Description

• Methanol (wood alcohol) is a clear, colorless liquid with an odor similar to ethanol (drinking alcohol), but with a slightly sweeter taste. It is commonly used as an antifreeze, solvent, fuel, and as a denaturant for ethanol (1).
• Ingestion of methanol may occur by patients seeking ethanol substitutes, as a suicide attempt, by accidental ingestion, or by ingestion of denatured alcohol or from methanol contamination in products from illicit distillation (“moonshine”).
• Methanol ingestion leads to CNS depression and inebriation. The metabolism of methanol leads to the formation of formic acid, which leads to the symptoms of cellular hypoxia and metabolic acidosis, among other metabolic disturbances (2).

Epidemiology

Incidence
Most prominent in males >18 years of age, or by accidental ingestion by children

Prevalence
In 2007, 2,252 cases of methanol ingestion were reported to the US Poison Control Centers. Of these, 26 patients were classified as experiencing “major” disability, and 11 additional patients died (3,4).

Risk Factors

• Chronic alcoholism
• Access to illicitly distilled alcohol products
• Accidental ingestion of solvents or cleaning supplies by children

General Prevention

• Education of at-risk populations
• Proper storage of methanol-containing products and the use of embittering agents

Pathophysiology

• Methanol itself is rapidly absorbed, but is relatively nontoxic, causing mainly CNS sedation.
• Toxic effects of methanol ingestion occur over several hours as it is slowly converted by liver alcohol dehydrogenase to formaldehyde, which is then rapidly oxidized via aldehyde dehydrogenase to formic acid (formate anion).
• Formate anion can lead to retinal injury, with optic disc hyperemia, and can lead to permanent blindness.
• Secondary symptoms of methanol poisoning generally arise ≥10 hours after the initial exposure. These include blurring or loss of vision and metabolic acidosis. Death by respiratory failure may occur (5).

Commonly Associated Conditions

Chronic alcoholism