Objective: Previous studies have already shown the possibility of impairment during a hangover phase, after alcohol ingestion, when the blood alcohol concentration has returned to zero. The prevalence of drivers being in a hangover phase, in the driving population, and the relation to impairment relevant for traffic safety has, however, not been previously studied. The aim of this study was to investigate the prevalence and the concentrations of the 2 ethanol metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS), in blood, indicating very recent alcohol intake, among apprehended drivers, in which no psychoactive substances, including alcohol, were detected. The aim was also to study these findings in relation to the impairment observed in these drivers.
Methods: Blood samples, drawn from suspected drunk or drugged drivers, were analyzed for a broad repertoire of psychoactive substances, with a clinical test for impairment (CTI) being performed at the same time. One hundred and forty-six cases, in which no psychoactive substances were detected and where a valid CTI was performed, were analyzed for EtG and EtS in blood. The prevalence and concentrations were related to the conclusions of the CTIs.
Results: EtS and EtG were detected in a total of 19 of the 146 cases (13%). Among the "impaired" drivers, EtG and EtS were detected in 16 cases (18%), whereas among "not impaired" drivers they were detected in 3 cases (5%). There were significantly more detections of EtS (and EtG) among the impaired group of drivers compared to the nonimpaired drivers (P =.030), and the concentrations of both EtG (P =.027) and EtS (P =.026) were significantly higher in the group of impaired drivers compared to the nonimpaired drivers. There was a statistically significant positive correlation between the concentrations of EtG (Spearman's rho = 0.170, P =.041) and EtS (Spearman's rho = 0.189, P =.022) and the degree of impairment.
Conclusions: EtG and EtS were prevalent findings in blood collected from the apprehended drivers, testing negative for all psychoactive substances. The higher rates of detections of EtG and EtS in impaired compared to nonimpaired drivers, and also the positive correlation between concentrations of EtG and EtS and the degree of impairment, indicate that hangover symptoms may be relevant for traffic safety.
Keywords: DUI; alcohol; blood alcohol; impairment.