Status of alcohol absorption in drinking drivers killed in traffic accidents

One issue which constantly confronts the forensic toxicologist in drinking driver cases is the relationship between the breath or blood alcohol concentration (AC) of the driver at the time of an event such as a traffic stop or an accident and the AC measured at a time subsequent to the event. In theory, the AC can be rising, on a plateau or declining at the time of the event. Several studies have indicated that the overwhelming majority of drinking drivers are on a plateau or are post-absorptive at the time of the event. In this study, driver fatality cases investigated by the Office of the Chief Medical Examiner, State of Maryland during a three-year period were reviewed. Included in this study were cases positive for alcohol in the blood at a cutoff of 0.01 g/dL and death occurring within 15 min of the accident. In fact, many of these deaths were instantaneous or near instantaneous based on the injuries documented by the medical examiner at autopsy. The blood and urine were analyzed for alcohol by head-space gas chromatography and urine AC to blood AC ratios were calculated. A total of 129 cases were included in this study. Eleven of the 129 cases (8.5%) had urine to blood AC ratio less than 1.0. It is likely that these individuals were in the absorptive phase at the time that the accident occurred. Thirty-two cases had a urine to blood AC ratio between 1.0 and 1.2 inclusive. In these cases, the subject could be viewed as in the plateau phase of the blood AC versus time curve. The remaining 86 cases had a urine to blood AC ratio greater than 1.2. This suggests that these individuals were in the post-absorptive state at the time of the accident. The information acquired from this study provides additional evidence to support the notion that the vast majority of individuals are not in the absorptive phase at the time of a traffic stop or an accident.