Investigations on the BAC/BrAC quotient during the absorption phase and its significance for the waiting time until the start of breath alcohol measurements

In order to exclude influences of residual mouth alcohol an interval of 20 minutes is mandatory in Germany between the end of alcohol consumption and breath alcohol analysis. This prescription disregards the fact that increased breath alcohol levels can occur during absorption phase. Drinking tests with 108 individuals consuming between 0.47 and 0.63 g ethanol per kg body weight resulted in BAC/BrAC quotients between 1.074 and 2.227 (mean 1.707) taking samples 20 minutes after the end of drinking. 25% of the participants had breath alcohol concentrations above the limit of 0.25 mg/l, while blood alcohol level didn't exceed 0.05%. In the case of law infringements it is not necessary to prove that there were any signs of insecure car driving resulting from alcohol consumption. Thus we have no proof that increased breath alcohol levels represent the degree of alcoholisation in a better way than blood alcohol does. To avoid unjustified problems with breath alcohol measurements during a possible or real absorption phase the interval between control of car drivers and breath analysis should be readjusted to 60 minutes. Alternatively, a reduction of breath alcohol values must be taken into consideration depending on drinking behaviour.