What is methanol poisoning and how does it happen?
Methanol is a colourless alcohol found in thousands of everyday products, such as paint, cosmetics and antifreeze.
However, overexposure or ingestion can lead to serious illness or death.
When methanol is ingested, it metabolises into formaldehyde and then formic acid, causing a person’s blood to become acidic.
According to the Methanol Institute, methanol is often deliberately and illegally added to drinks as it is cheaper than ethanol, which can be consumed.
This increases the drink’s alcohol content. It happens in some countries where taxes on legitimate alcohol or the cost of legitimate alcohol might be perceived as too high, added the institute.
Improper brewing of homemade alcohol can also produce methanol instead of ethanol.
Methanol is difficult to differentiate from ethanol. According to the institute, drinking just 25ml (or less than two tablespoons) to 90ml of methanol can be fatal without proper medical treatment.
Besides consumption, poisoning can also happen when high concentrations of methanol vapour are inhaled or if it is absorbed through the skin, said the United States National Institute for Occupational Safety and Health (NIOSH).
What are the symptoms of methanol poisoning?
Methanol poisoning can lead to serious consequences, with the fatality rate ranging from 20 per cent to 40 per cent if untreated, according to the international humanitarian organisation Doctors Without Borders.
Early stages of the poisoning can be difficult to distinguish from signs of drunkenness, said the Methanol Institute.
Severe symptoms usually do not occur until 12 to 24 hours after consumption. They include:
- Abdominal pain
- Nausea
- Vomiting
- Breathing difficulty
- Blurred vision
- Blindness
- Seizures
Methanol poisoning can also cause a person to go into a coma.
If the methanol is consumed alongside ethanol, it might take days before the symptoms set in, according to Doctors Without Borders.
These symptoms typically last a few days for the majority of the patients if they survive.
There may also be delayed effects following methanol poisoning. Besides death, other health effects include blindness, brain damage, difficulty walking and moving properly, as well as damage to the peripheral nervous system, said NIOSH.
How is it treated?
According to the Methanol Institute, methanol poisoning can be treated successfully if diagnosed within 10 to 30 hours of ingestion.
Someone who has been poisoned should be taken to a hospital which has dialysis equipment. Dialysis can remove the methanol, the toxic metabolite formate and effectively corrects the acid build-up in the body.
The medication fomepizole is also an antidote for the poisoning but the drug is expensive and unavailable in some parts of the world.
According to Doctors Without Borders, ethanol is the most commonly used antidote to block the metabolisation of methanol.
A person’s liver will process the ethanol first, delaying the onset of methanol poisoning and allowing for more time to process methanol out of their system.
“However, giving a sufficient amount of ethanol is difficult, and the blood alcohol level is often too low or too high,” said Doctors Without Borders, adding that the preferred antidote is still fomepizole.
According to the Methanol Institute, dialysis ensures the most comprehensive removal of methanol from a person’s system.
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