Context: At least 47 people have died and nearly 100 others are battling for their lives after consuming a methanol-spiked alcohol in Tamil Nadu.
What is the alcohol in liquor?
- Liquor is differentiated by its alcohol content – from the 5% or so of beer to the 12% or so of wine to the 40% or so of distilled spirits (all by volume).
- In the beverages consumed for recreational purposes, the alcohol used is ethanol.
Ethanol:
- Ethanol: Ethanol (C2H5OH), in low doses, is a psychoactive drug that reduces the level of neurotransmission in the body leading to its typical intoxicating effects.
- The World Health Organisation has found that no level of alcohol consumption is safe for our health.
- Long-term use leads to dependence, heightens the risk of some cancers and heart disease, and may eventually cause death.
- Inside the body, it is metabolised in the liver and the stomach by alcohol dehydrogenase (ADH) enzymes to acetaldehyde. Then, aldehyde dehydrogenase (ALDH) enzymes transform the acetaldehyde into acetate. The adverse effects of alcohol consumption, from the hangover to cancer, are due to acetaldehyde.
What is spurious liquor?
- Spurious liquor is characterised by the liquid mixture containing methanol as well. Such liquors are typically homemade to which methanol is added to strengthen the intoxicating effects (in colloquial parlance, its kick) and/or to increase its bulk volume.
- The Food Safety and Standards (Alcoholic Beverages) Regulations 2018 stipulate the maximum permissible quantity of methanol in different liquors. These values span a wide range, including “absent” in coconut fenny, 50 grams per 100 litres of country liquor, and 300 grams per 100 litres of pot-distilled spirits.
Methanol:
- The methanol molecule (CH3OH) consists of one carbon atom bonded with three hydrogen atoms and one hydroxyl group.
- Methanol is a toxic industrial chemical mentioned in the Schedule I of the Manufacture, Storage and Import of Hazardous Chemical Rules 1989.
- The most common way to produce methanol is to combine carbon monoxide and hydrogen in the presence of copper and zinc oxides as catalysts at 50-100 atm of pressure and 250° C.
Applications of Methanol:
Methanol has several industrial applications:
- Production of chemicals: Methanol is a basic building block for the production of many chemicals, including formaldehyde, acetic acid, MTBE (methyl tert-butyl ether) and other aromatic hydrocarbons.
- Fuel: Methanol is a clean-burning fuel that can be blended with petrol or used in pure form in specially designed engines.
- Solvent: Methanol is a good solvent and is used in various industrial and commercial applications, such as in the production of paints, coatings, inks, and cleaning agents.
- Antifreeze: Methanol is used as an antifreeze because it has a low freezing point. It is often mixed with water to create a coolant for engines.
How does spurious liquor kill?
- The deadliness of spurious liquor arises from methanol. The human body contains infinitesimal quantities of methanol (4.5 ppm in the breath of healthy individuals) as a result of eating some fruits. But even for an adult, more than 0.1 ml of pure methanol per kilogram of body-weight can be devastating.
- Once ingested, methanol is metabolised in the liver by ADH enzymes to form formaldehyde (H-CHO). Then, ALDH enzymes convert formaldehyde to formic acid (HCOOH). The accumulation of formic acid over time leads to a baneful condition called metabolic acidosis. Acidosis can lead to acidemia: when the blood’s pH drops below its normal value of 7.35, becoming increasingly acidic.
- Formic acid also interferes with an enzyme called cytochrome oxidase, which in turn disrupts cells’ ability to use oxygen and leads to the build-up of lactic acid, contributing to acidosis.
- Further, consuming methanol also leads to “methanol-induced optic neuropathy”- a serious condition that may result in long-term or irreversible visual impairment or even blindness due to damage and loss of function of the optic nerve and retina.
- Eventually, Methanol-poisoning can cause swelling in the brain, haemorrhage, and death.
Immediate ways to treat Methanol poisoning:
- One is to administer ethanol (of a pharmaceutical grade, by healthcare workers). This may sound counterintuitive but ethanol competes very well with methanol for the ADH enzymes, which metabolise ethanol around 10x faster. As a result, the methanol is kept from being metabolised to formaldehyde.
- Second option is to administer an antidote called fomepizole, which has a similar mechanism: it slows the action of the ADH enzymes, causing the body to produce formaldehyde at a rate that the body can quickly excrete, preventing the deadlier effects from kicking in.
- Other options include:
- Undertaking a dialysis to remove methanol and formic acid salts from the blood, and mitigating damage to the kidneys and the retina.
- Administering folinic acid which encourages the formic acid to break up into carbon dioxide and water.