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Alcohol in forensic medicine — absorption, elimination and the law

Alcohol is absorbed mainly in the small intestine and usually peaks in blood 30–90 minutes after drinking, is eliminated at a roughly constant rate (zero-order kinetics), so an estimated concentration at an earlier time can be back-calculated — cautiously and as a range — and in a body drinking must be distinguished from postmortem alcohol production.

לקריאה בעברית

Why it matters in the exam

Questions on absorption ask where it occurs and what affects it: a small part is absorbed in the stomach and most in the small intestine; food in the stomach delays emptying and so lowers and delays the peak, while carbonated drinks and drinking on an empty stomach speed it. Elimination takes place in the liver mainly through alcohol dehydrogenase, at an average rate of about 0.15 grams per litre per hour, with a range of 0.10 to 0.25; in chronic drinkers the rate is higher. The Widmark formula relates the amount of alcohol, body weight and a distribution factor to the blood concentration.

In Israel, the limit for an ordinary driver is 50 milligrams of alcohol per 100 millilitres of blood or 240 micrograms per litre of exhaled air; for a young, new or professional driver the limit is much lower — 10 milligrams per 100 millilitres of blood or 50 micrograms per litre of air. Alcohol causes skin vasodilation, tachycardia and arrhythmias, mainly atrial fibrillation after heavy drinking; chronic use causes dilated cardiomyopathy, liver disease and a lower seizure threshold.

In a body, decomposition and bacteria can produce alcohol after death, especially when there is glucose in the blood and in decomposed or burned bodies. Femoral blood, vitreous humour and urine are therefore compared: alcohol in vitreous and urine in a ratio that fits the blood supports drinking in life, and alcohol in blood alone in a decomposed body raises suspicion of postmortem production. Urine concentration is higher than blood in the elimination phase and lower in the absorption phase. In severe intoxication death is caused by respiratory depression, aspiration of vomit and hypothermia, and sometimes by injury in a fall.

Key points

• Absorption mainly in the small intestine; peak after 30–90 minutes.
• Elimination at a constant rate of about 0.15 grams per litre per hour.
• Israel: 50 mg per 100 mL blood for an ordinary driver; 10 for young, new or professional.
• In a body: compare blood, vitreous and urine.
• Death in intoxication: respiratory depression, aspiration, hypothermia.

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Sources

• Jones AW. Alcohol, its absorption, distribution, metabolism and excretion in the body and pharmacokinetic calculations, WIREs Forensic Science, 2019 — Absorption, elimination rate and Widmark calculations
• פקודת התעבורה ותקנות התעבורה (שיכרות), נוסח עדכני — Blood and breath alcohol limits for drivers
• Knight's Forensic Pathology, 4th edition (2016) — Alcohol and its effects

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.