Alcohol is inebriant poison. The active ingredient of all liquors is alcohol and it chemically known as ethyl alcohol or ethanol. The alcoholic content classifies the liquors into beers, wines and spirits. The first two are undistilled products while spirits are distilled products.
There are three categories of Alcohols:
1. Monohydroxy Alcohols – This type of alcohols have only one hydroxyl (OH) group. For example- ethanol, methanol, isopropanol etc.
2. Dihydroxy Alcohols – This type of alcohols have two hydroxyl (OH) groups and are referred as glycols. For example – Ethylene glycol, Propylene glycol etc.
3. Trihydroxy Alcohols – They are not really alcohols, but are only derivatives. For example – Propane derivative glycerol or glycerine.
- Alcohol in pure form is colorless and transparent liquid .
- It has pleasant odour and a burning taste.
- It is mixable with water in all proportions.
- It is an “amphophyle”.
- The aliphatic alcohol forms a homologous series starting with methanol, ethanol, n-propanol, isopropanol etc. The first three are readily soluble in water in all proportions but as the carbon chain length increases, it is almost insoluble in water.
- All alcohols have general formula R-OH.
- The specific gravity of ethanol is 0.79.
- It boils at 78.4 degree Celsius.
- It causes irritation when it comes in contact with tender body tissue.
Alcohol is obtained by the fermentation of sugars, molasses, grains, fruit juices and starches. It is a complex enzymatic process. The enzymes are obtained from yeast. It is carried out under controlled conditions. The final fermented mass contains about 10% alcohol. It is concentrated and purified by distillation.
Types of alcohol
1. Absolute alcohol – This type of alcohol contains 99% w/w ethanol (dehydrated alcohol).
2. Rectified spirit – This type of alcohol contains 90% w/w ethanol (distilled).
3. Proof spirit – It refers to a standard mixture of alcohol and water of relative density. The ethanol content of various alcoholic beverages is expressed by volume percent or by proof. Nowadays, alcohol is referred by percentage alcohol by volume (% v/v). This is equivalent to the number of milliliter of pure alcohol per 100 ml of the drink.
Uses of Alcohol
- Medicinal and therapeutic
- Antidote in methanol poisoning
It depends on age, sex and health of the individual. About 150–250 ml of absolute alcohol may be an average fatal dose for an adult. The consumption of full bottle (750 ml) of whisky can cause death.
It may appear within 10-24 hours. But in some cases, death may take place even after a number of days.
When the alcoholic drink is taken, it immediately starts getting absorbed in the body through the stomach membrane and small intestine. About 20% is absorbed almost immediately while the rest is absorbed in about half an hour to two hours. Body tissues of the certain persons absorb alcohol more easily than others. Alcohol on absorption enters the blood stream and is distributed uniformly in the all the body fluids. Bones, hair, nails and fats of the body do not absorb it. The equilibrium is reached in about half an hour to 2 hours depending upon the factors like food, tolerance, concentration etc. However, if the drinking is continued, the equilibrium is not reached. Alcohol concentration during the drinking period will be higher in the arteries than in veins. Thus, if alcohol absorption is rapid and portal vein concentration is high, most of the alcohol escapes into the systemic circulation whereas with slow absorption, more alcohol is removed by first pass metabolism. This is one reason why drinking alcohol on an empty stomach produces a much greater effect. Vaporized ethanol may be rapidly absorbed by inhalation.
There are various factors that affect absorption of alcohol are as follows-
Food – Presence of food in the stomach prolongs the absorption of alcohol. Presence of starch, proteins and fatty food retards the absorption. It is stated that with presence of food in stomach, as much as 17 to 20 percent of alcohol ingested escapes absorption and never appears in the blood.
Concentration – Diluted alcohol or alcohol with high concentration are absorbed slowly whereas alcohol in the concentration of 10 to 20 percent are absorbed rapidly.
Habit and tolerance – In habituated person alcohol is absorbed rapidly.
Drug – Some drugs may interfere with absorption.
Gastrectomy – Gastrectomy may cause rapid absorption of alcohol.
Metabolism and Elimination
Alcohol in the systemic circulation is metabolized through three pathways that are as follow:
● Alcohol dehydrogenase (ADH) pathway – In the cell cytosol.
● Microsomal Ethanol Oxidizing System (MEOS) – It is located on the endoplasmic reticulum.
