Comparing the BACs of drivers in fatal crashes with a random sample of similar drivers on the road who have not been involved in a crash is a standard method for estimating the extent to which driving after drinking raises of risk of being in a crash relative to sober drivers. In 1996, the third national roadside survey provided a random sample of drivers using US roads which was compared with drivers in fatal crashes using the fatality analysis reporting system (FARS) maintained by the National Highway Traffic Safety Administration (NHTSA). That study showed that at a given BAC the relative risk of being in a crash was the same for adult men and women. However fewer women than men reach the high BAC levels(.08 and greater) which are typical of drinking drivers in fatal crashes so fewer women are involved in alcohol related crashes. In contrast to adults, the 1996 study found that men under age 21 were at greater risk at a given BAC than young women under 21, Suggesting that young women were more careful drivers an drove les at high risk time such as late at night.
The national roadside survey conducted 10 years later in 2007 provided another opportunity to compute the relative risk of crash involvement based on BAC. As in 1996, adult men and women were found to exhibit the same level of relative risk at any given BAC. However in contrast in 1996, there was no difference between young men and young women in the relative risk of being involved in an alcohol-related crash, given that they had the same BAC. We found that the relative risk for young women had increased over the decade since 1996 apparently reflecting an increase in risk taking and risk exposure through more nighttime driving and perhaps more drinking and more high-risk driving. While the relative risk for young female drinking drivers increased, the risk of crash involvement for non-drinking young men under 21 increased. The data from the surveys do not indicate why these changes occurred. but perhaps the increase in crash involvement of sober young drivers is related to the increasing use of cell phones while driving.
Another opportunity to study potential changes in the relative risk of crashing will occur in 2013 within the next national roadside survey will be conducted. The 2007 survey has provided a number of clues to the changing impaired driving scene in the US. We will use this experience to add questions to the 2013 survey to help clarify why we are seeing changes in the relative risk of crashing of drivers under 21. For a full copy of the article go to web site of the Journal of Studies on Alcohol and Drugs