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General Studies 3 >> Science & Technology

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1. Context

As of 10 p.m. on May 16, as many as 22 people had died after consuming spurious liquor in
the Chengalpattu and Villupuram districts of Tamil Nadu, while more than 30 others were still being treated in hospitals. The incidents occurred barely a month after the State government said that it had brought such deaths under control.

2. 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 in question is almost always ethanol.
  • Technically, in this context, ethanol is a psychoactive drug that, in low doses, reduces the level of neurotransmission in the body, leading to its typically intoxicating effects.
  • Contrary to popular belief, the World Health Organization has found that “no level of [its] consumption is safe for our health”.
  • Long­term use leads to dependence, heightens the risk of some cancers and heart disease, and may eventually cause death. 
  • Ethanol (C2H5OH) is one carbon atom bonded to three hydrogen atoms and one more carbon atom; the second carbon atom is also bonded to two hydrogen atoms and the hydroxyl group, also known as the ion OH–.
  • Inside the body, it is metabolized 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.

3. What is Spurious Liquor?

  • Spurious liquor is characterized by a liquid mixture containing methanol as well.
  • The police have thus far determined that the spurious liquor in both the Chengalpattu and Villupuram incidents arose from the same source, and that arrack sellers had purchased industrial­grade methanol from factories and sold it to the victims. (Arrack is distilled from the fermented sap of the palm tree.)
  • In many older cases, such liquor is typically a home­made liquor, such as arrack, to which methanol was 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 liters in country liquor, and 300 grams per 100 liters in pot­distilled spirits.

4. What is Methanol?

  • The methanol molecule (CH3OH) consists of one carbon atom bonded with three hydrogen atoms and one hydroxyl group.
  • Schedule I of the Manufacture, Storage, and Import of  Hazardous Chemical Rules 1989 includes methanol.
  • The Indian standard IS 517 applies to how the quality of methanol is to be ascertained, and together with the Tamil Nadu Denatured Spirit, Methyl Alcohol, and Varnish (French polish) Rules 1959, what signage, and methanol packaging should carry.
  • The most common way to produce methanol is to combine carbon monoxide and hydrogen in the presence of copper and zinc oxides as catalysts of 50100 atm of pressure and 250°C.
  • In the preindustrial era, going back to ancient Egypt, people also made methanol (together with several other byproducts) by heating wood to a very high temperature.
  • Methanol has several industrial applications, including as a precursor to acetic acid, formaldehyde, and aromatic hydrocarbons.
  • It is also used as a solvent and as an antifreeze. In Tamil Nadu, the manufacture, export, import, storage, and sale of methanol require licenses under the 1959 Rules.

5. How does Spurious Liquor Kill?

  • The deadline for spurious liquor arises from methanol. In every hooch tragedy in the history of India and of the world since 1945 the poison has been methanol.
  • The human body contains infinitesimal quantities of methanol (4.5 ppm in the breath of healthy individuals, as per a 2006 study) 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 metabolized in the liver by ADH enzymes to form formaldehyde (HCHO).
  • 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, a condition wherein the blood's pH drops below its normal value of 7.35, becoming increasingly acidic.
  • The blood's pH is normally maintained by a balance between an acid-like carbon dioxide, and a base, like the bicarbonate ion (HCO3-).
  • As methanol is metabolized, the concentration of the bicarbonate ion drops, leading to acid gaining the upper hand.
  • Formic acid also interferes with an enzyme called cytochrome oxidase, which in turn disrupts cells' ability to use oxygen and leads to the buildup of lactic acid, contributing to acidosis.

6. Treatment

  • Once methanol is ingested, the body takes some time to eliminate it. One estimate suggests that as much as 33% is still left behind after 48 hours.
  • It is completely absorbed via the gastrointestinal tract and the blood methanol level can reach its maximum value within 90 minutes.
  • There are two 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. As a result, the methanol is kept from being metabolized to formaldehyde.
  • The other 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.
  • Both courses of action are limited by the availability of their characteristic compounds. Fomepizole is expensive whereas Pharmaceuticalgrade ethanol needs to be administered under supervision.
  • Healthcare workers may also have the individual undertake a dialysis to remove methanol and formic acid salts from the blood and litigate damage to the kidneys and retina.
  • They may also administer folinic acid, which encourages the formic acid to break up into carbon dioxide and water. Both fomepizole and folinic acid are in the WHO’s list of essential medicines. 
For Prelims: World Health Organization, Methanol (C2H5OH), Alcohol dehydrogenase (ADH) enzymes, Acetaldehyde, Arrack, Methanol molecule (CH3OH), Formaldehyde (HCHO), Formic acid (HCOOH), Bicarbonate ion (HCO3-).
For Mains: 1. What are the effects of methanol poisoning and discuss the industrial applications of methanol?
Source: The Hindu

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