisons including chloroform, gasoline, and mercury salts. The only thing these measures accomplished, however, was to poison and kill an estimated 10,000 Americans by the time the Prohibition ended.
These days, epidemics of toxic alcohol poisoning still occur around the world in poor areas, like the tea plantations in India, where unscrupulous bootleggers sell cheap alcohol laced with methanol or lead. Lead can be leached from truck radiators, which are frequently used in crude distillation setups. Drinkers discern very little difference between clean alcohol and alcohol laced with methanol, and the body’s immediate reaction to the alcohol is the same. It’s only hours later, once the methanol has been digested and converted to formic acid, that the poison presents itself with convulsions, blindness, and death. During the Prohibition, the government’s efforts to poison alcohol disproportionately affected poorer citizens, who often had to seek out alcohol at illicit speakeasies. More affluent Americans had the resources to illegally import safe liquor from Europe, Canada, and the Caribbean. From the Prohibition to today, the problem of toxic alcohol poisoning is an enduring and transnational issue that targets our most vulnerable communities.
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