Amount of alcohol contained in venous blood (BAC), expressed in milligrams per gram or in per mille (1 per mille = 1 g alcohol in 1 kg blood or 1 mg/g). The measurement is taken in serum (blood without blood cells and coagulation factors) and is converted to blood content. The enzyme ADH (alcohol dehydrogenase) is used to determine the blood alcohol. This makes it possible to determine any impairment of concentration and sanity caused by alcohol. The taking of a blood sample can be enforced by a court (not enforceable in Austria - however, legally the same consequence follows as if one had been heavily intoxicated). To determine the BAC on corpses, blood may only be taken from the inguinal vein. Alternatively, eye chamber fluid may be used.
The Swedish chemist Erik Widmark (1889-1945) developed the "Widmark formula" named after him in 1922 for determining BAC. In addition to Widmark's formula, there are other calculation methods named after the "inventors" (Seidel, Ullrich, Watson) that take body length and age into account in addition to body weight and gender. The Widmark formula is used as the basis for electronic BAC determination devices. With the help of this formula, the blood alcohol content can be calculated with an accuracy of plus/minus 0.1 per mille: c = A / (r * G)
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Fachjournalistin, Lektorin und Verkosterin, Wien