A UC San Diego study shows that blood-alcohol content (BAC) well below the U.S. legal limit of .08 percent is associated with incapacitating injury and death in car wrecks. In general, accident severity is significantly higher on weekends, between 8 p.m. and 4 a.m. and in the summer months, June through August. But researchers found that the relationship between BAC and more dangerous car accidents persists for any given time on any day of the year. The study, led by sociologist David Phillips, appears in the June 20, 2011 online issue of Addiction.
Phillips and coauthor Kimberly Brewer examined data from the Fatality Analysis Reporting System (FARS), which includes information on all persons in the U.S. who were involved in fatal car accidents – 1,495,667 people in the years 1994 to 2008. The data covers all U.S. counties, all days of the week and all times of day. It also includes reports on blood-alcohol content in increments of 0.01.
The authors looked at different levels of accident severity by examining the ratio of severe injuries to minor ones. Phillips said:
Accidents are 36.6 percent more severe even when alcohol was barely detectable in a driver’s blood.
According to the authors, even with a BAC of .01, there are 4.33 serious injuries for every non-serious injury versus 3.17 for sober drivers.
There are at least three mechanisms that help to explain this finding. Phillips said:
Compared with sober drivers, buzzed drivers are more likely to speed, more likely to be improperly seat-belted and more likely to drive the striking vehicle, all of which are associated with greater severity.
There also seems to be a strong “dose-response” relationship between all these factors, the authors write. The greater the blood-alcohol content, the greater the average speed of the driver and the greater the severity of the accident, for example, which is why there are drunk-driving laws.
BAC limits vary greatly by country. In Germany, the limit is .05; in Japan, .03; and in Sweden, .02. Phillips said:
Up till now, BAC limits have been determined not only by rational considerations and by empirical findings but also by political and cultural factors.
We hope that our study might influence not only U.S. legislators, but also foreign legislators, in providing empirical evidence for lowering the legal BAC even more. Doing so is very likely to reduce incapacitating injuries and to save lives.
Bottom line: Researchers David Phillips and Kimberly Brewer examined data from the Fatality Analysis Reporting System (FARS) and determined that an alcohol buzz – any blood alcohol content below the legal limit of 0.08 – is linked to the level of severity in car accidents. Results of their study appear in the June 20, 2011 online issue of Addiction.
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