Moonshine is intended to be ethanol, the same alcohol found in all consumable spirits, but it often carries the risk of contamination with methanol. Defined as an illegally distilled spirit, moonshine is produced without commercial oversight, making the product highly variable in quality and safety. The risk of poisoning comes from methanol, a toxic alcohol that is introduced and concentrated during the production process due to improper techniques. This contamination transforms the spirit into a hazardous substance.
Ethanol The Desired Alcohol
Ethanol, also known as ethyl alcohol, is the compound that provides the psychoactive effects in all alcoholic beverages. Its chemical formula is CH3CH2OH, distinguished by the presence of two carbon atoms. Ethanol is produced naturally when yeast consumes sugars and starches in a process called fermentation, yielding alcohol and carbon dioxide. This fermentation step is the foundation for all spirits, including the fermented “mash” used to create moonshine.
The goal of the distiller is to concentrate this specific alcohol by separating it from water and other compounds in the fermented liquid. Ethanol is the only alcohol safe for human consumption in moderate amounts. It is the core ingredient that gives spirits their potency, flavor, and character.
Methanol The Dangerous Impurity
Methanol, or methyl alcohol, is a much simpler alcohol molecule with the chemical formula CH3OH, containing only a single carbon atom. This structural difference makes methanol highly toxic to the human body. Methanol is a natural byproduct that forms during fermentation, particularly when starting materials contain high amounts of pectin, such as fruit mashes made from apples or grapes.
Enzymes in the fermented material break down this pectin, leading to the formation of small amounts of methanol. While fermented beverages like wine or beer contain methanol, the concentration is too low to cause harm. However, during distillation, this methanol becomes dangerously concentrated, changing it from a trace element into a potent poison.
How Contamination Occurs During Distillation
The danger of methanol contamination arises from the physics of the distillation process. Distillation works by heating the fermented liquid, or “wash,” and separating components based on their different boiling points. Methanol has a lower boiling point, approximately 148.5°F (64.7°C), than ethanol, which boils at 173.1°F (78.4°C).
Because methanol vaporizes first, it concentrates in the first liquid to condense, known as the “heads” or “foreshoots.” Experienced and responsible distillers must make a precise separation, or “cut,” by discarding this initial portion of the distillate to remove the methanol and other volatile, undesirable compounds. Contamination occurs when a careless distiller fails to discard enough of this methanol-rich fraction, mixing the toxic heads into the drinkable “hearts.”
Health Consequences of Methanol Poisoning
Methanol itself has relatively low toxicity, but the body metabolizes it into highly toxic substances, which cause severe health consequences. Once ingested, the liver enzyme alcohol dehydrogenase converts methanol first into formaldehyde, and then rapidly into formic acid. This accumulation of formic acid is the primary source of the poisoning, leading to a condition called high-anion-gap metabolic acidosis.
The severe acidosis and formic acid directly attack the central nervous system, particularly the optic nerve. This leads to the most well-known consequence of methanol poisoning: irreversible toxic blindness. Ingestion of as little as 10 milliliters of pure methanol can cause permanent visual damage. Larger amounts can lead to organ failure, coma, and death.