BANGKOK – Alcohol contaminated with methanol is suspected to be the cause of the deaths of six foreign tourists who fell ill after a night in the popular backpacking destination of Vang Vieng in Laos on November 12.

Here are some facts:

What is methanol poisoning?

Methanol is a toxic alcohol used in industrial and household products such as antifreeze, copier fluids, deicers, paint thinner, varnish and windshield wiper fluid.

Colorless, flammable and with a similar smell, it can easily be confused with its molecular ethanol, which is usually found in alcoholic beverages.

But methanol is toxic to humans, with exposure or ingestion extremely dangerous if untreated.

Drinking as little as 25ml to 90ml can be fatal, according to the Methanol Institute, a global trade association for the industry.

It is absorbed from the gut in less than 10 minutes, but patients may appear normal for the first 12 to 24 hours after ingestion.

It then causes nausea, vomiting and severe abdominal pain, followed by hyperventilation and difficulty breathing.

Partial or complete blindness from methanol poisoning is common and, if left untreated, can lead to coma and even death.

However, in smaller amounts, prompt diagnosis—within 10 to 30 hours of ingestion—and treatment can reduce the most severe symptoms.

People with suspected methanol poisoning should see a medical toxicologist or poison control center immediately.

So far, an Australian woman, a British woman, two Danish citizens and an American have been confirmed dead after a suspected methanol poisoning from consumption of contaminated alcohol.

How does it get into drinks?

Accidental poisonings can occur after drinking cheap homemade booze or contaminated alcohol.

But methanol is often deliberately added to alcoholic beverages as a cheaper alternative to ethanol.

This is especially the case in countries where the price or taxes on legal alcoholic beverages may be considered too high.

Unscrupulous businesses or individuals may add industrial methanol to alcoholic beverages to increase their potency.

Canned or bottled spirits from trusted retailers tend to be safer and less likely to be adulterated than mixed drinks from bars.