The effect of time factors on blood alcohol levels in accident victims.

Variations of alcohol involvement (AI) by time as well as the effect of the time interval between the last alcohol intake and accident occurrence, arrival, and specimen collection on blood alcohol concentrations (BAC) were studied in 1012 accident victims. In was found that 53% of accidents on Saturdays were alcohol-related, the corresponding percentage being 39% on Fridays and Sundays and 31% on other days. AI rose from its lowest figure (16%) in the morning to its highest (67%) in the following small and early hours. Most of the alcohol-involved accidents occurred with rising blood alcohol suggesting that this stage of intoxication might have a higher injury risk than the later stage with decreasing blood alcohol. The delay before arrival and specimen collection often led to a drop in BAC values which should be remembered when planning studies on AI in accidents and when interpreting the results of such investigations.