Introduction to Ethanol - Forensic Experiments - Lecture Slides, Slides of Forensics

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Ethanol

(Alcohol)

Alcohol and forensic medicine

 Alcohol assumes an importance in clinical forensic medicine because of its link with criminal activity.

 Traffic accidents , suicide , and rape are correlated with the concurrent use of alcohol.

 Child physical and sexual abuse , spouse abuse, and elder abuse are also associated with alcohol use.

Ethanol

 Ethanol, also known as ethyl alcohol, drinking alcohol or grain alcohol.  It is produced by the enzymatic action of yeast on carbohydrate in the absence of oxygen (fermentation).  It is a flammable, toxic chemical compound with a distinctive odor which has been used by human since prehistoric times.  Its molecular formula is C2H5OH.  It is found in alcoholic beverages.

Alcohol concentration

of some drinks

 Beer, lager ,stout 2.5-4%

 Cider (variable) 3-5%

 Table wines (unfortified) 9-12%

 Fortified wines ( sherry, port, vermouth ) 18-20%

 Spirits ( brandy, gin, whisky, rum, vodka ) 37-42%

 Liqueurs (variable) 15-55%

Spectrum of alcohol use/abuse:

**1. Non-drinkers

2. Social drinkers** Drink socially, < 4 units per day 3. Heavy drinkers Regularly and heavily Men >7 units per day Women>5 units per day 4. Binge drinkers Irregularly and heavily

5. Alcohol abuser

Physical , psychological and social problems Dependence criteria are not met

6. Dependent( addicted) drinker

Subjective awareness of compulsion to drink Drink seeking behavior Tolerant to alcohol Physical , psychological and social problems

Absorption of Alcohol

 Absorption is by passive diffusion.

 Can happen in any part of the gastrointestinal tract.

 Mostly in stomach (20%) and upper small intestine (80%).

 Peak concentration is reached 30- minutes after ingestion.

 the duodenum and jejunum – has the maximum capacity for absorption, compared with the gastric mucosa.

 Accordingly, any condition that delivers alcohol into the small intestine more quickly than normal will lead to more rapid absorption.

Factors decreasing absorption

 Food in the stomach (especially fatty food which delay the emptying of the stomach and dilutes alcohol concentration).

 High concentration of alcohol (higher concentration than 20% will irritate the stomach and increase mucous secretion).

Distribution

 Distributed through portal blood stream to all tissues

 Equilibrium between the blood and tissues is reached 1-2 hours after ingestion

Measurement of absorbed alcohol :  In blood: it is the most useful measurement, but depends on several factors like gender, drinking history, amount and nature of the meal and the timing, so it’s not very accurate.

 In urine: it is more concentrated than blood. Ratio 4:

 In breath: small concentration 1:2300 to that of blood. At 37 C 1mg/100ml in blood = 0.43 μg/100ml in breath. Blood/breath ratio depends on the temperature, concentration of alcohol and depth of respiration.

Elimination

 Almost all alcohol is detoxified by the liver, only 2-10% being excreted unchanged by kidneys, lungs, sweat, salivary and mammary glands.

 Alcohol( by alcohol dehydrogenase) acetaldehyde

 Acetaldehyde (by acetaldehyde dehydrogenase) acetic acid

 acetic acid( by Krebs cycle)CO2 and water.

Effects of ethanol on different

body organs