● Peroxidase- Catalase system – In hepatic peroxisomes.
Immediately after absorption the system starts elimination of alcohol. About 90% of it is metabolized by the system mainly by liver. The enzyme dehydrogenase converts alcohol first to acetaldehyde and finally to water and carbon dioxide. The rate of metabolism is slightly less than 0.02% of the blood alcohol concentration per hour. The rest of the alcohol about 10% is eliminated by the lungs, sweat pores and through urine as such. This alcohol is utilized for test purposes by taking appropriate sample of the body fluid.
The rate of elimination varies with individuals. The commonly accepted rate of elimination is about 10 ml of absolute alcohol per hour.
Mechanism of action
- Alcohol affects the central Nervous system in all amounts that decreases activity of neurons with behavioral stimulation at low blood level.
- Alcohol produces simultaneous changes in many neurotransmitters and increases the fluidity of neuronal cell membranes.
- Alcohol in small doses interferes with cortical function like conduct, judgment, self-criticism and release of inhibitory tone but in larger doses depresses the medullary processes.
Stages of Alcohol Intoxication
- Stage of Sobriety.
- Stage of Euphoria.
- Stage of Excitement.
- Stage of Stupor.
- Stage of Confusion.
- Stage of Coma.
Sign and Symptoms
- Sense of well-being, self-confidence and exhilaration.
- The person becomes talkative.
- The face becomes flushed.
- Gradual loss of self-control.
- Stage of confusion, perception
- The vision becomes blurred.
- Voice becomes slurred.
- Severe sleep, severe headache and gradually passes into a stage of unconsciousness.
- Dilation of pupils.
- Respiratory failure
- Loss of appetite
- Nausea, vomiting, especially in the morning, and diarrhea
- Tremors of tongue and hands.
- Loss of memory, insomnia, impaired power of judgment, confusion and abnormal mental behaviour.
- Respiratory Paralysis.
- In- coordination of muscles.
- Stertorous breathing.
Forensic Examination or Test for Detection
● General Appearance – state of clothing (whether soiled by vomitus or feces), behaviour, disposition.
● Record vital data such as temperature, pulse, respiratory rate and blood pressure.
● Speech – Whether it’s normal, thick, slurred or over-precise.
● Breath – Whether smell of alcohol present or absent.
● Gait – Observe whether the gait is normal or staggering.
● Writing – The person should be asked to write few lines in a language familiar to him. Note the time taken to write, repetition or omission of words, ability to read his/her own handwriting.
● Eyes – Note the state of conjunctiva, pupillary size and reflex, visual acuity and presence or absence of nystagmus.
Determination of Alcohol in Body Fluid
- Normal Titration
- Gas Chromatography
- Breath Analyzer Test
- Cavett’s modified method
- Kozelka and Hine’s Method
- Bedside Test
► In early stage, if a patient is brought then gastric lavage is administered. It should be done with sodium bicarbonate. If the patient comes late, gastric lavage is not administered as it removes only a small amount of alcohol from the alimentary canal. If the victim is unconscious, gastric lavage should be done only after protecting the airway by endotracheal tube.
► CT scan of head should be done.
► Intravenous fluids should not be given in large doses.
► Hemodialysis may be done in severe cases.
► Vitamin B should be given to all patients where glucose is administered.
► Maintain adequate blood pressure and circulation.
► Administer thiamine 100 mg intravenously followed by glucose 25 to 50 gm intravenously to protect against development of Wernicke-Korsakoff syndrome.
► Manage hypothermia in usual way
► Access status of acidosis. A worsening acidosis after thiamine, glucose and fluid therapy should raise the possibility of ethylene glycol or other ingestion.
- The findings are suggestive of asphyxial death.
- The rigor mortis may be delayed.
- Decomposition may be retarded in some cases.
- The alcoholic smell can be appreciated well when body cavities are opened. The mucosa of stomach and intestine may be found to be congested.
- The liver, lungs and brain are congested.
- The blood is dark and fluid.
- The viscera should be preserved in saturated solution of common salt.
- Dr. K.S. Narayan Reddy. The essential of forensic medicine and toxicology.34th edition.
- VV Pillay.Modern medical toxicology.4th edition.
- Richard Saferstein. Criminalistics-An introduction to forensic science. 11th Edition.