The role played by alcohol in traffic deaths is vastly under-reported

It's no secret that drinking and driving can be a deadly mix. But the role of alcohol in U.S. traffic deaths may be substantially underreported on death certificates, according to a study in the March issue of the Journal of Studies on Alcohol and Drugs.Between 1999 and 2009, more than 450,000 Americans were killed in a traffic crashes. But in cases where alcohol was involved, death certificates frequently failed to list alcohol as a cause of death.Why does that matter?