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# Blood Alcohol Concentration

blood alcohol concentration (GB)

Name (BAK) for the amount of alcohol in the venous blood, which is given in milligrams per gram or in parts per thousand (1 per thousand = 1 g alcohol in 1 kg blood or 1 mg / g). The measurement is carried out in serum (blood without blood cells and coagulation factors) and is converted to blood content. The enzyme is used to determine blood alcohol ADH (Alcohol dehydrogenase) is used. The Swedish chemist Univ. Prof. Erik Widmark (1889-1945) developed in 1922 the "Widmark's formula" named after him for determining the BAK. In addition to the Widmark formula, there are also other calculation methods (Seidel, Ullrich, Watson) named after the “inventors”, which take into account not only body weight and gender, but also body length and age. The Widmark formula is used as the basis for electronic BAK determination devices.

With the help of the Widmark formula, the blood alcohol content can be calculated with an accuracy of plus / minus 0.1 per mille: c = A / (r * G)

• c: blood alcohol content in parts per thousand
• A: Alcohol ingested in grams
• r: Distribution factor in the body (water in the body) = 0.7 for men and 0.6 for women
• G: body weight in kilograms

There alcohol is only water-soluble, it is not distributed in the bones and in the adipose tissue, so this proportion of body mass is not available. The factor is lower for women because they have a higher percentage of body fat on average. Men should also assume a correspondingly lower weight G if they are overweight, since body fat is neither conducive to distribution nor alcohol breakdown.

Amount of alcohol consumed in grams = V * e * p
To calculate the mass of alcohol (A) in a liquid (beer, wine, schnapps), the volume (V) of the drink measured in deciliters with the alcohol content in volume percent (e) and the density (specific weight) of alcohol (p = 0.8 kg / l or 0.08 g / cl) are multiplied. For a liter of wine (100 cl) with 12% vol alcohol, the 12 cl alcohol present in this case corresponds to a weight of 96 g. With three glasses cognac with 4 cl each you get 12 cl cognac (a little less than “a figure of eight”), this is 4.8 cl alcohol with a weight of 38.4 g at 40% vol alcohol. To calculate the blood alcohol concentration, the amount of the drink in cl must be multiplied by the alcohol content in vol% and then multiplied by 0.08. Two calculation examples:

A man with 85 kilograms and a woman with 70 kg each enjoy three eighths of wine (0.375 l = 37.5 cl) with 12% vol alcohol: 37.5 * 12 * 0.08 = 36 g alcohol

reduced body weight = body weight in kg * distribution factor:
Man with 85 kg: 0.7 * 85 = 59.5 kg
Woman with 70 kg: 0.6 * 70 = 42.0 kg

Alcohol level = alcohol / reduced body weight
Man 36 g / 59.5 kg = 0.60 ‰ - best assumption 0.38 ‰
Woman 36 g / 42.0 kg = 0.86 ‰ - best assumption 0.59 ‰

A possible alcohol breakdown is not taken into account in the first value. Neither is the fact that 10% and 30% (an average of 20%) can be deducted from the amount because the alcohol is not fully absorbed by the body. Assuming this 20% and a reduction of 0.1 ‰ each, the "best assumption" results.

The alcohol consumed passes from the stomach (20%) and small intestine (80%) first into the bloodstream and then into the body tissue (absorption). The distribution depends on the amount of blood (approx. 5 to 7l) and the body size or body area, the more extensive, the better the alcohol is distributed. However, as already mentioned, adipose tissue cannot absorb alcohol. Therefore, alcohol is distributed more in a tall, lean person and there is relatively less alcohol concentration in the blood compared to a small, fat person. The intake is relatively slow and, depending on the contents of the stomach, is only completed one to two hours after the end of drinking. This amount is also referred to as residual alcohol.

The liver is the only organ that can break down alcohol by up to 90%, the rest is excreted through the kidneys with urine or sweat. The organ begins the alcohol breakdown at the earliest 15 minutes "after the first sip" and continues this linearly regardless of further consumption. The more someone is used to alcohol, the higher the elimination rate. The human body breaks down 0.1 to 0.2 ‰ per hour. A thumb formula: Half a liter of beer (5% vol) or an eighth of wine (12% vol), each with ~ 12 mg alcohol, is broken down in one to two hours. A faster breakdown of the residual alcohol is not possible through coffee consumption, increased exercise or sleep. See further information at health,